Given that Congress has provided EPA with specific toxicity criteria, and that listed chemicals are statutorily defined as `` toxic chemicals, '' the Agency does not believe that additional `` toxicity'' criteria would be appropriate. One reason is that the Agency is concerned that this would imply that TRI data on the toxic chemicals that meet the statutory toxicity criteria are of less value than TRI data that meet both the statutory toxicity criteria and some additional toxicity criteria that would be developed by EPA. EPA believes that bifurcating the list with an additional, non statutory toxicity criteria would be inconsistent with the intent of Congress. In addition, it is worth noting that some of the toxicity criteria presented by the commenters are fundamentally consistent with the toxicity criteria outlined in the statute. However, EPA notes that some of the criteria provided by the commenters are risk criteria rather than hazard criteria. For example, see ICCA Briefing Note on POPs (April 21, 1998) (Ref. 26). As discussed at length in the final rule adding 286 chemicals to the EPCRA section 313 list (59 FR 61432), the EPCRA section 313( d)( 2)( B) toxicity criteria (chronic toxicity) are hazard criteria, not risk criteria. The EPCRA section 313( d)( 2)( C) criteria are primarily hazard based with only a limited exposure component. To impose additional toxicity criteria for purposes of defining a PBT or a PT or BT chemical based on risk rather than hazard would be inconsistent with EPCRA section 313. See, e. g., Legislative History at 5186. Risk assessment may be appropriate for use under statutes that control the manufacture, use and/ or release of a chemical. However, EPCRA section 313 is an information collection provision that is fundamentally different from other environmental statutes that control or restrict chemical activities. For these reasons, EPA believes that it is inappropriate to add toxicity criteria, beyond the criteria provided by Congress at EPCRA section 313( d)( 2). 3. Persistence and bioaccumulation consideration under EPCRA section 313( d)( 2)( C)( ii) and (iii). The criteria that EPA has laid out in this rule for determining if a chemical is a persistent and/ or bioaccumulative chemical are not the same criteria EPA uses when conducting assessments for listing chemicals pursuant to EPCRA section 313( d)( 2)( C)( ii) and (iii). These sections of EPCRA allow EPA to consider whether a chemical meets the listing criteria based on `` its toxicity and persistence in the environment'' or `` its toxicity and tendency to bioaccumulate in the environment. '' Including consideration of persistence and/ or bioaccumulation modifies the way in which EPA assesses a chemical's toxicity for purposes of listing. EPA interprets the results of the toxicity data in light of a chemical's persistence and/ or bioaccumulation, and adjusts its concerns for the chemical's toxicity in accordance with the degree to which a chemical persists or bioaccumulates. For example, standard aquatic toxicity tests provide toxicity results in time frames that range from hours to a few weeks. For aquatic toxicity that results 58684 Federal Register / Vol. 64, No. 209 / Friday, October 29, 1999 / Rules and Regulations from such short exposure times, a chemical with a persistence half life of even 2 weeks will result in a greater potential for exposure and therefore increased concern for the concentration at which toxicity is expressed. In this case, EPA would be concerned about the chemical's persistence at levels well below a half life of 2 months or more. Because EPA's concern under these provisions is with the interrelationship between two chemical properties and how that affects whether the chemical can reasonably be anticipated to cause a significant adverse effect on the environment, EPA believes that it needs to be able to consider a broader range of values. By contrast, the persistence and bioaccumulation criteria established in today's rulemaking serve a different purpose; they are intended to operate independent of a chemical's toxicity, to identify a fixed class of chemicals. EPA has provided this explanation to clarify the different purposes of the persistence and bioaccumulation criteria established in this rule, and the use of persistence and bioaccumulation in assessments pursuant to EPCRA section 313( d)( 2)( C)( ii) and (iii).

C. Criteria as they Apply to Metals Many commenters contend that the persistence criteria proposed by EPA were developed for organic chemicals and cannot be applied to metals, or if applied, are not useful in screening for hazard. The critical parameter in determining risk is bioavailability, not persistence. This has been recognized by international organizations of which EPA is a member, so it is unclear why it is now necessary for EPA to deviate from these policies. Metals are not harmful if they are not in a bioavailable form. Moreover, metals are natural components of the earth's crust and many are accumulated by living organisms because they are essential nutrients. Two of the commenters state that because persistence is defined as `` the failure of a substance to readily biodegrade, '' this concept has no relevance for metals. EPA disagrees. The scientific literature contains many definitions of persistence which vary in detail, but center on a common theme: persistence is the ability of a chemical substance to remain in a particular environment in an unchanged form. This definition makes no mention whatsoever of any specific processes that may impact a substance's environmental fate, such as biodegradation. According to this definition, specific metal compounds may or may not be persistent depending on the form of the metal and environmental conditions, but the elemental metal itself obviously meets the definition, and this was acknowledged in the majority of comments received. That elemental metals are persistent by definition is widely accepted. While they may take different oxidation states that can be interconverted, the elemental metal itself cannot be destroyed. For example, chromium (VI) may convert to chromium (III). Both are simply different forms of chromium. All elemental metals therefore meet the 2 months half life criterion automatically. Given this, it is obviously false to assert, as did the majority of commenters on this issue, that EPA's proposed persistence criteria cannot be applied to metals. The position of many commenters was that in determining whether a metal or metal compound may actually pose a risk if released to the environment, bioavailability is much more important than the fact that a substance meets the formal `` definition'' of persistence. EPA agrees that bioavailability is important in determining the potential for the metal to be accumulated in organisms, but parent metals do have the potential to become available from metal compounds under common environmental conditions. Availability of the metal ion may be the result of biotic or abiotic processes. There are a number of environmental factors which EPA considers in determining the availability of the metal ion. These include hydrolysis, pH effects on solubility, photolysis, aerobic and anaerobic transformations, and in vivo transformations. As outlined in the remainder of this section, it is realistic to expect that, in general, metals when released into the environment can encounter conditions in which they are available at levels sufficient to exert toxicity and bioaccumulate. EPA also disagrees with the commenters' claims, direct or implied, that metals released to the environment as a result of human activity must be of negligible concern because they: · Cannot be converted to bioavailable forms; or even if initially bioavailable are rapidly sequestered in such a way that subsequent exposure is impossible; or · If bioavailable, are naturally wholesome and good because organisms need them to function. EPA disagrees with this simplistic view. Metals can enter the environment in bioavailable forms or can be converted in the environment into bioavailable forms. As shown below, metals and metal compounds may be available to bioaccumulate under many realistic and common environmental conditions. The commenters are correct in stating that metals released to the environment from anthropogenic sources are affected by prevailing environmental conditions, meaning broadly the wide variety of physical, chemical and biological processes that act upon them, and these collectively determine the form in which the metal ultimately exists. According to Klein (Ref. 28), interconversion of inorganic metal compounds can be quite rapid, especially for ionic forms, and as a result the chemical form in which an elemental metal is released may not be the predominant form post release. Generally, the ionic forms of inorganic metals are the most available. Availability is affected by many factors and its determination is complex. For metals environmental conditions can affect their availability. A detailed scientific discussion of the environmental fate of lead, which is representative of other metals, and that is illustrative of many of the more important environmental variables that affect availability is provided in Refs. 14, 28, 30, 50, 66a, 72, and 84. See also the preamble to EPA's recent proposal to lower the EPCRA section 313 reporting thresholds for lead and lead compounds (64 FR 42222). The same basic chemical properties and environmental variables will affect the degree of availability of a metal in the environment regardless of the specific metal. There is no metal that is unavailable under all conditions. EPA recognizes that lead and lead compounds are the subject of an EPA proposal under EPCRA section 313 (64 FR 42222). The inclusion of the discussion of the environmental fate of lead and lead compounds does not predetermine EPA's decision on the appropriate thresholds that should be set for lead and lead compounds. That determination will be based on a number of factors, including the bioaccumulation of lead. Microbial transformations in soil, water, and sediment are often important in determining the overall fate of metals and metal compounds, and therefore the potential for formation of bioavailable forms. Metals known to undergo microbial oxidation/ reduction processes include, antimony, arsenic, iron, mercury, selenium, and tellurium (Ref. 11). Arsenic microbiology illustrates the importance of environmental conditions in the interconversion of inorganic forms of arsenic. Microbial populations in activated sludge can oxidize arsenite to arsenate under aerobic conditions, but under anaerobic conditions such as often predominate in sediments, arsenate can be reduced to arsenite and 58685 Federal Register / Vol. 64, No. 209 / Friday, October 29, 1999 / Rules and Regulations beyond. Both arsenites and arsenates can be available in the environment (Ref. 11). Microorganisms can reduce mercury in the form of mercuric chloride to elemental mercury, and are also capable of producing elemental mercury from organomercurials such as phenylmercuric acetate and methylmercuric chloride. Although the reduction of Hg 2¶ to elemental mercury can be regarded as decreasing availability, the elemental mercury formed is volatile and more likely to enter the global atmospheric circulation. Mercury is perhaps better known for its potential to be biomethylated by bacteria in the environment (Ref. 11). Mercury has very high stability constants with organic ligands and can form true organometallic compounds (Ref. 6). As indicated by Stumm and Morgan (Ref. 49), metals and metalloids that form stable alkyl compounds are of special concern because they may be volatile; may accumulate in cells; and are toxic to the central nervous system of higher organisms. Methylmercury is highly bioaccumulative and is by far the best studied example of microbial bioalkylation. However, methylation of arsenic is also fairly well characterized, involves the replacement of substituent oxygen atoms by methyl groups (e. g., arsenate is biomethylated to form dimethylarsine), and is important in the transfer of arsenic from sediment to the atmosphere (Ref. 11). Lead, germanium, selenium, tellurium, tin, and several other metals can also be biomethylated (Ref. 49). Many of the commenters noted that certain metals are indeed micronutrients (e. g., cobalt, copper, and iron), and are accumulated precisely because they are required for certain cellular functions. It does not follow, however, that any amount of the same metal is acceptable or desirable. Accumulation of essential elements is usually governed by homeostatic mechanisms that control uptake (Ref. 28), but excessive uptake is possible and can be toxic to an organism. For example, selenium which is a micronutrient can cause selenosis at doses as low as 0.023 milligrams per kilogram per day (mg/ kg/ day). Clinical signs of selenosis include the characteristic `` garlic odor'' of excess selenium excretion in the breath and urine, thickened and brittle nails, hair and nail loss, lowered hemoglobin levels, mottled teeth, skin lesions, and central nervous system (CNS) abnormalities (peripheral anesthesia, acroparesthesia, and pain in the extremities) (Ref. 61). Similarly, copper, which is an essential nutrient, at high doses can cause vascular injury and hemolytic anemia. It should also be noted that copper exhibits high acute and chronic toxicity to aquatic organisms that results in the death of the organism (61 FR 54381, October 18, 1996) (FRL± 5396± 9), and inhalation of hexavalent chromium is known to cause cancer in humans (Ref. 60), even though chromium in very small oral doses is a micronutrient (Ref. 25). Moreover, the commenters freely cite Allen (Ref. 4), Chapman (Ref. 18) and other authors to the effect that metals are accumulated `` deliberately'' depending on the physiological needs of the organism, but it is clear that this applies only to metals that are essential nutrients. Metals are generally taken into cells by nutrient metal transport systems, and these are not sufficiently specific to completely exclude nonessential metals, some of which may be toxic and/ or bioaccumulative. In this situation nutrient metals can be displaced from their binding sites by undesirable, toxic metals, which then gain access to the cell interior with concomitant exclusion of the essential metal (Ref. 49). Toxic metal ions are then free to react with critical enzymes or otherwise disrupt cellular functions if they reach certain levels. Often this toxicity occurs at relatively low doses. For example, inorganic arsenic is a known human carcinogen and causes chronic toxicity at doses as low as 0.014 mg/ kg/ day (Ref. 59). Lead has no known biological function in humans but is readily absorbed and has been shown to cause various toxic effects. For example, children can suffer permanent damage from lead poisoning, resulting in lowered intelligence, learning disabilities, hearing loss, reduced attention span, and behavioral abnormalities (Ref. 66). EPA concludes that under many environmental conditions, metals and metal compounds may be available to express toxicity and to bioaccumulate, and that these effects are not necessarily limited to metals that are not essential nutrients. It is appropriate, therefore, to be concerned about the potential adverse effects, and one step in this direction is to more accurately assess emissions from anthropogenic activities. EPCRA section 313 provides that opportunity. Precedent for this concern exists at the international level in the form of a protocol for heavy metals under the UNECE LRTAP, which is currently being negotiated. The draft protocol expresses concern ``. . .that emissions of certain heavy metals are transported across national boundaries and may cause damage to ecosystems. . .and may have harmful effects on human health. . ., '' and specifically advocates assessing and controlling emissions caused by human activities (Ref. 54). Several commenters raised the issue of EPA participation in various international organizations, claiming that any attempt to apply EPA's proposed persistence and bioaccumulation criteria and/ or assessment approach to metals would violate the policies of these organizations, whose positions EPA has previously endorsed. These claims are false because the commenters either misunderstand or misstate the aforementioned policies. The main focus of the commenter's attention is two documents, the OECD's Harmonized Integrated Hazard Classification System for Human Health and Environmental Effects of Chemical Substances (Ref. 41), and the North American Agreement on Environmental Cooperation (NAAEC) 's Process for Identifying Candidate Substances for Regional Action under the Sound Management of Chemicals Initiative (Ref. 39). A report from a joint Canada/ European Union Technical Workshop on metals (Ref. 17) was also cited by commenters and reached similar conclusions. The OECD document's pronouncements on metals are contained in paragraphs 22 and 23 of that document. Paragraph 22 reads as follows:

For inorganic compounds and metals, the concept of degradability as applied to organic compounds has limited or no meaning. Rather the substance may be transformed by normal environmental processes to either increase or decrease the bioavailability of the toxic species. Equally, the use of bioaccumulation data should be treated with care. Specific guidance will be [but has not yet been] provided on how these data for such materials may be used in meeting the requirements of the classification criteria. (Ref. 41)

By `` degradability as applied to organic compounds'' OECD means molecular degradation, most often by microbial degradation and/ or hydrolysis or other abiotic processes, to progressively simpler organic chemical structures, leading eventually to inorganic substances like carbon dioxide and water. But, note, paragraph 22 does not in any way suggest that metals are not persistent. Moreover, it does not suggest that OECD hazard classification criteria cannot be applied, only that `` care'' (i. e., professional judgment) is required in the interpretation of data relative to the classification criteria. In fact, EPA agrees that bioavailability is important in determining the potential for the metal to be accumulated in organisms. 58686 Federal Register / Vol. 64, No. 209 / Friday, October 29, 1999 / Rules and Regulations The Agency has analyzed information on the environmental fate of metals, and, as noted above, asserts its professional judgment that the parent metals do have the potential to become available from metal compounds under commonly encountered environmental conditions. Therefore, the Agency's treatment of metals is consistent with the OECD's intent. The same holds with respect to NAAEC's pronouncements under the SMOC (Ref. 39). The focus of NAAEC/ SMOC (Ref. 39) is the development of North American Regional Action Plans (NARAPs) for substances that pose significant risk to human health and the environment in all three member countries (namely, Mexico, Canada, and the United States). To date, NARAPs have been established for DDT/ chlordane, PCBs, and mercury (note: a metal). NAAEC/ SMOC (Ref. 39) acknowledges the persistence of metals, but highlights the role of expert judgment in assessing potential bioavailability of metals and metal compounds:

For naturally occurring substances such as metals and minerals, the Task Force understands that the direct application of the persistence and bioaccumulation criteria proves very difficult..... Organometals can behave like other persistent organic pollutants in their metallic form, and as certain compounds, metals tend to be infinitely persistent though not necessarily in a form that is bioavailable, and in some cases, they naturally bioaccumulate for beneficial purposes in organisms (i. e., essential elements). Expert judgment is essential for a meaningful evaluation of these substances.

Further, an earlier section of the document (Ref. 39) states,

It is understood that expert scientific judgment plays a significant role in acknowledging and addressing the difficulties posed by quantitative criteria for persistence and bioaccumulation, particularly in relation to naturally occurring substances like metals and minerals where the potential for transformation to complexes or metallic species which are more or less bioavailable, are emerging as important considerations.

It is difficult to read into the preceding any intention to exclude metals and metal compounds from consideration, as many commenters imply, and more specifically, to declare that these substances have no potential to pose risk because they are never released in bioavailable forms; cannot be converted to bioavailable forms under any foreseeable circumstances, etc. On the contrary, it is clear from the preceding language as well as the inclusion of mercury among the NARAPs developed to date that any substance judged to be potentially bioavailable and that otherwise meets the SMOC criteria, whether organic or inorganic, should not be excluded as a candidate for action. As outlined above, it is realistic to expect that, in general, released metals can encounter conditions in which they are available at levels sufficient to exert toxicity and bioaccumulate. Therefore, the Agency's treatment of metals is consistent with international policy under NAAEC/ SMOC (Ref. 39). Finally, EPA reminds commenters that a mechanism already exists to address concerns for any metal compound for which the data show that the metal cannot become available. The issue of bioavailability was addressed previously for EPCRA section 313 chemical assessments through EPA's policy and guidance concerning petitions to delist individual members of the metal compound categories listed under EPCRA section 313 (56 FR 23703, May 23, 1991). This policy states that if the metal in a metal compound cannot become available as a result of biotic or abiotic processes, then the metal will not be available to express its toxicity, and by extension, to bioaccumulate. If the intact metal compound is not toxic and the metal is not available from the metal compound, then such a chemical is a potential candidate for delisting. EPA has received fewer than 10 petitions to delete individual metal compounds because the petitioner contended that the metal portion of the metal compound would not be available under environmental conditions or in vivo.

D. Multimedia Modeling One commenter contends that EPA should clarify how and when multimedia models will be used in the evaluation of PBT chemicals. EPA should not use the EQC model or other multimedia models as the sole determinant of potential risk. If exposure and use information is available, a detailed technical evaluation based on these data is preferred over modeling based on hypothetical exposure and loading scenarios. The purpose of this rulemaking is to lower reporting thresholds for certain EPCRA section 313 substances that are being designated as persistent and bioaccumulative, and to list several additional substances that meet EPCRA section 313 listing criteria and are also persistent and bioaccumulative. Although neither quantitative risk nor exposure assessments have been performed, nor are they required under EPCRA, designation as a PBT does imply the existence of potential risk. However, contrary to the comment, EPA has not proposed that multimedia models be used as the sole factor in determining persistence. As clearly stated in the proposed rule, EPA intends to use such modeling `` as an additional factor, in conjunction with reaction halflifes for individual media, bioaccumulation/ bioconcentration factors, etc., in justifying [the] actions proposed. '' In the proposed rule EPA did explain in a general way (at 64 FR 703) how models would be used in PBT evaluation, and stated that results of multimedia modeling may be used to override compartment (medium) specific degradation half lifes, but only if all model inputs are judged sufficiently accurate. This leaves unspecified what specific value( s) might be used for overall environmental persistence criteria (expressed either as an overall residence time or overall halflife To date no international scientific or regulatory authority has proposed any such criterion for POPs/ PBT chemicals, and the complex relationship between compartment specific and overall persistence criteria is in fact a major topic of current research. One commenter raises concerns regarding the modification EPA made to the EQC III model that deleted advective losses and sediment burial. EPA modified the model to exclude advective losses and sediment burial because if these processes are included the persistence based on destruction will be underestimated. In multimedia modeling, advection can be viewed as the flow into or out of the evaluative environment or `` box. '' These include processes such as downstream flow in surface waters, dispersion downwind in air, and burial in sediments. The model considers these non destructive processes to result in loss from the evaluative environment in the same way that destruction does. However, these processes simply result in the transport of a chemical to another part of the environment downwind or downstream from where it is released, or its deposition into sediments, but not the destruction of the chemical. The persistence of a chemical calculated when the model is run considering advective losses include non destructive transport processes which remove the chemical from the evaluative environment. For example, the environmental persistence of a chemical released to water which does not significantly partition to sediments, degrade, or volatilize will reflect the rate at which the water to which it is released flows out of the evaluative environment. In this example, the 58687 Federal Register / Vol. 64, No. 209 / Friday, October 29, 1999 / Rules and Regulations relative rate of non destructive transport out of the evaluative environment may be more rapid than the processes which result in the destruction of the chemical. Thus, the persistence calculated by the model will be less than if advective transport from the evaluative environment was not considered. EPA used the model to evaluate persistence based on destruction in a multimedia environment. This is consistent with EPCRA section 313 persistence criteria in that the criteria are based on destruction, not transport of the chemical. The Level III nonequilibrium partitioning, steady state mass balance) models are preferred for developing qualitative and quantitative predictions of chemical distribution, pathways, and relative concentrations (Ref. 16). Level III models can also be used to assess persistence (Ref. 33). At steady state (level III) conditions the amount of chemical is unchanging with time and the input and output rates for a compartment are equal. The overall residence time of the chemical is the mass of the chemical in the compartment divided by the input or output rates. This represents the average time the chemical will reside in the compartment. Output may be by reactions that result in the destruction of the chemical or by advective flow (non destructive) usually in air or water. When the model is modified to eliminate advective flow, the persistence of a chemical based on the rates of reactions that result in the destruction of the chemical can be assessed. Webster et al (Ref. 82) used this approach in evaluating the environmental persistence of chemicals using a multimedia fate model and noted that if advective loss is included, the residence time is reduced and can give a misleading impression of a short persistence. It was also noted that these advective losses ``. . .merely relocate the chemical; they do not destroy it. '' EPA also used a modified version of the EQC level III model as a tool to assist on the characterization of the persistence of the chemicals subject to this rule. In this version of the model only irreversible transformation contributes to net loss of a chemical. In other words, the model was modified to represent a `` closed box'' in which the effect of processes that serve only to move the chemical from within the evaluative environment to outside of it, primarily in air and water (advective losses) were nullified. Sediment processes responsible for transport of the chemical from the evaluative environment such as sediment burial were similarly treated. The intent of this modification was to make sure that only processes responsible for the destruction of the chemical were considered in evaluating its persistence in a multimedia environment. EPA supports the use of level III multimedia models modified, as described, for their ability to simultaneously consider reaction rates and partitioning so as to give a reasonable assessment of the persistence of chemicals in the multimedia environment. However, EPA notes that its reliance on the multimedia modeling was limited. As discussed in the proposed rule (at 64 FR 703) and in Unit VI. B. 2., EPA primarily considered mediaspecific data and made a case by case determination about the persistence of each chemical.

E. Thresholds The issue most frequently raised by commenters was the Agency's choice of thresholds and the factors that EPA considered in lowering the thresholds. Many commenters contended that EPA should not consider burden in choosing thresholds. They believe that EPA should set a threshold of 10 pounds for PBT chemicals and 1 pound for that subset of PBT chemicals that are both highly persistent and highly bioaccumulative. Some commenters believe that EPA should set a threshold of 1 pound for all chemicals that are PBT chemicals. Numerous commenters believe that the threshold for reporting should be zero. Other commenters believe that burden should have been a greater consideration in EPA's choice of reporting thresholds. Many of these commenters believe that EPA should set thresholds based on some percentage of releases that would be reported. EPA disagrees with these commenters. As explained in the proposal, the Agency considered a number of factors to determine the appropriate thresholds that should be established for these chemicals. EPA relied on the language of EPCRA sections 313( f)( 2) and (h), and the legislative history to elicit the following principles to guide its exercise of discretion in lowering the thresholds, and in selecting the specific thresholds for PBT chemicals: (1) The purposes of EPCRA section 313; (2) the `` verifiable, historical data'' that convinces EPA of the need to lower the thresholds; (3) the chemical properties shared by the members of the class of toxic chemicals for which EPA is lowering the thresholds i. e., the degree of persistence and bioaccumulation; and (4) the reporting burden imposed by revised thresholds to the extent that such consideration would not deny the public significant information from a range of covered industry sectors. Further, EPA believes that in the language of EPCRA section 313, and its legislative history, Congress provided direction on the appropriate weight to allocate to each of these considerations in implementing EPCRA section 313( f)( 2). These considerations underlay the entire process by which EPA determined the appropriate thresholds. But, as noted below, the Agency's choice of revised thresholds was governed, and ultimately constrained, by EPCRA section 313's overriding purpose, which is to provide government agencies, researchers, and local communities, with a comprehensive picture of toxic chemical releases and potential exposures to humans and ecosystems. In general, EPA's implementation of EPCRA section 313 is guided by the statutory purposes described by EPCRA section 313( h), which provides:

The release forms required under this section are intended to provide information to the Federal, State, and local governments and the public, including citizens of communities surrounding covered facilities. The release form shall be available. . .to inform persons about releases of toxic chemicals to the environment; to assist governmental agencies, researchers, and other persons in the conduct of research and data gathering; to aid in the development of appropriate regulations, guidelines, and standards; and for other similar purposes.

In addition to section 313( h), EPA was also guided by several statements on the principles intended to guide EPA's implementation of EPCRA section 313 made by Representative Edgar, one of EPCRA section 313's principal architects, during debate on the Conference Report. See, Legislative History at 5313± 16. In the course of his statement, Representative Edgar also articulated EPCRA section 313's overriding purpose, which is:

to provide a comprehensive view of toxic chemical exposure and, hopefully, provide a basis for more sensible and effective local, State, and national policies. Legislative History at 5316 (emphasis added).

Based on the existing reporting requirements, the Agency believes that there are still significant gaps in the picture the TRI data provides local communities, government agencies, and researchers. One of the most significant of these gaps is a comprehensive picture of the releases and potential exposure of PBT chemicals to humans and the environment. Currently, only a very limited picture of releases and other waste management of PBT chemicals is available from the TRI data, in part, as a result of the current thresholds. For 58688 Federal Register / Vol. 64, No. 209 / Friday, October 29, 1999 / Rules and Regulations example, under the current reporting thresholds, in 1997, EPA received only 29 reports on mercury and mercury compounds, and 6 reports on PCBs. This does not present a `` comprehensive view of toxic chemical exposure. '' In addition, information on the releases and other waste management of PBT chemicals is particularly significant because these chemicals both persist and bioaccumulate. Individually, each of these attributes has the potential to pose increased exposures to humans and the environment. Toxic chemicals possessing both attributes have the potential to pose significant exposures to humans and ecosystems over a longer period of time; even small amounts of PBT chemicals that enter the environment can accumulate to elevated concentrations in the environment and in organisms, and therefore have a greater potential to result in adverse effects on human health and the environment. As a first step in addressing the significant gap of information on PBT chemical releases and waste management, EPA considered whether to lower the reporting thresholds for PBT chemicals. EPA then looked to section 313( f)( 2) for further guidance on how to proceed. Since lowering the thresholds ensures that `` all facilities subject to the requirements of [section 313] '' will continue to report, the requirement in section 313( f)( 2) that a revised threshold obtain a `` substantial majority of total releases of each chemical at all facilities subject to the requirements of this section'' can be met without the need for quantitative support. Consequently, EPA looked to other sources of Congressional direction in the statute and legislative history to guide its exercise of discretion in establishing revised thresholds. Given that there is no guidance on implementing section 313( f)( 2) in the Conference Report, EPA looked to the debate on the Conference Report. In this context, Representative Edgar, stated:

It is also important to clarify the intent of Congress in establishing thresholds for reporting under this section. . . .These thresholds were designed to obtain reporting on both a substantial majority of the Nation's toxic chemical releases and to obtain reporting from a large number of firms. These thresholds reflect Congress' judgement that such thresholds appropriately balance the need for information against the burden on facilities required to provide such information. The EPA is authorized to revise these thresholds, but only if such revised thresholds continue to obtain reporting on a substantial majority of total releases. Any determination by the EPA regarding the ability of revised thresholds to obtain reporting on a substantial majority of releases, especially if such revised thresholds raise the statutory levels, must be based on verifiable, historical data which presents a convincing case that the statutory levels must be revised. Legislative History at 5313 (emphasis added).

And during the House debate, Representative Swift noted that any revised threshold `` should be designed to improve the usefulness of the reports. It must be structured to obtain reporting on a substantial majority of the total nationwide releases of the toxic chemical at all facilities covered by section 313. '' Id. at 5338 (emphasis added).

In determining how to structure its threshold revisions, and particularly how it would improve the usefulness of the reports, EPA also consulted EPCRA's purposes, laid out in subsection (h). In this context, EPA also considered the statements made by Senator Stafford during debate on the Conference Report:

This section also requires the Administrator to computerize the data reported on the required forms and to make these data public by various means. Successful implementation of this requirement is vital to the basic purpose of the program. The data should be managed in the computer in such a way as to allow a wide variety of analyses. For example, it should be possible to retrieve data, not only about individual facilities, but also aggregate data organized by type of chemical, type of effect, geographic location, company name, etc. as well as combinations of these parameters. . . . Legislative History at 5186 (emphasis added).

Based on this Congressional guidance, EPA reached several conclusions. First, ample `` verifiable, historical data'' exists to support EPA's conclusions that PBT chemicals persist for long periods of time in the environment and bioaccumulate in organisms, including humans; that this persistence and bioaccumulation can result in higher exposures to humans and the environment; and that to `` obtain a substantial majority of the Nation's toxic chemical releases, '' lower thresholds for PBT chemicals are warranted. For example, PCBs have been found throughout the Great Lakes in sediments, water, and aquatic organisms. Multimedia analyses indicate that the majority (80± 90%) of human exposure to chlorinated organic compounds, such as PCBs comes from the food pathway, a lesser amount (5± 10%) from air, and minute amounts (less than 1%) from water. Most of the data available on human exposure to PCBs in the Great Lakes come from the analyses of contaminant levels in drinking water and sport fish. The consumption of contaminated sport fish and wildlife can significantly increase human exposure to the Great Lakes critical pollutants, such as PCBs. The sport fish are exposed to PCBs by consumption of sediments and through water (Ref. 76). See also Refs. 75 and 77. Further, EPA strongly believes that increased reporting on PBT chemicals will improve the usefulness of the data on these chemicals. There are currently very few reports for some of the PBT chemicals, such as mercury, mercury compounds and PCBs. The currently available data provide a distorted picture of potential exposures to humans and the environment, because at the current thresholds only a fraction of the releases from facilities otherwise subject to EPCRA section 313 are reported. This limited reporting results in a significant underestimation of the releases from the industry sectors covered by EPCRA section 313. As such, the current data are of limited use for evaluating the potential exposures to humans and the environment of toxic chemicals that persist and bioaccumulate. Expanding the picture of releases, and therefore potential exposures, will increase the utility of all the TRI data on these chemicals. See, e. g., Economic Analysis, Chapter 6.4 (Ref. 67). On these bases, EPA determined that revising the thresholds would be an important first step in closing the information gap on PBT chemicals. The Agency then began the process of determining the appropriate levels at which to establish the revised thresholds. For a number of technical and policy reasons, EPA chose an approach focused on two classes of PBT chemicals: (1) Toxic chemicals that meet the EPCRA section 313 persistence and bioaccumulation criteria discussed in Unit VI. B., i. e., those toxic chemicals that have half lifes of 2 months or greater in water/ sediment or soil and that have bioaccumulation or bioconcentration factors of 1,000 and (2) the subset of PBT chemicals that are highly persistent and highly bioaccumulative, i. e., those toxic chemicals that have half lifes of 6 months or greater in water/ sediment or soil and that have bioaccumulation or bioconcentration factors of 5,000 or greater. First, for the most persistent and bioaccumulative toxic chemicals any release will lead to elevated concentrations in the environment and in organisms. EPA believes that such highly persistent and highly bioaccumulative toxic chemicals are of international, as well as national concern, because of the extent of their 58689 Federal Register / Vol. 64, No. 209 / Friday, October 29, 1999 / Rules and Regulations persistence and bioaccumulation. As discussed elsewhere in this preamble, these facts have been widely recognized; there are a number of international agreements that ban, restrict, or phase out the manufacture, use and/ or release of highly persistent and highly bioaccumulative toxic chemicals. Similarly, toxic chemicals that are persistent and bioaccumulative are of national, regional, and local concern. As discussed elsewhere in this preamble, toxic chemicals that are persistent and bioaccumulative present a significant concern to many local communities due to the proximity of the communities to industrial sources. All other things being equal, a pollutant reaches nearby populations in less time than distant ones. Thus, toxic chemicals that persist and bioaccumulate can pose significant exposures to communities and ecosystems that immediately surround industrial sources as well as those communities that are subject to regional transport. Given the international support for the extreme limitations on the use and release of toxic chemicals that are highly persistent and highly bioaccumulative, and the significant exposures that persistent and bioaccumulative toxic chemicals can pose to both local communities and broader regions of the United States and North America, EPA believes that it is appropriate to lower the reporting thresholds for both (1) Persistent and bioaccumulative toxic chemicals and (2) for highly persistent and highly bioaccumulative toxic chemicals. In addition, EPA believes this information is important to the public, government agencies, and researchers; for example, the information reported by facilities under the lower thresholds will help these groups assess the loading of the PBT chemicals in both local and regional ecosystems, e. g., a small lake or river or a larger ecosystem such as the Great Lakes or the Chesapeake Bay. See also, Economic Analysis at Chapter 6, pages 32± 50 for examples of other uses of TRI data (Ref. 67). Second, EPA considered how the revised thresholds would provide the information on PBT chemicals needed to assist the public to obtain `` a comprehensive view of toxic chemical exposure, '' as well as to assist government agencies, researchers, and other persons to conduct research and to establish appropriate regulations, guidelines and standards, in accordance with the directives laid out in subsection (h). EPA determined that providing greater information on two identifiable classes of chemicals best achieved these ends. It is consistent with the actions of a significant number of the groups that would use this information; for example, as discussed in Unit VI. B., UNEP is in the process of negotiating an international agreement on the class of persistent organic pollutants with half lifes of 6 months and BCF/ BAF values of 5,000. See also Economic Analysis at Chapter 6, pages 46± 48 for examples of how TRI data will be used (Ref. 67). Moreover, EPA determined that data on members within the same class are more easily comparable; the members of the classes EPA established in this rulemaking share a qualitatively comparable level of concern based on their potential for increased exposure. The Agency believed that creating two distinct classes of comparable chemicals would significantly enhance the ability of researchers, government agencies, and other similar persons, to use the reports. Establishing distinct classes of comparable chemicals normalizes the subsequent years' data, providing a baseline against which data users can ascertain trends over time. Consequently researchers can more easily distinguish, and therefore track, the releases and other waste management of highly PBT chemicals, to evaluate the efficacy and progress of the policy strategies intended to address the risks of PBT chemicals, such as the Binational Great Lakes Water Quality Initiative. Finally, administrative convenience argued for establishing a limited number of alternate thresholds. As a practical matter, it would be burdensome for both the Agency and the regulated community to track a variety of individual thresholds for separate chemicals. In addition, because this was only the Agency's initial rulemaking to lower thresholds for certain PBT chemicals, EPA intended that the revised thresholds establish a set of categories that would be generally applicable to future designated PBT chemicals. All of these considerations led the Agency to conclude that it should establish two sets of revised thresholds based on two classes of PBT chemicals. Thus, having concluded it was appropriate to focus the rulemaking on two classes of chemicals, persistent and bioaccumulative toxic chemicals and that subset of PBT chemicals that are highly persistent and highly bioaccumulative, EPA began the process of determining the specific thresholds that would achieve the purposes of subsections (f)( 2) and (h). The intrinsic properties of PBT chemicals argue for very low thresholds. The subset of PBT chemicals that are highly persistent and highly bioaccumulative warrant, in the absence of other considerations, a threshold approaching zero. Any release of these toxic chemicals is of global concern because they can persist for long periods of time, can maintain their identity even after undergoing long range transport, and can bioaccumulate to a significant degree. As discussed above, and at length in Unit VI. B., the potential impacts that can result from any release of toxic chemicals that are highly persistent and highly bioaccumulative have been widely recognized. There are a number of international agreements that ban, restrict, or phase out the manufacture, use and/ or release of the most persistent and bioaccumulative toxic chemicals. However, EPA believes that a zero threshold would be impractical. Attempting to require facilities to determine if they manufacture, process, or otherwise use any amount whatsoever of these chemicals would be extremely burdensome and perhaps technically impossible. Without an actual numerical threshold, many facilities might report some amount of these chemicals in a misguided attempt to assure compliance. This could lead to misleading and inaccurate data on the actual sources of these chemicals. EPA believes that rather than setting a zero reporting threshold it would be better to set a very low threshold that provides facilities with a clear indicator of when they are required to report. In general for purposes of EPCRA section 313, 1 pound is the practical equivalent of zero for these chemicals. EPA explained these considerations in the proposed rule (64 FR 712) and has received no information from commenters that convinces the Agency to pursue a different approach. EPA then considered the relative degree of persistence and bioaccumulation between the two classes of chemicals. EPA wanted to establish two sets of revised thresholds with the same approximate relationship to each other, as the relative exposure potentials of PBT chemicals to that subset of highly persistent and highly bioaccumulative PBT chemicals. Simply stated, chemicals with half lifes of 6 months or greater and a BAF/ BCF of 5,000 or greater have a higher exposure potential than chemicals with half lifes of 2 months or greater and a BAF/ BCF of 1,000 or greater. However, although, as discussed below, EPA could establish a qualitative relationship, the Agency could not reliably quantify the relative exposure potential across the board for all of the members of both classes. Therefore, in attempting to translate the qualitative exposure potential of PBT 58690 Federal Register / Vol. 64, No. 209 / Friday, October 29, 1999 / Rules and Regulations chemicals to that subset of PBT chemicals that are highly persistent and highly bioaccumulative into a qualitative threshold relationship, EPA considered both the attributes of these chemicals and factors specific to thresholds. The manufacture, process, and otherwise use thresholds are not equivalent to release thresholds although, in many cases, the quantity manufactured or otherwise used will be very similar to the quantity released. Thus, even if EPA were able to quantify the relative exposure potential of PBT chemicals and that subset of PBT chemicals that are highly persistent and highly bioaccumulative, based on their degrees of persistence and bioaccumulation, and their interrelationship, the Agency would not rely solely on this to select a quantitative threshold relationship between these two classes of chemicals because: (1) The manufacturing, processing, and otherwise use thresholds are not equivalent to release thresholds, and (2) the quantity released, not the quantity manufactured, processed or otherwise used, is a critical factor in determining exposure. Nonetheless, EPA believes that the relative reporting thresholds should be based to some extent upon the qualitative differential between the potential exposures that may result from releases of PBT chemicals and that subset of PBT chemicals that are highly persistent and highly bioaccumulative. There is not a direct quantifiable relationship between the potential exposures that can result from equivalent releases of a toxic chemical that persists in the environment with a half life of 6 months and that has a bioaccumulation factor of 5,000 and releases of a toxic chemical that persists in the environment with a half life of 2 months and that has a bioaccumulation factor of 1,000. The potential exposure to humans and the environment will depend upon a number of factors, including release patterns, environment variables such as soil type, surface water chemistry, the types and distribution of flora and fauna, and fish consumption patterns. However, EPA did consider the relative differences in the potential exposures between these two classes. For example, after 1 year, there will be more than 15 times as much of a highly persistent chemical that remains in the environment than of a persistent chemical, all other things being equal. Similarly, fish will accumulate more than 5 times as much of the highly bioaccumulative chemical than of the bioaccumulative chemical, all other things being equal. While EPA believes that it can qualitatively describe the relative relationship of highly persistent chemicals to persistent chemicals and the relative relationship of highly bioaccumulative chemicals to bioaccumulative chemicals, the Agency cannot at the present time, define the relative relationship of persistence and bioaccumulation between the two classes of chemicals. This is in large part due to the many variables that must be considered in determining the potential exposures both due to the interaction of these chemical attributes and the large number of environmental factors that must be considered when evaluating persistence and bioaccumulation together. Although EPA could not develop an exact quantitative threshold relationship between the two classes of chemicals, the Agency did consider the factors discussed above and did rely to some extent on the numerical relationships between the highly persistent and persistent chemicals and the highly bioaccumulative and bioaccumulative chemicals. Therefore, given that: (1) Highly bioaccumulative toxic chemicals will accumulate approximately 5 times greater than bioaccumulative toxic chemicals, (2) highly persistent toxic chemicals will remain in the environment after 1 year, at a level about 15 times greater than persistent toxic chemicals, (3) the fact that the EPCRA section 313 reporting thresholds are not release thresholds but that in some instances the quantities manufactured or otherwise used will be very similar to the quantity released, and (4) toxic chemicals that persist in the environment with half lifes of 2 months and bioaccumulation factors of 1,000 or greater can be of both local and regional concern, EPA believes that the threshold for PBT chemicals should be a factor of 10 greater than the threshold for that subset of PBT chemicals that are highly persistent and highly bioaccumulative. EPA believes that this ratio balances the uncertainties and factors, including numerical factors, that the Agency considered. Therefore, based on the chemicals' intrinsic characteristics, EPA would establish thresholds of 1 pound for that subset of PBT chemicals that are highly persistent and highly bioaccumulative and 10 pounds for PBT chemicals. However, the legislative history of section 313( f)( 2) indicates that in establishing the original thresholds, Congress recognized the burden imposed on the regulated community. Lowering thresholds necessarily will increase that burden. Therefore, EPA determined it would be reasonable to include some consideration of reporting burden in selecting thresholds for PBT chemicals. But EPA accorded less weight to burden than to the other considerations discussed above. First, neither section 313( f)( 2), section 313( h), nor any other provision of EPCRA requires EPA to consider burden. Second, EPA was mindful of the fact that in several places in the legislative history Congress made clear it never intended impacts on reporting facilities to outweigh the public's right to know about their potential exposures to toxic chemicals. For example, although Representative Edgar recognized that Congress had considered burden in establishing the statutory thresholds, he did not include reporting burden as one of the general principles that should guide the Agency's implementation of EPCRA section 313 as a whole. Rather, he stated:

This is a new Federal initiative, and I recognize the desire of some of my colleagues to move ahead cautiously to ensure that burdens imposed on industry are not excessive. Frankly, my concern rest with the families that live in the shadows of these chemical and manufacturing plants. I have put myself in their shoes and have fought for a program that looks after their needs. This legislation gets us well on the path to the full disclosure they deserve. Legislative History at 5316. See also, Legislative History at 5185± 86 (Senate debate on the Conference Report). As noted in Unit VI. A, one of the major pieces of Congressional guidance on the establishment of alternate thresholds was to obtain a comprehensive picture of `` total nationwide releases of the toxic chemical at all facilities covered by section 313. '' This language, plus other Congressional directives on implementing section 313 generally, such as section 313( h), reflect an interest in obtaining information from a broadly representative range of sources. Consequently, EPA determined that the Agency should consider burden only to the extent that it would not deny the public significant information from a range of covered industry sectors. Therefore, EPA estimated the number of reports that would be submitted by each industry sector for four groups of thresholds, 1 and 10 pounds, 10 and 100 pounds, 100 and 1,000 pounds, and 1,000 pounds for both classes of chemicals. These options were selected for the following reasons. EPA needed a reasonable but finite number of options to evaluate, and the options described above represent a reasonable picture of the entire range of potential revised thresholds. Data limitations on the manufacturing, processing, and otherwise use of PBT chemicals in the numerous industries, processes, and uses covered by EPCRA section 313 58691 Federal Register / Vol. 64, No. 209 / Friday, October 29, 1999 / Rules and Regulations constrained EPA's ability to make meaningful and reliable distinctions between threshold options that are less than an order of magnitude apart. For example, while EPA believes it can reliably estimate the difference in the number of reports from a 10 pound reporting threshold and a 100 pound reporting threshold, EPA believes that the data are insufficient to allow it to make a meaningful and reliable distinction in estimates of options that are closer than an order of magnitude such as 35 pounds and 50 pounds. EPA explained its data limitations in the proposal, and commenters provided no information that would allow the Agency to increase the resolution of its analysis. Consequently, for the final rule, EPA analyzed options that were orders of magnitude apart from the two thresholds identified through its technical review: 1 pound for highly persistent and highly bioaccumulative chemicals, and 10 pounds for persistent and bioaccumulative chemicals. Based on information provided in the economic analysis for this rulemaking, at the technical reporting thresholds EPA would obtain information from a broad range of facilities (Ref. 67a). The analysis showed that at a threshold of 1 pound, the public would obtain information from all industry sectors that are currently subject to EPCRA section 313, and that have been identified as manufacturing, processing, or otherwise using those highly persistent highly bioaccumulative toxic chemicals that are part of this rulemaking (except dioxin and dioxinlike compounds which are discussed below). At a threshold of 10 pounds, the public would obtain information from all industry sectors that are currently subject to EPCRA section 313, and that have been identified as manufacturing, processing, or otherwise using those PBT chemicals that are part of this rulemaking. At the technical reporting thresholds, the estimated costs of the additional reports filed would have totaled $355 million in the first year, and $193 million in subsequent years (Ref. 67). EPA considered these costs, even though it cannot quantify the value of the information obtained or lost at the various thresholds, and cannot quantify the relationship between the reporting costs and the value of the information reported, or lost, at a particular threshold. At thresholds of 10 pounds for highly persistent and highly bioaccumulative chemicals and 100 pounds for persistent and bioaccumulative chemicals, EPA is still able to obtain a significant amount of information on both classes of PBT chemicals from a wide range of industry sectors and sources. For example, no reporting on TBBPA would be lost from any sources or industry sectors at 100 pounds, and some information on octachlorostyrene would be potentially lost from only one industry sector, pesticide manufacturing facilities. At these thresholds, EPA does, however, lose information significant to local communities; for example, EPA loses considerable reporting on mercury and mercury compounds at 10 pounds, but the loss of information is localized in a limited number of industry sectors, and the public will still obtain some reporting from all of the currently covered industry sectors (Ref. 67a). For this threshold option, EPA estimated the total burden at these thresholds to be $191 million for the first year, and $105 million for subsequent years (Ref. 67). At thresholds of 100 and 1,000 pounds and higher, EPA's analysis indicated that the public, government agencies, and researchers would lose information on many of the PBT chemicals from certain industry sectors and sources. For example, at a threshold of 100 pounds for toxic chemicals that are highly persistent and highly bioaccumulative, the Agency would not obtain reporting on mercury and mercury compounds generated in boilers in the manufacturing sector or information on octachlorostyrene from the primary metal industries (Ref. 67a). However, at these thresholds, EPA estimated the total first year costs to be $99 million and $55 million in subsequent years (Ref. 67). These analyses led EPA to several conclusions. First, thresholds of 10 pounds for highly persistent and highly bioaccumulative chemicals and 100 pounds for persistent and bioaccumulative chemicals, achieve a significant reduction in reporting burden. Second, at these thresholds EPA obtains information from a broad distribution of industry sectors. Although EPA also loses information significant to local communities at these thresholds, it maintains the overall distribution of reporting from a broad range of industry sectors nationally. EPA could have attempted to compensate for the community level loss of information on individual members of the classes of PBT chemicals (i. e., by establishing separate thresholds of 1 pound or 10 pounds for individual chemicals), but only by failing to take reporting burden into account for those individual chemicals. As explained previously, the availability of the data limited EPA's ability to distinguish meaningfully between thresholds separated by less than an order of magnitude. In addition, establishing separate thresholds would sacrifice many of the benefits of receiving information from comparable facilities using comparable chemicals, discussed earlier in this unit. Thus greater information for local communities would be achieved at the expense of the increased utility of the reports for other purposes established under EPCRA section 313( h) e. g., assisting governmental agencies, researchers, agencies and other persons in the conduct of research and data gathering; and aiding in the development of appropriate regulations, guidelines, and standards. EPA believes that, to be consistent with the overriding policy directive in subsection (h), it must achieve a balance between improving the utility of the reports for all of the groups that rely on TRI data. Finally, as noted earlier in this Unit, administrative convenience argues against the establishment of individual thresholds. Among other issues, it would be burdensome on both EPA and the regulated community to track a variety of separate thresholds. Moreover, EPA intends the revised thresholds established in this rulemaking for the two classes of PBT chemicals to be generally applicable to future members of the two classes; absent a strong technical or policy concern to the contrary, it would ultimately be inconsistent with the purposes of EPCRA section 313 for chemicals that share such common characteristics to have vastly different thresholds. Therefore, EPA believes its selection of thresholds of 100 pounds for PBT chemicals and 10 pounds for that subset of PBT chemicals that are highly persistent and highly bioaccumulative, balances the purposes of EPCRA section 313 and the Agency's desire to provide a comprehensive picture on releases and potential exposures of PBT chemicals, while factoring in an appropriate degree of the consequent impact on the regulated community. Dioxin and dioxin like compounds are highly persistent and highly bioaccumulative toxic chemicals. As discussed above, toxic chemicals that are highly persistent and highly bioaccumulative warrant, in the absence of other considerations, a threshold approaching zero. But, for the reasons discussed previously in this section, EPA does not believe that a zero threshold would be practical. However, because the dioxin and dioxin like compounds are manufactured in extremely small amounts, EPA needed to select a threshold lower than that for the other highly persistent and highly 58692 Federal Register / Vol. 64, No. 209 / Friday, October 29, 1999 / Rules and Regulations bioaccumulative chemicals in order to obtain any reporting. In choosing reporting thresholds for these chemicals, the Agency considered the extent of the information on dioxin and dioxin like compounds that would be made available to the public, government agencies and researchers. EPA considered whether this level of information would provide them with `` a comprehensive view of toxic chemical exposure, '' given the attributes of dioxin and dioxin like compounds, and with `` broad based national information. '' At a threshold of 0.1 gram, the public would obtain information from all industry sectors that are subject to EPCRA section 313 and that have been identified in the Inventory of Sources of Dioxin in the United States (Ref. 3). EPA does not believe that a higher threshold, i. e., 1.0 grams, would provide the public with broad based national information because there would be no information on the manufacture and release and other waste management of certain sectors. For example, at a higher threshold, EPA anticipates that there would be no reporting from hazardous waste incinerators, pulp mills, non high ferrous foundry industries, and secondary lead smelters (Ref. 67a). At thresholds lower than 0.1 gram, there is greater coverage within certain industry sectors, with a concomitant significant increase in burden. EPA believes its selection of a threshold of 0.1 gram for dioxin and dioxin like compounds balances the purposes of EPCRA section 313 and the Agency's desire to provide a comprehensive picture on releases and exposures of dioxin and dioxin like compounds while factoring in an appropriate degree of the resultant impact on the regulated community.

F. What Comments Did EPA Receive on Exposure and Risk Considerations and What Are EPA's Responses? One of the most significant issues raised by commenters relates to the Agency's lack of consideration of quantitative risk in modifying the section 313( f) reporting thresholds. Specifically, a number of commenters believe that EPA should use quantitative risk as a criterion in determining whether to lower the reporting thresholds and in choosing a particular reporting threshold for each PBT chemical. The commenters contend that EPA should conduct risk assessments and make a formal determination that at a particular threshold releases of the PBT chemical pose a risk before lowering the reporting threshold. While the majority of commenters who commented on the issue believe that EPA should make a risk determination before modifying the reporting thresholds, the rationale for their conclusions varied. Some commenters state that a risk determination is required by EPCRA because the intent of EPCRA is to provide information to the public of potential risks posed by the presence of toxic chemicals released to the environment in their communities. Some commenters state that in addition to addressing the substantial majority test, EPCRA section 313( f)( 2) requires EPA to use the degree of risk that releases will pose to communities as a determinant in choosing new thresholds. Other commenters state that consideration of risk is a required component of any action under EPCRA section 313. In support of this position, one of the commenters cites two D. C. Circuit Court decisions. Other commenters contend that it would be good public policy to choose a threshold based on risks. Some commenters contend that EPA should lower the reporting thresholds only for those chemicals that present the highest risks to the public. One commenter, however, believes that the Agency should not consider the degree of risk in making a determination to lower the reporting thresholds for PBT chemicals because the consideration of risk in past actions taken by EPA under other environmental statutes have not resulted in a decrease of human health or environmental risks due to PBT chemicals. The commenter states that the increasing number of fish advisories and the lingering and, in some cases, increasing levels of PBT chemicals in the environment and in fish, wildlife, and human tissue demonstrates the magnitude of the failure of the `` risk management strategy. '' EPA disagrees with the commenters' assertion that evidence of risk is required prior to lowering the threshold for any EPCRA section 313 chemical. Section 313( f)( 2) addresses revisions to the reporting thresholds. It does not require EPA to establish, prior to the lowering of reporting thresholds, that releases at a particular threshold will result in specific quantitative risks. That section expressly provides that the Administrator may establish a threshold amount for a toxic chemical different from the 25,000 pound threshold for manufacturing and processing activities and the 10,000 pound threshold for otherwise use activities. The only prerequisite for revising the reporting threshold for a toxic chemical is that the revised threshold obtain reporting on a substantial majority of total releases of the chemical at all facilities subject to the requirements of EPCRA section 313. As discussed in Units II. B. and VI. A., EPA believes that it has satisfied the requirements of EPCRA section 313( f)( 2) without the need for quantitative support. EPA believes that the commenters attribute a purpose to EPCRA that is inconsistent with that clearly intended by Congress. Specifically, Congress stated in EPCRA section 313( h) that:

The release forms required under this section are intended to provide information to the Federal, State, and local governments and the public, including citizens of communities surrounding covered facilities. The release form shall be available,. . .to inform persons about releases of toxic chemicals to the environment; to assist government agencies, researchers, and other persons in the conduct of research and data gathering; to aid in the development of appropriate regulations, guidelines, and standards; and for other similar purposes. 42 U. S. C. section 11023( h).

Neither EPCRA section 313( h) nor its legislative history directs EPA to limit the collection of information on releases to those releases that, from the Federal government's perspective, pose significant local human and environmental exposure and human health and environmental risks. See, e. g., Legislative History at 5186. Federal and local perspectives on what may be an acceptable risk are likely to be very different. The roles of local government and the Federal government differ significantly in terms of ensuring environmental quality. In passing EPCRA, Congress determined that it is for the public to take the information reported on the use and releases and other waste management of toxic chemicals, and to determine whether these releases result in potential risks that the community determines warrant further action given other factors, such as economic and environmental conditions, or particularly vulnerable human or ecological populations. Congress did not intend the Federal government to consider these specific local factors prior to determining whether certain information should be made public or prior to determining whether a different threshold should be established for one or more toxic chemicals. The intent of EPCRA section 313 is to move the determination of what risks are acceptable from EPA to the communities in which the releases occur. This basic local empowerment is a cornerstone of the right to know program. EPCRA section 313 establishes an information collection and dissemination program. The burden it imposes is significantly less than the 58693 Federal Register / Vol. 64, No. 209 / Friday, October 29, 1999 / Rules and Regulations burden imposed by a statute which controls the manufacture, use, and/ or disposal of a chemical. EPCRA section 313 requires that a facility use readily available data, or if such data are not available, reasonable estimates to prepare each chemical specific report. The statute does not require that the facility conduct monitoring or emissions measurements to determine these quantities. This is in contrast to other environmental statutes that may require a facility to monitor releases, change its manufacturing process, install a specific waste treatment technology, or dispose of wastes in a certain manner. As such, the Agency believes that as a matter of policy the standard that must be met to require information pursuant to EPCRA section 313 is less than that required to regulate a chemical under a statute such as the Clean Air Act. See, e. g., Legislative History at 5186. Further, contrary to assertions by some commenters, EPCRA section 313 does not require the collection of quantitative risk data nor does the statute require that risk data be disseminated to the public. Rather TRI data provide communities with information on releases and other waste management quantities. TRI data cannot, in themselves, provide information on quantitative risks to individual communities. A determination of the potential risk that a chemical release may pose is dependent upon a number of factors, including the toxicity of the chemical, the physical chemical properties of the chemical, the specific media to which the chemical is released, and sitespecific information that will determine the estimated exposures. While TRI data are not in themselves measures of risk, they are an important input that local communities can use along with the factors described in this section to determine potential risks to themselves, their children, their communities, and their environment that may result from releases of toxic chemicals. EPA's decision to lower the reporting threshold for PBT chemicals is rationally related to the EPCRA section 313 goals of informing communities, assisting research and data gathering, and aiding the development of regulations and guidelines. Because PBT chemicals persist in the environment for a significant period of time and bioaccumulate in animal tissues, PBT chemicals have the potential to be pervasive in the environment, in the food chain, and often in humans. In short, for PBT chemicals, releases and other waste management activities for relatively small amounts of PBT chemicals are of concern. Accordingly, pursuant to the intended purposes of EPCRA, even relatively small releases and other waste management activities for PBT chemicals need to be reported in order to inform communities, assist those engaged in research and data gathering, and to aid the development of regulations and guidelines. Lowered reporting thresholds for PBT chemicals are needed to obtain reporting on these relatively small releases and other waste management activities for PBT chemicals. Consequently, EPA believes that including consideration of the quantitative risk in establishing the thresholds would be poor public policy that would be inconsistent with the overall principles of EPCRA. Finally, the reference by one of the commenters to two D. C. Circuit Court decisions is misplaced. In support of its position that EPA must undertake a risk assessment of any toxic chemical it is considering for lower reporting thresholds, the commenter cites American Petroleum Institute v. Costle, 665 F. 2d 1176, 1187 (D. C. Cir. 1981), cert. denied, 455 U. S. 1034 (1982), and Milwaukee Metropolitan Sewerage District v. EPA, 40 F. 3d 392 (D. C. Cir. 1994). Neither case cited by the commenter addresses EPCRA. Nor do these cases establish a generally applicable principle of law that risk assessments are required prior to any government action. In Milwaukee Metropolitan Sewerage the court reviewed standards adopted by EPA in a Clean Water Act regulation. In American Petroleum Institute the court reviewed the primary and secondary national ambient air quality standards for ozone promulgated by EPA under the Clean Air Act. Both the Clean Air Act and the Clean Water Act have no bearing on EPCRA section 313. Unlike the statutes at issue in the cases cited by the commenter, consideration of risk is not a requirement of section 313( f)( 2) for modifying the reporting thresholds for EPCRA section 313 listed chemicals, and, in fact, the consideration of risk is generally not required for any rulemaking under section 313. Troy Corporation v. EPA, 120 F. 3d 277 (D. C. Cir. 1997). Some commenters further state that in proposing to change EPCRA section 313 reporting thresholds, EPA has not addressed any of the factors the Agency mentioned when it originally promulgated EPCRA section 313 regulations. In the February 16, 1988 final rule, EPA stated:

EPA may consider a number of factors for threshold modification including exposure factors such as population density, the distance of population from covered facilities, and the types of releases. Threshold modifications could also take into account the relative potency of the chemical or class of chemicals and effects of concern. (53 FR 4508).

In this statement, the commenters contend that EPA correctly mentions factors that relate to risk (i. e., exposure and relative toxicity). The current proposal to change reporting thresholds under EPCRA section 313 fails to address these factors. As is clearly evident in the quote from the February 16, 1988 final rule, EPA stated that these were things that it `` may consider'' or that could be taken into account. These statements do not require that the possible factors mentioned above be a basis for any change in the reporting thresholds nor do they preclude the consideration of factors such as the persistence and/ or bioaccumulation of toxic chemicals in modifying the reporting thresholds. This statement was not a commitment that EPA would consider risk in any decision to modify reporting thresholds. It merely provided examples of things that the Agency may consider. As explained in previous responses, EPA does not believe that it would be good public policy to consider factors related to quantitative risk with respect to establishing thresholds for PBT chemicals. Given the degree of persistence and bioaccumulation that these toxic chemicals exhibit, EPA believes that the value of this information to the public outweighs the policy considerations presented in favor of considering risk factors in establishing revised thresholds. Any other decision would be inconsistent with the legislative intent underlying EPCRA section 313. Finally, EPA notes that this decision is consistent with the approach adopted in modifying the thresholds to establish a 1 million pound manufacture, process, or otherwise use threshold for facilities that have 500 pounds or less of production related waste (59 FR 61488, November 30, 1994) (FRL± 4920± 5). Any decision to include risk considerations in establishing modified thresholds under section 313( f)( 2) would compel the Agency to re examine the thresholds established for facilities with less than 500 pounds of production related waste. Several commenters contend that a chemical's degree of persistence and bioaccumulation are unrelated to the chemical's exposure potential. They disagree that persistence and bioaccumulation are necessarily indicators of exposure or exposure potential. As an example, the commenter states that many of the compounds EPA is targeting are highly lipophilic, non water soluble 58694 Federal Register / Vol. 64, No. 209 / Friday, October 29, 1999 / Rules and Regulations compounds, and the greatest potential for bioaccumulative effects is through uptake from the water column. EPA should evaluate how these compounds partition in the environment. Those that are not bioavailable have limited exposure potential, and therefore limited risk. Thus, the commenter believes that EPA must consider exposure in conjunction with persistence and bioaccumulation. EPA disagrees with the commenters. All other things being equal, the chemical with a higher degree of persistence and bioaccumulation will have a greater exposure potential than the chemical with a lower degree of persistence and bioaccumulation. For example, all other things being equal, a chemical that has a half life in water of 4 months will have a higher exposure potential to aquatic organisms than a chemical with a half life in water of 1 month. Fifty percent of the first chemical will remain in the water after 4 months while only 12.5% of the second chemical will remain in the water after 4 months. After 4 months, aquatic organisms will be exposed to 4 times more of the first chemical than the second chemical. Clearly the chemical with the greater persistence has the higher exposure potential. EPA does not believe that the commenter's example supports their contention that persistence and bioaccumulation are unrelated to exposure potential. As EPA understands the commenter's example, chemicals that have the greatest bioaccumulation potential will not be bioavailable in water because they are highly lipophilic and non water soluble. Thus, because they are not bioavailable in water, they cannot bioaccumulate in aquatic organisms. A well studied example that clearly contradicts the commenter's claim is the bioaccumulation of polychorinated biphenyls (PCBs) in the Great Lakes. PCBs have BAFs as high as 141,000,000 (Table 1, at 64 FR 707± 8) and very, very low water solubility. PCBs have been found throughout the Great Lakes in sediments, water, and aquatic organisms. Multimedia analyses indicate that the majority (80± 90%) of human exposure to chlorinated organic compounds, such as PCBs comes from the food pathway, a lesser amount (5± 10%) from air, and minute amounts (less than 1%) from water. Most of the data available on human exposure to toxic substances in the Great Lakes come from the analyses of contaminant levels in drinking water and sport fish. The consumption of contaminated sport fish and wildlife can significantly increase human exposure to the Great Lakes critical pollutants. The sport fish are exposed to PCBs by consumption of sediments and in water, from which they bioaccumulate the PCBs (Ref. 62). Some commenters contend that EPCRA requires that EPA consider the risks that a chemical may pose when making determinations to add a chemical to the EPCRA section 313 list of toxic chemicals. In support of this position, one commenter cites two D. C. Circuit Court decisions. As discussed in detail in the final rule adding 286 chemicals to EPCRA section 313 (59 FR 61432), EPA disagrees with commenters that the Agency must include a risk assessment component to EPCRA section 313 determinations. While the Agency believes that there are limited circumstances where it may be appropriate to consider risk in making listing determinations, e. g., acute human health effects, EPA does not believe that the intent of EPCRA, the EPCRA section 313 toxicity criteria, or the legislative history support the contention that risk assessment is a required component of all EPCRA section 313 listing determinations. The EPCRA section 313 toxicity criteria require that exposure and risk factors be considered only when determining if the toxic chemical should be listed on EPCRA section 313 based on its acute human health effects, but even then in only a very limited manner. The statute mandates that EPA consider whether `` a chemical is known to cause or can reasonably be anticipated to cause significant adverse acute human health effects at concentration levels that are reasonably likely to exist beyond facility site boundaries. '' EPA has, and will continue to look at exposures reasonably likely to exist beyond facility site boundaries when making a listing determination pursuant to EPCRA section 313( d)( 2)( A). However, EPA notes that none of the toxic chemicals added in today's action were added pursuant to paragraph (A) of that section. The statute is silent on the issue of exposure considerations for the section 313( d)( 2)( B) and (C) criteria. The language of section 313 does not prohibit EPA from considering exposure factors when making a finding under either section 313( d)( 2)( B) or section 313( d)( 2)( C). However, the language of sections 313( d)( 2)( B) and (C) does not require the type of exposure assessment and/ or risk assessment argued by the commenters. EPA believes that it has the discretion under both section 313( d)( 2)( B) and section 313( d)( 2)( C) to consider, where appropriate, those exposure factors that may call into question the validity of listing of any specific chemical on EPCRA section 313. EPA believes that its position regarding the limited use of risk in listing decisions is consistent with the purpose and legislative history of EPCRA section 313, as illustrated in the following passage from the Conference report:

The Administrator, in determining to list a chemical under any of the above criteria, may, but is not required to, conduct new studies or risk assessments or perform sitespecific analyses to establish actual ambient concentrations or to document adverse effects at any particular location. (H. Rep. 99 962, 99th Cong., 2nd Sess., p. 295 (October 3, 1986)). See also Legislative History at 5186.

This passage indicates that Congress did not intend to require EPA to conduct new studies, such as exposure studies, or to perform risk assessments. Therefore, Congress did not consider these activities to be mandatory components of all section 313 decisions. EPA believes that this statement combined with the plain language of the statutory criteria clearly indicate that Congress intended that the decision of whether and how to consider exposure under EPCRA section 313( d)( 2)( B) and (C) should be left to the Agency's discretion. EPA has carefully considered when and how to use exposure to fully implement the right to know provisions of EPCRA. The Agency believes that exposure should be considered only in very limited circumstances when adding a chemical to EPCRA section 313( d)( 2)( B) or (C). The Agency's interpretation of the section 313( d)( 2) and (d)( 3) criteria for modifying the section 313 list of toxic chemicals is discussed in the final rule adding 286 chemicals to EPCRA section 313 (at 59 FR 61440± 2). And in fact, EPA's interpretation was upheld by the D. C. Circuit in Troy v. EPA, 120 F. 3d 277. The addition of chemicals pursuant to EPCRA section 313( d)( 2)( B) and (C) in today's rulemaking is consistent with this interpretation. The intent of EPCRA section 313 is to move the determination of which risks are acceptable from EPA to the communities in which the releases occur. This basic, local empowerment is a cornerstone of the right to know program. EPCRA section 313 establishes an information collection and dissemination program. It provides the public with information that can be used with other site specific factors to determine if releases into their communities result in risks that the community determines warrant further action given other factors, such as economic and environmental 58695 Federal Register / Vol. 64, No. 209 / Friday, October 29, 1999 / Rules and Regulations conditions, or particularly vulnerable human or ecological populations. In addition, the reference by one of the commenters to two D. C. Circuit Court decisions is misplaced. In support of its position that EPA must undertake a risk assessment of any toxic chemical it is considering to add to EPCRA section 313, the commenter cites American Petroleum Institute v. Costle, 665 F. 2d 1176, 1187 (D. C. Cir, 1981), cert. denied, 455 U. S. 1034 (1982), and Milwaukee Metropolitan Sewerage District v. EPA, 40 F. 3d 392 (D. C. Cir. 1994). As discussed in a previous response in this unit, neither case cited by the commenter addresses EPCRA. In addition, since both cases were decided prior to Troy, by the same court, that decided the specific issue raised by the commenter, nothing in the two earlier cases cited by the commenter can overrule that decision.

G. Which Chemicals is EPA Adding to the List of EPCRA Section 313 Toxic Chemicals? EPA is adding the following chemicals to the EPCRA section 313 list of toxic chemicals: dioxin and dioxinlike compounds, benzo( g, h, i) perylene, benzo( j, k) fluorene (fluoranthene), 3 methylcholanthrene, octachlorostyrene, pentachlorobenzene, tetrabromobisphenol A, vanadium (except alloys) and vanadium compounds. EPA conducted a hazard assessment on each chemical being added to the EPCRA section 313 list of toxic chemicals today. This assessment was separate and independent from the review conducted to determine each chemical's persistence and bioaccumulation potential, although EPA considered some of the same data in certain of its hazard assessments. EPA finds that each chemical being added today meets the criteria for chronic human toxicity and/ or environmental toxicity, as set forth at EPCRA sections 313( d)( 2)( B) and (C). A summary discussion of the basis for listing each of these chemicals as well as other related issue are presented in the remainder of this unit. A more extensive discussion of these issues is included in the Response to Comments document (Ref. 69) and supporting documents. 1. Dioxin and dioxin like compounds category. There were a number of comments received on the addition of the dioxin and dioxin like compounds category and these are addressed in detail in the Response to Comments document (Ref. 69). Most of the comments on the toxicity data that EPA presented in support of the addition of the category concern the dioxin like compounds since most commenters seemed to agree that 2,3,7,8 tetrachlorodibenzo p dioxin (dioxin or 2,3,7,8 TCDD) meets the criteria for listing under EPCRA section 313( d)( 2)( B). A number of commenters did not believe that there was sufficient information to add any of the dioxinlike compounds while several commenters argue that the data on the octa and heptachlorodibenzo p dioxins in particular were not sufficient. Commenters also argue that reliance on established toxicity equivalence factors (TEFs) does not provide sufficient support for determining that the dioxinlike compounds meet the EPCRA section 313( d)( 2)( B) criteria. EPA disagrees with the commenters that contend that there are not sufficient data to add the dioxin like compounds pursuant to EPCRA section 313( d)( 2)( B). 2,3,7,8 TCDD is generally recognized as one of the most studied toxic compounds found in the environment. To require the degree of documentation supporting toxicological classification of 2,3,7,8 TCDD as a necessary criterion for determining that other dioxin like compounds exhibit dioxin like toxicity or for listing under EPCRA section 313 is an arbitrary and unrealistic criteria. As discussed in more detail in the Response to Comments document (Ref. 69), a more scientifically supportable set of criteria for determining if compounds exhibit dioxin like toxicity was proposed by the World Health Organization European Centre for Environmental Health (WHO ECEH) and the International Programme on Chemical Safety (IPCS) consultation group. These criteria include: (1) A compound must show a structural relationship to TCDD; (2) a compound must bind to the Ah receptor; (3) a compound must elicit Ah receptormediated biochemical and toxic responses; and (4) a compound must be persistent and accumulate in the food chain. Each of the 2,3,7,8 substitute dioxins and furans included in the dioxin TEQ approach meet these criteria (Ref. 3). The commenters often quoted from the EPA Science Advisory Board (SAB) review of EPA's draft dioxin reassessment, to help support the claim that dioxin like compounds other than 2,3,7,8 TCDD should not be included in the toxic release inventory. The SAB report is a complex document containing a number of contrasting observations. Care must be taken to accurately capture the SAB's concerns. For example, in their Executive Summary, the SAB concluded that, `` The use of the TEFs as a basis for developing an overall index of public health risk is clearly justified''; they caution, however, `` that practical application depends on the reliability of the TEFs and the availability of representative and reliable data. '' In their summary conclusions, the SAB stated:

The document (EPA Draft Reassessment) represents a departure from the earlier EPA risk assessment for dioxin, which dealt primarily with 2,3,7,8 TCDD. In addressing a broad range of dioxin like compounds having the common property of binding to the Ah receptor and producing related responses in cells and whole animals, it creates opportunities for a holistic assessment of the cumulative impacts of these broadly distributed anthropogenic pollutants. Thus, while the environmental concentrations of each compound alone may be too low to produce effects of concern, the combined exposure may be producing effects that warrant concern. The use of the concept of TEFs and the concentrations of the compounds in foods and environmental media to produce an overall index of public health risk is clearly justifiable.

The character and thrust of these statements made by the SAB are significantly different from those selectively chosen by many of the commenters opposing the addition of some or all of the dioxin like compounds. The apparent contradiction between these broad concluding statements by the SAB and those cited by several commenters is due, in part, to commenters confusing the SAB criticisms of the text of the draft reassessment with statements about the general state of scientific knowledge. The SAB clearly felt that EPA needed to do a more rigorous job of discriminating between the inferences it drew about the toxicity of 2,3,7,8 TCDD, other 2,3,7,8 substitute dioxins and furans, and dioxin like PCBs. Many of the comments cited were intended to help EPA generate a more rigorous scientific discussion in its final reassessment document rather than to represent substantive conclusions reached by the SAB on the nature of dioxin toxicology. Fully taking these concerns into consideration it was still the SAB's overall judgment, as stated above, that `` the use of the TEFs as a basis for developing an overall index of public health risk is clearly justified. '' Some commenters argue that there are qualitative differences in the toxicity of the different 2,3,7,8 substituted isomers of polychlorinated dioxins (PCDDs) and furans (PCDFs). Specifically, there are structural differences between the more toxic, lower chlorinated isomeric PCDDs and PCDFs and the higher chlorinated cogeners to the extent that the octa and hepta PCDDs and PCDFs should not be added to the list of EPCRA section 313 58696 Federal Register / Vol. 64, No. 209 / Friday, October 29, 1999 / Rules and Regulations toxic chemicals. These arguments are not valid for several reasons. First, there are data from subchronic studies for both octa and hepta PCDDS and PCDFs which demonstrate dioxin like effects (Refs. 19, 21, 79, and 80). The new WHO TEFs are based on these subchronic studies (Ref. 78). While short term studies indicate limited dioxin like effects of these chemicals, these contrasting results are readily explained by the structural differences between the octa and hepta PCDDS and PCDFs compared to the lower chlorinated PCDDs and PCDFs. The relative potency of the dioxin like compounds is related to both their ability to bind to the Ah receptor and their pharmacokinetic properties (Ref. 20). The water solubility of PCDDs and PCDFs decrease with increasing chlorine substitution. Hence the octa and hepta PCDDS and PCDFs are significantly less soluble in aqueous solutions compared to the lower chlorinated PCDDs and PCDFs. These solubility problems limit the amount of chemical that can be absorbed in high dose acute toxicity studies. The lack of effect observed in the high dose acute studies is consistent with the limited aqueous solubility of these compounds. However, low dose subchronic studies allow the chemicals to be better absorbed and bioaccumulate to concentrations which produce biochemical and toxic effects (Refs. 19, 21, 79, and 80). Once again this is consistent with the evidence of dioxinlike effects of these chemicals observed in the low dose subchronic studies. Although not legally required to determine that a chemical meets the listing criteria under EPCRA section 313( d)( 2)( B), it should be noted that human exposure to octa and heptaPCDDs and PCDFs are subchronic low dose exposures, similar to the experimental studies which demonstrate dioxin like effects of these chemicals (Refs. 19, 21, 79, and 80). While there are structural differences between the octa and hepta PCDDs and PCDFs compared to the lower chlorinated PCDDs and PCDFs, these differences result in quantitative not qualitative differences in the toxicity of these chemicals. The quantitative differences are demonstrated by the lower potency of the octa and heptacongeners compared to TCDD. In addition, the TEFs reflect these quantitative differences by assigning lower TEF values to the octa and heptaPCDDS and PCDFs. While there is limited evidence that the shape of the dose response curve for induction of CYP1A1 activity in vitro for octachlorodibenzo p dioxin (OCDD) is different from TCDD, in vivo evidence indicates that the dose response for CYP1A1 induction by octachlorodibenzofuran (OCDF) in three tissues is equivalent to TCDD (Ref. 20). However, it should be noted that these are quantitative not qualitative differences. Commenters also argue that octa and hepta PCDDs and PCDFs should not be listed because `` there is a growing consensus in the scientific community that the potential risks posed by dioxins are largely driven by a limited number of dioxin and dioxin like compounds (tetra, penta, and hexa PCDDs and PCDFs and certain coplanar PCBs). '' It is important to remember that, as discussed in Unit VI. F., EPCRA section 313 is primarily a hazard based rather than a risk based statute. The `` growing consensus'' on dioxin toxicity is probably best captured by the revised TEFs recently established by the WHO (Ref. 78). In this review the scientific evidence for ascribing values of relative toxicity to octa and hepta PCDDs and PCDFs was specifically reviewed, as evidenced by the lowering of the TEF for OCDD and OCDF by a factor of 10. In the course of the deliberations by the WHO panel of internationally distinguished scientists, there was the opportunity to remove both octa and hepta PCDDs and PCDFs from the TEF listings. However, the WHO panel concluded that the best scientific interpretation of the data available was to leave hepta PCDDs and PCDFs unchanged and reduce but not eliminate OCDD from TEQ calculations. Even with this reduced toxicity, OCDD and OCDF clearly meet the listing criteria of EPCRA section 313( d)( 2)( B). EPA disagrees with the commenters that contend that TEFs are not adequate support for listing chemicals under EPCRA section 313. The development of TEFs has been a rigorous scientific effort involving a number of international panels of scientific experts and has involved the careful review of all relevant scientific literature. EPA believes that the development and review processes used for the generation of the TEFs was sound and represents a reasoned and reliable judgment on the dioxin toxicity of each of the 17 dioxin and dioxin like compounds. The Response to Comments document (Ref. 69) includes an extensive discussion of the history of the development of dioxin TEFs which demonstrates why EPA believes that the TEFs are well supported scientifically and consequently have been openly adopted by the international scientific and regulatory community. In addition, as EPA has previously explained (59 FR 61432), the Agency believes that EPCRA section 313 allows a chemical category to be added to the list, where EPA identifies the toxic effects of concern for at least one member of the category and then shows why those effects can reasonably be expected to be caused by all other members of the category. Here, individual toxicity data are not available for all members of the category; however, there is sufficient information to conclude based on generally accepted scientific principles, that all of these chemicals are highly toxic based on structural and physical/ chemical property similarities to those members of the category for which data are available. Thus, EPA reaffirms that there is sufficient evidence for adding dioxin and dioxin like compounds on EPCRA section 313 pursuant to EPCRA section 313( d)( 2)( B) based on the available cancer and other serious chronic health effects data for these compounds. Therefore, EPA is finalizing the listing of dioxin and dioxin like compounds on the EPCRA section 313 list. a. Manufacturing only qualifier for dioxins and dioxin like compound category. Comments were mixed with regard to EPA's proposal to add a manufacture only qualifier to the dioxin and dioxin like compounds category. Some commenters agree with EPA's statements in the proposed rule concerning the burden reduction aspects of the qualifier and the fact that as a result, the dioxin reporting would focus on facilities that manufacture dioxin and dioxin like compounds rather than those that process or otherwise use raw materials containing dioxin and dioxin like compounds that have accumulated in those raw materials. Some commenters state that the qualifier would avoid duplicative testing and administrative costs among many processing and using industries which do not necessarily discharge dioxins or furans into the environment. Some commenters state that all releases of dioxin and dioxin like compounds must be reported, not just those resulting from the manufacture of these chemicals. Other commenters note that a significant gap is created by the manufacture only qualifier because it would exclude the processing and otherwise use of chemicals than contain dioxin and dioxin like compounds as a result of the processes used to manufacture them. Commenters specifically cite pentachlorophenol as an example of a chemical that is contaminated with dioxin and dioxinlike compounds from its manufacturing process. Commenters state that the processing and use of such chemicals 58697 Federal Register / Vol. 64, No. 209 / Friday, October 29, 1999 / Rules and Regulations result in the release of dioxin and dioxin like compounds that would go unreported under the manufacture only qualifier. One commenter states that if the qualifier is finalized the commenter would like to see language that requires facilities to report if the background levels of dioxin are modified, concentrated, or somehow added to in the manufacturing process. Another commenter states that if the Agency wants to exempt animal sources of dioxin, such as dioxin contained in meat and other animal products, it should craft the rule to do so and not cut out other significant sources of dioxin in the environment by exempting all facilities that process material containing dioxin. EPA believes that in order to obtain any reporting on dioxin and dioxin like compounds a very low threshold is required, which is several orders of magnitude lower than the thresholds for other PBT chemicals. At such a low reporting threshold it is estimated that thousands of reports could potentially be filed by facilities, mainly food processing facilities, due to the amount of dioxins in the raw materials they process. The dioxins found in the meat and dairy products that food processors handle have been previously released, circulated in the environment, and bioaccumulated in animals; thus these are not additional loadings to the environment but loadings that have already occurred and cycled through the environment due to the persistence and bioaccumulative properties of these compounds. The unique combination of very low thresholds, the number of food processors that would be required to file, and the fact that they would be filing because of the bioaccumulation of previously released material, led EPA to add the manufacture only qualifier to the dioxins category. The qualifier was added in response to the unique set of conditions that apply to the reporting of dioxin and dioxin like compounds. The manufacture only qualifier was added to reduce reporting burden on facilities, mainly in the food processing industry, that results from the unique combination of circumstances related to the reporting for these chemicals and to focus on those activities that add to the loading of dioxins in the environment rather than on activities dealing with previously released and bioaccumulated chemicals. However, EPA acknowledges that the commenters who noted that the processing and otherwise use of chemicals contaminated with dioxin and dioxin like compounds as a result of their manufacturing process, are correct that these would be newly created and thus any releases of dioxin and dioxin like compounds that are due to the processing and otherwise use of such chemicals would be new loadings on the environment. In addition, EPA agrees, and has never stated otherwise, that the processing or use of chemicals contaminated with dioxin and dioxinlike compounds could result in the release of these chemicals to the environment. Given the fact that the manufacture of certain chemicals also results in the manufacture of dioxin and dioxin like compounds that remain with those chemicals as impurities, EPA believes that releases and other waste management quantities for the dioxin and dioxin like compounds found as impurities with those chemicals should be reported under the dioxin and dioxin like compounds category. Thus, EPA's original proposal would have created an exemption that was too broad. Consequently, EPA is modifying the qualifier to read as follows:

Dioxin and dioxin like compounds (Manufacturing; and the processing or otherwise use of dioxin and dioxin like compounds if the dioxin and dioxin like compounds are present as contaminants in a chemical and if they were created during the manufacturing of that chemical)

EPA believes that narrowing its proposal in this fashion is consistent with EPA's intention to focus on new loadings to the environment for dioxin and dioxin like compounds. One commenter states that the activity qualifier for dioxin and dioxin like compounds is intended to minimize the burden of reporting on naturallyoccurring constituents of raw materials and that this qualifier would be consistent with the PBT criteria set forth by Canada's Department of the Environment in their Toxic Substances Management Policy. The commenter states that the Canadian policy requires a chemical to be `` predominantly anthropogenic'' to be considered a PBT chemical. The commenter states that EPA's assumption that these compounds are ubiquitous in raw materials may be incorrect. The commenter further states that these compounds may be formed in combustion processes due to the ubiquitous presence of precursor chemicals in coal, such as natural hydrocarbons and chlorine. The commenter argues that it is not reasonable to expect the hydrocarbon nor the chlorine to be removed from the raw material prior to combustion. Thus, the `` incidental manufacture'' of extremely minute amounts of these chemicals may be unavoidable. EPA disagrees that the sole basis for its qualifier was to minimize the burden of reporting. The qualifier was added in response to the unique set of conditions that apply to the reporting of dioxin and dioxin like compounds. As noted above, EPA was, and remains, concerned that, because dioxin is ubiquitous in the environment, the reporting be focused on those facilities that actually add to the environmental loading of these chemicals. EPA did not state that dioxin and dioxin like compounds would be ubiquitous in all raw material and did not intend to imply that all raw materials contain these compounds. EPA stated that these compounds are ubiquitous in the environment and, thus, facilities that process raw materials containing these compounds might have to report because of the very low reporting threshold necessary to obtain reports from any sources, including those facilities that coincidentally manufacture them. In addition, although the qualifier may be consistent with Canada's Toxic Substances Management Policy, EPA has not proposed any requirement that a chemical must be `` predominantly anthropogenic'' to be considered a PBT chemical under EPCRA section 313. The commenter is correct that dioxin and dioxin like compounds may be manufactured in combustion processes due to the `` ubiquitous presence of precursor chemicals'' and that such `` incidental manufacture'' may be unavoidable. However, the mere presence of the dioxin precursors will not guarantee dioxin production. There are well documented conditions that favor the formation of dioxins during combustion, and in some cases it may be possible to stringently control fuel composition, flow times, temperature, and other conditions in order to substantially reduce or even eliminate the incidental manufacture of dioxins during combustion processes. b. Withdrawal of the proposal to include dioxin like PCBs in the dioxin category. Several commenters support EPA's decision to withdraw the proposal to modify the current PCB listing and move the 11 co planar PCBs to the proposed dioxin and dioxin like compounds category and retain the coplanar PCBs as part of the current PCB listing. Two commenters support EPA's decision to leave co planar PCBs out of the dioxin and dioxin like compounds category since the structure, metabolism, gene regulation, and toxicities of PCBs are substantially different from those of 2,3,7,8 tetrachlorodibenzo p dioxin. One commenter takes exception to the use of the term `` dioxin like'' as a way of describing PCBs and other chlorinated 58698 Federal Register / Vol. 64, No. 209 / Friday, October 29, 1999 / Rules and Regulations compounds and agrees that the PCBs should be kept out of the `` dioxin like'' class. Other commenters also argue that PCBs are more appropriately classified as PCBs, not dioxin like compounds. One commenter contends that since these chemicals are no longer allowed to be distributed in commerce, maintaining a separate EPCRA section 313 chemical category for these chemicals will streamline data management. This approach will also enable EPCRA section 313 reporting for this category of chemicals to be more consistent with existing data already collected for the purposes of complying with TSCA. Further the commenter asserts that approach is also consistent with EPA's Reinvention Policy and will enable `` one stop'' reporting. Another commenter asserts that it is unclear just how many grams of dioxinlike compounds would be excluded from this reporting since there are conflicting Agency proposals at work: the first is a much lower threshold for dioxins. The second includes only dioxins manufactured on site. Since PCBs are not generally manufactured on site, these 11 dioxin like compounds would not be reported under the proposal if they were included as dioxins. On the other hand, if all dioxins (manufactured, processed, and otherwise used) are included in the EPCRA section 313 threshold determination, these 11 PCBs could make the difference between a facility's reporting or not reporting dioxins. If the dioxin threshold remains as proposed, then the 11 PCBs should remain with the PCB category. Further the commenter argues that if the threshold is expanded to include sources other than those that manufacture dioxin onsite then the PCBs should be part of the dioxin like compounds category. If EPA does not modify the dioxin threshold to include all dioxin uses, the 11 dioxinlike PCBs should remain with the PCB category. While EPA agrees with the commenters that the co planar PCBs should remain as part of the current PCB listing, the Agency does not agree with all of the reasons the commenters have presented. As EPA stated in the proposed rule:

. . .EPA has determined that all PCBs persist and bioaccumulate. Since PCBs persist and bioaccumulate, EPA believes that they should be subject to lower reporting thresholds, and thus there is no need to move the 11 co planar PCBs to the proposed dioxin and dioxin like compounds category. Therefore, EPA has decided to withdraw its proposal to modify the current listing for PCBs and instead proposes to lower the reporting thresholds for the current PCB listing which covers all PCBs. EPA believes that, since all PCBs persist and bioaccumulate, it is appropriate to lower the reporting threshold for this class of chemicals and that this proposal is less burdensome than requiring separate reporting on the dioxin like PCBs as part of the proposed dioxin and dioxin like compounds category (at 64 FR 710).

EPA did not base its decision on a determination that co planar PCBs were not `` dioxin like'' and keeping them under the current PCB listing should not be interpreted as such a determination. Also, since EPA is not expanding the qualifier for the dioxin and dioxin like compounds category to include all processing and otherwise use activities, the amounts of co planar PCBs that might be reportable under the category would not be expected to contribute significantly to threshold determinations for the category at most facilities. Four commenters specifically do not support EPA's decision to withdraw the proposal to modify the current PCB listing. Commenters assert that the aggregation of dioxin like PCBs together with other PCBs will fail to provide reporting of useful information on dioxin like PCBs. The commenters either contend that the PCBs should be included in the dioxin like compounds category or the PCBs and all dioxin like compounds should be reported separately. One commenter argues that the aggregate reporting of dioxin like PCBs and other PCBs fails to provide any information on the release of dioxin like PCBs to meet the research, regulatory, or public information goals of EPA's proposal. This commenter raises several points. The commenter contends that specifically, even if some facilities releasing dioxin like PCBs reported these releases as a portion of their total PCBs production of 10 pounds annually or greater, information on dioxin like PCBs releases would still be unobtainable. The commenter asserts that aside from the food chain, where some dioxin like PCBs tend to concentrate disproportionately, available measurements indicate that these dioxin compounds are only a small portion of the mass of all PCB compounds. The commenter further argues that some of these dioxin compounds such as PCB 126 are far more toxic than other dioxin like and non dioxin like PCBs. Thus, the commenter asserts that in addition to all of the problems of dioxin like chemical aggregate reporting, one would not know what, if any, portion of the total PCBs reported were dioxin like. The commenter contends that the dioxinlike co planar PCBs also should be reported individually so that a TEQ for all 28 dioxin and dioxin like compounds can be calculated. Another commenter argues that based on information about current body burdens of co planar PCBs, they compose as much or an even greater percentage of one's overall exposure than the 17 dioxin and dioxin like compounds. This commenter cites an EPA document that stated that: ``[ e] stimates of exposure to dioxin like CDDs and CDFs based on dietary intake are in the range of 1 3 pg TEQ/ kg/ day. Estimates based on the contribution of dioxin like PCBs to toxicity equivalents raise the total to 3 6 pg TEQ/ kg/ day. '' Some commenters contend that reporting the co planar PCBs differently from the 17 dioxin and dioxin like compounds would make any assessment of the overall release and potential health impact of these types of compounds difficult. One commenter argues that PCBs are currently contaminating sediments and industrial sites nationally and have ruined fish as a natural resource for human consumption across the nation and that the distinction between dioxin like PCBs and dioxin like compounds made under this rule is a distinction without a difference. This commenter urges EPA to include all dioxin like compounds, including PCBs, in the dioxin like compounds category and to require strict accounting from all sources which release these compounds and which manufacture them, incidentally or by design. One commenter contends that the failure to report dioxin like PCBs as a distinct entity separate from other PBT chemicals may hold back information on a significant portion of the total dioxin like hazard from releases by facilities that report under EPCRA section 313, even if all dioxin and furan releases were reported. The commenter argues that environmental exposure measurements, such as those from fish in San Francisco Bay and from human tissues nationally, indicate that dioxinlike PCBs contribute a very significant portion of the total toxicity hazard from exposure to all dioxin like chemicals. The commenter also asserts that PCB releases might in some cases represent an inadequately measured yet significant portion of the ongoing dioxin release hazard. If, for example, PCB 126 comprises even 1 ¤10 of the PCBs release measured from San Francisco Bay Area sources, it would contribute substantially to total dioxin like toxicity emission from some of these facilities. The commenter contends that the failure to provide release information on dioxin like PCBs under EPA's proposal 58699 Federal Register / Vol. 64, No. 209 / Friday, October 29, 1999 / Rules and Regulations may result in failure to inform the public about a significant portion of the total dioxin toxicity that is still released. EPA agrees that PCBs are toxic chemicals of concern that have caused significant contamination of the environment and that co planar PCBs may have dioxin like health effects. However, this does not, in itself, create a requirement that the co planar PCBs must be moved from their current PCB listing to the dioxin and dioxin like compounds category. EPA does not believe that the co planar PCBs must be reported separately from the non coplanar PCBs because they may be more toxic than other PCBs. In general, chemical categories consist of chemicals that vary in their level of toxicity but this variability alone does not mean that release information must be reported separately for each chemical in the category. EPA believes that all PCBs are of concern and that leaving the coplanar PCBs under the current PCB listing will still provide the public with useful and important information. In deciding not to move the co planar PCBs to the dioxin category, EPA also considered any potential additional burden associated with splitting the reporting for PCBs into two different listings, as well as the fact that facilities are not likely to be able to determine quantities of the specific co planar PCBs in question. Specifically, EPA considered the lack of readily available estimation techniques for determining quantities of co planar PCBs, as opposed to other PBT chemicals and the PCB listing as a whole (co planar PCBs will be included in the estimation of PCBs). EPA determined that since all PCBs are of concern and since the reporting threshold for all of the PCBs under the PCB listing would be lowered substantially, that requiring separate reporting on the co planar PCBs was not warranted. One commenter contends that the failure to report dioxin like PCBs would fail to provide information on that subgroup of dioxin like compounds for which there is the greatest need for additional information. The commenter argues that EPA's evaluation of the emission of dioxin like chemicals nationwide shows that there is less information on releases of dioxin like PCBs than there is for other dioxin compounds. The commenter asserts that similarly, their survey of source information in the San Francisco Bay Area shows that, despite many measurements of dioxin and furan releases, and despite a handful of source measurements confirming PCBs, there are few or no source measurements for dioxin like PCBs. The commenter argues that the information on releases from facilities is even less available for the dioxin like PCBs than it is for the other dioxin like chemicals and that EPA's analysis in the proposed rule fails to consider adequately this extreme need for source release information. EPA agrees that there is far less information available on co planar PCBs than for dioxin and other dioxin like compounds. Much less testing and analysis has been conducted for these chemicals. This would pose an additional problem for reporting on the co planar PCBs separately from the other PCBs. EPA considered the ability to estimate quantities of specific coplanar PCBs and determined that there is a lack of readily available estimation techniques for co planar PCBs. In fact, at this time, the Agency would not be able to provide guidance for making a reasonable estimate of quantities of coplanar PCBs that may be manufactured in certain processes. In addition, EPCRA section 313 does not require any additional monitoring beyond that required by other provisions of law so listing the co planar PCBs separately would not mean that additional source measurements would be developed. Thus, listing under EPCRA section 313 will not require the development of additional monitoring data that could be used to make reasonable estimations of thresholds or releases and other waste management quantities. Given the lack of information available for estimating quantities of co planar PCBs and the potential additional burden associated with splitting the reporting for PCBs into two different listings, EPA decided to leave the co planar PCBs under the current PCB listing. One commenter asserts that the burden on industrial producers of dioxin like PCBs is not an appropriate reason for excluding dioxin like PCBs from the dioxin and dioxin like compounds category because this will not meet EPCRA's right to know goal for dioxin like PCBs. The commenter contends that EPA's cost analysis does not address dioxin like PCBs specifically and thus, EPA's rationale in Unit VI. of the preamble of the proposed rule (64 FR 688) that `` this proposal is less burdensome than requiring separate reporting on the dioxin like PCBs'' is not based on any cost analysis in EPA's proposal. The commenter argues further that in any case, aggregate reporting of dioxin like PCBs with a 10 pound threshold will fail to obtain the required reporting on a substantial majority of dioxin like PCBs or to provide needed information about dioxin like PCB releases and therefore, EPA's perceptions regarding reporting burden cannot properly outweigh the public's need for the information which is denied under EPA's new proposal. The commenter refers to the proposal to retain dioxin like PCBs under the PCB listing as the `` less than 10 pounds exemption. '' The commenter asserts that existing evidence demonstrates that many dioxin producing processes such as waste incinerators, oil fired boilers, and other processes also produce potentially significant amounts of PCBs which are released to the environment from these facilities. The commenter argues that this evidence suggests that at least some facilities reporting under EPCRA section 313 are likely to be releasing dioxin like PCBs as a portion of these PCB releases. The commenter contends that the evidence also suggests that most or all releases of dioxin like PCBs at these facilities may be associated with total annual PCB production of less than 10 pounds per facility and thus, EPA may not meet the requirement that a substantial majority of dioxin like PCBs be reported under this exemption. Reporting burden was not the sole or even most important factor in EPA's decision not to move the co planar PCBs to the dioxin and dioxin like compounds category. In reaching its final decision, EPA considered the fact that additional information would be collected on all PCBs by lowering the threshold for the PCB listing and that the additional information that would be collected was sufficient for EPCRA section 313 purposes, as well as less burdensome. Even in its proposal EPA did not conclude that reporting burden alone outweighed the public's right toknow about chemical releases. As stated in other responses to this issue, EPA is also concerned about the ability to estimate quantities of specific co planar PCBs since there is a lack of readily available estimation techniques for coplanar PCBs. It is correct that EPA did not attempt to quantify the reduction in burden that would result from not including the co planar PCBs in the dioxin and dioxin like compounds category. However, EPA believes that it would be inherently less burdensome since facilities would not have to attempt to determine if they can estimate co planar PCBs separately and filing one form would obviously be easier and less confusing than attempting to track and adjust the amounts that must be applied to two different listings and filing two reports. With regard to the issue of obtaining reporting on a substantial majority of `` dioxin like PCB'' releases, as stated in EPCRA section 313( f)( 2), the 58700 Federal Register / Vol. 64, No. 209 / Friday, October 29, 1999 / Rules and Regulations determination of whether a revised threshold meets the `` substantial majority'' standard is measured against the `` total releases of the chemical at all facilities subject to the requirements of this section. '' As EPA stated in the proposed rule:

For purposes of determining what constitutes a `` substantial majority of total releases'', EPA interprets `` facilities subject to the requirements'' of section 313 as the facilities currently reporting, ... (at 64 FR 689).