EPA disagrees with the commenters' suggestion that the OPP RED for pendimethalin concludes that it does not meet the EPCRA 313 persistence criteria. As stated in an earlier response, `` moderate'' persistence has no relevance in the context of the proposed rule. A chemical is considered persistent if it has half lifes of 2 days in air or 2 months in soil, sediment, or water, respectively. The commenter implies that OPP has concluded that pendimethalin does not meet the persistence criteria by selectively citing the OPP RED while failing to acknowledge other information OPP discussed in the document confirming the persistence of pendimethalin. OPP did not make any formal summary conclusions regarding the overall environmental persistence of pendimethalin. The commenter has selectively cited from the RED by taking a few comments out of context while ignoring additional findings which demonstrate that pendimethalin meets the persistence criteria. The first statement cited by the commenter addresses dissipation in the environment. Two of the three processes (soil binding and volatilization) responsible for dissipation do not result in the destruction of the chemical and cannot be directly related to persistence. Volatilization results in the relocation of the chemical to the atmosphere. Binding to soil does not destroy pendimethalin and under some soil conditions has been shown to increase persistence. While microbial metabolism of pendimethalin can result in its destruction, it has been shown to be a slow process under many environmental conditions. The commenter cites OPP's qualitative description of the persistence of pendimethalin in aerobic soil environments as slight to moderate. This does not serve as, nor did OPP intend for this statement to represent, a quantitative description of pendimethalin's persistence in soil. OPP does not attempt to relate this characterization to a numeric range of persistence values in the RED, and the 58718 Federal Register / Vol. 64, No. 209 / Friday, October 29, 1999 / Rules and Regulations commenter does not provide a rationale for concluding that OPP's language indicates that pendimethalin does not meet the EPCRA section 313 persistence criteria. The final sentence of the citation points out factors that decrease persistence, but a more detailed reading of the RED on the subject of pendimethalin persistence in aerobic soils reveals that its persistence increases as temperature and soil moisture decrease, and soil organic carbon increase. The commenter performed a Level III EQC Multimedia Modeling assessment for pendimethalin assuming `` best case, reasonable case, and worst case'' scenarios. The calculated overall environmental persistence was determined for pendimethalin to be 5 days, 58 days, and 142 days under the `` best, reasonable, and worst case'' scenarios, respectively. The results of the multimedia model indicated that pendimethalin will have a persistence in the environment of less than 2 months, assuming a reasonable case scenario. The commenter claims that multimedia modeling results indicate that pendimethalin will not be persistent according to the EPCRA section 313 persistence criteria. The commenter notes that the values it calculated using the EQC model are much lower than the 30 days and 487 days calculated for EPA (Ref. 51) assuming best case and worst case scenarios. The commenter alleges that EPA assumed that half lifes in soil, sediment and water were identical, 54 days and 1,322 days, respectively (Ref. 7). The data presented above, however, indicate that these were erroneous assumptions. The half lifes for pendimethalin dissipation in water, soil, and sediment are not identical, and the 1,322 day half life is an outlier. The commenter concludes that pendimethalin will have a low to moderate persistence whether found in the air, water, soil, or sediment compartments of the environment. The commenter asserts that this is supported by field and laboratory degradation studies, multimedia modeling, and EPA's FIFRA registration environmental assessment of pendimethalin. Therefore, pendimethalin should not be classified as persistent for purposes of inclusion on the EPCRA section 313 list of PBT chemicals. EPA disagrees that pendimethalin will have low persistence in the environment whether laboratory and field studies or multimedia modeling are considered. Multimedia mass balance models offer the most convenient means to estimate overall environmental persistence from information on sources and loadings, chemical properties and transformation processes, and intermedia partitioning. For the chemicals included in the proposed rule, EPA used a modified version of the EQC model (Ref. 33) to estimate overall environmental persistence. Overall persistence estimated in this way is used as an additional factor, in conjunction with reaction half lifes for individual media, bioaccumulation/ bioconcentration factors, in justifying the determination made by EPA in this rule. The EQC model is based on the fugacity approach first delineated by Mackay (Ref. 31) and subsequently applied to numerous environmental processes (Ref. 32). It uses an `` evaluative environment'' in which environmental parameters such as bulk compartment dimensions and volumes (e. g., total area, volume of soil and sediment, etc.) are standardized, so that overall persistence for chemicals with different properties and rates of transformation may be compared on an equal basis (Ref. 15). EPA used a version of the EQC level III model (Ref. 33) which was modified to focus on net losses by deleting model terms for advective losses (movement out of the evaluative environment of air and water potentially containing a chemical) and sediment burial (Ref. 82). In this version of the model only irreversible transformation contributes to net loss of a chemical. The overall persistence obtained from this model is calculated as the total amount in the evaluative environment when steady state is achieved, divided by the total loss rate. The results thus obtained are neither an overall environmental half life nor a compartment (or transformation) specific half life; rather they are equivalent to an environmental residence time. When only irreversible transformation contributes to net loss

i. e., under the conditions of this version of the EQC model overall environmental persistence times can be converted to half lifes by multiplying the former by ln 2 (i. e., 0.693). The overall half life calculated in this way is for dissipation in the environment as a whole and cannot be related directly to any individual compartment. The commenter selected mediaspecific environmental half lifes for use as input to the EQC model. The values were characterized as `` best, '' `` reasonable'' and `` worst'' case. No justification was given for this classification. It appeared that the shortest half lives were categorized as `` best case. '' Based on the information provided by the commenter, it was not always possible to determine whether the half lifes for soil or water selected by the commenter for use as input to the EQC model were for destruction of chemical, or its dissipation from the medium. As noted previously, dissipation half lifes do not necessarily represent destruction of the chemical since non destructive transport processes such as volatilization can be responsible for loss from the medium. Their use in multimedia modeling could potentially underestimate overall environmental persistence. This is particularly important since the modified EQC model predicted that greater than 90% of the pendimethalin would partition to soil at steady state. If a soil half life based on loss from soil by nondestructive processes was used rather than one based on the destruction of pendimethalin, its persistence would have been underestimated. In its modeling of the overall environmental persistence of pendimethalin EPA used the highest, lowest and mean values for the ranges of media specific half lifes from valid studies as inputs to the modified EQC model, not the highest and lowest as stated by the commenter. These included a half life for pendimethalin in soil of 1,322 days. EPA determined that the study was properly conducted and chose the half life value of 1,322 days for soil because it represented the most environmentally protective half life derived from a valid study. The calculated overall environmental persistence half lifes were 1 month, 8 months, and 16 months based on the highest, mean, and lowest half lifes, respectively. For chemicals in this rulemaking, EPA considered the multimedia modeling EQC results in characterizing persistence in the overall environment. EPA only intended to use multimedia modeling results to override the medium specific persistence data in limited circumstances, e. g., only if all model inputs are judged to be accurate (and, as noted above, the commenter's inputs cannot be determined to be accurate). But even if EPA were to use the EQC model to assess persistence, pendimethalin would be considered persistent because, with the EPA inputs described above, EQC overall environmental persistence half lifes were calculated to be greater than 6 months using the mean and maximum air, soil, and water half lifes calculated. In response to this comment (even though it was unclear whether the commenter was basing its assertion on degradation data or dissipation data), EPA conducted a new EQC assessment for pendimethalin using the same halfVerDate 58719 Federal Register / Vol. 64, No. 209 / Friday, October 29, 1999 / Rules and Regulations life inputs selected by the commenter. The calculated overall environmental persistence half life was greater than 2 months using the longest half lifes provided by the commenter for air, soil, water, and sediment. These results support EPA's assertion that the persistence of pendimethalin in the environment meets the EPCRA section 313 persistence criteria. The commenter argues that the scientifically based risk assessments conducted on pendimethalin as a part of the pesticide registration process should not be ignored, and that EPA should review pesticide PBT chemical classifications with EPA registration information to ensure an accurate analysis has been performed. The commenter notes that EPA has determined through the review of a complete set of studies that this material used at an approximate rate of 1.0 to 2.0 pounds of active ingredient per acre does not present an unreasonable risk to human health or the environment, that low levels of pendimethalin in manufacturing wastewater releases do not pose an unacceptable risk to the environment, and that reported EPCRA section 313 air releases do not pose a significant risk to human health or the environment. The commenter concludes that based on the weight of evidence it is clear that releases of pendimethalin from manufacturing do not pose a significant threat to human health and the environment and that pendimethalin should not be branded as having a high potential for harm as indicated by the proposed listing as a PBT chemical and lowering of the reporting threshold. EPA disagrees that the risk assessments cited by the commenter are relevant to the characterization of pendimethalin as a PBT chemical. The characterization of chemicals as PBT chemicals for the purpose of this rule are based on intrinsic physical chemical properties. Risk is not an intrinsic property of a substance, but rather the result of the combination of intrinsic hazard (toxicity) a substance possesses and the exposure to a target organism under a defined set of circumstances. It is possible for a substance to present a risk under one set of exposure conditions, but not another. In contrast, a substance characterized as a PBT chemical will remain a PBT chemical, regardless of the exposure to it or its levels in the environment. (See Unit VI. C.) Toxic chemicals that persist and bioaccumulate are of particular concern because they remain in the environment for significant periods of time and concentrate in the organisms exposed to them. Furthermore, these PBT chemicals can have serious human health and environmental effects resulting from low levels of release and exposure. EPA believes that the substances subject to this rule have been characterized as PBT chemicals using scientifically sound indicators based on the intrinsic properties of the substances. The PBT characterization is independent of the risk the substance may pose under a given set of circumstances. These substances have been characterized as persistent, bioaccumulative and toxic and, therefore, meet the criteria for lowered reporting thresholds. Further, FIFRA requires the Agency to determine that pesticidal uses of a chemical do not cause `` unreasonable adverse effects on the environment, '' which is defined in FIFRA section 2( bb) as `` any unreasonable risk to man or the environment taking into account the economic, social, and environmental costs and benefits of the use of pesticides'' (7 U. S. C. section 136( bb)). FIFRA is a regulatory statute, and the impacts of regulation can be immediate and direct (e. g., banning of a chemical), and as such EPA examines not only the hazards presented by the chemical, but also the specific exposure scenarios, and weighs the risks against the benefits of the chemical. The `` unreasonable adverse effects'' determination under FIFRA is specific to the intentional use of the chemical as a pesticide and does not address other uses or releases of the chemical that may result from manufacture, processing, or other use. Furthermore, a determination under FIFRA that the use of a chemical will not result in an `` unreasonable adverse effect'' is not a determination that the chemical is not hazardous or persistent or that the use of the chemical is without risk, but merely that the benefits of agricultural use as a pesticide outweigh its risks as an agricultural pesticide or that the pesticide chemical residues on food or feed meet the standards of section 408 of the Federal Food, Drug, and Cosmetic Act. EPCRA section 313 was not enacted to serve the same purpose as FIFRA. Listing on EPCRA section 313 provides communities with some of the information required to determine what risks may result from the manufacture, processing, and use of a chemical, and to allow local communities to determine for themselves whether such risks are acceptable, information not provided under FIFRA. h. Toxaphene. In the proposal, EPA preliminarily determined that toxaphene has persistence half life values in soil of 1 to 11 years and a persistence half life value in water of 1 to 5 years. EPA has reviewed information and all comments received on toxaphene's persistence characteristics. Taking into account this information, as indicated in Table 3, EPA finds that toxaphene persists in the environment with a half life of 2 months or greater and therefore meets the persistence criterion established in this rulemaking. A complete discussion of EPA's findings on this chemical can be found in EPA's Response to Comments document for this rulemaking (Ref. 69) and/ or in EPA's support documents for this rulemaking. (Ref. 7). In addition, toxaphene persists in the environment with a half life of greater than 6 months which supports EPA's decision to lower the threshold to 10 pounds. i. Trifluralin. In the proposal, EPA preliminarily determined that trifluralin has persistence half life values in soil of 99 to 394 days and a persistence halflife value in water of 5 to 37 days. EPA has reviewed information and all comments received on trifluralin's persistence characteristics. Taking into account this information, as indicated in Table 3, EPA finds that trifluralin persists in the environment with a halflife of 2 months or greater and therefore meets the persistence criterion established in this rulemaking. A complete discussion of EPA's findings on this chemical can be found in EPA's Response to Comments document for this rulemaking (Ref. 69) and/ or in EPA's support documents for this rulemaking (Ref. 7). j. Polycyclic aromatic compounds. In the proposal, EPA preliminarily determined that PACs have persistence half life values in soil that ranged from 20 days to 13 years. All but a few had half lifes well in excess of 6 months. These chemicals had persistence halflife values in water that ranged from 79 days to 44 years. EPA received one significant comment addressing the persistence potential of PACs, which is discussed below. EPA has reviewed information and all comments received on PACs' persistence characteristics. Taking into account this information, as indicated in Table 3, EPA finds that PACs persist in the environment with half lives of 2 months or greater and therefore meet the persistence criterion established in this rulemaking. A complete discussion of EPA's findings on this chemical category can be found in EPA's Response to Comments document for this rulemaking (Ref. 69) and/ or in EPA's support documents for this rulemaking (Ref. 7). One commenter contends that EPA has incorrectly ignored biotreatment 58720 Federal Register / Vol. 64, No. 209 / Friday, October 29, 1999 / Rules and Regulations studies in evaluating persistence for PACs. EPA has also ignored a large body of recent research on sequestration and other phenomena that collectively act to reduce the bioavailability of soil contaminants, such as PACs. Biotreatment studies include activated sludge or other wastewater treatment studies. As EPA stated in the proposed rule (at 64 FR 700), the reason for excluding such studies is that wastewater treatment in general and activated sludge in particular represent conditions that are far removed from ambient (surface) waters, soils, and sediments. Data on environmental fate and persistence of substances in wastewater and activated sludge normally cannot be extrapolated to the other conditions. The commenter seems most concerned about land biotreatment (bioremediation) studies, but in fact goes well beyond the concept of treatability, appearing to infer that EPA has ignored all biodegradation studies of PACs. However, this is incorrect because all mixed culture biodegradation studies other than activated sludge tests i. e., field tests as well as lab studies that used authentic soil, water and/ or sediment grab samples were considered in determining persistence for all of the listed substances. The commenter also discusses recent research indicating that bioavailability of a substance may decline with time of incubation in soil, and suggests that EPA should include `` reasonable bioavailability factors'' in its determination of persistence. As an example of why this is relevant, there has been a concern that Superfund site remediation actions may be mistargeted if they are based on residues released from the soils by vigorous extraction procedures, since chemical substances in soil may become nonbioavailable yet still be extractable for analytical purposes. Additionally, bioremediation may fail to destroy all of a substance that such analysis shows is present, if some portion is sequestered in a nonbioavailable state. Further, the commenter contends that chemicals (including many PACs) are not bioavailable if the bioavailability is considerably less than 100%. The commenter does further specify a numerical bioavailability criteria. The commenter over generalizes from the research findings, using selective citation and quotation from the literature to give the impression that all is now known and any substance released to soil is as good as gone toxicologically speaking. Other reports can be quoted to the effect that the many factors determining bioavailability, sequestration, etc. are far from completely resolved, and deserve much further research. Moreover, sequestration does not necessarily imply non bioavailability. For example, in a study of PAC sequestration and bioremediation, Tang et al. (Ref. 51a) state that:

The results of the present study suggest that extensive biodegradation by microorganisms does not necessarily remove all of the fraction of an aged compound that is bioavailable since some uptake by worms occurred even after the laboratory scale bioremediation. . . .it is also possible that a portion of a compound that is sequestered is available to different degrees to dissimilar organisms. . . .It may be that the mass of material that becomes sequestered should be considered as existing in two forms. One form may be unavailable to all organisms because it is physically remote and thus inaccessible. The second form may be differentially available, and its assimilation, toxicity, and/ or biodegradation may depend on the properties of the species and its ability to mobilize the molecules from this nonremote location. [There is] danger if it is assumed that the disappearance of lethality denotes the absence of bioavailability.... The point is reinforced by the case of DDT, which is sequestered in soil (13) and whose lethality to insects totally disappears as a result of such sequestration (5), yet a portion of that insecticide was still assimilated by earthworms introduced into soil that was treated in the field with DDT more than 40 years before the bioassay was performed. . . .( emphasis added)

And in a similar paper on DDT and dieldrin, Robertson and Alexander (Ref. 43a) state that:

The significance of soil properties in controlling sequestration is evident in the early observation that the degree of sequestration of lindane after 22 months was greatest in a muck, intermediate in extent in a loam, and least in a sandy loam (11). Thus, soil properties must be considered in attempting to predict the bioavailability of persistent compounds. It is also evident from the data presented herein that the bioavailability of a sequestered toxicant varies with the exposed species. Thus, the declines in toxicity of aged DDT and dieldrin to the three test insects were quite different; whereas the lethality of the sequestered compound to one species had almost disappeared, it still was effective against a second. (emphasis added)

The conclusion is manifest: it is that although chemical substances released to soil may become sequestered over time, it cannot be assumed that this process necessarily leads to nonbioavailability even when the time horizon is years. Site and speciesspecific factors, as well as substance properties, are important in determining bioavailability. Therefore, it is appropriate to be concerned about the bioavailability in soil and sediment of PACs and other substances that meet the PBT criteria established for this rulemaking. Further, there is no scientific reason why a chemical can only be considered bioavailable if its bioavailability approaches 100%. The degree of bioavailability will vary depending upon the environmental conditions. In addition, as noted above the degree of bioavailability will also be species dependent. Therefore, EPA believes that the commenter's approach is overly simplistic. k. Benzo( g, h, i) perylene. In the proposal, EPA preliminarily determined that benzo( g, h, i) perylene has persistence half life values in soil of 173 days to 1.8 years and persistence halflife values in water of greater than 100 days. EPA has reviewed information and all comments received on benzo( g, h, i) perylene's persistence characteristics. Taking into account this information, as indicated in Table 3, EPA finds that benzo( g, h, i) perylene persists in the environment with a halflife of 2 months or greater and therefore meets the persistence criterion established in this rulemaking. A complete discussion of EPA's findings on this chemical can be found in EPA's Response to Comments document for this rulemaking (Ref. 69) and/ or in EPA's support documents for this rulemaking. (Ref. 7). In addition, benzo( g, h, i) perylene persists in the environment with a half life of greater than 6 months which supports EPA's decision to lower the threshold to 10 pounds. 1. Mercury and mercury compounds. Because metals may convert to different oxidation states but can never be destroyed, all metals meet the 6 months half life criterion automatically. EPA received a few significant comments addressing mercury and mercury compounds' persistence. These are discussed below. EPA has reviewed information and all comments received on mercury and mercury compounds' persistence characteristics. Taking into account this information, as indicated in Table 3, EPA finds that mercury and mercury compounds persist in the environment with half lives of 2 months or greater and therefore meet the persistence criterion established in this rulemaking. A complete discussion of EPA's findings on this chemical category can be found in EPA's Response to Comments document for this rulemaking (Ref. 69) and in EPA's support documents for this rulemaking (Ref. 7). In addition, mercury and mercury compounds persist in the environment with a half life of greater 58721 Federal Register / Vol. 64, No. 209 / Friday, October 29, 1999 / Rules and Regulations than 6 months which supports EPA's decision to lower the threshold to 10 pounds. One commenter asserts that EPA should not classify all forms of mercury as persistent. The commenter agrees that Hg (0) is properly characterized as persistent. However, the commenter contends that EPA is incorrect in characterizing Hg (II) as persistent because it is removed rapidly from the atmosphere via wet and dry deposition. EPA believes that the commenter confuses residence time with half life; these terms do not represent equivalent processes. There is a distinction between atmospheric `` half life, '' which is the amount of time necessary for half of the chemical present to be destroyed in the medium, and atmospheric `` residence time'' which is the length of time a chemical resides in a particular environmental medium. For the purposes of this rule `` half life'' includes only irreversible chemical transformations resulting in the destruction of chemical whereas `` residence time'' includes factors such as transport of the substance to another medium, for example, wet and dry deposition, sorption, complexation or sequestration; and reversible changes in speciation (i. e., oxidation reduction reactions). EPA agrees that Hg (0) has an average `` residence time'' in the atmosphere of about 1 year and that Hg (II) may be deposited relatively quickly by wet and dry deposition processes, leading to a `` residence time'' of hours to months (Ref. 42a). But the shorter residence times noted for Hg (II) are due to physical transport from the medium, rather than irreversible transformations resulting in the destruction of chemical. Hg (0) released to the atmosphere is rapidly converted to Hg (II) through ozone mediated oxidation. However, this is not an irreversible reaction, nor does it result in the destruction of the substance since the Hg (II) produced from oxidation of Hg (0) by ozone can be reduced back to Hg (0) by sulfite (Ref. 28a). The persistence of mercury will not be mitigated simply by redox reactions of Hg (0) to and from Hg (II). Whether as Hg (0) or as Hg (II), mercury persists in the environment. Environmental processes may cause it to change oxidation states or to be transported from one environmental medium to another; however, these processes will not destroy it. EPA agrees that the report cited provides reasonable estimates of the fraction of mercury emissions from each source category that is likely to be in the form of Hg (II) versus the fraction as Hg (0). However, this information is not relevant to the assessment of the persistence of mercury and mercury compounds because persistence considers destruction only. m. Polychlorinated biphenyls. In the proposal, EPA preliminarily determined that polychlorinated biphenyls (PCBs) have persistence half life values in soil that ranged from 1 to 7 years and persistence half life values in water that ranged from 56 to 98 days. EPA has reviewed information and all comments received on PCBs' persistence characteristics. Taking into account this information, as indicated in Table 3, EPA finds that PCBs persist in the environment with half lifes of 2 months or greater and therefore meet the persistence criterion established in this rulemaking. A complete discussion of EPA's findings on this chemical listing can be found in EPA's Response to Comments document for this rulemaking (Ref. 69) and/ or in EPA's support documents for this rulemaking (Ref. 7). In addition, all of the PCBs persist in the environment with a halflife of greater than 6 months which supports EPA's decision to lower the threshold to 10 pounds. n. Hexachlorobenzene. In the proposal, EPA preliminarily determined that hexachlorobenzene has persistence half life values in soil of 3 to 6 years. EPA has reviewed information and all comments received on hexachlorobenzene's persistence characteristics. Taking into account this information, as indicated in Table 3, EPA finds that hexachlorobenzene persists in the environment with a halflife of 2 months or greater and therefore meets the persistence criterion established in this rulemaking. A complete discussion of EPA's findings on this chemical can be found in EPA's Response to Comments document for this rulemaking (Ref. 69) and in EPA's support documents for this rulemaking (Ref. 7). In addition, hexachlorobenzene persists in the environment with a halflife of greater than 6 months which supports EPA's decision to lower the threshold to 10 pounds. o. Octachlorostyrene. In the proposal, EPA preliminarily determined that OCS has persistence half life values in soil of 3 to 6 years. EPA received one significant comment addressing OCS's persistence potential which is discussed below. EPA has reviewed information and all comments received on OCS's persistence characteristics. Taking into account this information, as indicated in Table 3, EPA finds that OCS persists in the environment with a half life of 2 months or greater and therefore meets the persistence criterion established in this rulemaking. A complete discussion of EPA's findings on this chemical can be found in EPA's Response to Comments document for this rulemaking (Ref. 69) and/ or in EPA's support documents for this rulemaking (Ref. 7). In addition, OCS persists in the environment with a half life of greater than 6 months which supports EPA's decision to lower the threshold to 10 pounds. One commenter believes that OCS should not be considered to be a PBT chemical. The commenter admits that OCS has the potential to bioaccumulate and may theoretically persist in the environment, but cites falling environmental levels of OCS and the lack of evidence of human and environmental toxicity as justification for why OCS should not be considered to be a persistent, bioaccumulative and toxic chemical. The commenters contend that pentachlorobenzene and hexachlorobenzene are not good analogs for OCS. EPA disagrees. As discussed in Unit VI. G., EPA believes that OCS meets the EPCRA section 313 toxicity criteria. Further, EPA believes that OCS is highly persistent. No measured half life data for soil or water that met the standards for data acceptability could be located for octachlorostyrene (CAS No. 29082± 74± 4). Therefore, EPA used half lifes for the structural analogs pentachlorobenzene (CAS No. 608± 93± 5) and hexachlorobenzene (CAS No. 118± 74± 1) for estimating half lifes for OCS. EPA believes that pentachlorobenzene and hexachlorobenzene are good analogs for OCS because they, like OCS, are highly chlorinated benzene derivatives, which are structurally very similar. By analogy, OCS is expected to have a half life in soil of greater than 6 months and greater than 2 days in air (Ref. 7). These halflifes are sufficient to designate OCS as persistent using the criteria described in the proposed rule. EPA believes that its use of analog data is scientifically supportable because like OCS both analogs are highly chlorinated monocyclic aromatics. EPA believes that the degree of toxicity as well as the degree of persistence and bioaccumulation are inherent to a chemical. The absolute level of a chemical in the environment does not affect its degree of persistence, bioaccumulation, or whether or not it has been shown to cause adverse effects to aquatic organisms. The absolute level in the environment is a factor of both how much is entering the environment and the persistence of the chemical in the environment. The degree to which a chemical is present in aquatic organisms is not only a measure of the BAF, but also inputs into the environment and 58722 Federal Register / Vol. 64, No. 209 / Friday, October 29, 1999 / Rules and Regulations persistence. The assertions made by the commenter do not support their contentions concerning the toxicity, persistence, or bioaccumulation of OCS. p. Pentachlorobenzene. In the proposal, EPA preliminarily determined that pentachlorobenzene has persistence half life values in soil of 194 days to more than 22 years. EPA received no significant comments addressing pentachlorobenzene's persistence potential. EPA has reviewed information and all comments on pentachlorobenzene's persistence characteristics. Taking into account this information, as indicated in Table 3, EPA finds that pentachlorobenzene persists in the environment with a halflife of 2 months or greater and therefore meets the persistence criterion established in this rulemaking. A complete discussion of EPA's findings on this chemical can be found in EPA's Response to Comments document for this rulemaking (Ref. 69) and/ or in EPA's support documents for this rulemaking (Ref. 7). In addition, pentachlorobenzene persist in the environment with a half life of greater than 6 months which supports EPA's decision to lower the threshold to 10 pounds. q. Tetrabromobisphenol A. In the proposal, EPA preliminarily determined that TBBPA has persistence half life values in soil of 44 to 179 days and persistence half life values in water of 48 to 84 days. EPA received several significant comments addressing TBBPA's persistence and discusses them below. EPA has reviewed information and all comments received on TBBPA's persistence characteristics. Taking into account this information, as indicated in Table 3, EPA finds that TBBPA persists in the environment with a half life of 2 months or greater and therefore meets the persistence criterion established in this rulemaking. A complete discussion of EPA's findings on this chemical can be found in EPA's Response to Comments document for this rulemaking (Ref. 69) and/ or in EPA's support documents for this rulemaking (Ref. 7). One commenter states that EPA's determination that TBBPA is persistent in the environment appears to be based upon a model which uses default data, that it is difficult to interpret EPA's methodology for applying its EQC Model Output for Toxics Release Inventory PBT Rule Chemicals, and it therefore is not clear how EPA arrived at the conclusion that TBBPA is persistent. EPA disagrees that it is unclear how the EQC model was used in the assessment of chemical persistence and that EPA used only default data. EPA provided discussion on the conduct of the multimedia modeling in the document titled EQC Model Output for Toxics Release Inventory PBT Rule Chemicals (Ref. 33). EPA used chemicalspecific input data (i. e., half lifes in air, soil, water, and sediment and chemical properties) where available in all multimedia modeling runs. No default data were used in lieu of chemicalspecific inputs. All chemical specific inputs for each chemical were listed in this document. Further, EPA explained its use of the modified EQC model not only in the support document identified earlier, but also in the preamble to the proposed rule. In its description of the modeling EPA stated:

Multimedia mass balance models offer the most convenient means to estimate overall environmental persistence from information on sources and loadings, chemical properties and transformation processes, and intermedia partitioning. For the chemicals included in this proposed rule EPA used the [modified] EQC model. . .to estimate overall environmental persistence. Overall persistence estimated in this way is used as an additional factor, in conjunction with reaction half lifes for individual media, bioaccumulation/ bioconcentration factors, etc., in justifying actions proposed in this rule.

The EQC model is based on the fugacity approach first delineated by Mackay (Ref. 31) and subsequently applied to numerous environmental processes (Ref. 32). It uses an `` evaluative environment'' in which environmental parameters such as bulk compartment dimensions and volumes (e. g., total area, volume of soil and sediment) are standardized, so that overall persistence for chemicals with different properties and rates of transformation may be compared on an equal basis (Ref. 15). EPA used a version of the EQC level III model (Ref. 33) which was modified to focus on net losses by deleting model terms for advective losses (movement out of the evaluative environment of air and water potentially containing a chemical) and sediment burial (Ref. 82). In this version of the model only irreversible transformation contributes to net loss of a chemical. The overall persistence obtained from this model is calculated as the total amount in the evaluative environment when steady state is achieved, divided by the total loss rate. The results thus obtained are neither an overall environmental half life nor a compartment (or transformation) specific half life; rather they are equivalent to an environmental residence time. When only irreversible transformation contributes to net loss

i. e., under the conditions of this version of the EQC model overall environmental persistence times can be converted to half lifes by multiplying the former by ln 2 (i. e., 0.693). The overall half life calculated in this way is for dissipation in the environment as a whole and cannot be related directly to any individual compartment. In the analysis EPA used the highest, lowest and mean values for the ranges of half lifes for soil, air, and water as inputs to the model. These half lifes were collected from the literature from scientifically sound studies and were subject to data quality standards. The overall environmental persistence halflife for TBBPA calculated based on the EQC model was greater than 2 months but less than 6 months using the longest half lifes for air, soil, water, and sediment. These results support EPA's assertion that the persistence of TBBPA in the environment will meet the EPCRA section 313 persistence criteria. The commenter believes that TBBPA does not meet the persistence criteria for air. To support this contention the commenter refers to a study cited in a World Health Organization (WHO) document (Ref. 83). Specifically the commenter cites photodegradation studies that demonstrated that the halflife of TBBPA absorbed onto silica gel exposed to ultraviolet (UV) radiation was 0.12 day in air. In addition, the commenter contends that studies of the photolysis of TBBPA in the presence of UV light and hydroxyl radicals show that TBBPA was totally degraded within 5 to 6 days with an estimated 33± hour half life. The commenter did not provide these studies or provide references to the original studies. Further, the same commenter cites WHO EHC 172 (Ref. 83) for data on photodegradation to support the claim that TBBPA does not meet the persistence criteria for air. A review of the citation provided by the commenter reveals that it is a secondary reference taken from unpublished data from Bayer (Ref. 10). EPA was unable to review the full unpublished study to determine the quality of the data, only the summary found in the WHO document was available. In the WHO summary of the Bayer study TBBPA adsorbed onto silica gel and was exposed to ultraviolet irradiation at the 254 nanometer (nm) wavelength. Eight metabolites were detected and a half life value of 0.12 days obtained. WHO noted that ``[ i] t is difficult to derive environmental conclusions from the results of these experiments. '' EPA believes that the environmental relevance of the test results is doubtful. 58723 Federal Register / Vol. 64, No. 209 / Friday, October 29, 1999 / Rules and Regulations While the experiment may demonstrate the potential for TBBPA to undergo photodegradation under laboratory conditions, the experimental conditions, to the extent they could be determined from the short summary provided, were not environmentally relevant. In order for a molecule to undergo photochemical change it must absorb light. It is well known that only the transitions corresponding to ultraviolet/ visible light absorption are inherently energetic enough to lead to chemical reactions. The wavelengths of importance for photochemical transformations is thus ultraviolet/ visible light with a wavelength of 110 750 nm. When environmental photochemistry at or near the earth's surface is considered, the wavelengths of light of importance are further narrowed because the stratospheric ozone layer effectively prevents UV irradiation of less than 290 nm from reaching the earth's surface. Thus, only the light of the 290 750 nm wavelength absorbed by a molecule can potentially lead to photochemical changes of that molecule in the environment near the earth's surface. EPA believes that because the subject study utilized UV irradiation at the 254 nm wavelength, a wavelength that does not reach the earth's surface due to mitigation by stratospheric ozone, the half life derived is not relevant and, therefore, cannot be used to determine the persistence of TBBPA in air. The commenter also refers to studies of the photolysis of TBBPA in the presence of UV light and hydroxyl radicals in which TBBPA was shown to totally degrade within 5 to 6 days with an estimated 33± hour half life. No additional information or references were provided to enable EPA to evaluate these findings for use in the characterization of the atmospheric halflife TBBPA. The commenter contends that TBBPA's molecular structure makes it inherently biodegradable. The hydroxyl moiety on the TBBPA molecule can be readily transformed by organisms in the environment. The parent TBBPA molecule is no longer present once this biotransformation takes place. Therefore, based on TBBPA's structure alone, the Agency should consider TBBPA as unlikely to be environmentally persistent. EPA disagrees with the statement that based on structure alone, the Agency should consider TBBPA as unlikely to be environmentally persistent. While EPA generally believes that measured values from well conducted studies are preferable to structure activity relationships (SAR) as an indicator of persistence, the Agency believes that it is possible to make some general statements about the biodegradability of TBBPA based on its structure. Current knowledge of structure biodegradability relationships suggests that the presence of multiple bromines on an aromatic molecule adversely effects biodegradation. In fact, when the biodegradability of TBBPA is assessed with EPA structure activity relationship tools for predicting biodegradation from structure (Refs. 46 and 47), the presence of multiple aromatic bromines, a carbon with four single bonds, and the molecular weight of TBBPA are all structural features that reduce biodegradability. Therefore, even if EPA were to base its assessment of the persistence of TBBPA on its molecular structure, the Agency would conclude that it is not readily biodegradable. The commenter contends that TBBPA will not meet the persistence criteria for water, soil, and sediment because TBBPA will biodegrade in these media. The commenter cites the results of several biodegradation studies as demonstrating that TBBPA is not persistent in these media. The commenter states that even though degradation studies have shown that TBBPA is not `` readily biodegradable'' (i. e., TBBPA is not mineralized to a significant extent by sewage sludge within 28 days) there are studies that indicate it is not persistent. Specifically, in studies submitted to EPA in 1989, TBBPA has been shown to be subject to biodegradation both in soil and sediment under aerobic or anaerobic conditions; TBBPA's estimated half life derived from these studies is 50 days. In studies submitted by the Brominated Flame Retardants Industry Panel to EPA, TBBPA also was shown to undergo degradation in a sediment/ water system with an estimated half life of 48 to 84 days. (These data were reported under the Agency's TSCA Section 4 test rule.) The commenter argues that these data demonstrate that TBBPA does not meet most widely (and internationally) accepted criteria for persistence in soil or sediments (See Unit VI. B.) Therefore, TBBPA should not be considered to be persistent for purposes of EPCRA Section 313. The commenter cites additional research conducted on the biodegradation of TBBPA under aerobic and anaerobic conditions in soil (Refs. 47) and asserts that the data indicate that `` TBBPA does not meet the most widely and internationally accepted criteria. '' EPA discusses its assessment of the Springborn soil biodegradation studies elsewhere in the Response to Comments document (Ref. 69). As explained earlier, the international persistence criteria are not relevant to the classification of persistence under the criteria adopted by the Agency, and EPA disagrees that TBBPA should not be considered persistent because it does not meet the `` most widely (and internationally) accepted'' criteria. (See Unit VI. B.) The commenter makes the argument that TBBPA has been shown to be subject to biodegradation in soil and sediment under aerobic and anaerobic conditions with `` estimated'' half lifes of 50 days. Although the commenter derived a biodegradation half life, the method used to do so and the validity of the value could not be determined because no supporting information was provided. EPA questions the validity of the 50± day half lifes estimated by the commenter on those grounds. The commenter refers to two soil grab sample studies and a sediment/ water microbial system study. These studies investigated the biodegradation of TBBPA in three different soil types in the presence (aerobic) and absence (anaerobic) of oxygen, and the biodegradation of TBBPA in a system containing sediment and river water in the presence of oxygen. In the aerobic soil studies less than 6% ultimate biodegradation (complete biodegradation to CO2) was observed over the 64± day test period. The major portion of TBBPA remained in the soil. Analysis showed after 64 days 74 to 82% TBBPA remained in a Massachusetts sandy loam soil, 36 to 40% remained in an Arkansas silt loam, and 41 to 43% remained in a California clay loam soil. Over the course of the experiments, TBBPA either remained in soil undegraded, underwent minor structural changes (primary biodegradation), or to a very small extent (< 6%), underwent complete biodegradation to CO2. Individual values for evolved CO2 in each soil type over time were not reported and biodegradation half life values were not calculated. If it is assumed in the absence of values for CO2 evolution at sampling times spaced evenly over the test period reported data, that TBBPA underwent a steady rate of degradation over the duration of the experiments, approximate half lifes of 44 to 179 days can be estimated (Ref. 7). Biodegradation half lifes from the aerobic soil biodegradation experiments can be approximated. The half life is defined as the amount of time necessary for the destruction of half of the chemical present in the medium. Given that the duration of the soil biodegradation test is 64 days (equivalent to greater than 2 months), a 58724 Federal Register / Vol. 64, No. 209 / Friday, October 29, 1999 / Rules and Regulations chemical that undergoes less than 50% biodegradation by the end of the test period would have a half life of greater than 2 months and meet the EPCRA 313 persistence criteria for soil. In one of the soils in which TBBPA was tested (a Massachusetts sandy loam soil) 74 to 82% of the original TBBPA applied remained in the soil unchanged at the end of the 64± day test period. Thus, in this study, TBBPA was shown to have a half life in soil of greater than 2 months since less than 50% degradation of TBBPA occurred in 64 days. The biodegradation of TBBPA in the same three soils as above under anaerobic conditions in a 64± day test has also been studied. The results showed that 44 to 57% of the TBBPA applied to soil remained undegraded in the Massachusetts sandy loam soil after a 64± day test period, 53± 65% in an Arkansas silt loam soil, and 90% in a California clay loam soil. Less than 50% destruction of the test chemical occurred over a 64± day (> 2 month) test period in all soils tested. Thus, in this study, TBBPA was shown to have a halflife in soil of greater than 2 months since less than 50% degradation of TBBPA occurred in 64 days. Aerobic sediment water microbial test systems containing natural sediments and river water were used to measure degradation half lifes for TBBPA in 56± day experiments. Half lifes calculated for the biodegradation of TBBPA ranged from 48 to 84 days. Researchers found an apparent correlation between halflifes and TBBPA concentration, and half lifes and microbial concentrations. Thus, in this study, TBBPA was shown to have a half life in sediment water systems of greater than 2 months when either the larger value or the mean of the two values is considered. Further, the commenter claims that abiotic degradation of TBBPA in water also is expected. The calculated half life of decomposition of TBBPA by UV radiation in water was 10.2 days in spring, 6.6 in summer, 25.9 in autumn, and 80.7 days in winter. Therefore, TBBPA is not expected to be persistent in water. No other information was provided. The commenter cites WHO EHC 172 (Ref. 83) for data on photodegradation to support the claim that TBBPA does not meet the persistence criteria for water. In its review of the literature to evaluate the persistence of TBBPA, EPA found no information on its photodegradation in water. A review of the citation provided by the commenter reveals that it is a secondary reference taken from an unpublished study from Bayer (Ref. 10). EPA was unable to review the full unpublished study to determine the quality of the data. Only the summary found in the WHO document was available. The Bayer study on photodegradation in water yielded calculated half lifes ranging from 6.6 days to 80.7 days with the longest halflife calculated during the winter, when solar irradiation is least intense and the shortest half life occurring in the summer, when the solar irradiation is most intense. The commenter did not include the fact that the effect of cloud cover lengthened the calculated half life by a factor of 2. Water depth was also found to influence the direct photodegradation of TBBPA. At the surface of a water body, solar irradiation is fairly uniform; however, as depth increases, both the water itself and materials in it can attenuate the transmission of solar energy through the water column. Irradiance has been shown to decrease by greater than 90% for both ultraviolet and visible light at a depth of 5 meters in a eutrophic lake (Ref. 52). EPA disagrees with the commenter's conclusion that TBBPA photodegradation in water will be sufficiently rapid that it will not meet the persistence criteria. Based on the study cited by the commenter which includes an 80± day ( > 2 month) halflife for photodegradation of TBBPA in winter, and the mitigating effects of water depth and cloud cover on rates of photodegradation, EPA believes that a half life of greater than 2 months in water is supported. EPA, therefore asserts that based on these findings, TBBPA meets the EPCRA section 313 persistence criteria of greater than 2 months in soil and water. 2. BioaccumulationÐ a. Dioxin and dioxin like compounds. In the proposal, EPA preliminarily determined that dioxin and dioxin like compounds have BCF values that range from 1,259± 42,500 with 6 chemicals over 5,000 and 6 chemicals between 3,500 and 5,000. EPA has reviewed information and all comments received on dioxin and dioxin like compounds' bioaccumulation characteristics. As indicated in Table 3, EPA finds that dioxin and dioxin like compounds bioaccumulate in the environment with BAF/ BCF values greater than 1,000 and therefore meet the bioaccumulation criterion established in this rulemaking. A complete discussion of EPA's findings on this chemical category can be found in EPA's Response to Comments document for this rulemaking (Ref. 69) and/ or in EPA's support documents for this rulemaking (Ref. 71). In addition, most of the members of the dioxin and dioxin like compounds category bioaccumulate in the environment with a value close to, or well above, 5,000, which supports EPA's decision to lower the threshold to 0.1 gram. b. Aldrin. In the proposal, EPA preliminarily determined that aldrin has a BCF value of 3,715. EPA has reviewed information and all comments received on aldrin's bioaccumulation characteristics. Taking into account this information, as indicated in Table 3, EPA finds that aldrin bioaccumulates in the environment with a BAF/ BCF value greater than 1,000 and therefore meets the bioaccumulation criterion established in this rulemaking. A complete discussion of EPA's findings on this chemical can be found in EPA's Response to Comments document for this rulemaking (Ref. 69) and/ or in EPA's support documents for this rulemaking (Ref. 71). c. Chlordane. In the proposal, EPA preliminarily determined that chlordane has a BCF value of 11,050. EPA has reviewed information and all comments received on chlordane's bioaccumulation characteristics. Taking into account this information, as indicated in Table 3, EPA finds that chlordane bioaccumulates in the environment with a BAF/ BCF value greater than 1,000 and therefore meets the bioaccumulation criterion established in this rulemaking. A complete discussion of EPA's findings on this chemical can be found in EPA's Response to Comments document for this rulemaking (Ref. 69) and/ or in EPA's support documents for this rulemaking (Ref. 71). In addition, chlordane bioaccumulates in the environment with a BCF value greater than 5,000 which supports EPA's decision to lower the threshold to 10 pounds. d. Heptachlor. In the proposal, EPA preliminarily determined that heptachlor has a BCF value of 19,953. EPA has reviewed information and all comments received on heptachlor's bioaccumulation characteristics. Taking into account this information, as indicated in Table 3, EPA finds that heptachlor bioaccumulates in the environment with a BAF/ BCF value greater than 1,000 and therefore meets the bioaccumulation criterion established in this rulemaking. A complete discussion of EPA's findings on this chemical can be found in EPA's Response to Comments document for this rulemaking (Ref. 69) and in EPA's support documents for this rulemaking (Ref. 71). In addition, heptachlor bioaccumulates in the environment with a BAF/ BCF value greater than 5,000 which supports EPA's decision to lower the threshold to 10 pounds. 58725 Federal Register / Vol. 64, No. 209 / Friday, October 29, 1999 / Rules and Regulations e. Isodrin. In the proposal, EPA preliminarily determined that isodrin has a BCF value of 20,180. EPA has reviewed information and all comments received on isodrin's bioaccumulation characteristics. Taking into account this information, as indicated in Table 3, EPA finds that isodrin bioaccumulates in the environment with a BAF/ BCF value greater than1,000 and therefore meets the bioaccumulation criterion established in this rulemaking. A complete discussion of EPA's findings on this chemical can be found in EPA's Response to Comments document for this rulemaking (Ref. 69) and/ or in EPA's support documents for this rulemaking (Ref. 71). In addition, isodrin bioaccumulates in the environment with a BAF/ BCF value greater than 5,000 which supports EPA's decision to lower the threshold to 10 pounds. f. Methoxychlor. In the proposal, EPA preliminarily determined that methoxychlor has a BCF value of 8,128. EPA has reviewed information and all comments received on methoxychlor's bioaccumulation characteristics. Taking into account this information, as indicated in Table 3, EPA finds that methoxychlor bioaccumulates in the environment with a BAF/ BCF value greater than 1,000 and therefore meets the bioaccumulation criterion established in this rulemaking. A complete discussion of EPA's findings on this chemical can be found in EPA's Response to Comments document for this rulemaking (Ref. 69) and/ or in EPA's support documents for this rulemaking (Ref. 71). g. Pendimethalin. In the proposal, EPA preliminarily determined that pendimethalin has a BCF value of 1,944. EPA has reviewed information and all comments received on pendimethalin's bioaccumulation characteristics. Taking into account this information, as indicated in Table 3, EPA finds that pendimethalin bioaccumulates in the environment with a BAF/ BCF value greater than 1,000 and therefore meets the bioaccumulation criterion established in this rulemaking. A complete discussion of EPA's findings on this chemical can be found in EPA's Response to Comments document for this rulemaking (Ref. 69) and/ or in EPA's support documents for this rulemaking (Ref. 71). h. Toxaphene. In the proposal, EPA preliminarily determined that toxaphene has a BCF value of 34,050. EPA has reviewed information and all comments received on toxaphene's bioaccumulation characteristics. Taking into account this information, as indicated in Table 3, EPA finds that toxaphene bioaccumulates in the environment with a BAF/ BCF value greater than 1,000 and therefore meets the bioaccumulation criterion established in this rulemaking. A complete discussion of EPA's findings on this chemical can be found in EPA's Response to Comments document for this rulemaking (Ref. 69) and/ or in EPA's support documents for this rulemaking (Ref. 71). In addition, toxaphene bioaccumulates in the environment with a BAF/ BCF value greater than 5,000 which supports EPA's decision to lower the threshold to 10 pounds. i. Trifluralin. In the proposal, EPA preliminarily determined that trifluralin has a BCF value of 5,674. EPA has reviewed information and all comments received on trifluralin's bioaccumulation characteristics. Taking into account this information, as indicated in Table 3, EPA finds that trifluralin bioaccumulates in the environment with a BAF/ BCF value greater than 1,000 and therefore meets the bioaccumulation criterion. A complete discussion of EPA's findings on this chemical can be found in EPA's Response to Comments document for this rulemaking (Ref. 69) and/ or in EPA's support documents for this rulemaking (Ref. 71). j. Polycyclic aromatic compounds. In the proposal, EPA preliminarily determined that PACs have BCF values that ranged from 800 to 31,440 with 16 of the 21 members of the category having BCF values greater than 5,000. EPA received several comments concerning the PACs category listing and the bioaccumulation data which are addressed below. EPA has reviewed information and all comments received on PACs' bioaccumulation characteristics. Taking into account this information, as indicated in Table 3, EPA finds that PACs bioaccumulate in the environment with BAF/ BCF values greater than 1,000 and therefore meet the bioaccumulation criterion established in this rulemaking. A complete discussion of EPA's findings on this chemical category can be found in EPA's Response to Comments document for this rulemaking (Ref. 69) and/ or in EPA's support documents for this rulemaking (Ref. 71). Three of the commenters support the retention of a single PACs category while one commenter believes that splitting the category into two categories would be the most appropriate option. Additional specific comments were as follows. One commenter stated that PACs are typically found as mixtures in incoming natural organic raw materials, such as coal and that it would be difficult to separate information into two reporting categories. Another commenter stated that reporting as one category is also more consistent with the Great Lakes Binational Toxics Strategy Level 2 listing for these chemicals. A commenter stated that the alternate proposal to create two PAC categories would be unnecessarily burdensome for the regulated community since reporting facilities would be required to speciate their PAC releases, and, if chemicals from both categories exceeded reporting thresholds, file two Form R reports, instead of one. One commenter stated that use of a single PACs category will simplify the reporting requirements; thus, it will reduce reporting burden. Several commenters stated that according to the proposed rule, 16 of the 21 members of the category had BCF values greater than 5,000 and that one proposal would regard the entire PACs category to be highly persistent and bioaccumulative, regardless of each individual PAC's actual persistence and bioaccumulative properties. Several commenters stated that they believed that splitting the category into two categories would be the most appropriate course. Another commenter stated that no chemical should be added to the highly persistent/ bioaccumulative category when it does not fit the criteria and that in order to gain the most accurate information, two separate categories would be the superior solution. The commenter stated that lowering the reporting threshold for the PACs category to 10 pounds is unjustified considering that, according to EPA data, many of the individual PACs within the category do not meet the PBT criteria. EPA considered splitting the PACs category into two or three categories or listings, but EPA believes, as do most of the commenters, that the most appropriate option is to retain a single PACs category. The PACs category was created because the members of the category are chemically and structurally very similar, share the same toxicological effect (carcinogenicity), and typically are produced, released, and otherwise managed as waste as complex mixtures rather than individual chemicals. As such it would be more difficult to estimate releases if the category were split into two or three categories based on the currently available bioaccumulation data. These reasons support retaining a single PACs category. EPA agrees with those commenters that stated that the retention of a single PACs category would be the simpler and less burdensome option. EPA also 58726 Federal Register / Vol. 64, No. 209 / Friday, October 29, 1999 / Rules and Regulations recognizes that, based on currently available information, not all members of the PACs category meet the highly persistence and highly bioaccumulative criteria. Of the 21 chemicals in the PACs category proposed for a lower threshold, 5 have BCF values that nominally do not meet the highly bioaccumulative criteria, while the rest exceed the highly bioaccumulative criteria. Given the structural similarities of the members of this category and the higher bioaccumulation values for 16 of the 21 PACs, the 5 BCF values below 5,000 may underestimate, to some extent, the bioaccumulation potential of these compounds. For purposes of this rulemaking, EPA is classifying the PACs category as persistent and bioaccumulative rather than highly persistent and highly bioaccumulative. Thus, the PACs category will have a reporting threshold of 100 pounds. However, the Agency will continue to assess the bioaccumulation potential of this category and specifically whether the lower bioaccumulation values for 5 members of the category are appropriate. k. Benzo( g, h, i) perylene. In the proposal, EPA preliminarily determined that benzo( g, h, i) perylene has a BCF value of 25,420. EPA has reviewed information and all comments received on benzo( g, h, i) perylene's bioaccumulation characteristics. Taking into account this information, as indicated in Table 3, EPA finds that benzo( g, h, i) perylene bioaccumulates in the environment with a BAF/ BCF value greater than 1,000 and therefore meets the bioaccumulation criterion established in this rulemaking. A complete discussion of EPA's findings on this chemical can be found in EPA's Response to Comments document for this rulemaking (Ref. 69) and/ or in EPA's support documents for this rulemaking (Ref. 71). In addition, benzo( g, h, i) perylene bioaccumulates in the environment with a BCF value greater than 5,000 which supports EPA's decision to lower the threshold to 10 pounds. l. Mercury and mercury compounds. In the proposal, EPA preliminarily determined that mercury and mercury compounds have BCF values that ranged from 7,000 to 36,000. EPA has reviewed information and all comments received on mercury and mercury compounds' bioaccumulation characteristics. Taking into account this information, as indicated in Table 3, EPA finds that mercury and mercury compounds bioaccumulate in the environment with BAF/ BCF values greater than 1,000 and therefore meet the bioaccumulation criterion established in this rulemaking. A complete discussion of EPA's findings on this chemical category can be found in EPA's Response to Comments document for this rulemaking (Ref. 69) and/ or in EPA's support documents for this rulemaking (Ref. 71). In addition, mercury and mercury compounds bioaccumulate in the environment with a value above 5,000, which supports EPA's decision to lower the threshold to 10 pounds. m. Polychlorinated biphenyls. In the proposal, EPA preliminarily determined that PCBs have BCF values that ranged from 4,922 to 196,900. All of the PCBs, except one, had BCF values far exceeding 5,000. The one exception, 2,3,3', 4,4', 5,5' heptachlorobiphenyl, had a BCF value of 4,922. EPA has reviewed information and all comments received on PCBs' bioaccumulation characteristics. Taking into account this information, as indicated in Table 3, EPA finds that PCBs bioaccumulate in the environment with BAF/ BCF values greater than 1,000 and therefore meet the bioaccumulation criterion established in this rulemaking. A complete discussion of EPA's findings on this chemical listing can be found in EPA's Response to Comments document for this rulemaking (Ref. 69) and/ or in EPA's support documents for this rulemaking (Ref. 71). In addition, with one exception, all of the PCBs listed bioaccumulate in the environment with a value far exceeding 5,000, which supports EPA's decision to lower the threshold to 10 pounds. n. Hexachlorobenzene. In the proposal, EPA preliminarily determined that hexachlorobenzene has a BCF value of 29,600 to 66,000. EPA has reviewed information and all comments received on hexachlorobenzene's bioaccumulation characteristics. Taking into account this information, as indicated in Table 3, EPA finds that hexachlorobenzene bioaccumulates in the environment with a BAF/ BCF value greater than 1,000 and therefore meets the bioaccumulation criterion established in this rulemaking. A complete discussion of EPA's findings on this chemical can be found in EPA's Response to Comments document for this rulemaking (Ref. 69) and/ or in EPA's support documents for this rulemaking (Ref. 71). In addition, hexachlorobenzene bioaccumulates in the environment with a BAF/ BCF value greater than 5,000 which supports EPA's decision to lower the threshold to 10 pounds. o. Octochlorostyrene. In the proposal, EPA preliminarily determined that OCS has a BCF value of 33,113. EPA received one significant comment addressing OCS's bioaccumulation potential which is discussed below. EPA has reviewed this comment and information on OCS's bioaccumulation characteristics. Taking into account this information, as indicated in Table 3, EPA finds that OCS bioaccumulates in the environment with a BAF/ BCF value greater than 1,000 and therefore meets the bioaccumulation criterion established in this rulemaking. A complete discussion of EPA's findings on this chemical can be found in EPA's Response to Comments document for this rulemaking (Ref. 69) and/ or in EPA's support documents for this rulemaking. (Ref. 71). In addition, OCS bioaccumulates in the environment with a BAF/ BCF value greater than 5,000 which supports EPA's decision to lower the threshold to 10 pounds. One commenter argued that OCS should not be included in the EPCRA section 313 PBT chemicals list. The commenter contends that OCS was included as a PBT chemical simply because it appears on several lists of persistent and bioaccumulative chemicals and not based on a thorough evaluation of its bioaccumulation. The commenter states that OCS has the potential to bioaccumulate, but nonetheless, OCS levels in fish and aquatic species in the Great Lakes continue to decline. The commenter provides a report on the Great Lakes region and argues that OCS should not be considered a PBT chemical since environmental concentration data show OCS levels in the environment are decreasing at a rate of 8% to 30% per year. EPA disagrees with the commenter's conclusions. The commenter does not dispute the bioaccumulation values EPA presented in the proposed rule. Rather the commenter agrees that OCS has the potential to bioaccumulate but contends that since environmental concentrations are declining in the Great Lakes region OCS should not be considered a PBT chemical. The fact that OCS levels in the Great Lakes region may be declining is not a basis for concluding that OCS is not a PBT chemical or that it cannot bioaccumulate. There are a number of reasons that could explain a decrease in environmental concentrations of OCS but they do not change the fact that OCS has been shown to be highly bioaccumulative. OCS was included as a PBT chemical because it meets the EPCRA section 313 criterion for bioaccumulation laid out in the proposed rule, not simply because it has appeared on several other lists of PBT chemicals. p. Pentachlorobenzene. In the proposal, EPA preliminarily determined 58727 Federal Register / Vol. 64, No. 209 / Friday, October 29, 1999 / Rules and Regulations that pentachlorobenzene has a BCF value of 8,318. EPA has reviewed information and all comments received on pentachlorobenzene's bioaccumulation characteristics. Taking into account this information, as indicated in Table 3, EPA finds that pentachlorobenzene bioaccumulates in the environment with a BAF/ BCF value greater than 1,000 and therefore meets the bioaccumulation criterion established in this rulemaking. A complete discussion of EPA's findings on this chemical can be found in EPA's Response to Comments document for this rulemaking (Ref. 69) and/ or in EPA's support documents for this rulemaking (Ref. 71). In addition, pentachlorobenzene bioaccumulates in the environment with a BAF/ BCF value greater than 5,000 which supports EPA's decision to lower the threshold to 10 pounds. q. Tetrabromobisphenol A. In the proposal, EPA preliminarily determined that TBBPA was found to have BCF values of 780; 1,200; and 3,200. EPA received one significant comment addressing TBBPA's bioaccumulation which is discussed below. EPA has reviewed the comments and information on TBBPA's bioaccumulation characteristics. Taking into account this information, as indicated in Table 3, EPA finds that TBBPA bioaccumulates in the environment with a BAF/ BCF value greater than 1,000 and therefore meets the bioaccumulation criterion established in this rulemaking. A complete discussion of EPA's findings on this chemical can be found in EPA's Response to Comments document for this rulemaking (Ref. 69) and/ or in EPA's support documents for this rulemaking (Ref. 71). One commenter contends that the available data on TBBPA do not support its classification as a PBT chemical. The commenter argues that the oyster BCF value of 780 does not support the proposed criterion of 1,000. The commenter also notes that EPA fails to consider that TBBPA is not retained in the body once dosing stops in a BCF test and that TBBPA is rapidly eliminated. The commenter states that rapid elimination limits any potential for biomagnification. The commenter notes that only the highest chironomid BCF value (3,200) was cited by EPA and not the fact that this is from a range of 650± 3,200. EPA believes that the available data do support classification of TBBPA as a PBT chemical. Measured BCF values of 780, 1,200, and 3,200 were obtained from TSCA section 4 tests with oysters, fish and chironomids, respectively. The measured BCF values of 1,200 and 3,200 for fish and chironomids respectively, clearly satisfy the EPCRA section 313 bioaccumulatioin criterion of 1,000. EPA is aware that TBBPA will be eliminated from the body eventually once exposure to the chemical is halted; however, continuous or intermittent exposures of TBBPA to organisms may result in significant tissue residues depending on the exposure or release scenarios. The issue of biomagnification of TBBPA is not relevant to determining if TBBPA is a PBT chemical. As discussed in Unit VI. B. 3., biomagnification is not required in order to have a concern for chemicals that bioaccumulate. The highest chironomid BCF value was listed because it is considered as a worst case indication of bioaccumulation in sediment dwelling invertebrates.

I. Exemptions and Other Reporting Requirements 1. De minimis exemption. Many of the commenters assert that the initial reasons for adopting the de minimis exemption are still valid and that this exemption should be maintained for PBT chemicals. Specifically, several commenters contend that the de minimis exemption was initially adopted to alleviate undue burden on reporting facilities and that the elimination of this exemption for PBT chemicals will significantly increase the reporting burden for this rulemaking. EPA disagrees with the commenters' contention that the initial reasons for adopting the de minimis exemption are valid for PBT chemicals. As originally explained in the 1988 final rule implementing the reporting provisions of EPCRA section 313, reiterated in the 1997 final rule adding seven new industry sectors, and discussed in the proposal to this final rule, EPA promulgated the de minimis exemption for several reasons, of which burden was only one. In addition to burden reduction, EPA promulgated the de minimis exemption because: (1) The Agency believed that facilities newly covered by EPCRA section 313 would have limited access to information regarding low concentrations of toxic chemicals in mixtures that are imported, processed, otherwise used or manufactured as impurities; (2) the Agency did not believe that these low concentrations would result in quantities that would significantly contribute to threshold determinations and release calculations at the facility (53 FR 4509); and (3) the exemption was consistent with information collected under the Occupational Safety and Health Administration's (OSHA) Hazard Communication Standard (HCS). If EPA had adopted the exemption only to reduce burden, the exemption would have covered all uses of de minimis quantities of the toxic chemical in mixtures. The exemption, however, includes only limited uses of the toxic chemical in mixtures (i. e., importing, processing, otherwise use, and manufacturing impurities) that were roughly tailored to whether EPA expected that facilities were reasonably likely to have information that would allow them to determine thresholds and make release calculations. The purpose of the PBT rulemaking, however, is different from past rulemakings in that it is intended to capture information on significantly smaller quantities of releases and other waste management associated with these chemicals. Most of the PBT chemicals addressed in this rule have been shown to cause adverse effects at concentrations far less than the de minimis levels. For example, dioxins have been shown to cause adverse effects at levels in the parts per trillion. In addition, after 10 years of experience with the program, the Agency believes there are many sources of information in addition to material safety data sheets (MSDSs), readily available to reporters to use in making EPCRA section 313 determinations. Some of these sources of information include EPA guidance documents (e. g., EPCRA Section 313 Industry Guidance: Electricity Generating Facilities (EPA 745± B± 99± 003)) and trade association guidance documents (e. g., National Council of the Paper Industry for Air and Stream Improvement (NCASI) Technical Bulletins and NCASI's Handbook of Chemical Specific Information for SARA Title III Section 313 Form R Reporting). In addition, relevant information has become much more accessible to covered facilities over the past 10 years. For example, although the United States Geological Survey's U. S. Coal Quality Database has been in existence since the mid 1970s, only more recently has it been made available on the Internet. (http:// energy. er. usgs. gov/ products/ databases/ UScoal/ index. htm). Further, the Agency believes that it underestimated how much information covered facilities had available to them in 1988 regarding small concentrations of toxic chemicals in mixtures. Therefore, given that: (1) Covered facilities have several sources of information available to them regarding the concentration of PBT chemicals in mixtures; (2) even minimal releases of persistent bioaccumulative chemicals may result in significant adverse effects and these small 58728 Federal Register / Vol. 64, No. 209 / Friday, October 29, 1999 / Rules and Regulations quantities can reasonably be expected to significantly contribute to the lower thresholds; and (3) the concentration levels originally chosen, in part, to be consistent with the OSHA HCS are inappropriately high for PBT chemicals, EPA believes that the reasons for the de minimis exemption that the Agency held for previous rulemakings do not apply to PBT chemicals. A few commenters assert that reviewing each MSDS, when a facility may have many MSDSs for mixtures used on site, to see if it includes trace quantities of PBT chemicals will be very time consuming. They contend that they do not have the manpower to track products on an individual basis looking for trace quantities of PBT chemicals and that these activities will be very burdensome. EPA disagrees that eliminating the de minimis exemption for PBT chemicals will greatly increase burden under EPCRA section 313. Covered facilities are not required to report on toxic chemicals in mixtures and trade name products for which they have no concentration information or such information that is not reasonably known. However, if facilities do have information concerning the concentration of PBT chemicals in mixtures, such as on MSDSs, EPA does not believe it is more burdensome for facilities to identify and evaluate process streams containing relatively small quantities of PBT chemicals than for larger quantities of chemicals. Although some burden is associated with the identification and evaluation of process streams, EPA disagrees that the elimination of the de minimis exemption would vastly increase the extent of this required effort. Covered facilities will need to identify and evaluate process streams when considering a PBT chemical in concentrations below the de minimis level in the same manner they already do for toxic chemicals found in process streams in concentrations above the de minimis level. The additional burden can be attributed to resources spent considering and reporting on information they currently are allowed to disregard. Further, as explained above, EPA adopted the de minimis exemption for several reasons, of which burden reduction was only one, and EPA does not believe that these original reasons apply to this PBT rulemaking. Some commenters assert that it is unrealistic for EPA to assume that industry will report only on what they know without making an effort to fill the data gaps and that enforcement actions could arise from reports based on only what is known to a facility. EPA disagrees, however, because covered facilities are expected to have reasonable knowledge of the toxic chemicals present at their site and need only document their considerations concerning threshold determinations and release and other waste management calculations. As stated in EPCRA section 313( g)( 2):

[i] n order to provide the information required under this section, the owner or operator of a facility may use readily available data (including monitoring data) collected pursuant to other provisions of law, or, where such data are not readily available, reasonable estimates of the amounts involved. Nothing in this section requires the monitoring or measurement of the quantities, concentration, or frequency of any toxic chemical released into the environment beyond that monitoring and measurement required under other provisions of law or regulation. . . . (emphasis added)


[Federal Register Volume 82, Number 94 (Wednesday, May 17, 2017)]
[Notices]
[Page 22659]
[FR Doc No: 2017-09953]

-----------------------------------------------------------------------

DEPARTMENT OF ENERGY

Federal Energy Regulatory Commission

[Docket No. ER17-1577-000]

Reuel Energy LLC; Supplemental Notice That Initial Market-Based
Rate Filing Includes Request for Blanket Section 204 Authorization

    This is a supplemental notice in the above-referenced proceeding of
Reuel Energy LLC`s application for market-based rate authority, with an
accompanying rate tariff, noting that such application includes a
request for blanket authorization, under 18 CFR part 34, of future
issuances of securities and assumptions of liability.
    Any person desiring to intervene or to protest should file with the
Federal Energy Regulatory Commission, 888 First Street NE., Washington,
DC 20426, in accordance with Rules 211 and 214 of the Commission's
Rules of Practice and Procedure (18 CFR 385.211 and 385.214). Anyone
filing a motion to intervene or protest must serve a copy of that
document on the Applicant.
    Notice is hereby given that the deadline for filing protests with
regard to the applicant's request for blanket authorization, under 18
CFR part 34, of future issuances of securities and assumptions of
liability, is May 31, 2017.
    The Commission encourages electronic submission of protests and
interventions in lieu of paper, using the FERC Online links at http://www.ferc.gov. To facilitate electronic service, persons with Internet
access who will eFile a document and/or be listed as a contact for an
intervenor must create and validate an eRegistration account using the
eRegistration link. Select the eFiling link to log on and submit the
intervention or protests.
    Persons unable to file electronically should submit an original and
5 copies of the intervention or protest to the Federal Energy
Regulatory Commission, 888 First Street NE., Washington, DC 20426.
    The filings in the above-referenced proceeding are accessible in
the Commission's eLibrary system by clicking on the appropriate link in
the above list. They are also available for electronic review in the
Commission's Public Reference Room in Washington, DC. There is an
eSubscription link on the Web site that enables subscribers to receive
email notification when a document is added to a subscribed docket(s).
For assistance with any FERC Online service, please email
<EMAIL_ADDRESS>or call<PHONE_NUMBER> (toll free). For
TTY, call<PHONE_NUMBER>.

    Dated: May 11, 2017.
Kimberly D. Bose,
Secretary.
[FR Doc. 2017-09953 Filed 5-16-17; 8:45 am]
 BILLING CODE 6717-01-P