To provide a safety factor so that none or only a few organisms will perish, it has been found experimentally that a criterion of 2O C below maximum temperature is usually sufficient ( Black, 1953). To provide safety for all the organisms, the temperature causing a median mortality for 5 0 percent of the population would be calculated and reduced by 2'

C in the case of an elevated temperature. Available scientific information includes upper and lower incipient lethal temperatures,

coefficients I1at1 and llbll for the thermal resistance equation, and information of size, life stage, and geographic source of the particular test species ( Appendix 11 C, NAS, 1974).

Maximum temperatures for an extensive exposure ( e. g., more than 1 week) must be divided into those for warmer periods and winter. Other than for reproduction, the most temperature

sensitive life function appears to be growth ( Coutant, 1972).

Coutant ( 1972) has suggested that a satisfactory estimate of a limiting maximum weekly mean temperature may be an average of the optimum temperature for growth and the temperature  or zero net growth.

Because of the difficulty in determining the temperature of zero net growth, essentially the same temperature can be derived by adding to the optimum essentially to temperature ( for growth or other physiological functions) a factor calculated as one

third of the difference between the ultimate upper incipient lethal temperature and the optimum temperature ( NAS, 1974). In equation form:

Maximum weekly ( ultimate upper optimum) average = optimum + 1/ 3 ( incipient lethal  temperature) temperature temperature ( temperature)

Since temperature tolerance varies with various states of development of a particular species, the criterion f o r a  p a r t i c u l a r l o c a t i o n would be c a l c u l a t e d f o r t h e most important l i f e form l i k e l y t o be p r e s e n t d u r i n g a p a r t i c u l a r month. One c a v e a t i n using t h e maximum weekly mean temperature is t h a t t h e l i m i t f o r s h o r t t e r m exposure must n o t be exceeded. Example c a l c u l a t i o n s f o r predicting t h e summer maximum temperatures f o r short term s u r v i v a l and f o r extensive exposure f o r various f i s h s p e c i e s a r e p r e s e n t e d i n T a b l e 11. These c a l c u l a t i o n s u s e t h e above e q u a t i o n s and d a t a from EPA's Environmental Research Laboxatory i n Duluth.

The w i n t e r maximum t e m p e r a t u r e must n o t exceed t h e ambient water t e m p e r a t u r e by more t h a n t h e amount o f change a specimen acclimated t o t h e plume temperature can t o l e r a t e . Such a change c o u l d o c c u r by a c e s s a t i o n of t h e s o u r c e of h e a t o r by t h e specimen being d r i v e n from a n a r e a by a d d i t i o n o f b i o c i d e s o r o t h e r f a c t o r s . However, there are inadequate d a t a t o estimate a s a f e t y f a c t o r f o r t h e Isno stress" l e v e l from c o l d shocks ( NAS,

1974). F i g u r e 2 was developed from a v a i l a b l e d a t a i n t h e l i t e r a t u r e ( ERL Duluth, 1 9 7 6 ) and can be used f o r e s t i m a t i n g a l l o w a b l e winter temperature increases.

Coutant ( 1 9 7 2 ) h a s reviewed t h e e f f e c t s of t e m p e r a t u r e on a q u a t i c l i f e reproduction and development. Reproductive e v e n t s are noted a s perhaps t h e most t h e r m a l l y restricted of a l l l i f e p h a s e s assuming o t h e r f a c t o r s a r e a t o r n e a r optimum l e v e l s .

N a t u r a l s h o r t t e r m t e m p e r a t u r e f l u c t u a t i o n s a p p e a r t o c a u s e reduced reproduction of f i s h and invertebrates. TABLE 11. Example Calculated Values for Maxima for Survival for Juveniles and Adults During the Summer ( Centigrade and Fahrenheit).

Species Growtha Maxima Maximum Weekly Average Temperatures for Growth and Short Term b Atlantic salmon Bigmouth buffalo Black crappie Bluegill Brook trout Carp Channel catfish Coho salmon Emerald shiner Freshwater drum Lake herring ( Cisco) Largemouth bass Northern pike Rainbow trout Sauger Smallmouth bass Smallmouth buffalo Sockeye salmon Striped bass Threadfin shad White bass White crappie White sucker Yellow perch 20 ( 68)

27 ( 81) 32 ( 90) 19 ( 66)

32 ( 90) 18 ( 64) 30 ( 86)

17 ( 63) 32 ( 90) 28 ( 82) 19 ( 66) 25 ( 77) 29 ( 84)

18 ( 64)

28 ( 82) 28 ( 82) 29 ( 84) 23 ( 73)

35 ( 95) 24 ( 75)

35 ( 95) 24 ( 75)

25 ( 77)

30 ( 86) 24 ( 75) 34 ( 93)

22 ( 72)

a  Calculated according to the equation ( using optimum temperature for growth)

maximum weekly average temperature for growth = optimum temperature + 1/ 3 ( ultimate incipient lethal temperature

optimum temperature.

b  Based on temperature ( OC) = l / b ( log" time( min.)  a)

2O C, acclimation at the maximum weekly average temperature  or summer growth, and data in Appendix 11 C of Water Quality Criteria, published by National Academy of Sciences.

c  Based on data for larvae ( ERL Duluth, 1976). 0 . , There are indadequate data available quantitating the most temperature sensitive life stages among various aquatic species.

Uniform elevation of temperature a few degrees but still within the spawning range may lead to advanced spawning for spring spawning species and delays for fall spawners. Such changes may not be detrimental unless asynchrony occurs between newly hatched juveniles and their normal food source. Such asynchrony may be most pronounced among anadromous species or other migrants who pass from the warmed area to a normally chilled, unproductive area. Reported temperature data on maximum temperatures for spawning and embryo survival have been summarized in Table 12 ( from ERL Duluth 1976).

Although the limiting effects of thermal addition to estuarine and marine waters are not as conspicuous in the fall,

winter, and spring as during the summer season of maximum heat stress, nonetheless crucial thermal limitations do exist. Hence,

it is important that the thermal additions to the receiving waters be minimized during all seasons of the year. Size of harvestable stocks of commercial fish and shellfish, particularly near geographic limits of the fishery, appear to be markedly influenced by slight changes in the long term temperature regime ( Dow, 1973).

Jefferies and Johnson ( 1974) studied the relationship between temperature and annual variation in 7 year catch data for winter flounder, Pseudopleuronectes _____ I americanus in Narragansett Bay,

Rhode Island, revealed that a 78 percent decrease in annual catch correlated closely with a 0.5OC increase in the average temperature over the 30 month period between spawning and recruitment into the fishery. Sissenwine's 1974 model predicts a 68 percent reduction of recruitment in ye1 Powtail flounder,

Limanda  ferrugiia, with a l0C long term elevation in southern New England waters. TABLE 12.

Summary of Reported Values for Maxima for Embryo Survival During the Spawning Season ( Centigrade and Fahrenheit) Maximum Weekly Average Temperature for Spawning and Short Term Species Atlantic Salmon Bigmouth Buffalo Black Crappie Bluegill Brook Trout carp Channel Catfish Coho Salmon Emerald Shiner Freshwater Drum Lake Herring ( Cisco) Largemouth Bass Northern Pike Rainbow Trout Sauger Smallmouth Bass Smallmouth Buffalo Sockeye Salmon Striped Bass Threadfin Shad White Bass White Crappie White Sucker Yellow Perch Spawning, Embryo Survivalb 5 17 25 9 21 27 10 24 21 3 21 11 9 17 17 10 18 18 17 18 10 12 I 10 ( 41) 7 77 1 34 70) 33 ( 63) 27 48) 13 81) 29 50) 13 75) 28 70) 26 37) 8 70) 27 52) 19 48) 13 50) 21 63 1 21 13 63) 50) 64 1 24 64 1 34 63) 26 23 20 64)

20 50) 54)

a  the optimum or mean of the range of spawning temperatures reported for the species ( ERL Duluth, 1976).

b  the upper temperature for successful incubation and hatching reported for the species ( ERL Duluth, 1976)

c  upper temperature for spawning. Community balance can be influenced strongly by such temperature dependent factors as rates of reproduction,

recruitment, and growth of each component population. A few degrees elevation in average monthly temperature can appreciably alter a community through changes in interspecies relationships.

A 50 percent reduction in the softshell clam fishery in Maine by the green crab, Carcinus maenus, illustrates how an increase in winter temperatures can establish new predator prey relationships. Over a period of 4 years, there was a natural amelioration of temperature and the monthly mean for the coldest month of each year did not fall below 2OC. This apparently precluded appreciable ice formation and winter cold kill of the green crab and permitted a major expansion of its population,

with increased predation of the softshell clam resulting ( Glude,

1954: Welch, 1968).

Temperature is a primary factor controlling reproduction and can influence many events of the reproductive cycle from gametogenesis to spawning. Among marine invertebrates,

initiation of reproduction ( gametogenesis) is often triggered during late winter by attainment of a minimum environmental threshold temperature. In some species, availability of adequate food is also a requisite ( Pearse, 1970; Sastry, 1975: devlaming,

1971). Elevated temperature can limit gametogenesis by preventing accumulation of nutrients in the gonads. This problem could be acute during the winter if food availability and feeding activity is reduced. Most marine organisms spawn during the spring and summer; gametogenesis is usually initiated during the 0 previous fall. It should also be noted that some species spawn only during the fall ( herrinhg) , while others during the winter and very early spring. At the higher latitudes, winter breeders include such estuarine community dominants as acorn barnacles,

Balanus balanus and B. balanoides, the edible blue mussel Mytilus _

 I edulis sea urchin, Strongylocentrotus drobachiensis, sculpin,

and the winter flounder, Pseudopleuronectes  americanus. The two boreal barnacles require temperatures below 10 ° C before egg production will be initiated ( Crisp, 1957). It is clear that adaptations for reproduction exist which are dependent on temperature conditions close to the natural cycle.

Juvenile and adult fish usually thermoregulate behaviorally by moving to water having temperatures closest to their thermal preference. This provides a thermal environment which approximates the optimal temperature for many physiological functions, including growth ( Neil1 and Magnuson. 1974). As a consequence, fishes usually are attracted to heated water during the fall, winter, and spring. Avoidance will occur as warmer temperature exceeds the preferendum by 1 to 3OC ( Coutant, 1975).

This response precludes problems of heat stress for juvenile and adult fishes during the summer, but several potential problems exist during the other seasons. The possibility of cold shock and death of plume entrained fish resulting from winter plant shutdown is well recognized. Also, increased incidence of disease and a deterioration of physiological condition has been observed among plume entrained fishes, perhaps because of insufficient food ( Massengill, 1973). A weight loss of approximately 10 percent for each lo C rise in water temperature has been observed in fish when food is absent. ( Phillips et al.,

1960) There may also be indirect adverse effects on the indigenous community because of increased predation pressure if thermal addition leads to a concentration of fish which are dependent on this community for their food.

Fish migration is often linked to natural environmental temperature cycles. In early spring, fish employ temperature as their environmental cue to migrate northward ( e. g., menhaden,

bluefish) or to move inshore ( winter flounder). Likewise, water temperature strongly influences timing of spawning runs ofan

adromous fish into rivers ( Leggett and Whitney, 1972). In the autumn, a number of juvenile marine fishes and shrimp are dependent on a drop in temperature to trigger their migration from estuarine nursery grounds for oceanic dispersal or southward migration ( Lund and Maltezos, 1970; Talbot, 1966).

Thermal discharges should not alter diurnal and tidal temperature variations normally experienced by marine communities. Laboratory studies show thermal tolerance to be enhanced when animals are maintained under a diurnally fluctuating temperature regime rather than at a constant temperature ( Costlow and Bookhout, 1971; Furch, 1972; Hoss, et al.,). A daily cyclic regime can be protective additionally as it reduces duration of exposure to extreme temperatures ( Pearce,

1969; Gonzalez, 1972). 0 Summer thermal maxima should be established to protect the various marine communities within each biogeographic region.

During the summer, naturally elevated temperatures may be of  1 sufficent magnitude to cause death or emigration ( Glynn, 1968;

Vaughn, 1961). This more commonly occurs in tropical and warm temperate zone waters, but has been reported for enclosed bays and shallow waters in other regions as well ( Nichols, 1918).

Summer heat stress also can contribute to increased incidence of disease or parasitism ( Sinderman, 1965) : reduce or block sexual maturation ( Thorhaug, et al., 1971: deVlaming, 1972); inhibit or block embryonic cleavage of larval development ( Calabrese, 1969) ;

reduce feeding and growth of juveniles and adults ( 011a and Studholme, 1971) : result in increased predation ( Gonzalez, 1972);

and reduce productivity of macroalgae and seagrasses ( South and Hill, 1970; Zieman, 1970). The general ceilings set forth here are derived from studies delineating limiting temperatures for the more thermally sensitive species or communities of a biogeographic region.

Thermal effects data are presently insufficient to set general temperature limits for all coastal biogeographic regions.

The data enumerated in the Appendix, plus any additional data subsequently generated, should be used to develop thermal limits which specifically consider communities relevant to given water bodies.

( QUALITY CRITERIA FOR WATER, JULY 1976) PB 263943 SEE APPENDIX C FOR METHODOLOGY 2,3,7,8 TETRACHMRODIBENZO P DIOXIN CRITERIA:

Aquatic Life Not enough data are available concerning the effects of 2,3,7,8 TCDD on aquatic life and its uses to allow derivation of national criteria. The available information indicates that acute values for some freshwater animal species are > 1.0 ug/ L;

some chronic values are < 0.01 ug/ L; and the chronic value for rainbow trout is < 0.001 ug/ L. Because exposures of some species of fishes to 0.01 ug/ L for < 6 days resulted in substantial mortality several weeks later, derivation of aquatic life criteria for 2,3,7,8 TCDD may require special consideration. Predicted bioconcentration factors ( BCFs) for 2,3,7,8 TCDD range from 3,000 to 900,000, but the available measured BCFs range from 390 to 13,000. If the BCF is 5,000, 0 concentrations > 0.00001 ug/ L should result in concentrations in edible freshwater and saltwater fish and shellfish that exceed levels identified in a U. S. FDA health advisory. If the BCF is > 5,000 or if uptake in a field situation is greater than that in laboratory tests, the value of 0.00001 ug/ L will be too high.

Human Health For the maximum protection of human health from the potential carcinogenic effects of 2,3,7,8 TCDD exposure through ingestion of contaminated water and contaminated aquatic orqanisms, the  .

ambient water concentration should be zero. This criterion is based on the nonthreshold assumption f o r 2,3,7,8 TCDD. However,

zero may n o t be an a t t a i n a b l e l e v e l a t t h i s t i m e .

( 4 9 F . R . 5831, February 15, 1984) SEE APPENDIX B FOR METHODOLOGY TETRACHLOROETHYLENE Aquatic Life The available data for tetrachloroethylene indicate that acute and chronic toxicity to freshwater aquatic life occurs at concentrations as low as 5,280 and 840 ug/ L,

respectively, and would occur at lower concentrations among species that are more sensitive than those tested.

The available data for tetrachloroethylene indicate that acute and chronic toxicity to saltwater aquatic life occurs at concentrations as low as 10,200 and 450 ug/ L,

respectively, and would occur at lower concentrations among species that are more sensitive than those tested.

Human Health For the maximum protection of human health from the potential carcinogenic effects of exposure to tetrachloroethylene through ingestion of contaminated water and contaminated aquatic organisms, the ambient water concentrations should be zero, based on the nonthreshold assumption for this chemical. However, zero level may not be attainable at the present time. Therefore, the levels which may result in incremental increase of cancer risk over the lifetime are estimated at and The corresponding recommended criteria are 8.0 ug/ L, 0.80 ug/ L,

and 0.08 ug/ L, respectively. If these estimates are made for consumption of aquatic organisms only, excluding consumption of water, the levels are 88.5 ug/ L, 8.85 ug/ L, and 0.88 ug/ L,

respectively.

( 45 F. R. 79318, November 28, 1980) SEE APPENDIX B FOR METHODOLOGY CRITERIA: THALLIUM Aquatic Life The available data for thallium indicate that acute and chronic toxicity to freshwater aquatic life occurs at concentrations as low as 1,400 and 40 ug/ L, respectively, and would occur at lower concentrations among species that are more sensitive than those tested. Toxicity to one species of fish occurs at concentrations as low as 20 ug/ L after 2,600 hours of exposure.

The available data for thallium indicate that acute toxicity to saltwater aquatic life occurs at concentrations as low as 2,130 ug/ L and would occur at lower concentrations among species that are more sensitive than those tested. No data are available concerning the chronic toxicity of thallium to 0 sensitive saltwater aquatic life.

Human Health For the protection of human health from the toxic properties of thallium ingested through water and contaminated aquatic organisms, the ambient water criterion is determined to be 13 U9/ L.

For the protection of human health from the toxic properties of thallium ingested through contaminated aquatic organisms alone, the ambient water criterion is determined to be 48 ug/ L.

( 45 F. R. 79318, November 28, 1980) 0 SEE APPENDIX B FOR METHODOLOGY m CRITERIA: TOLUENE Aquatic Life The availab 2 data for toluene indicate t at acute toxicity to freshwater aquatic life occurs at concentrations as low as 17,500 ug/ L and would occur at lower concentrations among species that are more sensitive than those tested. No data are available concerning the chronic toxicity of toluene to sensitive freshwater aquatic life.

The available data for toluene indicate that acute and chronic toxicity to saltwater aquatic life occurs at concentrations as low as 6,300 and 5,000 ug/ L, respectively, and would occur at lower concentrations among species that are more sensitive than those tested.

0 Human Health For the protection of human health from the toxic properties of toluene ingested through water and contaminated aquatic organisms, the ambient water criterion is determined to be 14.3 w / L .

For the protection of human health from the toxic properties of toluene ingested through contaminated aquatic organisms alone, the ambient water criterion is determined to be 424 W/ L

( 45 F. R. 79318, November 28, 1980)

NOTE: The U . S . EPA is currently developing Acceptable Daily Intake ( ADI) or Verified Reference Dose ( RfD) values  or Agency wide use for this chemical. The new value should be substituted when it becomes available. The January, * 1986, draft Verified Reference Dose document cites an RfD of 0.3 mg/ kg/ day for toluene. SEE APPENDIX B FOR METHODOLOGY 0 TOXAPHENE CRITERIA:

Aquatic  Life For toxaphene the criterion to protect freshwater aquatic life as derived using the Guidelines is 0.013 ug/ L as a 24 hour average, and the concentration should not exceed 1.6 ug/ L at any time.

For saltwater aquatic life the concentration of toxaphene should not exceed 0.070 ug/ L at any time. No data are available concerning the chronic toxicity of toxaphene to sensitive saltwater aquatic life.

Human Health For the maximum protection of human health from the potential carcinogenic effects of exposure to toxaphene through ingestion of contaminated water and contaminated aquatic organisms,

the ambient water concentration should be zero, based on the non threshold assumption for this chemical. However, zero level may not be attainable at the present time. Therefore, the levels which may result in incremental increase of cancer risk over the lifetime are estimated at and The corresponding recommended criteria are 7.1 ng/ L, 0.71 ng/ L, and 0.07 ng/ L, respectively. If these estimates are made for consumption of aquatic organisms only, excluding consumption of water, the levels are 7.3 ng/ L, 0.73 ng/ L, and 0.01 ng/ L,

respectively. 0  . \

( 45 F. R. 79318, November 28, 1980) SEE APPENDIX B FOR METHODOLOGY CRITERIA: TRICHLOROETHYLENE Aquatic Life The available data for trichloroethylene indicate that acute toxicity to freshwater aquatic life occurs at concentrations as low as 45,000 ug/ L and would occur at lower concentrations among species that are more sensitive than those tested. No data are available concerning the chronic toxicity of trichloroethylene to sensitive freshwater aquatic life but the behavior of one species is adversely affected at concentrations as low as 21,900 ug/ L.

The available data for trichloroethylene indicate that acute toxicity to saltwater aquatic life occurs at concentrations as low as 2,000 ug/ L and would occur at lower concentrations among species that are more sensitive than those tested. No data are available concerning the chronic toxicity of trichloroethylene to sensitive saltwater aquatic life. 0 Human Health For the maximum protection of human health from the potential carcinogenic effects of exposure to trichloroethylene through ingestion of contaminated water and contaminated aquatic organisms, the ambient water concentration should be zero, based on the nonthreshold assumption for this chemical. However,

zero level may not be attainable at the present time. Therefore,

the levels which may result in incremental increase of cancer risk over the lifetime are estimated at lom5, loe6, and lo'*

The corresponding recommended criteria are 27 ug/ L, 2.7 ug/ L, and 0 I _

0.27 ug/ L, respectively. If these estimates are made for consumption of aquatic organisms only, excluding consumption of water, the levels are 807 ug/ L, 80.7 ug/ L, and 8.07 ug/ L,

respectively.

( 45 F. R. 79318, November 28, 1980) SEE APPENDIX B FOR METHODOLOGY CRITERIA: VINYL CHLORIDE Aquatic Life No freshwater organisms have been tested with vinyl chloride and no statement can be made concerning acute or chronic toxicity.

No saltwater organisms have been tested with vinyl chloride and no statement can be made concerning acute or chronic toxicity.

Human Health For the maximum protection of human health from the potential carcinogenic effects of exposure to vinyl chloride through ingestion of contaminated water and contaminated aquatic organisms, the ambient water concentrations should be zero, based on the nonthreshold assumption for this chemical. However,

zero level may not be attainable at the present time.

Therefore, the levels which may result in incremental increase of cancer risk over the lifetime are estimated at 1 0  5 r and The corresponding recommended criteria are 20 ug/ L, 2.0 ug/ L, and 0 . 2 ug/ L, respectively. If these estimates are made for consumption of aquatic organisms only, excluding consumption of water, the levels are 5 , 2 4 6 ug/ L, 5 2 5 ug/ L, and 5 2 . 5 ug/ L,

respectively.

( 4 5 F. R. 79318, November 2 8 , 1980) SEE APPENDIX B FOR METHODOLOGY ZINC CRITERIA:

A q u a t i c  L i f e For t o t a l recoverable zinc t h e crit rion t o p r o t e c t f r e hwater aquatic l i f e a s derived using t h e Guidelines is 47 ug/ L as a 24

hour a v e r a g e and t h e c o n c e n t r a t i o n ( i n ug/ L) s h o u l d n o t e x c e e d t h e n u m e r i c a 1 v a l u e g i v e n b y 0.83 [ l n ( h a r d n e s s ) ]+ 1.95) a t any t i m e . For example, a t e ( h a r d n e s s e s of 50, 1 0 0 , and 200 mg/ L a s CaC03 t h e c o n c e n t r a t i o n of t o t a l r e c o v e r a b l e z i n c s h o u l d n o t exceed 180,

320, and 570 ug/ L a t any t i m e .

For t o t a l recoverable z i n c t h e c r i t e r i o n t o p r o t e c t s a l t w a t e r aquatic l i f e a s derived using t h e Guidelines is 58 ug/ L a s a 24

hour average and t h e concentration should not exceed 190 ug/ L a t any t i m e .

Human H e a l t h S u f f i c i e n t data a r e not a v a i l a b l e f o r zinc t o d e r i v e a level which would p r o t e c t a g a i n s t t h e p o t e n t i a l t o x i c i t y of t h i s compound. Using a v a i l a b l e o r g a n o l e p t i c d a t a , t o c o n t r o l undesirable t a s t e and odor q u a l i t y of ambient water t h e estimated l e v e l is 5 mg/ L. It should be recognized t h a t organoleptic data have l i m i t a t i o n s a s a b a s i s f o r e s t a b l i s h i n g a water q u a l i t y c r i t e r i a , and have no demonstrated r e l a t i o n s h i p to p o t e n t i a l adverse human health effects.

( 45 F. R. 79318, November 28, 1980) SEE APPENDIX B FOR METHODOLOGY I ~

APPENDIX A DERIVATION OF THE 1985 CRITERION  Derivation of numerical national water quality criteria for the protection of aquatic organisms and their uses is a complex process that uses information from many areas of aquatic toxicology. After a decision is made that a national criterion is needed for a particular material, all available information concerning toxicity to, and bioaccumulation by, aquatic organisms is collected, reviewed for acceptability, and sorted. If enough acceptable data on acute toxicity to aquatic animals are available, they are used to estimate the highest 1 hour average concentration that should not result in unacceptable effects on aquatic organisms and their uses. If justified, this concentration is made a function of a water quality characteristic such as pH, salinity, or hardness. Similarly,

data on the chronic toxicity of the material to aquatic animals are used to estimate the highest 4 day average concentration that should not cause unacceptable toxicity during a long term exposure. If appropriate, this concentration is also related to a water quality characteristic.

Data on toxicity to aquatic plants are examined to determine whether plants are likely to be unacceptably affected by concentrations that should not cause unacceptable effects on animals. Data on bioaccumulation by aquatic organisms are used to determine if residues might subject edible species to restrictions by the U. S. Food and Drug Administration or if such residues might harm some wildlife consumers of aquatic life. All other available data are examined  or adverse effects that might be biologically important.

If a thorough review of the pertinent information indicates that enough acceptable data are available, numerical national water quality criteria are derived for fresh water or saltwater or both to protect aquatic organisms and their uses from unacceptable effects due to exposures to high concentrations for short periods of time, lower concentrations for longer periods of time, and combinations of the two.

I. Collection of Data

A. Collect all available data on the material concerning ( a) toxicity to, and biqaccumulation by, aquatic animals and plants, ( b) FDA action levels [ 12], and ( c) chronic feeding studies and long term field studies with wildlife species that regularly consume aquatic organisms.

B. All data that are used should be available in typed, dated, and signed hard copy ( pub1 ication,

manuscript, letter, memorandum, etc.) with enough supporting information to indicate that acceptable test procedures were used and that the results are probably reliable. In some cases it may be appropriate to obtain additional written information from the investigator, if possible.

Information that is confidential or privileged or otherwise not available for distribution should not be used.

C. Questionable data, whether published or unpublished, should not be used. For example, data should usually be rejected if they are from tests that did not contain a control treatment, tests in which too many organisms in the control treatment died or showed signs of stress or disease, and tests in which distilled or deionized water was used as the dilution water without addition of appropriate salts.

D. Data on technical grade materials may be used if appropriate, but data on formulated mixtures and emulsifiable concentrates of the material of concern should not be used.

E. For some highly volatile, hydrolyzable, or degradable materials it is probably appropriate to use only results of flow through tests in which the concentrations of test material in the test solutions were measured often enough using acceptable analytical methods.

F. Data should be rejected if they were obtained using:

1. Brine shrimp, because they usually occur naturally only in water with salinity greater than 35 g/ kg.

2 . Species that do not have reproducing wild populations in North America ( See Appendix 1).

3 . Organisms that were previously exposed to substantial concentrations of the test 0 t.

material or other contaminants. G. Questionable data, data on formulated mixtures and emulsifiable concentrates, and data obtained with nonresident species or previously exposed organisms may be used to provide auxiliary information but should not be used in the derivation of criteria.

11. Required  Data  A. Certain data should be available to help ensure that each of the four major kinds of possible adverse effects receives adequate consideration.

Results of acute and chronic toxicity tests with representative species of aquatic animals are necessary so that data available for tested species can be considered a useful indication of the sensitivities of appropriate untested species.

Fewer data concerning toxicity to aquatic plants are required because procedures for conducting tests with plants and interpreting the results of such tests are not as well developed. Data concerning bioaccumulation by aquatic organisms are required only if relevant data are available concerning the significance of residues in aquatic organisms. I B. To derive a criterion for freshwater aquatic organisms and their uses, the following should be available:

1. Results of acceptable acute tests ( see Section IV) with at least one species of freshwater animal in at least eight different families such that all of the following are included:

a.

b.

C.

d.

e.

f.

g.

h. the family Salmonidae in the class Osteichthyes a second f a m i l y in t h e c l a s s Osteichthyes, preferably a commercially or recreationally important warmwater species ( e. g., bluegill, channel catfish, etc.)

a third family in the phylum Chordata ( may be in the class Osteichthyes or may be an amphibian, etc.)

a planktonic crustacean ( e. g., cladoceran,

copepod, etc.)

a benthic crustacean ( e. g., ostracod,

isopod, amphipod, crayfish, etc.)

an insect ( e. g., mayfly, dragonfly,

damselfly, stonefly, caddis fly, mosquito,

midge, etc.)

a family in a phylum other than Arthropoda or Chordata ( e. g., Rotifera, Annelida,

Mol lusca, etc.)

a family in any order of insect or any phylum not already represented.

2. Acute chronic ratios ( see Section TI) with species of aquatic animals in at least three different families provided that of the three species: a. a t least one is a f i s h b. a t least one is an invertebrate c. a t l e a s t one i s a n a c u t e l y s e n s i t i v e freshwater s p e c i e s ( the o t h e r two may be saltwater species).

3. Results of a t least one acceptable test w i t h a freshwater alga o r vascular p l a n t ( see Section V I I I ) . I f p l a n t s a r e among t h e a q u a t i c organisms t h a t a r e most s e n s i t i v e t o t h e m a t e r i a l , r e s u l t s of a t e s t with a p l a n t i n another phylum ( d i v i s i o n ) should a l s o be available.

4 . A t l e a s t one acceptable bioconcentration f a c t o r dete'rmined w i t h a n a p p r o p r i a t e freshwater s p e c i e s , i f a maximum permissible t i s s u e concentration is a v a i l a b l e ( see Section IX) .

C. To d e r i v e a c r i t e r i o n f o r s a l t w a t e r a q u a t i c organisms and t h e i r uses, the following should be available:

1. Results of acceptable acute tests ( see Section I V ) w i t h a t l e a s t one s p e c i e s of s a l t w a t e r animal i n a t l e a s t e i g h t d i f f e r e n t f a m i l i e s such t h a t a l l of the following are included:

a. two families i n t h e phylum Chordata b. a family i n a phylum other than Arthropoda o r Chordata c. either the Mysidae or Penaeidae family d. three other families not in the phylum Chordata ( may include Mysidae or Penaeidae, whichever was not used above)

e. any other family.

2 . Acute chronic ratios ( see section VI) with species of aquatic animals in at least three different families provided that of the three species:

a. at least one is a fish b. at least one is an invertebrate c. at least one is an acutely sensitive saltwater species ( the other one may be a freshwater species).

3 . Results of at least one acceptable test with a saltwater alga or vascular plant ( see Section VIII. If plants are among the aquatic organisms most sensitive to the material,

results of a test with a plant in another phylum ( division) should also be available.

4 . At least one acceptable bioconcentration factor determined with an appropriate saltwater species, if a maximum permissible tissue concentration is available ( see Section IX) *

D. If all the required data are available, a numerical criterion can usually be derived, except in special 0 % .

cases. For example, derivation of a criterion might n o t be p o s s i b l e i f t h e a v a i l a b l e acute

c h r o n i c r a t i o s v a r y by more t h a n a f a c t o r of 1 0 w i t h no apparent pattern. A l s o , i f a c r i t e r i o n is to be r e l a t e d t o a water q u a l i t y c h a r a c t e r i s t i c T ( see S e c t i o n s V and V I I ) , more d a t a w i l l be necessary.

Similarly, i f a l l required data a r e not a v a i l a b l e ,

a numerical c r i t e r i o n should not be derived except i n s p e c i a l cases. For example, even i f not enough a c u t e and chronic d a t a are a v a i l a b l e , it might be p o s s i b l e t o derive a c r i t e r i o n i f t h e a v a i l a b l e data c l e a r l y indicate t h a t the Final Residue Value should be much lower than either the Final Chronic Value or the Final P l a n t Value.

E. Confidence i n a c r i t e r i o n u s u a l l y increases a s t h e amount of a v a i l a b l e p e r t i n e n t data i n c r e a s e s .

Thus, additional data a r e u s u a l l y desirable.

111. Final A c u t e Value A. Appropriate measures of t h e a c u t e ( short term)

t o x i c i t y o f t h e m a t e r i a l t o a v a r i e t y o f s p e c i e s of a q u a t i c animals are used t o c a l c u l a t e t h e F i n a l Acute Value. The Final Acute Value is an estimate ' of t h e concentration of t h e material corresponding t o a cumulative p r o b a b i l i t y of 0.05 i n t h e a c u t e t o x i c i t y v a l u e s f o r t h e g e n e r a w i t h which acceptable a c u t e tests have been conducted on t h e material. However, i n some cases, i f t h e Species Mean A c u t e V a l u e o f a c o m m e r c i a l l y o r recreational 1 y important species is lower than t h e c a l c u l a t e d F i n a l Acute Value, t h e n t h a t Species Mean A c u t e Value r e p l a c e s t h e c a l c u l a t e d F i n a l Acute Value i n order t o provide protection f o r t h a t important species.

B. Acute t o x i c i t y tests should have been conducted using acceptable procedures [ 13].

C. Except f o r tests w i t h s a l t w a t e r a n n e l i d s and mysids, r e s u l t s of a c u t e tests during which t h e t e s t organisms were fed should not be used, unless data i n d i c a t e t h a t t h e food d i d n o t a f f e c t t h e t o x i c i t y of t h e t e s t material.

D. R e s u l t s o f a c u t e t e s t s conducted i n unusual d i l u t i o n water, e. g., d i l u t i o n water i n which t o t a l 0 organic carbon o r p a r t i c u l a t e m a t t e r exceeded 5 mg/ L, should not be used, unless a r e l a t i o n s h i p is developed between acute t o x i c i t y and organic carbon o r p a r t i c u l a t e matter o r u n l e s s d a t a show t h a t organic carbon, p a r t i c u l a t e m a t t e r , etc., do not affect toxicity.

E. Acute values should be based on endpoints which r e f l e c t t h e t o t a l s e v e r e a c u t e adverse impact of t h e t e s t m a t e r i a l on t h e organisms used i n the test. Therefore, only t h e following kinds of data on acute t o x i c i t y t o a q u a t i c animals should be used: 1. T e s t s w i t h daphnids and o t h e r cladocerans should be s t a r t e d with organisms less than 24 hours o l d and t e s t s with midges should be stressed with second o r t h i r d i n s t a r larvae.

The r e s u l t should be t h e 48 hr EC50 based on p e r c e n t a g e of organisms immobilized p l u s percentage of organisms k i l l e d . I f such an EC50 i s n o t a v a i l a b l e from a t e s t , t h e 48 hr LC50 should be used i n p l a c e of t h e d e s i r e d 48 hr EC50. An EC50 o r LC50 of l o n g e r t h a n 4 8 hours can be used as long as t h e animals were n o t f e d and t h e c o n t r o l animals were acceptable a t t h e end of t h e test.

a 2. The r e s u l t of a t e s t w i t h embryos and l a r v a e o f b a r n a c l e s , b i v a l v e m o l l u s c s ( c l a m s ,

mussels, oysters, and s c a l l o p s ) , sea urchins,

l o b s t e r s , c r a b s , shrimp, and abalones should be t h e 96 hr EC50 based on t h e percentage of organisms with incompletely developed s h e l l s p l u s t h e percentage of organisms k i l l e d . I f such an EC50 is n o t a v a i l a b l e from a t e s t , t h e l o w e r o f t h e 96 h r EC50 based on t h e percentage of organisms w i t h incompletely developed shells and t h e 96 hr LC50 should be used i n p l a c e of t h e desired 96 hr EC50. I f t h e duration of t h e t e s t w a s between 48 and 96 hours, t h e EC50 o r LC50 a t t h e end of t h e test should be used. 3. T h e acute v a l u e s from tests w i t h a l l o t h e r freshwater and s a l t w a t e r animal s p e c i e s and o l d e r l i f e s t a g e s o f b a r n a c l e s , b i v a l v e m o l l u s c s , s e a u r c h i n s , l o b s t e r s , c r a b s ,

shrimps, and abalones should be t h e 96 hr EC50 b a s e d on t h e p e r c e n t a g e o f o r g a n i s m s e x h i b i t i n g loss of e q u i l i b r i u m p l u s t h e percentage of organisms immobilized p l u s the percentage OF organisms k i l l e d . I f such a n EC50 is n o t a v a i l a b l e from a t e s t , t h e 96 hr LC50 should be used i n p l a c e of t h e desired 96 hr EC50.

4 . T e s t s w i t h s i n g l e c e l l e d organisms a r e not considered a c u t e t e s t a , even i f t h e d u r a t i o n was 96 hours o r less. 0 5. If t h e tests were conducted p r o p e r l y , acute v a l u e s reported a s " g r e a t e r than" v a l u e s and t h o s e which a r e above t h e s o l u b i l i t y of t h e t e s t m a t e r i a l s h o u l d be u s e d , because r e j e c t i o n o f s u c h a c u t e v a l u e s would unnecessarily lower t h e F i n a l Acute Value by e l i m i n a t i n g a c u t e v a l u e s for r e s i s t a n t species.

F. If t h e acute t o x i c i t y of t h e material t o aquatic animals apparently has been shown t o be r e l a t e d t o a water q u a l i t y c h a r a c t e r i s t i c such as hardness o r p a r t i c u l a t e m a t t e r f o r f r e s h w a t e r animals o r s a l i n i t y or p a r t i c u l a t e m a t t e r f o r s a l t w a t e r animals, a Final Acute Equation should be derived based on t h a t water q u a l i t y characteristic. G o t o Section V.

G. If t h e a v a i l a b l e d a t a i n d i c a t e t h a t one or more l i f e s t a g e s a r e a t l e a s t a f a c t o r of 2 more r e s i s t a n t than one ormore o t h e r l i f e s t a g e s o f t h e same species, the data for the more r e s i s t a n t l i f e stages should not be used i n t h e c a l c u l a t i o n of t h e Species Mean Acute Value ( SMAV) because a species c a n o n l y be c o n s i d e r e d p r o t e c t e d from a c u t e t o x i c i t y i f a l l l i f e stages are protected.

H. T h e agreement o f t h e d a t a w i t h i n and between species should be considered. Acute v a l u e s t h a t appear t o be questionable i n comparison w i t h other acute and chronic data f o r the same species and for other species i n the same genus probably should not be used i n c a l c u l a t i o n of a Species Mean Acute Value. For example, i f the acute values a v a i l a b l e For a species o r genus d i f f e r by more than a f a c t o r of 1 0 , some or a l l of t h e v a l u e s probably should not be used i n calculations.

I. For each species f o r which a t l e a s t one a c u t e v a l u e i s a v a i l a b l e , the Species Mean Acute Value should be c a l c u l a t e d a s t h e geometric mean of t h e r e s u l t s of a l l flow through tests i n which t h e concentrations of test material were measured. For a species for which no such r e s u l t i s a v a i l a b l e , the Species Mean Acute Value should be calculated as t h e geometric mean of a l l a v a i l a b l e a c u t e v a l u e s , i. e., r e s u l t s of flow through tests i n which t h e concentrations were not measured and r e s u l t s of s t a t i c and renewal t e s t s based on i n i t i a l concentrations of t e s t m a t e r i a l ( nominal c o n c e n t r a t i o n s a r e a c c e p t a b l e f o r most t e s t m a t e r i a l s i f measured c o n c e n t r a t i o n s a r e n o t available).

NOTE: Data reported by o r i g i n a l investigators should not be rounded o f f . R e s u l t s of a l l intermediate c a l c u l a t i o n s s h o u l d b e rounded [ 14] to f o u r significant d i g i t s .

The geometric mean of N numbers is t h e Nth root of 0 NOTE:

t h e product of t h e N numbers. Alternatively, the geometric mean can be c a l c u l a t e d by adding t h e logarithms of t h e N numbers, d i v i d i n g t h e sum by N, and t a k i n g t h e a n t i l o g of t h e q u o t i e n t . The geometric mean of t w o numbers is t h e square root of t h e p r o d u c t of t h e two numbers, and t h e geometric mean of one number is t h a t number.

E i t h e r n a t u r a l ( base 0 ) or common ( b a s e 1 0 )

logarithms can be used to c a l c u l a t e geometric means as long a s they a r e used consistently w i t h i n each set of d a t a , i. e., t h e a n t i l o g used must match the logarithm U s e d . NOTE: Geometric means, rather than arithmetic means, are used here because t h e distributions of sensitivities of individual organisms in toxicity tests on most materials and the distributions of sensitivities of species within a genus are more likely to be lognormal than normal. Similarly,

geometric means are used for acute chronic ratios and bioconcentration factors because quotients are likely to be closer to lognormal than normal distributions. In addition, division of the geometric mean of a set of numerators by the geometric mean of the set of corresponding denominators will result in the geometric mean of the set of corresponding quotients.

J. For each genus  or which one or more Species Mean Acute Values are available, the Genus Mean Acute Value should be calculated as the geometric mean of the Species Mean Acute Values available f o r the genus.

K. Order the Genus Mean Acute Value from high to low.

L. Assign ranks, R, to the Genus Mean Acute Value from vvlvv for the lowest to *' N"  or the highest.

If two or more Genus Mean Acute Values are identical, arbitrarily assign them successive ranks.

M. Calculate the cumulative probability, P,  or each Genus Mean Acute Value as R/ ( N+ l). N. Select t h e four Genus Mean Acute Value which have cumulative p r o b a b i l i t i e s c l o s e s t t o 0.05 ( i f there a r e l e s s than 59 Genus Mean Acute Value, these w i l l always be t h e f o u r lowest Genus Mean Acute Values).

Using t h e selected Genus Mean Acute Values and Fs,

calculate:

S2= E ( l n GMAV) 2) ( ( E l n GMAV)) 2/ 4)

( PI  (( E / " ~ ) ) 2 / 4 ) 0.

L = ( E( 1n GMAV)  S( E(/ Ap)))/ 4 A = S(/" O. OS) + L FAV = e A ( See [ 113 f o r development of t h e c a l c u l a t i o n procedure and Appendix 2 f o r example calculation and computer program.)

NOTE: Natural logarithms ( logarithms t o base el denoted a s I n ) a r e used h e r e i n merely because they a r e e a s i e r t o use on some hand c a l c u l a t o r s and computers t h a n common ( base 1 0 ) l o g a r i t h m s .

Consistent u s e of e i t h e r w i l l produce t h e same result.

P. If f o r a commercially o r r e c r e a t i o n a l l y important s p e c i e s t h e geometric mean of t h e a c u t e v a l u e s f r o m f l o w  t h r o u g h t e s t s i n w h i c h t h e concentrations of t e s t material were measured i s lower than the calculated F i n a l Acute Value, then t h a t geometric mean should be used a s t h e F i n a l Acute Value instead of the c a l c u l a t e d Final Acute Value.

Q. GO to section VI.  IV. Final Acute Equation 0 A. When enough data are available to show that acute toxicity to two o r more species is similarly related to a water quality characteristic, the relationship should be taken into account as described in Sections B G below or using analysis of covariance [ 15,16]. The two methods are equivalent and produce identical results. The manual method described below provides an unuerstanding of this application of covariance analysis, but computerized versions of covariance analysis are much more convenient for analyzing large data tests. If two or more factors affect toxicity, multiple regression analysis should be used.

B. For each species for which comparable acute toxicity values are available at two or more different values of the water quality characteristic, perform a least squares regression of the acute toxicity values on the corresponding values of the water quality characteristic to obtain the slope and its 95 percent confidence limits  or each species.

NOTE: Because the best documented relationship fitting these data is that between hardness and acute toxicity of metals in fresh water and a log log relationship, geometric means and natural logarithms of both toxicity and water quality are used in the rest of this section. For relationships based on other water quality characteristics such as pH, temperature, or salinity, no transformation or a different transformation might fit the data better, and appropriate changes will be necessary throughout this section.

C . Decide whether the data for eachspecies are useful, taking into account the range and number of the tested values of the water quality characteristic and the degree of agreement within and between species. For example, a slope based on six data points might be of limited value if it is based only on data for a very narrow range of values of the water quality characteristic. A slope based on only two data points, however,

might be useful if it is consistent with other information and if the two points cover a broad enough range of the water quality characteristic.

In addition, acute values that appear to be questionable in comparison with other acute and chronic data available for the same species and for other species in the same genus probably should not be used. For example, if after adjustment for the water quality characteristic,

the acute values available for a species or genus d i f f e r by more than a f a c t o r of 1 0 , probably some o r a l l of the v a l u e s should be rejected. I f useful slopes a r e not a v a i l a b l e f o r a t least one f i s h and one i n v e r t e b r a t e o r i f t h e a v a i l a b l e s l o p e s a r e t o o d i s s i m i l a r o r i f t o o f e w d a t a a r e a v a i l a b l e t o adequately d e f i n e t h e r e l a t i o n s h i p between a c u t e t o x i c i t y and t h e water q u a l i t y characteristic, return t o Section IV. G, using t h e r e s u l t s of tests conducted under conditions and i n waters s i m i l a r t o those commonly used f o r t o x i c i t y tests with the species.

D. I n d i v i d u a l l y f o r each species c a l c u l a t e the geometric mean of t h e a v a i l a b l e acute values and t h e n d i v i d e each of t h e a c u t e v a l u e s f o r species by the mean f o r the species. T h i s normalizes t h e v a l u e s so t h a t t h e g e o m e t r i c mean o f t h e normalized values f o r each species individual1 y and f o r any combination of species is 1.0.

E. S i m i l a r l y normalize t h e v a l u e s of t h e water q u a l i t y c h a r a c t e r i s t i c f o r e a c h s p e c i e s individually.

F. I n d i v i d u a l l y f o r each species perform a l e a s t squares regression of t h e normalized acute t o x i c i t y v a l u e s on t h e corresponding normalized values of the water q u a l i t y characteristic. The r e s u l t i n g slopes and 95 percent confidence l i m i t s ~. w i l l be i d e n t i c a l t o those obtained i n Section B. NOW, however, i f t h e d a t a a r e a c t u a l l y p l o t t e d ,

t h e l i n e of best f i t f o r each i n d i v i d u a l s p e c i e s w i l l go through t h e p o i n t 1, l i n t h e center of t h e graph.

G. Treat a l l the normalized data as i f they were a l l f o r t h e same species and perform a l e a s t squares regression of a l l the normalized acute values on the corresponding normalized values of the water q u a l i t y c h a r a c t e r i s t i c t o obtain t h e pooled acute s l o p e , V , and its 95 p e r c e n t confidence l i m i t s .

If a l l the normalized data a r e a c t u a l l y plotted,

t h e l i n e of best f i t w i l l go through t h e p o i n t 1, l i n t h e center of t h e graph.

H. For each species aalculate t h e geometric mean, W,

of the a c u t e t o x i c i t y v a l u e s and t h e geometric mean, X I of t h e v a l u e s of t h e w a t e r q u a l i t y characteristic. ( These were calculated i n s t e p s D and E.)

I. For each s p e c i e s c a l c u l a t e t h e logarithm, Y , of t h e Species Mean Acute Value a t a selected value,

2, of t h e water q u a l i t y c h a r a c t e r i s t i c using t h e equation:

Y = I n W  v ( l n X  In 2 ) .

J. For each species c a l c u l a t e t h e SMAV a t Z using t h e equation: SMAV = eY.

NOTE: Alternatively, the Species Mean Acute Values a t Z can be obtained by skipping s t e p H u s i n g t h e equations i n steps I and J t o a d j u s t each acute value individually t o 2, and then calculating the geometric mean of t h e a d j u s t e d v a l u e s  or each species individually. T h i s a l t e r n a t i v e procedure allows an examination of the range of t h e adjusted acute values f o r each species.

K. Obtain the F i n a l Acute Value a t Z by using the procedure described i n Section 1V. J 0.

L. I f t h e S p e c i e s Mean Acute V a l u e a t Z of a commercially o r r e c r e a t i o n a l l y important species is lower than the calculated Final Acute Value a t Z, t h e n t h a t Species Mean Acute Value should be used as t h e Final Acute Value a t Z instead of the calculated Final Acute Value.

M. The F i n a l Acute Equation is w r i t t e n as: F i n a l A c u t e V a l u e = . ( V [ l n ( w a t e r q u a l i t y c h a r a c t e r i s t i c ) ] + I n A  V [ l n Z]), where V =

pooled acute s l o p e a n d A = F i n a l A c u t e v a l u e a t 2.

Because V, A, and 2 are known, t h e F i n a l Acute Value can be calculated f o r any selected value of the water q u a l i t y c h a r a c t e r i s t i c .

V.  Final Chronic Value A. Depending on t h e d a t a t h a t a r e a v a i l a b l e concerning chronic t o x i c i t y t o a q u a t i c animals,

the Final Chronic Value might be calculated i n the same manner a s t h e F i n a l Acute Value o r by dividing t h e Final Acute Value by the Final Acute NOTE :

B. Chronic R a t i o . I n some c a s e s it may n o t be possible to calculate a F i n a l Chronic Value.

As t h e name implies, the acute chronic r a t i o is a way of r e l a t i n g acute and chronic t o x i c i t i e s . The acute chronic r a t i o is b a s i c a l l y t h e i n v e r s e of t h e a p p l i c a t i o n f a c t o r , b u t t h i s new name i s better because it is more d e s c r i p t i v e and should h e l p p r e v e n t c o n f u s i o n between ' a p p l i c a t i o n f a c t o r s " and " s a f e t y f a c t o r s . " Acute chronic r a t i o s and a p p l i c a t i o n f a c t o r s a r e ways of r e l a t i n g t h e a c u t e and c h r o n i c t o x i c i t i e s of a material t o aquatic organisms. Safety f a c t o r s are used to p r o v i d e an e x t r a margin of s a f e t y beyond the known or e s t i m a t e d s e n s i t i v i t i e s of a q u a t i c organisms. Another advantage of t h e acute chronic r a t i o i s t h a t it w i l l u s u a l l y be g r e a t e r than 1;

t h i s should avoid t h e confusion as to whether a l a r g e a p p l i c a t i o n f a c t o r is one t h a t is c l o s e to u n i t y or one t h a t has a denominator t h a t is much greater than t h e numerator.

Chronic values should be based on r e s u l t s of flow

t h r o u g h ( except r e n e w a l is a c c e p t a b l e f o r d a p h n i d s ) c h r o n i c t e s t s i n w h i c h t h e c o n c e n t r a t i o n s of t e s t m a t e r i a l i n t h e t e s t s o l u t i o n s w e r e p r o p e r l y measured a t a p p r o p r i a t e I t i m e s during the test. . * C . R e s u l t s of chronic tests i n which s u r v i v a l , growth, o r reproduction i n t h e c o n t r o l treatment was unacceptably low should n o t be used. The l i m i t s of a c c e p t a b i l i t y w i l l depend on t h e species.

D. R e s u l t s of chronic t e s t s conducted i n unusual d i l u t i o n water, e. g., d i l u t i o n water i n which t o t a l o r g a n i c carbon o r p a r t i c u l a t e m a t t e r exceeded 5 mg/ L, should n o t be used, u n l e s s a relationship is developed between chronic t o x i c i t y and organic carbon o r p a r t i c u l a t e matter o r unless data show t h a t organic carbon, p a r t i c u l a t e matter, etc., do not a f f e c t toxicity.

E. Chronic v a l u e s should be based on endpoints and l e n g t h s of exposure a p p r o p r i a t e t o t h e species.

Therefore, only r e s u l t s of t h e following kinds of chronic t o x i c i t y tests should be used:

1. L i f e c y c l e t o x i c i t y tests c o n s i s t i n g of exposures of each of t w o or more groups of i n d i v i d u a l s o f a s p e c i e s to a d i f f e r e n t concentration of t h e t e s t material throughout a l i f e c y c l e . To ensure t h a t a l l l i f e s t a g e s and l i f e p r o c e s s e s a r e exposed, t e s t s w i t h f i s h s h o u l d b e g i n w i t h embryos o r n e w l y hatched young less than 48 hours o l d , continue t h r o u g h m a t u r a t i o n and r e p r o d u c t i o n , and should end n o t l e s s than 2 4 days ( 90 days f o r salmonids) a f t e r t h e hatching of the next generation. T e s t s w i t h daphnids should begin w i t h young less t h a n 2 4 hours o l d a n d l a s t f o r n o t less t h a n 2 1 days. T e s t s w i t h mysids should begin w i t h young less than 24 hours o l d and c o n t i n u e u n t i l 7 days p a s t themediantime of first brood r e l e a s e i n t h e c o n t r o l s . For f i s h , data should be obtained and analyzed on s u r v i v a l and growth of a d u l t s and young,

maturation of males and females, eggs spawned per female, embryo v i a b i l i t y ( salmonids only) ,

and h a t c h a b i l i t y . For daphnids, d a t a should be obtained and analyzed on s u r v i v a l and young p e r f e m a l e . For mysids, d a t a s h o u l d be obtained and analyzed on s u r v i v a l , growth, and young per female.

2 . P a r t i a l l i f e c y c l e t o x i c i t y tests consisting of exposures of each of two or more groups of i n d i v i d u a l s o f a s p e c i e s o f f i s h to a c o n c e n t r a t i o n of t h e t e s t material through most portions of a l i f e cycle. P a r t i a l l i f e

cycle tests are allowed w i t h f i s h species that r e q u i r e more than a y e a r to reach s e x u a l maturity, so t h a t a l l major l i f e stages can be exposed t o t h e t e s t m a t e r i a l i n less t h a n 15 months. Exposure to t h e test material should begin with immature j u v e n i l e s a t l e a s t 2 months p r i o r to a c t i v e gonad development,

continue through maturation and reproduction, and end not less than 2 4 days ( 90 days for salmonids) after the hatching of the next generation. Data should be obtained and analyzed on survival and growth of adults and young, maturation of males and females, eggs spawned per female, embryo viability ( salmonids only), and hatchability.

3. Early life stage toxicity tests consisting of 28 to 32 day ( 6 0 days. post hatch for salmonids) exposures of the early life stages of a species of fish from shortly a, fter fertilization through embryonic, larval, and early juvenile development. Data should be obtained and analyzed on survival and growth.

NOTE: Results of an early life stage test are used as predictions of results of life cycle and partial life cycle tests with the same species.

Therefore, when results of a life cycle or partial life cycle test are available, results of an early life stage test with the same species should not be used. Also, results of early life stage tests in which the incidence of mortalities or abnormalities increased substantially near the end of the test should not be used because results of such tests are possibly not good predictions of the results of comparable life cycle or partial 1 if e cycle tests. 0 F. A chronic v a l u e may be obtained by c a l c u l a t i n g t h e geometric mean of t h e lower and upper chronic l i m i t s from a chronic t e s t o r by analyzing chronic d a t a using r e g r e s s i o n a n a l y s i s . A l o w e r chronic l i m i t is t h e h i g h e s t tested c o n c e n t r a t i o n ( a ) i n an acceptable c h r o n i c t e s t , ( b) which d i d n o t cause an unacceptable amount of adverse effect on any of the specified biological measurements, and ( c) below which no tested concentration caused an unacceptable effect. An upper c h r o n i c l i m i t is t h e l o w e s t t e s t e d c o n c e n t r a t i o n ( a ) i n a n a c c e p t a b l e c h r o n i c t e s t , ( b) which d i d cause an unacceptable amount of adverse e f f e c t on one or more of the specified biological measurements, and ( c) above which a l l tested c o n c e n t r a t i o n s a l s o caused such an e f f e c t .

NOTE: Because v a r i o u s a u t h o r s have used a v a r i e t y of terms and d e f i n i t i o n s t o i n t e r p r e t and r e p o r t r e s u l t s of chronic tests, reported r e s u l t s should be reviewed c a r e f u l l y . The amount of effect t h a t is considered unacceptable is o f t e n based on a s t a t i s t i c a l hypothesis t e s t , b u t might a l s o be defined i n terms of a specified percent reduction from t h e c o n t r o l s . A small p e r c e n t r e d u c t i o n ( e. g., 3 p e r c e n t ) might be considered acceptable even i f it i s s t a t i s t i c a l l y s i g n i f i c a n t l y d i f f e r e n t from t h e c o n t r o l , whereas a l a r g e p e r c e n t reduction ( e. g., 30 percent) might be c o n s i d e r e d u n a c c e p t a b l e e v e n i f it i s n o t s t a t i s t i c a l l y significant.

G . I f t h e chronic toxicity of t h e material t o aquatic animals apparently has been shown t o be r e l a t e d t o a water quality c h a r a c t e r i s t i c such a s hardness o r p a r t i c u l a t e matter f o r freshwater animals o r s a l i n i t y o r p a r t i c u l a t e matter f o r s a l t w a t e r a n i m a l s , a F i n a l Chronic Equation s h o u l d be d e r i v e d b a s e d o n t h a t w a t e r q u a l i t y characteristic. G o t o Section V I I .

H. I f chronic v a l u e s a r e a v a i l a b l e f o r s p e c i e s i n eight families a s described i n Sections I I I . B . 1 or I I I . C . 1 , a Species Mean Chronic Value ( SMCV)

should be calculated f o r each species f o r which a t l e a s t one c h r o n i c v a l u e i s a v a i l a b l e by c a l c u l a t i n g t h e geometric mean of a l l chronic values a v a i l a b l e f o r t h e species, and appropriate Genus Mean Chronic Values should be c a l c u l a t e d .

T h e F i n a l Chronic Value should t h e n be obtained using t h e procedure described i n S e c t i o n 1V. J 0 .

Then go t o Section V1. M.

I. For each chronic v a l u e f o r which a t l e a s t one c o r r e s p o n d i n g a p p r o p r i a t e a c u t e v a l u e i s available, c a l c u l a t e an acute chronic r a t i o , using for t h e numerator t h e g e o m e t r i c mean of t h e r e s u l t s of a l l a c c e p t a b l e f low through ( except 0 s t a t i c is acceptable f o r daphnids) acute tests i n the same dilution water and in which the concentrations were measured. For fish, the acute test( s) should have been conducted with juveniles.

The acute test( s) should have been part of the same study as the chronic test. If acute tests were not conducted as part of the same study,

acute tests conducted in the same laboratory and dilution water, but in a different study, may be used. If no such acute tests are available,

results of acute tests conducted in the same dilution water in a different laboratory may be used. If no such acute tests are available, an acute chronic ratio should not be calculated.

J. For each species, calculate the species mean acute chronic ratio as the geometric mean of all acute chronic ratios available for that species.

K. For some materials the acute chronic ratio seems to be the same for all species, but for other materials the ratio seems to increase or decrease as the Species Mean Acute Value ( SMAV) increases.

Thus the Final Acute Chronic Ratio can be obtained in four ways, depending on the data available:

1. If the Species Mean Acute Chronic ratio Seems to increase or decrease as the Species Mean Acute Value increases, the Final Acute Chronic Ratio should be calculated as the geometric mean of the acute chronic ratios for species whose Species Mean Acute Values are c l o s e to the Final Acute Value.

2 . If no major t r e n d is apparent and t h e acute

c h r o n i c r a t i o s f o r a number of s p e c i e s a r e w i t h i n a f a c t o r of 1 0 , t h e F i n a l Acute

Chronic Ratio should be c a l c u l a t e d a s t h e geometric mean of a l l the Species Mean Acute

Chronic Ratios a v a i l a b l e for both freshwater and saltwater species.

3 . For a c u t e tests conducted on metals and p o s s i b l y o t h e r substances w i t h embryos and l a r v a e of barnacles, b i v a l v e m o l l u s c s , sea urchins, lobsters, crabs, shrimp, and abalones ( see S e c t i o n I V . E . 2 ) , it i s p r o b a b l y a p p r o p r i a t e to assume t h a t t h e acute chronic 0 r a t i o is 2. Chronic tests are very d i f f i c u l t t o conduct w i t h most such s p e c i e s , b u t it is l i k e l y t h a t the s e n s i t i v i t i e s of embryos and l a r v a e would determine t h e r e s u l t s of l i f e

c y c l e tests. Thus, i f t h e l o w e s t a v a i l a b l e Species Mean Acute Values were determined with embryos and larvae of such species, t h e Final Acute Chronic Ratio should probably be assumed to be 2 , so t h a t t h e F i n a l Chronic Value is equal to t h e Criterion Maximum Concentration ( see Section X1. B)

a * . , ~ ..? a. ...,.. 4 . If the most appropriate Species Mean Acute

Chronic Ratios are less than 2 . 0 , and especially if they are less than 1.0,

acclimation has probably occurred during the chronic test. Because continuous exposure and acclimation cannot be assured to provide adequate protection in field situations, the Final Acute Chronic Ratio should be assumed to be 2 , so that the Final Chronic Value is equal to the Criterion Maximum Concentration ( see Section X1. B).

If the available Species Mean Acute Chronic Ratios do not fit one of these cases, a Final Acute Chronic Ratio probably cannot be obtained, and a Final Chronic Value probably cannot be calculated.

L. Calculate the Final Chronic Value by dividing the Final Acute Value by the Final Acute Chronic Ratio. If there was a Final Acute Equation rather than a Final Acute Value, see also Section VI1. A.

M. If the Species Mean Chronic Value of a commercially or recreational ly important species is lower than the calculated Final Chronic Value,

then that species Mean Chronic Value should be used as the Final Chronic Value instead of the calculated Final Chronic Value.

N. Go to Section VIII. VI. Final Chronic Equation 0  A. A Final Chronic Equation can be derived in two ways. The procedure described here in Section A will result in the chronic slope being the same as the acute slope. The procedure described in Sections B N usually will result in the chronic slope being different from the acute slope.

1. If acute chronic ratios are available  or enough species at enough values of the water quality characteristic to indicate that the acute chronic ratio is probably the same for all species and is probably independent of the water quality characteristic, calculate the Final Acute Chronic Ratio as the geometric mean of the available Species Mean Acute

Chronic Ratios. '

2 . Calculate the Final Chronic Value at the selected value Z of the water quality characteristic by dividing the Final Acute Value at Z ( see Section V. M) by the Final Acute Chronic Ratio.

3 . Use V = pooled acute slope ( see section V. M)

as L = pooled chronic slope.

4 . Go to Section VI1. M.

B. When enough data are available to show that chronic toxicity to at least one species is related to a water quality characteristic, the relationship should be taken into account as described in Sections B G or using analysis of covariance [ 15,16]. The two methods are equivalent and produce identical results. The manual method described below provides an understanding of this application of covariance analysis, but computerized versions of covariance analysis are much more convenient for analyzing large data sets. If two or more factors affect toxicity, multiple regression analysis should be used.

For each species for which comparable chronic toxicity values are available at two or more different values of the water quality characteristic, perform a least squares regression of the chronic toxicity values on the corresponding values of the water quality characteristic to obtain the slope and its 95 percent confidence limits for each species.

NOTE: Because the best documented relationship fitting these data is that between hardness and acute toxicity of metals in freshwater and a log log relationship, geometric means and natural logarithms of both toxicity and water quality are used in the rest of this section. For relationships based on other water quality characteristics such as pH, temperature, or s a l i n i t y , no t r a n s f o r m a t i o n or a d i f f e r e n t transformation might f i t t h e d a t a better, and appropriate changes w i l l be necessary throughout t h i s section. f t is probably preferable, but not necessary, to use t h e same transformation t h a t was u s e d w i t h t h e a c u t e v a l u e s i n s e c t i o n v .

D. Decide whether t h e d a t a f o r each s p e c i e s a r e u s e f u l , t a k i n g i n t o account t h e range and number of t h e t e s t e d v a l u e s of t h e w a t e r q u a l i t y c h a r a c t e r i s t i c and the degree of agreement w i t h i n and between species. For example, a s l o p e based on s i x d a t a p o i n t s m i g h t b e o f l i m i t e d v a l u e i f it is based only on data  or a v e r y narrow range of v a l u e s of t h e water q u a l i t y c h a r a c t e r i s t i c , A s l o p e based on o n l y two d a t a p o i n t s , however,

might be u s e f u l i f it is c o n s i s t e n t w i t h o t h e r information and i f t h e two p o i n t s cover a broad enough range of the water q u a l i t y characteristic.

I n a d d i t i o n , chronic v a l u e s t h a t appear to be questionable i n comparison w i t h o t h e r a c u t e and chronic d a t a a v a i l a b l e  or t h e same species and f o r o t h e r s p e c i e s i n t h e same genus probably s h o u l d n o t be used. For example, i f a f t e r adjustment f o r the water qua1 i t y c h a r a c t e r i s t i c ,

t h e c h r o n i c v a l u e s a v a i l a b l e f o r a s p e c i e s or genus d i f f e r by more than a factor of 10, probably some or a l l of the values should be rejected. I f a useful chronic slope is not available for at least one species or if the available slopes are too dissimilar or if too few data are available to adequately define the relationship between chronic toxicity and the water quality characteristic, it might be appropriate to assume that the chronic slope is the same as the acute slope, which is equivalent to assuming that the acute chronic ratio is independent of the water quality characteristic. Alternatively, return to Section VI. H, using the results of tests conducted under conditions and in waters similar to those commonly used for toxicity tests with the species.

E. Individually for each species calculate the geometric mean of the available chronic values and then divide each chronic value for a species by the mean for the species. This normalizes the chronic values so that the geometric mean of the normalized values for each species individually and for any combination of species is 1.0.

F. Similarly normalize the values of the water quality characteristic for each species individually.

G . Individually for each species perform a least squares regression of the normalized chronic toxicity values on the corresponding normalized values of the water quality characteristic. The resulting slopes and the 95 percent confidence limits will be identical to those obtained in Section B. Now, however, if the data are actually plotted, the line of best fit for each individual species will go through the point 1,1 in the center of the graph.

K. Treat all the normalized data as if they were all for the same species and perform a least squares regression of all the normalized chronic values on the corresponding normalized values of the water quality characteristic to obtain the pooled chronic slope, L, and its 95 percent confidence limits, If all the normalized data are actually plotted, the line of best fit will go through the point 1, l in the center of the graph.

I. For each species calculate the geometric mean, M I 0 of the toxicity values and the geometric mean, PI of the values of the water quality characteristic.

( These were calculated in steps E and F.) J.

NOTE :

K.

NOTE :

L.

M. For each s p e c i e s c a l c u l a t e t h e logarithm, Q, of t h e Species Mean Chronic Value a t a selected v a l u e , Z, of t h e water q u a l i t y characteristic using t h e equation: Q = I n M  L( ln P  I n Z).

Although it is n o t necessary, it w i l l u s u a l l y be best t o use t h e same v a l u e of t h e water q u a l i t y characteristic here as was used i n section V. I.

For each species c a l c u l a t e a Species Mean Chronic Value a t z using t h e equation: SMCV = eQ.

Alternatively, t h e Species Mean Chronic Values a t Z can be obtained by skipping s t e p J, u s i n g t h e equations i n s t e p s J and K t o a d j u s t each a c u t e value individually t o 2 , and then c a l c u l a t i n g the geometric means of t h e a d j u s t e d v a l u e s f o r each species individually. T h i s a l t e r n a t i v e procedure allows an examination of the range of the adjusted chronic values for each species.

Obtain the Final Chronic Value a t 2 by using the procedure described i n Section 1V. J 0.

I f t h e Species Mean Chronic Value a t Z of a commercially o r r e c r e a t i o n a l l y important species is lower than t h e calculated Final Chronic Value a t Z, then t h a t Species Mean Chronic Value should b e u s e d as t h e F i n a l C h r o n i c V a l u e a t Z i n s t e a d o f the calculated Final Chronic Value. N . The Final Chronic Equation i S written as: Final C h r o n i c V a l u e = e ( L [ l n ( w a t e r q u a l i t y c h a r a c t e r i s t i c ) ] + I n S  L [ l n Z ] ) , where L =

pooled chronic slope and S = Final Chronic Value a t 2. Because L, S and Z a r e known, t h e F i n a l Chronic Value can be calculated f o r any selected value of the water q u a l i t y characteristic.

Final Plant Value A. Appropriate measures of t h e t o x i c i t y of t h e material to aquatic p l a n t s a r e used to compare the r e l a t i v e s e n s i t i v i t i e s of a q u a t i c p l a n t s and animals. Although procedures for conducting and i n t e r p r e t i n g the r e s u l t s of t o x i c i t y tests w i t h p l a n t s are n o t w e l l developed, r e s u l t s of tests with p l a n t s usually indicate t h a t c r i t e r i a which adequately protect aquatic animals and their uses w i l l probably a l s o p r o t e c t a q u a t i c p l a n t s and their uses.

B. A p l a n t v a l u e i s the r e s u l t of a 96 hr t e s t conducted w i t h an a l g a o r a chronic t e s t conducted w i t h an aquatic vascular p l a n t .

NOTE: A t e s t of t h e t o x i c i t y of a metal to a p l a n t u s u a l l y should not be used i f the medium contained an excessive amount of a complexing agent, such as EDTA, t h a t might a f f e c t the t o x i c i t y of t h e metal.

Concentrations of EDTA above about 200 ug/ L should probably be considered excessive. C. T h e F i n a l P l a n t Value should be obtained by s e l e c t i n g t h e lowest r e s u l t from a t e s t w i t h an important a q u a t i c p l a n t species i n which t h e concentrations of t e s t material were measured and the endpoint was b i o l o g i c a l l y important.

V I I I . Final Residue Value A. The Final Residue Value is intended t o ( a) prevent concentrations i n commercially or r e c r e a t i o n a l l y i m p o r t a n t a q u a t i c s p e c i e s f r o m a f f e c t i n g marketability because of exceedence of applicable FDA a c t i o n l e v e l s and ( b) p r o t e c t w i l d l i f e ,

i n c l u d i n g f i s h e s and b i r d s , t h a t consume a q u a t i c organisms from demonstrated unacceptable effects.

The F i n a l Residue Value i s t h e l o w e s t of t h e r e s i d u e v a l u e s t h a t are obtained by d i v i d i n g maximum permissible t i s s u e c o n c e n t r a t i o n s by a p p r o p r i a t e b i o c o n c a n t r a t i o n or bioaccumulation f a c t o r s . A maximum p e r m i s s i b l e t i s s u e concentration i s either ( a) an FDA a c t i o n l e v e l [ 12] f o r f i s h o i l o r f o r t h e e d i b l e p o r t i o n of f i s h or s h e l l f i s h , or ( b) a maximum a c c e p t a b l e dietary intake based on observations on s u r v i v a l ,

growth, or reproduction i n a c h r o n i c w i l d l i f e feeding study or a long term w i l d l i f e f i e l d study.

I f no maximum permissible t i s s u e concentration is a v a i l a b l e , go to S e c t i o n X b e c a u s e no F i n a l Residue Value can be derived. B. ~ i o c o n c e n t r a t i o n actors ( B C F S ) a n d bioaccumulation f a c t o r s ( BAFs) a r e q u o t i e n t s of t h e concentration of a m a t e r i a l i n one o r more t i s s u e s of an a q u a t i c organism d i v i d e d by t h e average concentration i n the solution i n which t h e organism had been l i v i n g . A BCF i s intended to account Only f o r n e t uptake d i r e c t l y from water,

and t h u s almosthastobemeasured i n a l a b o r a t o r y test. Some uptake during t h e bioconcentration test might n o t b e d i r e c t l y fromwater if t h e food sorbs some of t h e t e s t material before it is e a t e n by t h e t e s t organisms. A BAF i s intended to account f o r n e t uptake from both food and water i n a r e a l

world situation. A BAF almost has to be measured i n a f i e l d situation i n which predators accumulate the material d i r e c t l y from water and by consuming prey that itself could have accumulated t h e m a t e r i a l from both food and water. The BCF and BAF a r e probably similar f o r a material w i t h a low BCF, b u t t h e BAF is probably higher t h a n t h e BCF f o r m a t e r i a l s w i t h high BCFs. Although BCFs are not too d i f f i c u l t to determine, very f e w BAFs have been measured acceptably because it is necessary to make enough measurements of t h e concentration of t h e m a t e r i a l i n water to show t h a t it was reasonably constant f o r a l o n g enough period of t i m e over the range of t e r r i t o r y inhabited by the organisms. Because so few acceptable BAFs are available, only BCFs will be discussed further.

However, if an acceptable BAF is available for a material, it should be used instead of any available BCFs.

C. If a maximum permissible tissue concentration is available for a substance ( e. g., parent material,

parent material plus metabolites, etc.) , the tissue concentration used in the calculation of the BCF should be for the same substance.

otherwise the tissue concentration used in the calculation of the BCF should be' that of the material and its metabolites which are structurally similar and are not much more soluble in water than the parent material.

D. 1. A BCF should be used only if the test was flow through, the BCF was calculated based on measured concentrations of the test material in tissue and in the test solution, and the exposure continued at least until either apparent steady state or 2 8 days was reached.

Steady state is reached when the BCF does not change significantly over a period of time,

such a 2 days o r 16 percent of the length of the exposure, whichever is longer. The BCF used from a test should be the highest of ( a)

the apparent steady state BCF, if apparent steady state was reached, ( b) the highest BCF obtained, if apparent steady state was not reached, and ( c) the projected steady state BCF, if calculated.

2 . Whenever a BCF is determined for a lipophilic material, the percent lipids should also be determined in the tissue( s) for which the BCF was calculated.

3 . A BCF obtained from an exposure that adversely affected the test organisms may be used only if it is similar to a BCF obtained with unaffected organisms of the same species at lower concentrations that did not cause adverse effects.

4 . Because maximum permissible tissue concentrations are almost never based on dry weights, a BCF calculated using dry tissue weights must be converted to a wet tissue weight basis. If no conversion factor is reported with the BCF, multiply the dry weight BCF by 0.1 for plankton and by 0 . 2 for individual species of fishes and invertebrates ~ 1 7 1 .

5. If more than one acceptable BCF is available for a species, the geometric mean of the available values should be used, except that if the BCFs are from different lengths of exposure and the BCF increases with length of exposure, the BCF f o r t h e l o n g e s t exposure should be used.

E. I f enough p e r t i n e n t data exist, several residue v a l u e s can be c a l c u l a t e d by d i v i d i n g maximum p e r m i s s i b l e t i s s u e concentrations by appropriate BCFs :

1. For each a v a i l a b l e maximum acceptable d i e t a r y intake derived from a chronic feeding study o r a long t e r m f i e l d s t u d y w i t h w i l d l i f e ,

i n c l u d i n g b i r d s and a q u a t i c organisms, t h e appropriate BCF is based on t h e whole body of aquatic species which constitute' or represent a major p o r t i o n of t h e d i e t of t h e t e s t e d w i l d l i f e species.

2 . For an FDA action l e v e l f o r f i s h o r s h e l l f i s h ,

t h e a p p r o p r i a t e BCF is t h e h i g h e s t geometric mean s p e c i e s BCF f o r t h e e d i b l e p o r t i o n ( muscle f o r decapods, muscle with o r without skin f o r f i s h e s , adductor muscle f o r s c a l l o p s ,

and t o t a l s o f t t i s s u e f o r o t h e r b i v a l v e molluscs) of a consumed species. The highest species BCF is used because FDA action l e v e l s a r e applied on a species by species basis.

F. For l i p o p h i l i c materials, it might be possible t o c a l c u l a t e additional residue values. Because the steady state BCF f o r a l i p o p h i l i c material Seems t o be p r o p o r t i o n a l t o p e r c e n t l i p i d s from one t i s s u e t o another and from one species t o another [ 18 20], extrapolations can be made from tested tissues or species to untested tissues or species an the basis of percent lipids.

1. For each BCF for which the percent lipids is known for the same tissue for which the BCF was measured, normalize the BCF to a 1 percent lipid basis by dividing the BCF by the percent lipids. This adjustment to a 1 percent lipid basis is intended to make all the measured BCFs far a material comparable regardless of the species or tissue'with which the BCF was measured.

2 . calculate the geometric mean normalized BCF.

Data for both saltwater and freshwater species should be used to determine the mean normalized BCF, unless the data show that the normalized BCFs are probably not similar,

3 . Calculate all possible residue values by dividing the available maximum permissible tissue concentrations by the mean normalized BCF and by the percent lipids values appropriate to the maximum permissible tissue concentrations, i. e.,

( maximum permissible tissue concentration) Residue value = ( mean normalized BCF)( appropriate percent lipids)

tissue concentration) Residue value = ( mean normalized BCF) ( appropriate percent lipids)

a. For an FDA action level for fish oil, the appropriate percent lipids value is 100.

b. For an FDA action level for fish, the appropriate percent lipids value is 11 for freshwater criteria and 10 for saltwater criteria because FDA action levels are applied on a species by

species basis to commonly consumed species. The highest lipid contents in the edible portions of important consumed species are about 11 percent for both the freshwater chinook salmon and lake trout and about 10 percent for the saltwater Atlantic herring [ 21].

c. For a maximum acceptable dietary intake derived froma chronic feeding studyora long term field study with wildlife, the appropriate percent lipids is that of an aquatic species o r group of aquatic species which constitute a major portion of the diet of the wildlife species.

G. The Final Residue Value is obtained by selecting the lowest of the available residue values. NOTE: In some cases the Final Residue Value will not be l o w enough. For example, a residue value calculated from an FDA action level will probably result in an average concentration in the edible portion of a fatty species that is at the action level. Some individual organisms, and possibly some species, will have residue concentrations higher than the mean value but no mechanism has been devised to provide appropriate additional protection. Also, some chronic feeding studies and long term field studies with wildlife identify concentrations that cause adverse effects but do not identify concentrations which do not cause adverse effects; again, no mechanism has been devised to provide appropriate additional protection. These are some of the species and uses that are not protected at all times in all places.

 x. other Data Pertinent information that could not be used in earlier sections might be available concerning adverse effects on aquatic organisms and their uses. The most important of these are data on cumulative and delayed toxicity, flavor impairment, reduction in survival,

growth, or reproduction, or any other adverse effect that has been shown to be biologically important.

Especially important are data for species for which no ~~ other data are available. Data from behavioral,

biochemical, physiological, microcosm, and field studies might also be available. Data might be available from tests conducted in unusual dilution water ( see 1V. D and VI. D), from chronic tests in which the concentrations were not measured ( see VI. B), from tests with previously exposed organisms ( see 1I. F) ,

and from tests on formulated mixtures or emulsifiable concentrates ( see 1I. D). Such data might affect a criterion if the data were obtained with an important species, the test concentrations were measured, and the endpoint was biologically important. '

XI. Criterion _.

A. A criterion consists of two concentrations: the Criterion Maximum Concentration and the Criterion Continuous Concentration.

B. The Criterion Maximum Concentration ( CMC) is equal to one half the Final Acute Value.

C. The Criterion Continuous Concentration ( CCC) is equal to the lowest of the Final Chronic Value,

the Final Plant Value, and the Final Residue Value, unless other data ( see Section X) show that a lower value should be used. If toxicity is related to a water quality characteristic, the Criterion continuous concentration is obtained from the Final Chronic Equation, the Final Plant Value, and the Final Residue Value by selecting the one, or the combination, that results in the lowest concentrations in the usual range of the water quality characteristic, unless other data ( see Section X) show that a lower value should be used.

D. Round [ 14] both the Criterion Maximum Concentration and the Criterion Continuous Concentration to two significant digits.

E. The criterion is stated as:

The procedures described in the Guidelines for Deriving Numerical National Water Quality Criteria for the Protection of Aquatic Organisms and Their Uses indicate that, except possibly where a locally important species is very sensitive, ( 1)

aquatic organisms and their uses should not be 0 affected unacceptably if the 4 day average concentration of ( 2) does not exceed ( 3) ug/ L more than once every 3 years on the average and if the 1 hour average concentration does not exceed ( 4)

ug/ L more than once every 3 years on the average.

where ( 1) = insert nlfreshwaternl or nrsaltwaternl ( 2) = insert name of material ( 3) = insert the Criterion Continuous Concentration ( 4) = insert the Criterion Maximum Concentration. Final R e v i e v A. T h e d e r i v a t i o n o f t h e c r i t e r i o n s h o u l d be c a r e f u l l y reviewed by rechecking each s t e p of t h e Guidelines. I t e m s t h a t s h o u l d be e s p e c i a l l y checked are:

1. I f unpublished d a t a a r e used, are t h e y w e l l documented?

A r e a l l required data a v a i l a b l e ? 2 .

3. Is the range of acute v a l u e s f o r any species greater than a f a c t o r of l o ?

4 . Is the range of Species Mean Acute Values for any genus g r e a t e r than a f a c t o r of lo?

5 . Is t h e r e more t h a n a f a c t o r of 10 difference between t h e ' f o u r lowest Genus Mean Acute Values?

6 . A r e any of t h e f o u r lowest Genus Mean Acute Valuesquestionable?

7 . Is the F i n a l Acute Value reasonable i n comparison with t h e Species Mean Acute Values and Genus Mean Acute Values?

8. For any c o m m e r c i a l l y or r e c r e a t i o n a l l y important s p e c i e s , is t h e geometric mean of t h e a c u t e v a l u e s from flow through tests i n which t h e concentrations of t e s t material were measured lower than the F i n a l Acute Value?

9. Are any of the chronic values questionable?

0 10.

11.

12 13.

14 *

15.

16. Are chronic values available for acutely sensitive species?

Is the range of acute chronic ratios greater than a factor of 10?

Is the Final Chronic Value reasonable in comparison with the available acute and chronic data?

Is the measured or predicted chronic value for any commercially or recreational ly important species below the Final Chronic Value?

Are any of the other data important?

Do any data look like they might be outliers?

Are there any deviations from the Guidelines?

Are they acceptable?

B. On the basis of a l l available pertinent laboratory and field information, determine if the criterion is consistent with sound scientific evidence. If it is not, another criterion, either higher or lower, should be derived using appropriate modifications of these Guidelines. APPENDIX B SUMHARY OF THE 1980 AQUATIC LIFE GUIDELINES The Guidelines f o r Deriving Water Q u a l i t y C r i t e r i a f o r t h e P r o t e c t i o n of Aquatic L i f e and i t s U s e s were developed t o describe an objective, i n t e r n a l l y consistent, and appropriate way of ensuring t h a t water q u a l i t y c r i t e r i a f o r a q u a t i c l i f e would provide, on t h e average, a reasonable amount of protection. The r e s u l t i n g c r i t e r i a are n o t intended t o provide 100 percent protection of a l l species and a l l uses of aquatic l i f e a l l of the t i m e , b u t t h e y a r e i n t e n d e d to p r o t e c t most species i n a balanced, healthy aquatic community.

Minimum data requirements are i d e n t i f i e d i n f o u r a r e a s ;

acute t o x i c i t y to animals ( eight data points), chronic t o x i c i t y t o animals ( three data points), t o x i c i t y t o p l a n t s , and residues.

Data on a c u t e t o x i c i t y a r e needed f o r a v a r i e t y of f i s h and invertebrate species and a r e used t o derive a Final Acute Value.

By taking i n t o account t h e number and r e l a t i v e s e n s i t i v i t i e s of t h e tested species, the Final Acute Value is designed t o protect most, b u t n o t n e c e s s a r i l y a l l , of t h e tested and u n t e s t e d species.

Data on chronic t o x i c i t y to animals can be used to d e r i v e a F i n a l Chronic V a l u e by two d i f f e r e n t means. If c h r o n i c v a l u e s a r e a v a i l a b l e f o r a s p e c i f i e d number and a r r a y of s p e c i e s , a F i n a l Chronic Value can be c a l c u l a t e d d i r e c t l y . I f n o t , an acute chronic ratio is derived and then used with the Final Acute Value to obtain t h e Final Chronic Value.

The F i n a l P l a n t Value is obtained by s e l e c t i n g t h e lowest p l a n t t o x i c i t y value based on measured concentrations. The Final Residue Value is intended t o protect w i l d l i f e which consume a q u a t i c organisms and t h e m a r k e t a b i l i t y of a q u a t i c organisms. Protection of the marketability of aquatic organisms i s , i n a c t u a l i t y , p r o t e c t i o n o f a u s e o f t h a t water body ( commercial f i s h e r y ) . Two kinds of d a t a are necessary t o c a l c u l a t e t h e F i n a l Residue Value: a b i o c o n c e n t r a t i o n f a c t o r ( BCF) and a maximum permissible t i s s u e concentration, which can be an FDAaction l e v e l or c a n b e t h e r e s u l t o f a c h r o n i c w i l d l i f e feeding study. For l i p i d  s o l u b l e p o l l u t a n t s , t h e BCF is normalized f o r percent l i p i d s and then t h e F i n a l Residue Value is c a l c u l a t e d by d i v i d i n g t h e maximum permissible t i s s u e concentration by the normalized BCF and by an appropriate percent l i p i d v a l u e . BCFs are normalized f o r p e r c e n t l i p i d s s i n c e the BCF measured f o r any i n d i v i d u a l a q u a t i c s p e c i e s is g e n e r a l l y proportional t o t h e percent l i p i d s i n t h a t species. a If s u f f i c i e n t data are a v a i l a b l e t o demonstrate t h a t one o r more of t h e f i n a l v a l u e s should be related t o a water q u a l i t y c h a r a c t e r i s t i c , such as s a l i n i t y , hardness, or suspended s o l ids,

t h e f i n a l v a l u e ( s ) a r e e x p r e s s e d a s a f u n c t i o n o f t h a t c h a r a c t e r i s t i c .

A f t e r t h e four f i n a l values ( Final Acute Value, Final Chronic Value, F i n a l P l a n t Value, and F i n a l Residue Value) have been obtained, the c r i t e r i o n is established w i t h the Final Acute value becoming t h e maximum v a l u e and t h e lowest of t h e o t h e r t h r e e values becoming the 24 hour average value. A l l of the data used t o c a l c u l a t e the four f i n a l values and any additional pertinent information are then reviewed to determine i f t h e c r i t e r i o n i s reasonable. I f sound s c i e n t i f i c evidence i n d i c a t e s t h a t t h e criterion should be raised or lowered, appropriate changes are made as necessary.

The November 28, 1980, Guidelines have been revised from the earlier published versions ( 4 3 FR 21506, May 18, 1978; 43 FR 29028, July 5, 1978; 4 4 FR 15926, March 15, 1979). Details have been added in many places and the concept of a minimum data base has been incorporated. In addition, three adjustment factors and the species sensitivity factor have been deleted. These modifications were the result of the Agency's analysis of public comments and comments received from the Science Advisory Board on earlier versions of the Guidelines. These comments and the Resultant modifications are addressed fully in Appendix D to this notice.

Criteria for the Protection of Human Health Interpretation of the Human Health Criteria 0 The human health criteria issued today are summarized in Appendix A of this Federal Register notice. Criteria for the protection of human health are based on their carcinogenic,

toxic, or organoleptic ( taste and odor) properties. The meanings and practical uses of the criteria values are distinctly different depending on the properties on which they are based.

The objective of the health assessment portions of the criteria documents is to estimate ambient water concentrations which, in the case of noncarcinogens, prevent adverse health effects in humans, and in the case of suspect or proven carcinogens, represent various levels of incremental cancer risk. Health assessments typically contain discussions of four elements: exposure, pharmacokinetics, toxic effects, and criterion formulation.

The exposure section summarizes information on exposure routes: ingestion directly from water, indirectly from consumption of aquatic organisms found in ambient water, other dietary sources, inhalation, and dermal contact. Exposure assumptions are used to derive human health criteria. Most criteria are based solely on exposure from consumption of water containing a specified concentration of a toxic pollutant and through consumption of aquatic organisms which are assumed to have bioconcentrated pollutants from the water in which they live. Other multimedia routes of exposure such as air,

nonaquatic diet, or dermal are not factored into the criterion formulation for the vast majority of pollutants because of lack of data. The criteria are calculated using the combined aquatic exposure pathway and also using the aquatic organism ingestion exposure route alone. In criteria reflecting both the water consumption and aquatic organism ingestion routes of exposure,

the relative exposure contribution varies with the propensity of a pollutant to bioconcentrate, with the consumption of aquatic organisms becoming more important as the bioconcentration factor ( BCF) increases. As additional information on total exposure is assembled for pollutants for which criteria reflect only the two specified aquatic exposure routes, adjustments in water concentration values may be made. The demonstration of significantly different exposure patterns will become an element of a process to adapt/ modify human health based criteria to local conditions, somewhat analogous to the aquatic life criteria modification process discussed previously. It is anticipated that States at their discretion will be able to set appropriate human health criteria based on this process. 0 Specific health based criteria are developed only if a weight of evidence supports the occurrence of the toxic effect and if dose/ response data exist from which criteria can be estimated.

The pharmacokinteics section reviews data on absorption,

distribution, metabolism, and excretion to assess the biochemical fate of the compounds in the human and animal system. The toxic effects section reviews data on acute, subacute, and chronic toxicity, synergistic and antagonistic effects, and specific information on mutagenicity, teratogenicity, and carcinogenicity.

From this review, the toxic effect to be protected against is identified taking into account the quality, quantity, and weight of evidence characteristic of the data. The criterion formulation section reviews the highlights of the text and specifies a rationale for criterion development and the mathematical derivation of the criterion number.

Within the limitations of time and resources, current published information of significance was incorporated into the human health assessments. Review articles nad reports were used for data evaluation and synthesis. Scientific judgment was exercised in reviewing and evaluating the data in each criteria document and in identifying the adverse effects for which protective criteria were published. 0 >. Criteria for suspect or proven carcinogens are presented as concentrations in water associated with a range of incremental cancer risks to man. Criteria for noncarcinogens represent levels at which exposure to a single chemical is not anticipated to produce adverse effects in man. In a few cases, organoleptic ( taste and odor) data form the basis for the criterion. While this type of criterion does not represent a value which directly affects human health, it is presented as an estimate of the level of a pollutant that will not produce unpleasant taste or odor either directly from water consumption or indirectly by consumption of aquatic organisms found in ambient waters. A criterion developed in this manner is judged to be as useful as other types of criteria in protecting designated water uses. In addition, where data are available, toxicity based criteria are also presented for pollutants with derived organoleptic criteria.

The choice of criteria used in water quality standards for these pcllutants will depend upon the designated use to be protected.

In the case of a multiple use water body, the criterion protecting the most sensitive use will be applied. Finally, for several pollutants no criteria are recommended because insufficient information is available for quantitative criterion formulation.

Risk Extrapolation Because methods do not exist to establish the presence of a threshold for carcinogenic effects, EPAIs policy is that there is no scientific basis for estimating " safe" levels for carcinogens.

The criteria for carcinogens, therefore, state that the recommended concentration for maximum protection of human health is zero. In addition, the Agency has presented a range of concentrations corresponding to incremental cancer risks of to ( one additional case of cancer in populations ranging from 10 million to 100,000, respectively). Other concentrations representing different risk levels may be calculated by use of the Guidelines. The risk estimate range is presented for information purposes and does not represent an Agency judgment on a " acceptable" risk level.

Summary of the Human Health Guidelines The health assessments and corresponding criteria were derived based on Guidelines and Methodology Used in the Preparation of Health Effect Assessment Chapters of the Consent Decree Water Criteria Documents ( the Guidelines ) developed by EPA'S Office of Research and Development. The estimation of 0 health risk associated with human exposure to environmental pollutants requires predicting the effect of low doses for up to a lifetime in duration. A combination of epidemiological and animal dose/ response data is considered the preferred basis for quantitative criterion derivation.

No effect ( noncarcinogen) or specified risk ( carcinogen)

concentrations were estimated by extrapolation from animal toxicity or human epidemiology studies using the following basic exposure assumptions: a 70 kilogram male person ( Report of the Task Group on Reference Man, International Commission for Radiation Protection, November 23, 1957) as the exposed individual; the average daily consumption of freshwater and 0 estuarine fish and shellfish products equal to 6.5 grams/ day; and the average ingestion of 2 liters/ day of water ( Drinking Water and Health, National Academy of Sciences, National Research Council, 1977). Criteria based on these assumptions are estimated to be protective of an adult male who experiences average exposure conditions.

Two basic methods were used to formulate health criteria,

depending on whether the prominent adverse effect was cancer or other toxic manifestations. The  01 lowing sections detail these methods.

Carcinogens Extrapolation of cancer responses from high to low doses and subsequent risk estimation from animal data are performed using a linearized multi stage model. This procedure is flexible enough to fit all monotonically increasing dose response data, since it incorporates several adjustable parameters. The multi stage model is a linear nonthreshold model as was the " one hit" model original 1 y used in the proposed criteria documents. The 1 inear nonthreshold concept has been endorsed by the four agencies in the Interagency Regulatory Liaison Group and is less likely to underestimate risk at the low doses typical of environmental exposure than other models that could be used. Because of the uncertainties associated with dose response, animal to human extrapolation, and other unknown factors; because of the use of average consumptions; and because of the serious public health consequences that could result if risks were underestimated, EPA believes that it is prudent to use conservative methods to estimate risk in the water quality criteria program. The linearized multistage model is more systematic and invokes fewer arbitrary assumptions than the " one hit" procedure previously used. 0 It should be noted that extrapolation models provide estimates of risk since a variety of assumptions are built into any model. Models using widely different assumptions may produce estimates ranging over several orders of magnitude. Since there is at present no way to demonstrate the scientific validity of any model, the use of risk extrapolation models is a subject of debate in the scientific community. However, risk extrapolation is generally recognized as the only tool available at this time  or estimating the magnitude of health hazards associated with nonthreshold toxicants and has been endorsed by numerous Federal agencies and scientific organizations, including EPA` s Carcinogen Assessment Group, the National Academy of Sciences, and the Interagency Regulatory Liaison Group, as a useful means of assessing the risks of exposure to various carcinogenic pollutants.

Noncarcinogens Health criteria based on toxic effects of pollutants other than carcinogenicity are estimates of concentrations which are not expected to produce adverse effects in humans. They are based upon Acceptable Daily Intake ( ADI) levels and are generally derived using no observed adverse ef fect level data from animal studies although human data are used wherever available. The AD1 is calculated using safety factors to account for uncertainties 0 inherent in extrapolation from animal to man. In accordance With the National Research Council recommendations ( Drinking Water and Health, National Academy of Sciences, National Research Council,

1977), safety factors of 10, 100, or 1,000 are used, depending on the quality and quantity of data. In some instances extrapolations are made from inhalation studies or limits to approximate a human response from ingestion using the Stokinger

Woodward model ( Journal of American Water Works Association,

1958). Calculations of criteria from ADIS are made using the standard exposure assumptions ( 2 liters of water, 6.5 grams of edible aquatic products, and an average body weight of 7 0 kg). APPENDIX C . THE PHILOSOPHY OF TRE 1976 WATER QUALITY CRITERIA

Water quality criteria specify concentrations of water constituents which, if not exceeded, are expected to support an organic ecosystem suitable for the higher uses of water. Such criteria are derived from scientific facts obtained from experimental or L~ J g& gg observations that depict organic responses to a defined stimulus or material under identifiable or regulated environmental conditions for a specified time period.

Water quality criteria are not intended to offer the same degree of strategy for survival and propagation at all times to all organisms within a given ecosystem. They are intended not only to protect essential and significant life in water and the direct users o f w a t e r , b u t a l s o t o p r o t e c t life that isdependent on life in water for its existence, or that may consume intentionally or unintentionally any edible portion of such life.

The criteria levels for domestic water supply incorporate available data for human health protection. Such values are different from the criteria levels necessary for protection of aquatic life. The Agency's interim primary drinking water regulations ( 40 Federal Register 59566 December 24, 1975), as required by the Safe Drinking Water Act ( 4 2 U. S. C. 300f, et seq.) , incorporate applicable domestic water supply criteria.

Where pollutants are identified in both the quality criteria for domestic water supply and the Drinking Water Standards, the concentration levels are identical. Water treatment may not significantly affect the removal of certain pollutants. What is essential and significant life in water? Do Daphnia or stonefly nymphs qualify as such life? Why does 1/ 100th of a concentration that is lethal to 5 0 percent of the test organisms ( LC50) constitute a criterion in some instances, whereas 1/ 2 or l/ lOth of some effect levels constitutes a criterion in other instances? These are questions that often are asked of those who undertake the task of criteria formulation.

The universe of organisms composing life in water is great in both kinds and numbers. As in the human population,

physiological variability exists among individuals of the same species in response to a given stimulus. A much greater response variation exists among species of aquatic organisms. Thus,

aquatic organisms do not exhibit the same degree of harm,

individually or by species, from a given concentration of a toxicant or potential toxicant within the environment. In establishing a level or concentration of a quality constituent as a criterion it is necessary to ensure a reasonable degree of safety for those more sensitive species that are important to the functioning of the aquatic ecosystem even though data on the response of such species to the quality constituent under consideration may not be available. The aquatic food web is an intricate relationship of predator and prey organisms. A water constituent that may in some way destroy or eliminate an important segment of that food web would, in all likelihood,

destroy or seriously impair other organisms associated with it. 1 0 Although experimentation relating to the effects of particular substances under control led conditions began in the early 19OO's, the effects of any substance on more than a few of the vast number of aquatic organisms have not been investigated.

Certain test animals have been selected by investigators for intensive investigation because of their importance to man, their availability to the researcher, and their physiological responses to the laboratory environment. As general indicators of organism responses such test organisms are representative of the expected results for other associated organisms. In this context Daphnia or stoneflies or other associated organisms indicate the general levels of toxicity to be expected among untested species. In addition, test organisms are themselves vital 1 inks within the food web that results in the fish population in a particular waterway.

The ideal data base for criteria development would consist of information on a large percentage of aquatic species and would show the community response to a range of concentrations for a tested constituent during a long time period. This information is not available but investigators are beginning to derive such information for a few water constituents. Where only 96 hour bioassay data are available, judgmental prudence dictates that a substantial safety factor be employed to protect all life stages of the test organism in waters of varying quality, as well as associated organisms within the aquatic environment that have not been tested and that may be more sensitive to the test constituent. Application factors have been used to provide the degree of protection required. Safe levels for certain chlorinated hydrocarbons and certain heavy metals were estimated by applying an 0.01 application factor to the 96 hour LC50 value a for sensitive aquatic organisms. Flow through bioassays have been conducted for some test indicator organisms over a substantial period of their life history. In a few other cases,

information is available for the organism's natural life or for more than one generation of the species. Such data may indicate a minimal effect level, as well as a no effect level.

The word '* criterion* I should not be used interchangeably with or as a synonym for the word '* standard.** The word '* criterion"

represents a constituent concentration or level associated with a degree of environmental effect upon which scientific judgment may be based. A s it is currently associated with the water environment it has come to mean a designated concentration of a constituent that, when not exceeded, will protect an organism,

an organism community, or a prescribed water use or quality with an adequate degree of safety. A criterion, in some cases, may be a narrative statement instead of a constituent concentration. on the other hand, a standard connotes a legal entity for a particular reach of waterway or  or an effluent. A water quality standard may use a water quality criterion as a basis for regulation or enforcement, but the standard may differ from a criterion because of prevailing local natural conditions, such as naturally occurring organic acids, or because of the importance of a particular waterway, economic considerations, or the degree of safety to a particular ecosystem that may be desired.

Toxicity to aquatic life generally is expressed in terms of acute ( short term) or chronic ( long term) effects. Acute toxicity refers to effects occurring in a short time period: often death is the end point. Acute toxicity can be expressed as the lethal concentration for a stated percentage of organisms tested, or the reciprocal, which is the tolerance limit of a percentage of surviving organisms, Acute toxicity for aquatic organisms generally has been expressed for 2 4 to 96 hOur exposures.

chronic toxicity refers to effects through an extended time period. Chronic toxicity may be expressed in terms of an observation period equal to the lifetime of an organism o r to the time span of more than one generation. Some chronic effects may be reversible, but most are not.

Chronic effects often occur in the species population rather than in the individual. o r the sperm does not remain viable, the species would be eliminated from an ecosystem because of reproductive failure. Physiological stress may make a species less competitive with others and may result in a gradual population decline o r absence from an area. The elimination of a microcrustacean that serves as a vital food during the larval period of a fish's life could result ultimately in the elimination of the fish from an area. The phenomenon of bioaccumulation of certain materials may result in chronic toxicity to the ultimate consumer in a rood chain. Thus, fish may mobilize lethal toxicants from their fatty tissues during periods of physiological stress. Egg shells of predatory birds may be weakened to a point of destruction in the nest. Bird chick embryos may have increased mortality rates. There may be a hazard to the health of man if aquatic organisms with toxic residues are consumed. If eggs fail to develop The fact that living systems, i. e., individuals, populations,

species, and ecosystems, can take up, accumulate, and bioconcentrate manmade and natural toxicants is well documented.

In aquatic systems biota are exposed directly to pollutant toxicants through submersion in a relatively efficient solvent ( water) and are exposed indirectly through food webs and other biological, chemical, and physical interactions. Initial toxicant levels, if not immediately toxic and damaging, may accumulate in the biota or sediment over time and increase to levels that are lethal or sublethally damaging to aquatic organisms or to consumers of these organisms. Water quality criteria reflect a knowledge of the capacity for environmental accumulation, persistence, and effects of specific toxicants in specific aquatic systems.

Ions of toxic materials frequently cause adverse effects because they pass through the semipermeable membranes of an organism. Molecular diffusion through membranes may occur for some compounds such as pesticides, polychlorinated biphenyls,

and other toxicants. Some materials may not pass through membranes in their natural or waste discharged state, but in water they may be converted to states that have increased ability to affect organisms. For example, certain microorganisms can methylate mercury, thus producing a material that more readily enters physiological systems. Some materials may have multiple effects: for example, an iron salt may not be toxic; an iron floc or gel may be an irritant or clog fish gills to effect asphyxiation; iron at l o w concentrations can be a trace nutrient but at high concentrations it can be a toxicant. Materials also can affect organisms if their metabolic byproducts cannot be excreted. Unless otherwise stated, criteria are based on the total concentration of the substance because an ecosystem can produce chemical, physical, and biological changes that may be detrimental to organisms living in or using the water.

In prescribing water quality criteria, certain fundamental principles dominate the reasoning process. In establishing a level or concentration as a criterion for a given constituent it was assumed that other factors within the aquatic environment are acceptable to maintain the integrity of the water.

Interrelationships and interactions among organisms and their environment, as well as the interrelationships of sediments and the constituents they contain to the water above, are recognized 0 as fact.

Antagonistic and synergistic reactions among many quality constituents in water also are recognized as fact. The precise definition of such reactions and their relative effects on particular segments of aquatic life have not been identified with scientific precision. Historically much of the data to support criteria development was of an ambient concentration organism response nature. Recently, data are becoming available on long

term chronic effects on particular species. Studies now determine carcinogenic, teratogenic, and other insidious effects of toxic materials.

Some unpolluted waters in the Nation may exceed designated criteria for particular constituents. There is variability in the natural quality of water and certain organisms become adapted to that quality, which may be considered extreme in other areas.

Likewise, it is recognized that a single criterion cannot identify minimal quality for the protection of the integrity of water for every aquatic ecosystem in the Nation. To provide an adequate degree of safety to protect against long term effects may result in a criterion that cannot be detected with present analytical tools. In some cases, a mass balance calculation can provide a means of assurance that the integrity of the waterway is not being degraded.

Water quality criteria do not have direct regulatory impact,

but they form the basis for judgment in several Environmental Protection Agency programs that are derived from water quality considerations. For example, water qual ity standards developed by the States under section 303 of the Act and approved by EPA are to be based on the water quality criteria, appropriately modified to take account of local conditions. The local conditions to be considered include actual and projected uses of the water, natural background levels of particular constituents,

the presence or absence of sensitive important species,

characteristics of the local biological community, temperature and weather, flow characteristics, and synergistic or antagonistic effects of combinations of pollutants.

Similarly, by providing a judgment on desirable levels of ambient water qual ity, water quality criteria are the starting point in deriving toxic pollutant effluent standards pursuant to section 307( a) of the Act. Other EPA programs that use water qual ity criteria involve drinking water standards, the ocean dumping program, designation of hazardous substances, dredge spoil criteria development, removal of in place toxic materials,

thermal pollution, and pesticide registration.

To provide the water resource protection for which they are designed, quality criteria should apply to virtually all of the Nation's navigable waters with modifications for local conditions as needed. To violate quality criteria for any substantial length of time or in any substantial portion of a waterway may result in an adverse affect on aquatic life and perhaps a hazard to man o r other consumers of aquatic life.

Quality criteria have been designed  to provide long term protection. Thus, they may provide a basis for effluent standards, but it is not intended that criteria values become effluent standards. It is recognized that certain substances may a be applied to the aquatic environment with the concurrence of a governmental agency for the precise purpose of controlling or managing a portion of the aquatic ecosystem: aquatic herbicides and piscicides are examples of such substances. For such occurrences, criteria obviously do not apply. It is recognized further that pesticides applied according to official label instructions to agricultural and forest lands may be washed to a receiving waterway by a torrential rainstorm. Under such conditions it is believed that such diffuse source inflows should receive consideration similar to that of a discrete effluent discharge and that in such instances the criteria should be applied to the principal portion of the waterway rather than to that peripheral portion receiving the diffuse inflow. e . , The format f o r presenting water quality criteria includes a concise statement of the dominant criterion o r criteria for a particular constituent followed by a narrative introduction, a rationale that includes justification for the designated criterion or criteria, and a listing of the references cited within the rationale. An effort has been made to restrict supporting data to those which either have been published o r are in press awaiting publication. A particular constituent may have more than one criterion to ensure more than one water use or condition, i. e., hard or soft water where applicable, suitability as a drinking water supply source, protection of human health when edible portions of selected biota are consumed, provision for recreational bathing or waterskiing, and permitting an appropriate factor of safety to ensure protection for essential warm or coldwater associated biota.

Criteria are presented  or those substances that may occur in water where data indicate the potential for harm to aquatic life,

or to water users, or to the consumers of the water o r aquatic life. Presented criteria do not represent an all inclusive list of constituent contaminants. omissions from criteria should not be construed to mean that an omitted quality constituent is either unimportant o r non hazardous. BIBLIOGRAPHY Adelman, I. R. and L. L. Smith, 1970. Effect of hydrogen sulfide on northern pike eggs and sac fry. 99: 501. Trans. Amer. Fish. SOC.,

Agriculture Handbook No. 60, 1954. Diagnosis and improvement of saline and alkali soils. L. A. Richards, editor, U. S. Govern ment Printing Office, Washington, D. C.

Anderson, B. G., 1960. The toxicity of organic insecticides to Daphnia. Second Seminar on Biol. Problems in Water Pollution. Robert A. Taft Sanitary Engineering Center Technical Report W60 3, Cincinnati, Ohio.

Bahner, L. H. and D. R. Nimmo, 1974. Methods to assess effects of combinations of toxicants, salinity, and temperature on estu marine animals. Proc. 9th Am. Conf. on Trace Substances in Env. Health, Univ. Miss.? olumbia, Mo.

Ballentine, R. X. and F. W. Kittrell, 1968. Observations of fecal colifonns in several recent stream pollution studies. ings of the Symposium on Fecal Coliform Bacteria in Water and Wastewater, May 21 22, 1968, Bureau of Sanitary Engineering, California State Department of Public Health.

Bell, H. L., 1971. Effect of low pH on the survival and emergence of aquatic insects. Water Res., 5: 313.

Bellan, et al., 1972. The sublethal effects of a detergent on the reproduction, development, and settlement in the polychae tous annelid Capitella capitata. Marine Biology, 14: 183. Proceed

Bender, M. E., 1969. The toxicity of the hydrolysis and breakdown products of malathion to the fathead minnow ( PimephalE promelas, Rafinesque). Water Res., 3: 571.

methyl parathion, parathion and azinphosmethyl in mice and fish: Onset and recovery of inhibition. Bull. Environ. Contam. Toxicol., 12: 117.

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