Freshwater chronic value

Snell, T.W. (2000) The distribution of endpoint chronic value, for freshwater rotifer, in G. Persoone, C. Janssen and W.M. De Coen (eds.), New Microbiotests for Routine Toxicity Screening and Biomonitoring, Kluwer Academic/Plenum Publishers, New York, pp. 185-190. 

Talmage et al. [4] analyzed an extensive TNT toxicity database and derived freshwater final acute and chronic values (FAV and FCV, respectively) of 4.99 and 0.410 pmoles E and the respective criterion maximum concentration (CMC) of 2.50 pmoles E that is, half the FAV. The lowest chronic effect value for fish, of 0.176 pmoles E, was suggested as a better screening benchmark than the calculated FCV until a sufficient chronic toxicity database becomes available [4], All these values are above the LOEC from nine-month life-cycle tests with fathead minnows, of 0.06 pmoles L 1 [76] (Table 4.2), suggesting that the proposed chronic values need to be revised for adequate long-term protection of aquatic life. 

Data available in the scientific literature were not sufficient for the calculation of Tier I acute or chronic WQC with other energetic compounds and their transformation products. Tier II secondary freshwater acute and chronic values (SAV and SCV, respectively) were derived by Talmage et al. [4] for TNB, 1,3-DNB, 3,5-DNA, 2-A-4,6-DNT, HMX, and RDX, by dividing the lowest genus mean acute value (GMAV) by the secondary acute factor (SAF Table 4.7). 

If data on a sufficient number and diversity of organisms are available, a final chronic value for a particular toxicant may be calculated in the same way that final acute values are determined. In practice, however, there are seldom sufficient data to allow a direct graphical estimation of the toxicant concentration that would exert a chronic stress on no more than 5% of the species in the system. In such cases an acute toxicity standard is established on the basis of an adequate amount of short-term toxicity tests, and an average acute/chronic toxicity ratio is then calculated on the basis of a smaller amount of information. The rationale for this procedure is that for a given pollutant the acute/chronic ratio is likely to be more constant between species than is the chronic or sublethal stress level itself Hence less information is required to estimate the acute/chronic ratio. The chronic toxicity standard is established by dividing the acute toxicity standard by the so-called final acute/chronic ratio. The EPA considers this procedure acceptable if acute/chronic ratios are available for at least three species and (a) at least one of the species is a fish, (b) at least one is an invertebrate, and (c) at least one is an acutely sensitive fi eshwater species or saltwater species when the ratio is being used to establish freshwater or marine criteria, respectively. 

An example of the calculation of a final acute/chronic ratio is shown in Table V for the pesticide dieldrin. Chronic values for this pesticide were available for only four species in 1980 when the guidelines for dieldrin were established (EPA, 1980a), and therefore it was necessary to use acute/chronic ratios to estabhsh the final chronic value. Acute toxicity values were available in only three of the four cases where chronic effects were studied, but the three species satisfied the criteria for calculating acute/chronic ratios in both freshwater and salt water. Since the acute/chronic ratios for the three species differed by less than a factor of 2, it was appropriate to calculate the final acute/chronic ratio for dieldrin by taking the geometric mean of the three ratios, which is [(11)(9.1)(6.2)] / = 8.5. Final acute values for dieldrin in freshwater (EPA, 1996b) and salt water are 0.48 and 0.71 ppb, respectively. Hence the final chronic values for dieldrininfreshwaterand saltwater areO.48/8.5 = 0.056 ppb and 0.71/8.5 = 0.084 ppb, respectively. 

Under the present system (EPA, 1996b), the two numbers in the criterion are calculated from the final acute value, the final chronic value, and the final plant value. The three values for dieldrin in freshwater and salt water are shown in Table VII. The criterion maximum concentration is equated to half the final acute value. Division by 2 in this case to some extent corrects for the fact that much of the acute toxicity information is based on observations of lethal effects, whereas the real concern is protection of organisms fi om sublethal stresses. The criterion continuous concentration is the smaller of the final chronic value and the final plant value. 

Our consensus is that if a marine (acute or chronic) EQS is needed, then it should be based on experimental marine data and not extrapolated from freshwater studies. If data are substituted from freshwater systems to marine (or vice versa), the proposed standard should only be considered as tentative (see Zabel and Cole 1999). A tentative value of this type is likely to be unreliable if used for regulation. 

Studies aimed at verifying this ratio have shown a 0.88 correlation coefficient for 11 freshwater species and 126 chemicals (Slooff et al., 1983). It was concluded on the basis of these results that compounds that produce acute toxicity also show chronic toxicity. Therefore, with the exception of substances with a very particular toxic action, it is possible to predict the chronic toxicity of a substance on a species based on the acute values obtained for the same compound with similar species (Giesy and Graney, 1989). 

Massachusetts Environmental toxicity values Freshwater Acute Chronic Marine Acute Chronic 20 gg/L 5.0 gg/L 300 gg/L 71 gg/L BNA 2001... 

REGULATORY STATUS MCLG 0 mg/L MCL 0.005 mg/L HAL(child) 10-day 0.09 mg/L NOEL 8.8 mg/kg/day Criterion to protect freshwater aquatic life -23,000 pg/L based on acute toxicity, 5,700 pg/L based on chronic toxicity, 920 pg/L/24 hr avg., concentration not to exceed 2100 pg/L any time Criterion to protect saltwater aquatic life 10,300 pg/L based on acute toxicity, 3,040 based on chronic toxicity, 400 pg/L/24 hr. avg., concentration not to exceed 910 pg/L any time no set value for criterion to protect human health because insufficient data EPA limit in drinking water 0.005 mg/L the following are guidelines for drinking water set by some states 1 pg/L (Arizona, Massachusetts), 6 pg/L (Kansas, Minnesota), 10 pg/L (California, Connecticut)... 

The national recommended water quality criteria for lead (65 FR 31682) derived by the U.S. EPA [per 304(a)(l)], as with all the pollutant criteria, included freshwater and saltwater acute and chronic criterion concentrations to protect aquatic life. The corresponding values (pgPb/l) are 65, 2.5, 210, and 8.1, respectively. As of June 1, 2010, there were no human health criteria for lead in terms of fish consumption or fish plus water consumption, previous values having been withdrawn (Table 28.2). 

U.S. EPA role in establishing water quality criteria and standards Water criteria promulgated under the CWA ( 304(a)(1) Pb water quality values are expressed as acute or chronic criteria for freshwater or salt water for freshwater, 65 and 2.5 p.g/1 for salt water, 210 and 8.1 pg/l No human health criteria for lead in fish or fish + water consumption... 

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