Ill. Admin. Code tit. 35, § 302.615 - Determining the Acute Aquatic Toxicity Criterion - Toxicity Independent of Water Chemistry

Current through Vol. 46, No. 16, April 15, 2022

If the acute toxicity of the chemical has not been shown to be related to a water quality characteristic, including but not limited to, hardness, pH, temperature, etc., the AATC is calculated by using the procedures below.

a) For each species for which more than one acute value is available, the Species Mean Acute Value (SMAV) is calculated as the geometric mean of the acute values from all tests.
b) For each genus for which one or more SMAVs are available, the Genus Mean Acute Value (GMAV) is calculated as the geometric mean of the SMAVs available for the genus.
c) The GMAVs are ordered from high to low.
d) Ranks (R) are assigned to the GMAVs from "l" for the lowest to "N" for the highest. If two or more GMAVs are identical, successive ranks are arbitrarily assigned.
e) The cumulative probability, P, is calculated for each GMAV as R/(N + l).
f) The GMAVs to be used in the calculations of subsection (g) must be those with cumulative probabilities closest to 0.05. If there are less than 59 GMAVs in the total data set, the values utilized must be the lowest obtained through the ranking procedures of subsections (c) and (d). "T" is the number of GMAV's which are to used in the calculations of subsection (g). T is equal to 4 when the data set includes at least one representative from each of the five taxa in Section 302.612 and a representative from each of the three taxa listed below. T is equal to 3 when the data includes at least one representative from each of the five taxa in Section 302.612 and from one or two of the taxa listed below. T is equal to 2 when the data set meets the minimum requirements of Section 302.612 but does not include representatives from any of the three taxa listed below. When toxicity data on any of the three taxa listed below are available, they must be used along with the minimum data required pursuant to Section 302.612.
1) A benthic crustacean, unless such was used pursuant to Section 302.612(a)(3), in which case an insect must be utilized.
2) A member of a phylum not used in subsections (a), (b) or f(1).
3) An insect from an order not already represented.
g) Using the GMAVs and T-value identified pursuant to subsection (f) and the Ps calculated pursuant to subsection (e), the Final Acute Value (FAV) and the AATC are calculated as:

FAV

=

exp(A) and

AATC

=

FAV/2

Where:

A

=

L + 0.2236 S;

L

=

[SUM(1n GMAV) - S(SUM(P**0.5 ))]/T; and

S

=

[[SUM((1n GMAV)**2) - ((SUM(1n

GMAV))**2)/T]/[SUM(P) - ((SUM(P**0.5))**2)/T]]**0.5

h) If a resident or indigenous species whose presence is necessary to sustain the commercial or recreational activities or prevent disruptions of the waterbody's ecosystem, including but not limited to loss of species diversity or a shift to a biotic community dominated by pollution-tolerant species, will not be protected by the calculated FAV, then the EC-50 or LC-50 for that species is used as the FAV.

Notes

Ill. Admin. Code tit. 35, § 302.615

Added at 14 Ill. Reg. 2899, effective February 13, 1990

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