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Short-term toxicity to fish

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Description of key information

Toxicity figure based on river water testing.

Key value for chemical safety assessment

LC50 for freshwater fish:
21.3 mg/L
LC50 for marine water fish:
59.3 mg/L

Additional information

The acute toxicity of DTDMAC for fish was investigated in a study by Lewis & Wee (1983) cited in the EU Risk Assessment DODMAC (2002). A static 96h US EPA test was used with well water and Lepomis macrochirus. LC50-values ranged from 0.62 to 3.0 mg/L. In these cases it is not known whether different water qualities might have been used or which other test parameters were varied.

Compared with the results described above the toxicity of DTDMAC for Lepomis macrochirus was reduced in natural surface water which received municipal wastewater effluent. 96h LC50-values of 10.1 to > 24.0 mg/L were derived. A combination with C12LAS reduced the adverse effects of DTDMAC in laboratory water tests. The 96h LC50-values at molar ratios of DTDMAC/ C12LAS ranging from 2:1 to 1:2 varied from 9.4 to 186 mg/L (nominal concentrations of active ingredient). In these tests of Lewis & Wee (1983), no information is given on the purity of the test substance but isopropanol or methanol was added as carrier solvent.

In ECETOC (1993) for different molar ratios of DTDMAC/C12LAS the following 96h LC50-values for Lepomis macrochirus are cited: 7.1 mg/L at 2:1; 17.6 mg/L at 1:2; 7.9 -171 mg/L at 1:1 (no more details on test procedure, Procter & Gamble, 1974 -86. Data as supplied to the ECETOC task force on DTDMAC 1992, cited in ECETOC (1993)).

The acute toxicity of DODMAC (97% purity, containing no MTTMAC) for Pimephales promelas was also investigated in different filtered natural river waters and well water enriched with different contents of humic acids (Versteeg & Shorter, 1992). Fish were exposed for 96 hours under static renewal conditions. In well water alone a LC50 of 3.55 mg/L (nominal) was derived (< 1 mg/L total organic carbon). In well water to which different amounts of dissolved humic acids extracted from natural rivers were added (1.6 - 2.2 mg/L total organic carbon) the corresponding LC50-values were 6.3 to 13.8 mg/L. In river water with a total organic carbon content of 4.6 mg/L (Dry Fork Creek,Ohio; pH = 8.4 - 8.6, hardness = 173 mg/L CaCO3) the LC50 was 21.3 mg/L. In another river with a total organic carbon content of 6.2 mg/L the LC50 was 36.2 mg/L (Little Miami River, Ohio; pH = 7.5 - 8.5, hardness = 175 mg/L CaCO3). In these tests the toxicity of DODMAC was positively correlated with the humic acid concentration and the total organic carbon content.

The acute toxicity of Quaternary ammonium compounds, di-C16 -18 (even numbered) - alkyldimethyl, chlorides was also evaluated with marine fish, juvenile turbot (Scophthalmus maximus), in a semi-static test over 96 hours in accordance with OECD testing guideline 203 (Hill, 2004). LC50 -96h was calculated to be 59.3 mg/L for this marine species in artificial seawater.

Newman in 1977 exposed bluegill sunfish and rainbow trout to DHTDMAC and this resulted in an acute 96 hour LC50 of 1.33 mg/L and 2.36 mg/L respectively. Behaviour observations during the test indicated that bluegill sunfish exposed to concentrations of 1.00 mg/L and higher became disorientated, demonstrated erratic swimming behaviour and showed signs of varied discoloration. rainbow trout at a concentration of 3.20 mg/L or higher became stressed and showed signs of dark discoloration.

Domrose in 1987 investigated DHTDMAC lethal effects to the rainbow trout (Salmo gairdneri). This test was carried out according to OECD 203. Fishes were exposed in separate test batches to different concentrations of the test sample in the test medium over a period of 96 hours (each tank with 5 fish, two tanks per concentration). Ten more fishes were simultaneously kept in a two control batches (2 x 5) of the pure test medium water at otherwise identical conditions. The toxic effects were found to be as follows: LC0 (96 h) = 1.2 mg/L, LC50 (96 h) = 3.4 mg/L and LC100 (96 h) = 10.0 mg/L.