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Short-term toxicity to aquatic invertebrates

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Description of key information

Methanol: EC50(48h): >10000 mg/L
KOH: Potassium hydroxide is a strong alkaline substance that dissociates completely in water to K+ and OH- (OECD SIDS potassium hydroxide, 2002).
Therefore the only posssible effect would result from the pH effect. However, pH will remain between environmentally expected ranges.

Key value for chemical safety assessment

Additional information

In a reliable standard static test with Daphnia magna no adverse effects were reported at 10000 mg/L after 48-h exposure (Kuehn, 1989). Toxicity values well above 10000 mg/L reported also for Daphnia magna in other studies support this finding: 22200 mg/L (EC50, 48h) (Rossini and Ronco 1996), 20803 mg/L (EC50, 24h) (Lilius et al. 1995), and 22910 mg/L (LC50, 24h) (Reiff 1976). Aditionally short-term toxicity data are available from tests conducted with other test organism: Mytilus edulis, LC50 (96h) = 15900 mg/L (Helmstetter et al. 1996) and Moina micrura, LC50 (96h) = 4820 mg/L. Although the lowest toxicity was reported for Moina micrura this is not a standard organism, which does not occur in cold-temperate regions. For this reason it is considered less relevant than Daphnia and was not used in in the PNEC derivation.

OECD SIDS (2002) assigned a low code of reliability (invalid or not assignable) to all available aquatic toxicity tests, as in general the tests were not conducted according to the current test guidelines (compare also with EU RAR of NaOH, section 3.2.1.1.4, page 30). Furthermore, in many tests reports there were no data on pH, buffer capacity and/or test medium composition, although this is essential information for toxicity tests with KOH.

The tests with NaOH and aquatic invertebrates resulted in acute LC50 values and toxic/lethal concentrations ranging from 30 to < or = 1000 mg/L (EU RAR NaOH).

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