o-toluidine

Short-term toxicity to aquatic invertebrates

Description of key information

48 h-EC50 value on Daphnia magna is 0.52 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

0.52 mg/L

Additional information

Two reliable studies on acute toxicity of o-toluidine to the invertebrate Daphnia magna are available. Maas-Dieperveen reported a 48 hours EC50 value of 0.52 mg/L which is the most sensitive value. The test was performed according to the Dutch Standardization Organization Method NEN 6501 without analytical monitoring. However, ecotoxicity studies with analytical monitoring indicated that o-toluidine was stable in water, and constant exposure concentrations over the test duration were assumed.

Data from a further test revealed an EC50 value of 15.6 mg/L after 48 hours with the OECD 202 for Daphnia magna. This is a nominal concentration, as no analytical monitoring was mentioned in the article.

Additionally reliable tests to other aquatic invertebrates are presented. An 72 h-EC0 value of 100 mg/l is reported for Mytilus edulis and Crassostrea gigas. No analytical monitoring was performed.

o-Toluidine was assessed within the scope of the ICCA/HPV-program, and the test procedure described by Abe et al. (2001) and Bringmann and Kuehn (1959 -1982) were scored to be reliable for assessment. Following the state-of-the-art, these studies are now considered as invalid due to insufficient documentation and/or unsuitable test systems, e.g. an EC50 could not be determined from specific values and no reason is given; it is not clear how the EC0 was determined regarding extremely low test concentrations; concerning test conditions the amounts of vitamins in test media are unclear.