o-TOLUIDINE CAS N°: 95-53-4 - UNEP Chemicals

OECD SIDS o-TOLUIDINE
According to OECD TG 204 "prolonged fish toxicity test" a NOEC of 12.5 mg/l (effective) for
Oryzias latipes was obtained after 21 days. The test was conducted according to the GLP principles
(CERI, 1996d).
For the daphnids tests conducted with OECD or national guidelines were chosen, and some contain
the lowest values.
In a test with Daphnia magna the pH effect on the toxicity was observed. There were only slight
differences between the obtained results (see on the table below). The method used was comparable
to the OECD test guideline 202 (Cronin, Zhao and Yu, 2000).
A test on the acute toxicity of o-toluidine to the invertebrate Daphnia magna was performed
according to the Dutch Standardization Organization Method NEN 6501. For a test period of
48 hours an EC50 value of 0.52 mg/l was reported (Maas-Diepeveen and van Leeuwen, 1986).
Following the guideline procedure OECD TG 202 a 48 h-EC50 of 5 mg/l was obtained with
Daphnia magna (Abe et al., 2001). Abe et al. (2001) also investigated the inhibition of embryo
development of Daphnia magna. 20 embryos were exposed to o-toluidine in 100 ml test solution
during 72 hours. The test was conducted at 20 °C and pH 7.6 - 8.9, with a dissolved oxygen
concentration of 7.8 - 9.1 mg/l. An EC50 of 0.62 mg/l was determined.
And finally, a GLP test performed according to the OECD TG 202 yielded an 48 h-EC50 of
15.6 mg/l (effective) (CERI, 1996b).
The toxicity towards other aquatic invertebrates was tested using several methods: Mytilus edulis
and Crassostrea gigas [semi-static test, synthetic sea water, 5 concentrations tested] (Knezovich
and Crosby, 1985), and Dugesia tigrina [Method based on ISO/TC 147/SC 5/GT 3 N 38] (Pionthek,
1999). See results in the Table below.
Concerning the algal toxicity, tests on three different species are available. The lowest available
EbC50 was 30.7 mg/l (effective) after 96 hours, in a test carried out according to the OECD TG 201
towards Selenastrum capricornutum. For the endpoint growth rate an ErC50 of 110.9 mg/l was
obtained. Concentrations were measured via HPLC (CERI, 1996c).
Another test performed according to the OECD TG 201 is available with the algae Chlorella
pyrenoidosa. The EbC50 value was 55 mg/l after 96 hours. This value was reported for the endpoint
maximum density (yield), i.e. biomass (Maas-Diepeveen and van Leeuwen, 1986); Lu, Yuan and
Zhao (2001) tested the toxicity of o-toluidine towards Scenedesmus obliquus following the
OECD TG 201 with a test period of 48 h. A 48 h-ErC50 of 490 mg/l was determined for the endpoint
growth rate.
The aforementioned results on aquatic toxicity except for the CERI tests (1996a, b, c, d, e) are
assumed to be nominal concentrations, as none of these publications or studies give a hint of
whether analytical monitoring was conducted or not. For the ecotoxicological data from the next
sections have to be made the same assumption.
UNEP PUBLICATIONS 37