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Description of key information

TETD (tetraethylthiuram disulphide, Disulfiram, CAS 97-77-8) is very toxic to aquatic organisms regarding acute and long term exposition.

Additional information

For the assessment of the aquatic toxicity of TETD (tetraethylthiuram disulphide, Disulfiram, CAS 97-77-8), experimental studies are available, which cover the short-term toxicity to all three trophic levels (fish, aquatic invertebrates and algae) and the long-term toxicity of two trophic level aquatic algae and Daphnia. All studies were performed according to the internationally accepted OECD guidelines and GLP.

The acute studies of algae, daphnia and fish resulted in an LC50 (96 h) of 0.067 mg/L (nominal), EC50 (48 h) of 0.150 mg/L (nominal) and EC50 (72 h) of >1.68 mg/L (based on geometric mean measured concentrations), respectively. Chronic data are available for algae and daphnia with an EC10 (72 h) values of 1.05 mg/L for the algae and an EC10 value of 0.00264 mg/L (based on the measured concentrations) for the chronic Daphnia. 

Based on the acute data, the most sensitive species was expected to be the chronic fish. However, due to analytical problems, the main test for the chronic fish test was considered as technically not feasible. An OECD 210 range finding study was run but the main test was cancelled as a pervasive background attributable to the test substance was observed throughout the test. The effects was as such, that no clear analytical dose verification was possible for the chronic fish test. Available results from the range-finding test on fish indicated that at least a nominal concentration of 1 to 10 µg/L would be required for the definitive test with the NOEC being in the range of 1 µg/L, which is within the same range as the chronic Daphnia study. Due to the impossibility to conduct the chronic fish test with appropriate analytical verification, the PNEC for TETD was therefore derived based on the long term daphnia study with an EC10 value of 0.00264 mg/L (measured concentration).

Furthermore, inhibitory effects on the activity of aquatic microorganisms were reported (EC50 = 3.11 mg a.i./L).