Registration Dossier

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

The acute toxicity of 1,3,5-triazine-2,4,6(1H,3H,5H)-trithione, trisodium salt (TMT, CAS No. 17766-26-6) to aquatic organisms was investigated for different trophic levels (fish, invertebrates and algae). However, the available studies for TMT exhibit a number of deficiencies, the study for algal toxicity is considered invalid.

Therefore, the assessment of the acute and long-term aquatic toxicity of TMT is based on read across of data to the surrogate substance 1,3,5-triazine-2,4,6(1H,3H,5H)-trithione (TMT-H3, CAS No. 638-16-4) in accordance with Regulation (EC) No 1907/2006, Annex XI, 1.5. "Grouping of substance and read across approach" (see read across justification in IUCLID section 13).

TMT-H3 is the acidic form of 1,3,5-triazine-2,4,6(1H,3H,5H)-trithione. Except for different cations (hydrogen vs sodium), the anion of both the source and target substance have an identical structure. Since dissociation of the sodium salt under environmental conditions (pH 4 -9) yields the same ionic species as the acidic form of the substance, this read across can be considered as justified.

For the read across substance TMT-H3, acute data for different trophic levels (fish, invertebrates and algae) are available. In the acute test with fish, the value for LC50 (96 h) exceeded the maximum test concentration of 100 mg/L (nominal, corresponding to 137.2 mg TMT/L). Daphnia magna turned out to be the most sensitive species with an EC50 (48 h) of 38 mg/L (nominal, corresponding to 52.1 mg TMT/L) and the toxicity test with algae yielded an ErC50 (72 h) > 94.9 mg/L (geom. mean measured, corresponding to 130.2 mg TMT/L).

Furthermore, long-term toxicity data with TMT-H3 for invertebrates and algae are available. The resulting NOEC values for D. magna and algae are in the same range: The NOEC (21 d) for D. magna is reported to be 4.6 mg/L (nominal, corresponding to 6.31 mg TMT/L) and the test with algae resulted in a NOEC (72 h) of 5.7 mg/L (geom. mean measured, corresponding to 7.8 mg TMT/L).

In all aquatic toxicity tests (with the exception of the algae toxicity test), the mean measured concentrations were within the range of 80 – 120% of nominal concentrations.

A nitrification inhibition test with activated sludge was carried out with TMT 15 as test material and revealed an EC50 (5 h) of 168 mg TMT/L for aquatic microorganisms.