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Sediment toxicity

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Description of key information

NOEC (27d) = 242  µg a.i./L (Chironomus riparius)

Key value for chemical safety assessment

Additional information

No studies on the toxicity of tetramethylthiuram disulfide(CAS No. 137-26-8) to sediment organisms are available.Therefore, a conclusion based on an analogue approach had to be drawn. Zinc(bis) dimethyldithiocarbamate (137-30-4) is structurally and composition-related to tetramethylthiuram disulfide. Both substances are hydrolytically unstable under relevant environmental conditions and undergo rapid biodegradation in water/sediment systems, with half-lives below 10 days (Völkl, 2001; Wyss-Benz, 1992, 1995). Thiram and Ziram have similar log Kow (1.73 Thiram; 1.65 Ziram) and log Koc values (3.3-4.4 Thiram; 2.5-4.0 Ziram), suggesting a comparable adsorption potential to sediment particles if present in the water phase.

Therefore, based on the available information an analogue approach from Ziram to Thiram is justified for this endpoint.

A study was conducted according to OECD Guideline No. 219: Sediment-Water Chironomid Toxicity Test using Spiked Water (2004) and a proposal for BBA-Guideline: Effects of plant production products on the development of sediment dwelling larvae ofChironomus ripariusin a water-sediment system (1995), under GLP conditions. After 27 days of exposure to the compound, significant effects were found on emergence rate and development at the two highest concentrations tested. No effects on emergence rate or development were observed up to (and including) a concentration of 320 µg/L Ziram 76 WG (242 µg/L Zinc(bis) dimethyldithiocarbamate), being this value the NOEC for the study.