Polysulfides, di-tert-dodecyl

Endpoint summary

Description of key information

Experimental results are available for fish, Daphnia, algae and microorganisms. Key studies chosen for these endpoints are included in this dossier. The following sections detail the robust summaries prepared for these studies.

Thiebaud (2000) is a GLP-compliant guideline study showing the growth inhibition effect of polysulfides, di-tert-dodecyl on Pseudokirchneriella subcapita over 72 hours. The maximum level of exposure, the observed saturation concentration (0.080 mg/L), resulted in no inhibition of the growth of Pseudokirchneriella subcapita. The study is considered reliable and suitable for use for this endpoint.

Thiebaud (1998) is a 48 hour, static, freshwater, GLP-compliant test on Daphnia magna, follows EU Method C2. The results indicate that this substance is not significantly acutely toxic to aquatic invertebrates at the limit of analytical detection and the limit of dispersibility. The validity criteria of the method were not met as the stability of the substance was not checked. The study is considered reliable with restriction and suitable for use for this endpoint.

Hoffmann (2010) is a GLP-compliant, static closed vessel limit test following OECD guideline 203. No further dose-response test was performed despite the limit test showing some toxic effects. Careful examination of WAF preparation shows that the absence of undissolved material cannot be no guaranteed. The study has consequently been classified as not reliable. No further information would have been gained about the toxicity of the test item from further acute dose-response testing. Further data on the poor water solubility of the substance justified that no further acute testing was warranted. Instead, chronic toxicity could be considered.

It has been hypothetized that, in view of the predicted very low water solubility and the prediction of ecotoxicity made using ECOSAR models (from USEPA's EPIWIN suite) for algae, daphnia and fish, acute and chronic on substance Polysulfides, di-tert-dodecyl, the resulting EC50s and chronic values are all higher than the limit of solubility.

Consequently, the aquatic chronic fish and invertebrate tests were waived but, according to REACH annexes, these two studies were requested by ECHA. These studies (OECD TG 210 and 211) have now been carried out and they confirm that no long term toxic effect is observed on fish (Pimephales promelas) and lotic invertebrate (Daphnia magna) at water solubility saturation level. Indeed, water solubility has been confirmed to be 0.00026 mg/L and in the two toxicity assays the exposure levels were managed to be slightly higher than saturation (0.00079 - 0.00084 mg/L).

This means that no PNEC can be derived for aquatic media (freshwater, marine water, including intermittent releases).

Besides, investigations of fate and eventually effects in sediments which is the likely target compartment given the properties of this substance have been proposed. An OECD TG 218 has been carried out and the results are reported in the adequate section.

The results of the available studies, including the recent chronic aquatic toxicity studies support that the substance polysulfides, di-tert-dodecyl, does not need to be classified concerning hazard to the environment, according to CLP regulation rules relevant to the "safety net" classification.