2-ethylhexyl mercaptoacetate

Short-term toxicity to aquatic invertebrates

Description of key information

The test substance concentrations were not maintained within 80 % of the initial concentration throughout the duration of the test despite the experimental precautions used for keeping stable the test substance concentrations. At the higher test concentration, only 26 % of the initial test substance were recovered at the end of the test. However, since the test solution analyses were not carried out at the same day than the sampling day (but alter 2 days for the set at time 0 and after 4 days for the set at time 48 hours), it was not possible to exactly quantify the degradation of the test substance at the end of the test period.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

0.39 mg/L

Additional information

No relevant data has been identified for 2-ethylhexyl mercaptoacetate (EHTG). Existing data for isooctyl mercaptoacetate (IOTG) was used for covering this endpoint.

EHTG and IOTG are both C-8 esters of thioglycolic acid. In addition, both EHTG and IOTG are hydrolytically unstable and rapidly oxidize, and have as a common degradate when hydrolyzed, thioglycolic acid (TGA; CAS No. 68-11-1). In addition to TGA, the hydrolysis breakdown product for EHTG is 2-ethylhexanol (CAS No. 104-76-7), an 8-carbon alcohol. For IOTG, the hydrolysis breakdown products are TGA and iso-octanol. The iso-octanol in this case is a mixture of 8-carbon alcohols, the major isomers being methylheptanols, and dimethylhexanols. Based on the close structural similarity of EHTG and IOTG, their chemical and physical properties and behavior are expected to be similar. Melting point, boiling point, vapor pressure and water solubility values are consistent with this expectation.   

The EC₅₀were calculated using nominal concentrations. The results are :

The EC₅₀-48h was calculated to be 0,39 mg/1 with 95 % confident interval ranging from 0,28 to 0,53 mg/l.