o-chlorobenzenethiol

Ecotoxicological Summary

Hazard for aquatic organisms

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

Additional information

Short-term toxicity to aquatic invertebrates: Key study. Method according to OECD 202, GLP study. In accordance to range-finding preliminary studies, a semi-static study was performed (renewal period 24h); at nominal concentrations of 0.013, 0.032, 0.08, 0.2 and 0.5 mg/L test item.Twenty Daphnia magna (<24 h old, 5 per replicate) were exposed to either a control medium or the test item concentrations specified for 48 hours. The test concentrations were analytically determined at the start and at the end of the renewal periods by means of a validated method. All validity criteria were fulfilled. As the measured concentrations deviated more than 20 per cent from the nominal in most cases, biological results are based on the measured geometric mean test item concentrations: 0.004; 0.012; 0.039; 0.124 and 0.318 mg/L.

At concentrations of 0.124 mg/L test item or higher, 100% of the daphnia were immobilised after 48h, whereas none were immobilised at 0.039 mg/L test item. Based on the results obtained, the 48h EC50 value of the test item on Daphnia magna is 0.091 mg/L, and the 48h NOEC is 0.039 mg/L.

Short-term toxicity to aquatic algae and cyanobacteria: Key study. Method according to OECD 201, GLP study. Based on a range-finding study, Pseudokirchneriella subcapitata was exposed to 0 (control), 0.051, 0.128, 0.32, 0.8, 2.0 and 5.0 mg/L test item (nominal). Four replicates were performed per concentration and seven for the control. Growth was monitored daily by measuring the number of cells in each culture. Analytical monitoring was performed using a validated method at the start and at the end of the experiment. As the measured values differed more than 20% from the nominal values, biological results are based on the measured geometric mean test item concentrations: 0.031, 0.092, 0.190, 0.420; 1.005 and 2.502 mg/L. With respect to the inhibitory effect of the test item, the 0-72 h average specific growth rates were significantly different from that of the control group in the examined concentration range. The 72h EC50 of the test item on freshwater algae was found to be 0.401 mg/L, the NOEC is 0.092 mg/L and the LOEC 0.190 mg/L, based on growth rate (r).

Conclusion on classification

Based on the available information (72h-NOEC = 0.092 mg/L in algae, 48h-NOEC = 0.039 mg/L in daphnia), the substance is classified as Aquatic Acute 1 and Aquatic Chronic 1 according to CLP Regulation (EC) No. 1272/2008.