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Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

The 24, 48, 72 and 96 hour median lethal concentrations (LC50) of PTH-Decahydroamide to the freshwater fish, rainbow trout (Oncorhynchus mykiss previously known as Salmo gairdneri) were determined under static test conditions at a temperature of 15 ± 1 °C. The 96 hour LC50 = 68 mg PTH-Decahydroamide/litre with 95% confidence intervals of 57 to 84 mg/L. The highest test concentration causing no mortality within the period of the test was 32 mg/L. The lowest that caused 100% mortality within the period of the test was 100 mg/L.

The 24 and 48 hour EC50 values of PTH-Decahydroamid to Daphnia magna were determined under static test conditions at a temperature of 20 ± 1 °C. The 48 hour EC50 was 45 mg PTH-Decahydroamid/litre with 95% confidence intervals of 33 to 65 mg/L. The highest nominal test concentration causing no immobility was 5.6 mg/L and the lowest that caused 100% immobility was 180 mg/L.

The toxicity of the test substance to aquatic algae was determined using OECD method 201. It was determined that PTH-Decahydroamide (Ro 31-9373/000) inhibited cell growth and reduced growth rate of Scenedesmus subspicatus significantly under the conditions of the present study at nominally 10 mg/l and higher. The inhibition rates were estimated for both the algal biomass b and the growth rate R after 72 hours test duration; based on nominal concentrations.

EbC50 (0-72 h)                     46 mg/l

ERC50 (0-72 h)                     74 mg/l

The NOEC was 4.8 mg/l for both cell growth inhibition and growth rate reduction when based on nominal concentrations. Since this concentration was below the detection limit of PTH-decahydroamide (Ro 31-9373/000) in water samples, no actual concentration could be determined.

No significant inhibition in respiration rate of the sludge (> 10 %) was recorded at 100 mg PTH-decahydroamide (Ro 31-9373/000) per litre. Thus under the conditions of the test PTH-decahydroamide (Ro 31-9373/ 000) was not toxic to waste water bacteria.