Endpoint Result (nominal) Assessment Conclusion EC50 (3 h) = > 71 mg/L Inhibition of bacterial Some inhibition of NOEC (4 h) = 8.9 mg/L respiration (notified chemical) bacterial respiration EC50 (4 h) = > 142 mg/L Inhibition of bacterial Not inhibitory to bacterial NOEC (4 h) = > 142 mg/L nitrification (notified chemical) respiration EC50 (17 h) = > 140 mg/L Acute toxicity bacterial Not inhibitory to bacterial – growth (notified chemical) respiration The result of 3 h EC50 71 mg/L is considered to be less reliable, as discussed in the ≥ following study summary. Based on the results 4 h EC50 142 mg/L and 17 h EC50 140 ≥ ≥ mg/L, the notified chemical is not inhibitory to bacterial respiration. 5.2.1.2 Inhibition of microbial activity (ND) Test Substance Notified chemical Method OECD TG 209 Activated Sludge, Respiration Inhibition Test Inoculum Activated sludge Exposure Period 3 hours Concentration Range Nominal: 1.1-140 mg/L Actual: Not determined Remarks Method Conducted in accordance with the test guidelines above, and – in compliance with GLP standards and principles. 3,5-dichlorophenol was used as the reference control. The respiration rate was determined by measurement of Biochemical Oxygen Demand during the test after 3 hours of exposure. Results IC50 > 71 mg/ NOEC 8.9 mg/L Remarks Results All validity criteria for the test were satisfied. – The results of this study may not be reliable as a maximum inhibition of 30% was found at a test substance concentration of 35 mg/L and the inhibition was less at the higher concentrations. Furthermore, it was reported that no inhibition was found at the highest concentration of 140 mg/L which may be due to a less than complete dissolution of the test substance. The 3 h EC50 was determined to be > 71 mg/L based on nominal concentrations.
Endpoint Result (nominal) Assessment Conclusion Inhibition of bacterial respiration (notified chemical) EC50 (3 h) = > 71 mg/L NOEC (4 h) = 8.9 mg/L Some inhibition of bacterial respiration Inhibition of bacterial nitrification (notified chemical) EC50 (4 h) = > 142 mg/L NOEC (4 h) = > 142 mg/L Not inhibitory to bacterial respiration Acute toxicity – bacterial growth (notified chemical) EC50 (17 h) = > 140 mg/L Not inhibitory to bacterial respiration The result of 3 h EC50 ≥ 71 mg/L is considered to be less reliable, as discussed in the following study summary. Based on the results 4 h EC50 ≥ 142 mg/L and 17 h EC50 ≥ 140 mg/L, the notified chemical is not inhibitory to bacterial respiration. 5.2.1.2 Inhibition of microbial activity (ND) Test Substance Notified chemical Method OECD TG 209 Activated Sludge, Respiration Inhibition Test Inoculum Activated sludge Exposure Period 3 hours Concentration Range Nominal: 1.1-140 mg/L Actual: Not determined Remarks – Method Conducted in accordance with the test guidelines above, and in compliance with GLP standards and principles. 3,5-dichlorophenol was used as the reference control. The respiration rate was determined by measurement of Biochemical Oxygen Demand during the test after 3 hours of exposure. Results IC50 > 71 mg/ NOEC 8.9 mg/L Remarks – Results All validity criteria for the test were satisfied. The results of this study may not be reliable as a maximum inhibition of 30% was found at a test substance concentration of 35 mg/L and the inhibition was less at the higher concentrations. Furthermore, it was reported that no inhibition was found at the highest concentration of 140 mg/L which may be due to a less than complete dissolution of the test substance. The 3 h EC50 was determined to be > 71 mg/L based on nominal concentrations.