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Toxicity to microorganisms

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Description of key information

Benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-C7-9 branched alkyl esters (CAS 125643-61-0): EC50(3h) > 1000 mg/L, NOEC: 1000 mg/L (Clarke, 2007) 

Key value for chemical safety assessment

EC50 for microorganisms:
1 000 mg/L
EC10 or NOEC for microorganisms:
1 000 mg/L

Additional information

Available studies assessing the toxicity to microorganisms of Benzenepropanoic acid, 3,5 -bis(1,1 -dimethylethyl)-4 -hydroxy-,C7 -9 branched alkyl esters (CAS 125643 -61 -0), Butyl 3,5 -bis(1,1 -dimethylethyl)-4 -hydroxybenzenepropanoate (CAS 52449 -44 -2), Benzenepropanoic acid 3,5 -bis(1,1 -dimethylethyl)-4 -hydroxy-2 -ethyl-hexylester (CAS 144429 -84 -5) and Vanlube BHC were conducted according to OECD guideline 209 and EPA OPPTS 850.6800 with certificated GLP compliance.

The respiration inhibition of Benzenepropanoic acid,3,5 -bis(1,1 -dimethylethyl)-4 -hydroxy-,C7 -9 branched alkyl esters (CAS 125643 -61 -0) on activated sewage sludge was investigated for a time period 3 hours (Clarke, 2007). Following a preliminary range-finding test, the inoculum was exposed to an aqueous dispersion of the test material at a concentration of 1000 mg/L (three replicate flasks) at a temperature of 21 °C with the addition of a synthetic sewage as a respiratory substrate. The rate of respiration was determined after 30 minutes and 3 hours contact time and compared to data for the control and a reference material, 3,5-dichlorophenol. The effect of the test material on the respiration of activated sewage sludge gave a 3-Hour EC50 of greater than 1000 mg/L. The No Observed Effect Concentration (NOEC) after 3 hours exposure was 1000 mg/L. It was considered unnecessary and unrealistic to test at concentrations in excess of 1000 mg/L. The reference material gave a 3-Hour EC50 value of 6.5 mg/L. Also Butyl 3,5 -bis(1,1 -dimethylethyl)-4 -hydroxybenzenepropanoate (CAS 52449 -44 -2) was investigated on its respiration inhibition on activated sewage sludge (Mead, 2000). Following a preliminary range-finding test, activated sewage sludge was exposed to an aqueous dispersion of the test material at a concentration of 1000 mg/L (three replicate flasks) for a period of 3 hours at a temperature of 21 °C with the addition of a synthetic sewage as a respiratory substrate. The rate of respiration was determined after 30 minutes and 3 hours contact time and compared to data for the control and a reference material, 3,5-dichlorophenol. The effect of the test material on the respiration of activated sewage sludge gave a 3-Hour EC50 of greater than 1000 mg/L. The No Observed Effect Concentration (NOEC) after 3 hours exposure was 1000 mg/L. It was considered unnecessary and unrealistic to test at concentrations in excess of 1000 mg/L. The reference material gave a 3-Hour EC50 value of 13 mg/L. In another study, after a preliminary range-finding test, activated sewage sludge (predominantly domestic) was exposed to an aqueous dispersion of Benzenepropanoic acid,3,5 -bis(1,1 -dimethylethyl)-4 -hydroxy-ethylhexylester (CAS 144429 -84 -5) at a concentration of 1000 mg/L (three replicate flasks) for a period of 3 hours at a temperature of 21 °C with the addition of a synthetic sewage as a respiratory substrate (Clarke, 2007). The rate of respiration was determined after 30 minutes and 3 hours contact time and compared to data for the control and a reference material, 3,5-dichlorophenol. The effect of the test material on the respiration of activated sewage sludge gave a 3-Hour EC50 of greater than 1000 mg/L. The No Observed Effect Concentration (NOEC) after 3 hours exposure was 1000 mg/L. It was considered unnecessary and unrealistic to test at concentrations in excess of 1000 mg/L. The reference material gave a 3-Hour EC50 value of 8.5 mg/L. Additionally, a similar experimental result is available, where activated sewage sludge was exposed to an aqueous dispersion of Vanlube BHC at a concentration of 1000 mg/L for a period of 3 hours at a temperature of approximately 21 °C with the addition of a synthetic sewage as a respiratory substrate (Mead, 2007). The rate of respiration was determined after 30 minutes and 3 hours contact time and compared to data for the control and a reference material, 3,5-dichlorophenol. The reference material gave a 3 -hour EC50 value of 9.6 mg/L, with 95 % confidence limits of 7.8 - 12 mg/L. The exposure of microorganims to the test material resulted in an EC50(3h) greater than 1000 mg/L. The No Observed Effect Concentration (NOEC) after 3 hours exposure was also greater than 1000 mg/L. It was considered unnecessary and unrealistic to test at concentrations in excess of these results.

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