Benzyl 4-hydroxybenzoate

Toxicity to microorganisms

Description of key information

Toxicity to micro-organisms study (Acute toxicity of parabens and their chlorinated by-products with Daphnia magna and Vibrio fischeri bioassays. 2009) was conducted onVibrio fischeri.The study was carried out using the test conditions and the operating protocol of theV. fischeriacute toxicity test (Environmental Protection Series, 1992). Test chemicals was of special-grade reagent and was used without purification.  The test bacteria was exposed to the test substancebenzylparabenwith exposure duration of 5 and 15 mins.Luminescence was measured with a Microtox luminometer (Model 500; Microbics Corp., Carlsbad, CA, USA) in the acute mode. The toxic effect values reflect the ratio of the decrease in bacterial light production to the remaining light. The Microtox statistical software, version 7, was used to calculate the toxic effect values for each sample dilution and the sample concentration inducing 50% light inhibition (EC50) for each log–log dose–response curve and their corresponding confidence limits. The toxicity was expressed in terms of effective concentration values and toxicity units (TUs). The TU value was calculated using EC50 (TU = 100 EC50−1).  The logarithms of then-octanol–water partition coefficients (logP) of the test compound was also determined using an HPLC method according to the OECD guideline. Based ondecrease in bacterial light production by the test organism V. fischeri, the EC50 value was found to be 0.0038 mg/l.

Key value for chemical safety assessment

EC50 for microorganisms:

0.004 mg/L

Additional information

Various studies were reviewed along with the prediction data to evaluate the effect of the test compound onaquaticmicroorganisms. These are summarized as follows:

 

Toxicity to micro-organisms study (Acute toxicity of parabens and their chlorinated by-products with Daphnia magna and Vibrio fischeri bioassays. 2009) was conducted onVibrio fischeri.The study was carried out using the test conditions and the operating protocol of theV. fischeriacute toxicity test (Environmental Protection Series, 1992). Test chemicals was of special-grade reagent and was used without purification. The test bacteria was exposed to the test substancebenzylparabenwith exposure duration of 5 and 15 mins.Luminescence was measured with a Microtox luminometer (Model 500; Microbics Corp., Carlsbad, CA, USA) in the acute mode. The toxic effect values reflect the ratio of the decrease in bacterial light production to the remaining light. The Microtox statistical software, version 7, was used to calculate the toxic effect values for each sample dilution and the sample concentration inducing 50% light inhibition (EC50) for each log–log dose–response curve and their corresponding confidence limits. The toxicity was expressed in terms of effective concentration values and toxicity units (TUs). The TU value was calculated using EC50 (TU = 100 EC50⁻¹). The logarithms of then-octanol–water partition coefficients (logP) of the test compound was also determined using an HPLC method according to the OECD guideline. Based ondecrease in bacterial light production by the test organismV. fischeri,the EC50 value was found to be 0.0038 mg/l.

 

Toxicity to micro-organisms study (Chapter 14 - Hydroxy Benzoate Preservatives (Parabens) in the Environment: Data for Environmental Toxicity Assessment, 2009) was conducted onVibrio fischerifor 30 mins. Microtox bioassay test was performed for the toxicity study. All stock solutions were prepared in methanol and serially diluted in distilled water to obtain the target concentrations. The methanol concentration in the exposure solutions, including controls, was 0.01% (v/v) in distillate water in the tested solutions. 2-4-dichlorophenol (DCP) was used as control solution. The test bacteria was exposed to the test substancebenzylparabenwith exposure duration of 15 and 30 mins.Bacterial luminescence inhibition was measured after 15 and 30 mins of exposure to tested solutions. Based ondecrease in bacterial light production by the test organismV. fischeri,the EC50 value after 15 and 30 exposure duration was found to be 0.11 mg/land LOEC value was found to be 0.02 mg/l.

 

Toxicity to micro-organisms study was conducted onPhotobacterium leiognathi SB strainfor 30 mins. Toxscreen bioassay test was performed for the toxicity study. All stock solutions were prepared in methanol and serially diluted in distilled water to obtain the target concentrations. The methanol concentration in the exposure solutions, including controls, was 0.01% (v/v) in distillate water in the tested solutions. 2-4-dichlorophenol (DCP) was used as control solution. The test bacteria was exposed to the test substancebenzylparabenwith exposure duration of 15 and 30 mins.Bacterial luminescence inhibition was measured after 15 and 30 mins of exposure to tested solutions. Based ondecrease in bacterial light production by the test organismPhotobacterium leiognathi SB strain,the EC50 value after 15 and 30 exposure duration was found to be 1.3 and 1.6 mg/l, respectively and LOEC value was found to be 0.25 mg/l.

 

Toxicity to micro-organisms study was conducted onTetrahymena thermophilafor 28 hrs. Protoxkit bioassay test was performed for the toxicity study. All stock solutions were prepared in methanol and serially diluted in distilled water to obtain the target concentrations. The methanol concentration in the exposure solutions, including controls, was 0.01% (v/v) in distillate water in the tested solutions. Potassium dichromate (K2Cr2O7) was used as control substance. The test organism was exposed to the test substancebenzylparabenwith exposure duration 28 hrs.Inhibition in bacterial growth was measured after 24 and 28 hrs of exposure to tested solutions. Based on growth inhibition of test organismTetrahymena thermophila,the EC50 value after 24 and 28 hrs was found to be 4.3 and 5.7 mg/l, respectively and LOEC value was found to be 0.48 mg/l. 

 

From above mentioned supporting studies the target chemical benzylparaben (CAS No 94-18-8), the majority values are indicative that the chemical is likely to causeaquaticmicroorganisms.