Isopropyl 4-hydroxybenzoate

Endpoint summary

Description of key information

Short term toxicity to fish:

study was conducted to assess the effect of test chemical isopropyl 4-hydroxybenzoate on the mortality of fish Danio rerio. Test conducted according to OECD Guideline 203 (Fish, Acute Toxicity Test). The test substance was partially soluble in water. Therefore, the stock solution was prepared by dissolving 1 g of the test substance in 1 liters of potable water (passed through reverse osmosis system) with continuous 24 hours stirring, after stirring stock was analytically detected and the concentration found to be 222.61 mg/L. On the basis of stock concentration 222.61 mg/L further test concentrations calculated which was as follows 1.562 mg/L, 3.125 mg/L, 6.25 mg/L,12.5 mg/L, 25 mg/L respectively and Zebra Fish Danio rerio were exposed to these concentration for 96 hours. Bowl aquaria containing 2 liters of potable water (passed through reverse osmosis system) were loaded with 8 fishes. A static procedure was used for the study and it was conducted in compliance with the OECD guideline 203. Based on nominal concentrations, experimental median lethal Concentrations [LC-50 (96 h)] for isopropyl 4-hydroxybenzoate on Zebra Fish Danio rerio was determine to be 3.125 mg/l. Based on the LC50 value, chemical consider to be toxic but on the basis of readily biodegradability criteria of test chemical, chemical consider to be nontoxic and not classified as per the CLP classification criteria.

Long term toxicity to fish:

Long term toxicity to fish was performed for 7 days at five different concentrations ranges from 1.0 to 25 mg/L. Four replicates of 10 P. promelas in 250 ml of test solution for each concentration were prepared and renewed daily. Fish were fed twice daily and mortality was observed daily. After 7 d of exposure, average weight per fish was calculated and compared to the control. Thus, on the basis of above result the LOEC for long term toxicity to P. promelas was observed to be 9.0 mg/L for test chemical Isopropylparaben (4191-73-5).

 

Short term toxicity to aquatic invertebrates:

Aim of this study first experimental key was to assess the short term toxicity of isopropyl 4-hydroxybenzoate to aquatic invertebrates daphnia magna. Study was performed according to the OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test) in a static system for the total exposure period of 48 hrs. The stock solution 100 mg/l was prepared by dissolving white powder in reconstituted water. The solution was kept in ultrasonic bath for 20 min. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with reconstituted test water. 0, 0.5, 1, 2, 4, 8 and 16 mg/l concentrations were used in the study. Effects on immobilisation were observed for 48 hours. With the test substance one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. After the exposure of chemical, effect concentration EC50 was calculated using nonlinear regression by the software Prism 4.0. The median effective concentration (EC50) for the test substance isopropyl 4-hydroxybenzoate in Daphnia magna was determined to be 3.79 mg/L on the basis of mobility inhibition effects in a 48 hour study. Based on the EC50 value, substance is likely to be hazardous to aquatic invertebrate but as the chemical was readily biodegradable in water thus on that criteria, chemical consider to be nontoxic and not classified as per the CLP classification criteria.

Long term toxicity to fish:

Long term toxicity test have been conducted on Ceriodaphnia dubia by Masanori Terasaki et.al (Environmental toxicology, 12 December 2013)for 7 days at concentrations of 0.66, 1.37, 2.34, 5.05, 9.77 mg/l. Significant differences in the number of offspring (P < 0.01)and time to brood (P < 0.05) were observed at the lowest(0.66 mg/l for iPP) dose groups. Therefore, the EC 50 values for long term toxicity to Ceriodaphnia dubia for isopropylparaben (4191-73-5) was found to be 1.2, 2.5 and 6.2 mg/l based on survival, number of off springs and Time to First Brood of Ceriodaphnia dubia.

Toxicity to algae:

Aim of this study was to evaluate the nature of chemical test chemical when comes in contact with the test organism Desmodesmus subspicatus (previous name: Scenedesmus subspicatus). Test was conducted according to the OECD guideline 201. The stock solution 100 mg/l was prepared by dissolving white powder in OECD growth medium. The solution was kept in ultrasonic bath for 20 min. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture. Various concentrations 0, 6, 12, 24, 50 and 100 mg/l were used. With the test substance one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. After the exposure of chemical, effect concentration EC50 was calculated using nonlinear regression by the software Prism 4.0. Effect on the growth of algae was determine after an exposure period of 72 hrs. Based on the growth rate inhibition of algae Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) due to the exposure of chemical the ErC50 was determine to be 43 mg/l. Based on the ErC50 value, substance is likely to be hazardous, but as the chemical was readily biodegradable in water thus on basis, chemical consider to be nontoxic and not classified as per the CLP classification criteria.

Toxicity to microorganism:

Toxicity to microorganism was performed on V. fischeri by bioluminescence inhibition test. Luminescence was measured with a Microtox luminometer acute mode. Bioluminescence was measured after different time duration from 5- 15 min. Thus, from experiment it was concluded that the EC50 value for toxicity to Vibrio fischeri for isopropyl 4-hydroxybenzoate (4191-73-5) was observed to be 0.62mg/l.

Additional information

Summarized result for the toxicity of test chemical on the growth and mortality of aquatic life’s including fish, invertebrate, algae and microorganism were studied and are as follows:

Short term toxicity to fish:

In different studies, the given test chemical has been investigated for toxicity of chemical on mortality of fishes to a greater or lesser extent. The studies are summarized as below –

 

The first key study was conducted to assess the effect of test chemical isopropyl 4-hydroxybenzoate on the mortality of fish Danio rerio. Test conducted according to OECD Guideline 203 (Fish, Acute Toxicity Test). The test substance was partially soluble in water. Therefore, the stock solution was prepared by dissolving 1 g of the test substance in 1 liters of potable water (passed through reverse osmosis system) with continuous 24 hours stirring, after stirring stock was analytically detected and the concentration found to be 222.61 mg/L. On the basis of stock concentration 222.61 mg/L further test concentrations calculated which was as follows 1.562 mg/L, 3.125 mg/L, 6.25 mg/L,12.5 mg/L, 25 mg/L respectively and Zebra Fish Danio rerio were exposed to these concentration for 96 hours. Bowl aquaria containing 2 liters of potable water (passed through reverse osmosis system) were loaded with 8 fishes. A static procedure was used for the study and it was conducted in compliance with the OECD guideline 203. Based on nominal concentrations, experimental median lethal Concentrations [LC-50 (96 h)] for isopropyl 4-hydroxybenzoate on Zebra Fish Danio rerio was determine to be 3.125 mg/l. Based on the LC50 value, chemical consider to be toxic but on the basis of readily biodegradability criteria of test chemical, chemical consider to be nontoxic and not classified as per the CLP classification criteria.

 

Similar short-term toxicity to Pimephales promelas was performed for 48 hrs at five nominal concentrations in a temperature-controlled incubator at 24°C with a 16:8 light: dark cycle.500 ml beaker was taken having 250 ml of test chemical. Test solution was prepared by dissolved in high-performance liquid chromatography grade acetone and delivered into RHW at 0.1% acetone. No aeration was used and LD 50 value was determined at 24 and 48 hrs. On the basis of above experiment result, the LD 50 value for Pimephales promelas for isopropylparaben (4191-73-5) was found to be 17.5 mg/L concentrations. Based on this value, it can be concluded that the test chemical Isopropyl 4-hydroxybenzoate can be considered as toxic to aquatic environment. Since the chemical is readily biodegradable in nature, chemical Isopropyl 4 -hydroxybenzoate can be considered as non-toxic to fish at environmentally relevant concentrations and can be considered to be not-classified as per the CLP classification criteria.

 

Thus based on the above both studies, chemical consider to be nontoxic and not classified as per the CLP classification criteria.

 

Long term toxicity to fish:

Long term toxicity to fish was performed for 7 days at five different concentrations ranges from 1.0 to 25 mg/L. Four replicates of 10 P. promelas in 250 ml of test solution for each concentration were prepared and renewed daily. Fish were fed twice daily and mortality was observed daily. After 7 d of exposure, average weight per fish was calculated and compared to the control. Thus, on the basis of above result the LOEC for long term toxicity to P. promelas was observed to be 9.0 mg/L for test chemical Isopropylparaben (4191-73-5).

 

Short term toxicity to aquatic invertebrates:

In different studies, the given test chemical has been investigated for toxicity of chemical on mobility of aquatic invertebrates to a greater or lesser extent. The studies are summarized as below –

 

Aim of this study first experimental key was to assess the short term toxicity of isopropyl 4-hydroxybenzoate to aquatic invertebrates daphnia magna. Study was performed according to the OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test) in a static system for the total exposure period of 48 hrs. The stock solution 100 mg/l was prepared by dissolving white powder in reconstituted water. The solution was kept in ultrasonic bath for 20 min. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with reconstituted test water. 0, 0.5, 1, 2, 4, 8 and 16 mg/l concentrations were used in the study. Effects on immobilisation were observed for 48 hours. With the test substance one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. After the exposure of chemical, effect concentration EC50 was calculated using nonlinear regression by the software Prism 4.0. The median effective concentration (EC50) for the test substance isopropyl 4-hydroxybenzoate in Daphnia magna was determined to be 3.79 mg/L on the basis of mobility inhibition effects in a 48 hour study. Based on the EC50 value, substance is likely to be hazardous to aquatic invertebrate but as the chemical was readily biodegradable in water thus on that criteria, chemical consider to be nontoxic and not classified as per the CLP classification criteria.

 

Above study was supported by the second study from peer reviewed journal. Acute immobilization test was performed in Daphnia magna was performed at different concentrations of isopropylparaben for 24- 48 hrs according to the OECD TG 202.Four groups of five organisms were used in 100 ml of glass beaker. Number of immobilized daphnids was checked after 24 and 48 hrs. After experiment it was found that, the EC50 value for short term toxicity to Daphnia magna for isopropylparaben (4191-73-5) was determined to be 30 mg/l concentration. Based on the value, the isopropylparaben was considered to be toxic to aquatic invertebrates but as it was readily biodegradable hence, it can be considered to be not classified as per the CLP regulations.

Similarly short-term toxicity to daphnia magna was performed for 48 hrs at five nominal concentrations in a temperature-controlled incubator at 24°C with a 16:8 light: dark cycle.100 ml beaker was taken having 80 ml of test chemical. Test solution was prepared by dissolved in high-performance liquid chromatography grade acetone and delivered into RHW at 0.1% acetone. No aeration was used and LD 50 value was determined at 24 and 48 hrs. On the basis of above experiment result the LD 50 value for Daphnia magna for isopropylparaben (4191-73-5) was found to be 8.5 mg/L concentrations. Based on the value, the isopropylparaben was considered to be toxic to aquatic invertebrates but as it was readily biodegradable hence, it can be considered to be not classified as per the CLP regulations.

Thus based on the above both studies, chemical consider to be nontoxic and not classified as per the CLP classification criteria.

 

Long term toxicity to fish:

Long term toxicity to aquatic invertebrates was summaries with key and supporting studies for isopropylparaben (4191-73-5) are as follows.

 

Long term toxicity test have been conducted on Ceriodaphnia dubia by Masanori Terasaki et.al (Environmental toxicology, 12 December 2013)for 7 days at concentrations of 0.66, 1.37, 2.34, 5.05, 9.77 mg/l. Significant differences in the number of offspring (P < 0.01)and time to brood (P < 0.05) were observed at the lowest(0.66 mg/l for iPP) dose groups. Therefore, the EC 50 values for long term toxicity to Ceriodaphnia dubia for isopropylparaben (4191-73-5) was found to be 1.2, 2.5 and 6.2 mg/l based on survival, number of off springs and Time to First Brood of Ceriodaphnia dubia.

 

Supporting to the above key study by Laura L. Dobbinset.al,(Environmental Toxicology and Chemistry, Vol. 28, No. 12, pp. 2744–2753, 2009) long term toxicity to Daphnia Magna was studied for 10 days at different concentrations. Neonates were used and half of the LC50 determined from the acute test was used as the highest sub chronic exposure concentration; a 0.5 dilution factor was then applied to prepare the remaining concentrations.10 replicates with one Daphnia was applied to each concentration were fed during study. Daily observed for mortality and number of neonates were done. So, on the basis of above result the endpoint for long term toxicity to Daphnia Magna was determined to be LOEC at 2 mg/L concentrations of isopropylparaben (4191-73-5).

 

Based on the key and supported studies values, the isopropylparaben was considered to be toxic to aquatic invertebrates but as it was readily biodegradable hence, it can be considered to be not classified as per the CLP regulations.

Toxicity to algae:

Aim of this study was to evaluate the nature of chemical test chemical when comes in contact with the test organism Desmodesmus subspicatus (previous name: Scenedesmus subspicatus). Test was conducted according to the OECD guideline 201. The stock solution 100 mg/l was prepared by dissolving white powder in OECD growth medium. The solution was kept in ultrasonic bath for 20 min. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture. Various concentrations 0, 6, 12, 24, 50 and 100 mg/l were used. With the test substance one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. After the exposure of chemical, effect concentration EC50 was calculated using nonlinear regression by the software Prism 4.0. Effect on the growth of algae was determine after an exposure period of 72 hrs. Based on the growth rate inhibition of algae Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) due to the exposure of chemical the ErC50 was determine to be 43 mg/l. Based on the ErC50 value, substance is likely to be hazardous, but as the chemical was readily biodegradable in water thus on basis, chemical consider to be nontoxic and not classified as per the CLP classification criteria.

Toxicity to microorganism:

Toxicity to microorganism was performed on V. fischeri by bioluminescence inhibition test. Luminescence was measured with a Microtox luminometer acute mode. Bioluminescence was measured after different time duration from 5- 15 min. Thus, from experiment it was concluded that the EC50 value for toxicity to Vibrio fischeri for isopropyl 4-hydroxybenzoate (4191-73-5) was observed to be 0.62mg/l.

Thus based on the above both studies, chemical consider to be nontoxic and not classified as per the CLP classification criteria.