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Classification & Labelling & PBT assessment

PBT assessment

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PBT assessment: overall result

benzyl butyrate
Type of composition:
boundary composition of the substance
State / form:
Reference substance:
benzyl butyrate
PBT status:
the substance is not PBT / vPvB

Classification of Benzyl butyrate for effects in the environment:


The chemical Benzyl butyrate (CAS no. 103-37-7) is used as a flavouring agent in foods and as a fragrances in perfumes etc. The aim was to assess whether the PBT criterion within Annex XIII was fulfilled for Benzyl butyrate. The PBT criterion was herein assessed based on experimental data in conjunction with standardized environmental fate models. Here follows a description of the PBT assessment.


Persistence assessment

The tested substance does not fulfil the P criterion within Annex XIII based on the assessment that here follows:


Biotic degradation

In an experimental key study, the ready Biodegradability of test chemical was determined by the Manometric respirometry. The method used is basically the one described under No. 301 F in the OECD Guidelines for Testing of Chemicals. A measured volume of inoculated   mineral   medium, containing a known concentration of test substance 30 mg/L as the nominal sole source of organic carbon, is stirred in a closed flask at a constant temperature (± 1 °C) for up to 28 days.   Evolved   carbon dioxide   is absorbed in sodium hydroxide pellets. The consumption of oxygen is determined by measuring the pressure drop in the respirometer flask. The Biological Oxygen Demand (BOD), amount of oxygen taken up by the microbial population during biodegradation of the test chemical (corrected for uptake by blank inoculum, run in parallel) is expressed as a percentage of ThOD (Theoretical Oxygen Demand, calculated from the elemental composition, assuming that carbon is oxidized to carbon dioxide, hydrogen to water and nitrogen to ammonium, nitrite or nitrate). Test chemical undergoes 88% biodegradation after 28 days (87%after 62 days) in the test conditions. The 10-day window criterion is also fulfilled (20% biodegradation on day 1 and 77% on day11). Thus, test chemical should be regarded as readily biodegradable according to this test. Test chemical did not inhibit the intrinsic respiration of the inoculum at the test concentration and was therefore considered to be non-toxic to the inoculum at the test concentration.


In a supporting study, the 28-days Manometric respirometry test following the OECD guideline 301F was performed to determine the ready biodegradability of the test chemical. % Degradation was calculated using the values of BOD and ThOD for test item and reference item. The BOD28value of test chemical was observed to be 1.967 mgO2/mg. ThOD was calculated as 2.424 mgO2/mg. Accordingly, the % degradation of the test item after 28 days of incubation at 20 ± 1°C according to manometric respirometry test was found to be 81.15%.Based on the results, the test item, under the test conditions, was determined to be readily-Biodegradable at 20 ± 1°C over a period of 28 days.


Thus, based on the available information, it indicates that chemical Benzyl butyrate was considered to be readily biodegradable in water and thus likely to be not persistent (Not P) in nature.


Environmental fate

According to the fugacity model levels III, the most likely environmental fate for this test chemical is soil (i.e.estimated to 72.6%). In soil, Benzyl butyrate was expected to have slow mobility based upon a Log KOC value of 3.323± 0.0005 at 25°C. The half-life in soil (30 days estimated by EPI suite) indicates that the chemical is not persistent in soil and the exposure risk to soil dwelling animals is moderate to low.


If released in to the environment, 24.8% of the chemical will partition into water according to the Mackay fugacity model level III in EPI suite version 4.1 (2017). However, the half-life (15 days estimated by EPI suite) indicates that the chemical is not persistent in water and the exposure risk to aquatic animals is moderate to low.


Moreover, its persistent characteristic is only observed in the sediment compartment but Fugacity modelling shows that sediment is not an important environmental fate (less than 1% i.e reported as 0.406% when estimated by EPI Suite version 4.1).


Hence it has been concluded that chemical Benzyl butyrate is not persistent (not P) in nature.


Bioaccumulation assessment

The tested substance does not fulfil the B criterion within Annex XIII based on the assessment that here follows:


Theestimated BCF value from authoritative database was evaluated to be 48.76 L/Kg and theoctanol water partition coefficient of the test chemical was determined to be 3.127± 0.001 at 25°C as per OECD TG no. 117 and from other reliable sources, the logKow was determined to be 3.06, respectively which is less than the threshold of 4.5. If this chemical is released into the aquatic environment, there should be a low risk for the chemical to bioaccumulate in fish and food chains.


Toxicity assessment

The tested substance does not fulfil the T criterion within Annex XIII based on the assessment that here follows:



The tested chemical is regarded to be not classified for carcinogenicity, mutagenicity and reprotoxicity, Further, there is no evidence of chronic toxicity, as identified by the classifications STOT (repeated exposure), category 1(oral, dermal, inhalation of gases/vapours, inhalation of dust/mist/fume) or category 2 (oral, dermal, inhalation of gases/vapours, inhalation of dust/mist/fume).


Aquatic organisms

All of the available short-term eco-toxicity data for fish, aq. invertebrates and algae for the substance Benzyl butyrate indicates the LC50/EC50 value to be in the range 12.5 to > 200 mg/L. These value suggest that the substance is likely to be hazardous to aquatic organisms. Since the chemical Benzyl butyrate is readily biodegradable in water, test chemical was considered as not hazardous to aquatic organismsat environmentally relevant concentrations and hence, considered to be ‘not classified’ as per the CLP regulation.


There are no available long-term toxicity evaluations for Benzyl butyrate. By speculation, long-term NOEC for aquatic organisms were not expected for the substance at concentration below 0.01 mg/L based on the data mentioned above.


The chemical was therefore not considered as hazardous to aquatic environments as per the criteria set out in Annex XIII.



Based on critical, independent and collective evaluation of information summarized herein, the tested compound does not fulfil the P, B and T criterion and has therefore not been classified as a PBT compound within Annex XIII.