3-phenylpropionic acid

PBT assessment

PBT assessment: overall result

PBT status:

the substance is not PBT / vPvB

Justification:

Classification of 3-phenylpropionic acid for effects in the environment:

 

The chemical 3-phenylpropionic acid (CAS no. 501-52-0) are for example used as a flavour and fragrance agent. The aim was to assess whether the PBT criterion within Annex XIII was fulfilled for 3-phenylpropionic acid. 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 from peer reviewed journal (Enzyme and Microbial Technology, 1999), biodegradation experiment was conducted for evaluating the percentage biodegradability of test substance 3 -phenylpropanoic acid (CAS no. 501 -52 -0). P. furiosus was used as a test inoculum. P. furiosus (DSM 3638) was grown anaerobically at 90°C in a basic medium. Yeast extract, cysteine, vitamins, and trace elements were added. Potato starch (5 g/1) was used as a carbon and energy source. Cells were grown in 100 ml bottles containing 50 ml medium, which was flushed with N2/CO2 (80/20) before inoculation. During growth, the bottles were shaken continuously at 200 rev./min. The medium was inoculated with a 2% preculture. At the start of growth the pH was 6.8 - 7.0 and was not adjusted during the experiment. Growth was determined by the increase in protein concentration and by dihydrogen production. Protein concentration was measured using the Coomassie Brilliant Blue-method with bovine serum albumin as standard. Dihydrogen production was analyzed by gas chromatography with N2 as internal standard. All samples [30 ml for GC analysis, 1 ml for high-performance liquid chromatography (HPLC) analysis] were centrifuged for 15 min at 18,000g.In the case of aromatic compounds; the supernatant was directly analyzed by HPLC. Aliphatic compounds were analyzed by GC. Before this analysis, the pH of 25 ml supernatant was decreased to 2.5 with 5 N HC1, and 5 g NaCl was added to the supernatant. These samples were extracted with 2 ml di-ethylether containing 0.1% 1-pentanol as an internal standard. The ether phase was analyzed. All experiments were repeated three times. The percentage degradation of test substance was determined to be 69%by GC and HPLC parameter in 25 hrs.3-phenyl-l-propanol was formed as a metabolite during the degradation of test chemical3-phenylpropanoic acid by P. furiosus. Thus, based on percentage degradation, chemical 3-phenylpropanoic acid can be considered to be readily biodegradable in nature.

 

In a supporting data, biodegradation study was conducted for evaluating the percentage biodegradability of test substance 3-phenylpropanoic acid (CAS no. 501-52-0) (D. M. WEBLEY et. al; 1955). Nocardia opaca (Bacterium) was used as a test inoculum. Organisms were grown on liquid medium, but the shaking machine was used. Medium containing 2% (w/v) glucose was used in 200 ml. lots in 1 1. Pyrex culture flasks. Incubation was at 25°C for 4-6 days. For the detection of intermediates, experiment was performed on the shaking machine used for the production of the cells. The same type of flask was employed containing 100ml of 0.0133M-phosphate (pH7.2), 5 -25µmole/ml. phenyl substituted acid (as sodium salt) and 200 -400mg (dry weight) of washed glucose-grown cells. Strict aseptic conditions were observed as the experiments were sometimes continued over a number of days. Samples were withdrawn periodically when required, centrifuged and examined spectrochemically. Chromatographic analyses were performed when desirable during the course or at the end of the experiment when the whole contents of the flasks were used. Samples were periodically removed, with aseptic precautions, centrifuged arid examined spectrochemically. Successive absorptionietric analyses of the phenylpropionic acid solution at intervals over the complete experiment shows that the benzoic acid concentration rises steadily until the substrate is exhausted, and the conversion is approximately quantitative; the concentration of cinnamic acid rises to a maximum and then falls to zero at the end of the experiment. It is clear, therefore, that cinnamic acid is an intermediate in the oxidation of phenylpropionic acid to benzoic acid by Nocardiaopaca. The formation of benzoic acid from phenylpropionic acid was finally confirmed by its isolation at the end of the experiment. Thus, based on this, it can be concluded that the chemical 3-phenylpropanoic acid is considered to be biodegradable in nature.

 

The experimental data for read-across substance Benzioc acid (CAS: 65-85-0) also indicate that it is readily biodegradable.

 

Environmental fate

According to the fugacity model levels III, the most likely environmental fate for this test chemical is soil (i.e.estimated to 77.7%). In soil, 3-phenylpropionic acid was expected to have moderate mobility based upon an estimated Log Koc of 1.73. 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, 22.1 % of the chemical will partition into water according to the Mackay fugacity model level III in EPI suite version 4.1 (2016). However, the half-life (15 days estimated by EPI suite) indicates that 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% when estimated by EPI Suite version 4.1).

 

Hence it has been concluded that 3-phenylpropionic acid is not persistent in nature.  

 

 

Bioaccumulation assessment

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

 

The estimated BCF value for the substance from various databases is in the range 1 - 4 L/kg wet wt. and the experimental octanol-water partition coefficient (log Kow) was 1.15 which is below 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:

 

Mammals

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 estimation for fish, invertebrates and algae for the substance indicates the LC50/EC50 value to be in > 100 mg/L indicating that the substance can be classified as non-hazardous to aquatic organisms as per the CLP criteria.

 

There are no available long-term toxicity evaluations for 3-phenylpropionic acid. The NOEC values for fish in 24 hour study is reported as 5 mg/L. By speculation, long-term NOEC for aquatic organisms were not expected for 3-phenylpropionic acid at concentration below 0.01 mg/L based on the data mentioned above.

 

The chemical was therefore considered as non-hazardous to aquatic environments as per the criteria set out in Annex XIII.

 

Conclusion

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.