o-anisic acid

PBT assessment

PBT assessment: overall result

PBT status:

the substance is not PBT / vPvB

Justification:

Classification of o-anisic acid for effects in the environment:

 

The chemical o-anisic acid (CAS no. 579-75-9) are used as a flavour agent; as an intermediate for chemical synthesis and as a laboratory chemical. The aim was to assess whether the PBT criterion within Annex XIII was fulfilled for o-anisic 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 (GUANG H. LU et. al, 2003), biodegradation study was conducted for 5 days for evaluating the percentage biodegradability of test substance 2-methoxybenzoic acid (CAS no. 579-75-9).The study was performed using the standard iodometric titration method. River water was used as a test inoculum obtained from Jilin section in the Songhua river. Temperature of the water sample was 15-20°C, pH 6.8 – 7.0 and dissolved oxygen was ranged between 7.8 – 9.0 mg/l, respectively. The bacterial counts were determined by standard plate count techniques and are about 1,200 to 3000 colony forming units/ml. Initial test substance conc. used in the study was 2 mg/l on the basis of ThOD. Residual DO of the test chemical was at least 1 mg/l at the final day. The test chemical was added to 250 ml BOD bottles. One milliliter of diluted water sample was cultivated in 15 ml of the medium at 31°C for 24 h, and the number of colonies was enumerated as the bacterial counts. The bottles were then filled to capacity with the water sample, sealed and incubated for 5 days at 20 ± 1°C.Two replicates were conducted for each chemical and each control (inoculum only).The DO concentrations were determined by the iodometric titration method. Biodegradability was assessed by measuring the BOD values in milligrams per liter (oxygen uptake values of test compound minus control). Biodegradability was expressed as the first-order kinetic rate constant (K) according to the traditional Monod equation (on the assumption that the bacterial counts were invariable during the experimental period).The total surface area of molecules, the heat of formation (Hf), and the energy of the highest occupied molecular orbital (EHOMO) of test chemical was calculated by the quantum chemical method Mopac Program. The linear regression analyses were performed with the SPSS® statistical package. An obvious negative correlation apparently exists between Hf and K, that is, the lower the Hf value (-422.08 kj/M), the higher the K value (1.06/d), and thus based on this relationship, test chemical was considered to be readily biodegradable by river bacteria.

 

In a supporting data, biodegradation experiment was conducted for 5 days for evaluating the percentage biodegradability of test substance 2-methoxybenzoic acid (CAS no. 579-75-9) (G. H. Lu et. al, 2002).The study was performed using the standard iodometric titration method. River water was used as a test inoculum obtained from Jilin section in the Songhua river. Temperature of the water sample was 15-20°C, pH 6.8 – 7.0 and dissolved oxygen was about 8.0 mg/l, respectively. The bacterial counts were determined by standard plate count techniques and are about 800-3000/ml. Initial test substance conc. used in the study was 2 mg/l on the basis of ThOD. Residual DO of the test chemical was at least 1 mg/l at the final day. The test chemical was added to 150 ml of water sample in 250 ml BOD bottles. The bottles were then filled to capacity with the water sample, sealed and incubated for 5 days at 20 ± 1°C. The DO concentrations were determined by the iodometric titration method. The test result was expressed as BOD% by comparing the measured BOD5 with ThOD. Mw, Hf and Ehomo of test chemical was calculated by the quantum chemical method MOPAC 6.0-AMI on energy minimized structures. The percentage degradation of test substance was determined to be 55.8% by using BOD parameter in 5 days. Thus, based on percentage degradation, 2-methoxybenzoic acid is considered to be biodegradable in nature.

 

Another biodegradation study was conducted for 14 days for evaluating the percentage biodegradability of test substance 2-ethyl-9,10-anthraquinone (CAS no. 84-51-5) (GERHARD ZELLNER et. al, 1990). Micro-organisms (Desulfovibrio vulgaris Marburg, Desulfovibrio simplex" XVI and Desulfovibrio sp. Strain MP47) was used as a test inoculum. Initial test substance conc. used in the study was 250 mg/20 ml. Parallel cultures in serum bottles containing 20 ml of medium and 250 mg of any one of the substrates mentioned above per litre were incubated under N2-CO2 (80:20%, 300 kPa) at 37°C on a shaker (100 rpm) for 4 weeks. Biotransformation of the substrates was analysed by at least two methods, including HPLC with two detector systems, UV spectroscopy at 254 nm (293 nm for pyridoxal hydrochloride), and thin-layer chromatography. Optical density of cultures was measured with a photometer at a wavelength of 578 nm. Optical density measurements of parallel cultures were corrected for the absorbance measured immediately after inoculation and for the absorbance reached in control cultures in the absence of an added electron donor for sulfate reduction. As no growth of test organism was obtained using the test chemical as a substrate, no transformation of 2-methoxybenzoic acid was determined in 28 days. Thus, 2 -methoxybenzoic acid is considered to be not readily biodegradable in nature.

 

The experimental data for read-across substance (CAS: 50-78-2) also indicate that they are readily biodegradable. Although one study (GERHARD ZELLNER et. al, 1990) indicate that the chemical 2-methoxybenzoic acid is not readily biodegradable, on the basis of overall reported results for target chemical 2-methoxybenzoic acid (from peer reviewed journal) and for its read across substance (from authoritative database J-CHECK), it can be concluded that the test substance 2-methoxybenzoic acid can be expected to be readily biodegradable 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 67.1%). In soil, o-anisic acid was expected to have moderate to rapid mobility based upon an estimated Log KOC in the range 0.0 – 2.2. 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, 32.2 % 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 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 o-anisic 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 is in the range 1 – 8.05 L/kg wet wt. 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 the range 78.8 - > 100 mg/L. These value suggest that the substance is likely to be hazardous to Aquatic organisms at environmentally relevant concentrations, but since the substance is readily biodegradable, it can be considered to be not classified as per the CLP regulation.

 

There are no available long-term toxicity evaluations for o-anisic acid. 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.

 

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.