Octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate

Endpoint summary

Additional information

1) Assessment of octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate

 

Abiotic degradation

The calculated half-life for the photo-oxidation (reaction with hydroxyl radicals) of octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate in air is 8.9 hours (SRC AOP v1.92). Although the substance contains an ester bond, hydrolysis is unlikely to be the main abiotic degradation process in water. Hydrolysis half-life is estimated to be >7 years at pH 7 and 264 days at pH 8 (SRC HYDROWIN v4.00).

 

Biodegradation

The substance is not readily biodegradable. However, fast primary degradation has been observed. The identified primary degradation product is benzenepropanoic acid, 3,5-bis(1,1 -dimethylethyl)-4-hydroxy- (“metilox acid”; CAS no. 20170-32-5). The other product is assumed to be accordingly 1-octadecanol (CAS 112-92-5). The rate of primary degradation seems to vary depending on the test conditions. Metilox acid is based on the available result from an OECD 301B -test not readily biodegradable. 1-Octadecanol is assumed to be not persistent based on BIOWIN–predictions.

 

Bioaccumulation

Based on a re-evaluation of an OECD 305C bioconcentration study with fish, octadecyl 3-(3,5-di-tert butyl-4-hydroxyphenyl)propionate has a BCF of < 210-1470 and hence a moderate to high bioaccumulation potential. In addition, due to the fast primary degradation, bioaccumulation of the substance is not likely to occur in the environment.

Calculations of the BCF with standard QSARs (EPISuite 4.00) resulted in low BCF values (BCFBAF v3.00, regression based estimate: BCF = 5.77 L/kg; Arnot-Gobas method (including biotransformation rate estimates: BCF 0.8954 L/kg). A calculated BAF value indicates similar low accumulation properties as suggested by BCF(BCFBAF v3.00, Arnot-Gobas method, including biotransformation rate estimates, upper trophic: BAF 2.975 L/kg). Furthermore, the maximum diameter is markedly above the OSIRIS cut-off criterion of 17Ä, with a diamax of 35.78 Ä (OASIS Catalogic v 5.10.6). Therefore, octadecyl 3-(3,5-di-tert butyl-4-hydroxyphenyl)propionate the substance is unlikely to cross biological membranes and to accumulate to a significant extend in biota.

 

Transport and distribution

Octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate exhibits a high potential for adsorption and negligible volatilization. Mackay Level I modeling revealed, that soil and sediment are the main target compartments for octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate (Mackay Level I 3.00). Level III fugacity modeling shows that after release to surface water 98% of octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate will partition to sediment, while 2% ends up in water. When released to soil 100 % will remain in this compartment. Negligible amounts will be distributed towards the other compartments (EPISuite 4.00).

 

 

2) Assessment of the major degradation product Metilox acid (CAS: 20170-32-5)

 

According to a data screening, the main metabolite, Metilox acid is not readily biodegradable. Due to its physico-chemical properties in the environment it is expected to end up in the soil and to a lesser degree in the water.

Metilox acid has, based on experimental data, a BCF of 532 or lower and it has hence low to moderate bioaccumulation potential. The second primary degradation product, 1-octadecanol, has a high bioaccumulation potential based on its estimated logKow (7.72), but is not likely to be bioaccumulated in the environment due to its ready biodegradability.

These substances are supposed to be subject for REACh registration and thereby thoroughly assessed during this process.