Octadecanedioic acid, 1,18-dimethyl ester

Endpoint summary

Description of key information

If octadecanedioic acid dimethyl ester (ODDAME) enters the environment, it is subject to various partitioning and abiotic and biological degradation processes. Relevant partitioning processes include adsorption to solids, such as soil and sediment, volatilization into air, and bioaccumulation within aquatic organisms. Degradation processes include hydrolysis in water and photo-oxidation in the atmosphere (abiotic processes) and biodegradation (biological process). 

 

Based on the vapor pressure, aqueous solubility, and molecular weight (342.52 g/mol), a Henry’s law constant of 6.585E-3 atm-m3/mol is calculated. Using the Henry’s law constant and standard assumptions, EPISuite v4.11 modeling yielded volatilization half-lives from a model lake and river to be about 7.4 days and 2 hours, respectively. This suggests that volatilization of ODDAME could be significant in certain natural water bodies. The estimated adsorption coefficient of at least 427,000 (log >5.63) based on OECD Guideline 121 suggests that ODDAME could sorb to natural suspended matter and sediment within natural water systems. Based on the estimated upper trophic bioaccumulation factor (BAF) of 10 L/kg (EPISuite v4.11, BCFBAF v3.01), the bioaccumulation potential for ODDAME is low. In addition, the predicted BAF for middle and lower trophic levels were 42 and 338 L/kg, respectively. The downwards trend in BAF from lower to higher trophic levels is indicative of biodilution, the opposite of biomagnification.

 

ODDAME would be considered stable in water at environmentally relevant pH values of 4 to 7, as indicated by predicted (EPISuite v4.11, Hydrowin v2.00) hydrolysis half-lives exceeding three years (pH 7). However, as pH increases above 7, ODDAME may become slightly less stable in water, as indicated by a predicted hydrolysis half-life of 133 days at pH 8. Using the standard model within EPISuite, the hydroxyl radical-mediated atmospheric photo-oxidation half-life of ODDAME that volatilizes into air is 6.1 hours.

ODDAME is considered “readily” biodegradable, based on an OECD 301B test for ready biodegradability that showed >60% biodegradation and satisfied the 10 day window validation criterion.

 

Fugacity modeling (Level III) was conducted for the components of ODDAME using EPI Suite (v.4.11). Input parameters included molecular weight 342.52 g/mol, melting point 59.2 deg C, water solubility <0.000616 mg/L, log Kow 7.56, and Henry's law constant of 6.58 x 10-3 atm-m3/mol. Equal releases to air, water and soil were assumed. Media-specific half-lives were selected or calculated by the model. For atmospheric photo-oxidation, the model used a half-life in air of 12.3 hours. Biodegradation half-lives in water, soil and sediment were 900, 1800, and 8100 hours, respectively. All other parameters used were the model default values. The results showed the distribution of ODDAME in the environment to be 0.835% to air, 14.2% to water, 81.2% to soil and 3.78% to sediment.