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Environmental fate & pathways

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The substance is rapidly hydrolysed to isophthalic acid and HCl. HCl, an inorganic substance, is not biodegradable. HCl is readily solubilised in water and process water is neutralised before emission if significant release is expected. Therefore, the environmental fate and distribution for this substance will be based on the behaviour of the primary degradate, isophthalic acid.

Isophthalic acid will compartmentalise into water based on the predominance of the anionic species in the environment. An OECD 301B study showed that terephthalic acid was ready biodegradable with >80% CO2 evolution after 14 days, indicating based on read across that isophthalic acid is also ready biodegradable. Supporting studies on isophthalic acid showed that the biological oxygen demand was 77.7% after 28 days in an OECD 301C ready test, further indicating complete mineralisation without any significant metabolites or degradation products. Direct UV analysis confirmed 96% loss of isophthalic acid. Therefore, persistence in the environment is not expected.

The pKa values of isophthalic acid (3.70 and 4.60; CSR section 1.3 Physico-Chemical Properties) indicate that isophthalic acid will exist as the anionic species in the environment. Isophthalic acid is not expected to adsorb to soil, suspended solids or sediment based upon the ACD labs (www.acdlabs.com) log D value (-2.34) at pH 7. Isophthalic acid has the potential to move rapidly in soil; however, rapid biodegradation is expected to mitigate potential transport to groundwater. Volatilisation of isophthalic acid from water surfaces and soil is not expected to be an important fate process based upon this compound's low Henry's Law constant (1.08E-7 Pa*m3/mol) and the predominance of the anionic species in the environment.