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Environmental fate & pathways

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Distribution in the environment


Thymidine is an organic solid at environmental temperatures. The substance is highly water soluble, has a low log Pow and low volatility. Released into the environment Thymidine is likely to distribute into water and soil. A predicted acid dissociation constant (pKa) value of 9.28 suggests that the substance will exist almost entirely as a charged molecule in the environmentally-relevant pH range of 6 – 9, with the substance existing primarily as a protonated cation and acting as a weak base. Therefore, when released to the environment Thymidine is expected to partition predominantly into water, although partitioning to soil and, to a lesser extent sediment, may also occur depending upon the compartment of release.




Thymidine was shown to be ready biodegradable in a biodegradation study, with 97 % degradation after 9 days and 99 % degradation after 28 days. With ready biodegradability confirmed, further assessment of degradation in sediment and water as well as soil was waived. Further, assessment of abiotic degradation was waived. 




Based on the log Pow of < 0.3 the substance is considered to have no bioaccumulation potential. Accumulation in the food chain is highly unlikely.

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