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Environmental fate & pathways

Adsorption / desorption

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Description of key information

Log Koc: 4.03 by HPLC method (OECD TG121)

Key value for chemical safety assessment

Additional information

The soil adsorption/desorption coefficient (log Koc) of C4 acrylate was estimated by HPLC. Several peaks were present on the chromatogram. The major component, contributing 65% of total peak area, had a log Koc of 4.03. Six other peaks were present at > 1% of the total peak area. Log Koc values for these peaks range from < 1.26 - 4.23. C4 acrylate solubility in pure water is 2.02 mg/L, but the maximum solubility attained in the fish toxicity study using modified ISO medium was ca. 0.4 mg/L. Modified ISO medium has ca. 1.5 mM CaCl2, and has a hardness of 180 mg/L as CaCO3. Per OECD TG 106, batch testing of adsorption should be done in 10 mM CaCl2, for which an even lower solubility is expected. Given water solubility and Koc, C4 acrylate constitutes a difficult to test material for which calculations provide an appropriate estimate of adsorption coefficient. To further characterize adsorption behavior, Koc values were calculated using KOCWIN v.2.00 (as implemented within EPISUITE v.4.20) using both molecular connective index (MCI) and log Kow-based methods, and by the log Kow method from European Chemicals Bureau: Technical Guidance Document on Risk Assessment, Chapter 4, 'Acetanilides, carbamates, esters, phenylureas, phosphates, triazines, triazoles, uracils'.  The log Kow value used for these calculations was 4.19. Values ranged from 1773 for the MCI method to 3120 for the Technical Guidance Document-based calculation (log Koc 3.25 to 3.49, respectively). Taken with the range of log Koc values for the components of C4 acrylate by HPLC, the calculated Koc values suggest that the key value sets a maximum value of the adsorption coefficient. No further testing is indicated.