Registration Dossier

Environmental fate & pathways

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Additional information

The tin bis(2 -ethylhexanoate) substance is dissociated into its 2-ethylhexanoate and Sn(II) components upon contact with water in the environment. The Sn(II) component has been shown to be speciated initially in water as Sn(OH)2 at pH encountered in the environment (pH 6 - 8); and this species will spontaneously oxidize in oxygenated water to form the insoluble inorganic solid Sn(IV)O2. The transport/distribution of this component will be governed by the same processes affecting other insoluble particles in the environment. The transport and distribution of the 2-ethylhexanoate component will be governed by pH, which influences its speciation among the free acid and anionic forms. The measured log Kow for the free acid form (predominant at pH < 2.8) is 2.64, while the log D for the anion form (predominant at pH > 6.8) is approximately 0.6. Based on this latter, environmentally-relevant value, the 2-ethylhexanoate substance is not expected to partition significantly to organic matter of soil or sediments, or to bioaccumulate in aquatic organisms. This low potential for adsorption to soil and sediment is evidenced the by predicted log Koc value of 1.61 (Koc = 41.3). Because this component of the tin bis(2 -ethylhexanoate) salt occurs as an ion at environmentally-relevant pH, it is moderately soluble in water and has low potential for volatilization from soil or water to the atmosphere.