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Environmental fate & pathways

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Hydrolysis

The abiotic degradation of the test item 4-Hydroxy TEMPO was conducted according to OECD TG 111, Regulation (EC) No 440/2008, method C.7., and in accordance with OPPTS 835.2110. A sufficient number of measurements were made to estimate if less than 10% of hydrolysis is observed after five days at 50°C. In the preliminary test at 50°C the test item was stable at pH 4, 7 and 9 due to the fact that the observed hydrolysis was less than 10% after five days (120 h) at the test temperature of 50 ± 0.5°C. Therefore no further testing was necessary. According to the guideline, a half-life period at 25°C of more than one year may be estimated.

Biodegradation:

The biotic degradation potential of 4-Hydroxy TEMPO was investigated according to EU-method C.4-A. After 28 days incubation the test item reached 9 % degradation. Therefore 4-Hydroxy-TEMPO cannot be considered ready biodegradable.

Bioaccumulation:

The bioaccumulation potential of 4-Hydroxy TEMPO was estimated by calculation of the BFC with EPIWIN software using BCFBAF v1.5. A BCF value of 3.162 L/kg wwt and a log Kow of 0.55 were calculated. Thus 4-Hydroxy-TEMPO can be considered that it is unlikely to have potential for bioaccumulation.

Adsorption/desorption:

The adsorption / desorption of 4-Hydroxy TEMPO was estimated by calculation of the log Koc with EPIWIN software using KOCWIN. A log Koc value of 0.7743 and a log Kow of 0.55 were calculated. Thus the test item can be considered that it is unlikely to have potential for adsorption / desorption.