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Environmental fate & pathways

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According to a Mackay level I calculation cis-cyclooctene will be distributed almost exclusively to the atmosphere (99.86 %) while distribution to other compartments is negligible (< 0.1 % each). The calculated Henry’s law constant of 36,400 Pa m3/mol at 20 °C indicates high volatility of cis-cyclooctene from surface waters. The adsorption coefficient on soil Koc of cis-cyclooctene was determined as 1000 (log Koc = 3.0; 25 ºC). This is borderline between moderate and high on the Blume scale.

 

The QSAR calculated rate constant for the OH sensitized photodegradation of cis-cyclooctene is approximately 6.43E-11 cm3/(molecule * s). At 500,000 OH radicals / cm3 (approximate 24-hour mean in central Europe), this corresponds to a half-life of 6 hours. The reaction with ozone is slightly faster and thereby reduces the atmospheric half-life of cis-cyclooctene by a factor of about 2. Although not readily biodegradable according to the guideline requirements, cis-cyclooctene can be metabolized by microorganism. Atmospheric OH and ozone sensitized photodegradation plus biodegradation are expected to be the predominant ways of removal from the environment while photolytical or hydrolytical degradation in surface water are expected to be of minor importance. The partition coefficient 1-octanol/water of cis-cyclooctene was determined as log Kow 5.0 at 25 °C, indicating a potential for bioaccumulation.