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Environmental fate & pathways

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Data for Standolized soybean oil were read-across from Standolized linseed oil.

The biodegradability of Linseed oil, polymerized was tested in different screening tests (OECD TG 301). It is concluded that the test substance is not readily biodegradable; however, the test substance is inherently biodegradable.

The results indicated a partial biodegradation in the screening tests for ready biodegradability, also after prolonged exposure (21 - 45% mineralisation).

A SCAS test was performed to test the ultimate biodegradability under more favorable conditions (OECD TG 302A). The removal ranged from 58 to 74%, also suggesting partial degradation. The biodegradation percentages did not increase when activated sludge of the SCAS units (pre-exposed for 4 and 9 weeks) was used as inoculum in the Closed Bottle tests, so apparently, adaptation does not take place.

Hydrolysis of the ester bonds and subsequent degradation of glycerol and fatty acids would result in a 65% carbon removal of Linseed oil, polymerized (based on the assumed structure). The persistent parts of linseed standoil are most likely the modified fatty acids and/or partially degraded modified fatty acids. The far-ends of the alkyl chains can be oxidized and carboxylated far-ends might be shortened through β-oxidation. This would result in water soluble substances and these were indeed detected (as DOC) in the effluent of the SCAS unit.

The biodegradation percentage found in the enhanced biodegradability test (Closed Bottle test) exceeds 20%. Linseed oil, polymerized most likely readily converts into water, CO2, persistent water soluble substances and biomass.

The result in the prolonged Closed Bottle test, 41 - 45% mineralisation after 60 days (under the conditions found to be most favourable), indicates that considerably more than half of the parent substance was degraded; this is equivalent to half-life time in water < 60 days.

Based on the lack of an analytical method, simulation tests for the degradation in surface water, sediment and soil are waived.

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