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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Reliable screening studies on biodegradation are available for eight out of ten DMA category members. These altogether 15 studies (4x RL 1, 11x RL 2) were performed according to OECD 301 guidelines and consistently demonstrated ready biodegradability of DMA. 

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

A pass-level criterion for most OECD 301-tests is the 10-day window requirement. For some of the studies summarized below this was not met. However, as all of the DMA category members consist of mixtures of substances with varying hydrocarbon chain lengths, the 10-d window isgenerally notapplicable for these substances.

Key studies for DMA category members C10, C12, C12-14, C14 and C12-18 DMA were performed according to OECD 301B (CO2-Evolution). Degradation levels between 67% (C12-14 DMA) and 93% (C12-18 DMA) were achieved within 28 days and thus for all of them the pass level for ready biodegradability is met. Several supporting studies performed according to OECD 301-guidelines are available corroborating these results (inherent biodegradability test for C14-DMA, ready biodegradability test for the other four compounds).

Key studies for DMA category members C16, C16-18, and C18 DMA were performed according to OECD 301D (Closed bottle test). Degradation levels within 28 days were 60% for C16 DMA and 68% for C18 DMA, again demonstrating ready biodegradability. In the closed bottle test with C16-18 DMA 58% degradation were achieved within 28 days and 66% within 42 days. For this compound an additional reliable (with restrictions) mechanistic (supporting) study is available, demonstrating ready biodegradability using a variety of inocula, namely activated sludge, river water, ditch water and soil. Furthermore, in this study mechanistic aspects of degradation were elucidated using isolated bacterial strains corroborating biodegradability for the category in general. Supporting studies are also available for C16 and C18 showing ready and inherent biodegradability, respectively.

In conclusion, from the broad experimental database it can be concluded with that DMA category members are readily biodegradable.