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Environmental fate & pathways

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FAT 40406/A was found to be not readily biodegradable.

Additional information

By the nature of their design and use, textile dyes are not intended to be readily biodegradable as this would assist in the rapid destruction of the dyestuff, rendering it unfit for purpose. There are ISO, European, American (AATCC) and national standards for the colour fastness of dyes. Dyes are required to have specific fastness properties. If the dyes were biodegradable, it would not be possible for them to have these fastness properties. As such, it is accepted that such substances are not readily biodegradable under relevant environmental conditions. A published study (Pagga & Brown, 1986) describes the results of the testing of 87 dyestuffs in short-term aerobic biodegradation tests. The authors of this publication concluded that dyestuffs are very unlikely to show any significant biodegradation in such tests and that 'there seems little point in carrying out such test procedures’ on dyestuffs.

In a ready biodegradability test performed according to OECD Guideline 301A (modified AFNOR test), biodegradation of the test substance by microorganisms was determined. In this study, a mixture of polyvalent bacteria (7 x 106/ml) from an effluent of a domestic sewage treatment plant (ARA-Rhein) was exposed to 40 mg/L DOC of test substance for 28 days. After 28 days no biodegradation was observed. The results from inhibitory control showed that no inhibition of the activity of the bacteria can be found.

Additinally in other two supporting studies on BOD and COD, the BOD5/COD ration was 0, hence no biodegradation can be expected.

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