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Diss Factsheets

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Test substance is considered to be neither inherently nor readily biodegradable.

Additional information

For assessment of the biodegradability of FAT 40138, two studies evaluating inherent biodegradability / biological elimination are available. Further, additional studies investigating BOD5 (Biological Oxygen Demand) and COD (Chemical Oxygen Demand) of the substance are also available. In a key study (1993) with FAT 40138/D, 2.4 % biological elimination was reported after 28 days. In another key study (1993) with FAT 40138/E, 7.1 % biological elimination was reported after 28 days. Based on these results, FAT 40138 can be considered to be not inherently biodegradable. In the key studies for BOD5 and COD (1992), the BOD5 was 0 mg O2/g and COD was 667 mg O2/g, hence giving a BOD5/COD ratio equal to 0, indicating substance to be not rapidly biodegradable. Similarly in other supporting studies conducted in 1980 (FAT 40138/A) and 1981 (FAT 40138/C), the BOD5/COD ratio was 0 and 0.015, again supporting the conclusion that FAT 40138 is not rapidly biodegradable. Based on the above discussion, FAT 40138 can be considered to be neither rapidly nor inherently biodegradable. 

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.