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Environmental fate & pathways

Endpoint summary

Administrative data

Description of key 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. 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. There are ISO, European, American (AATCC) and national standards available 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.

Additional information

Test reports for ready biodegradation and inherent biodegradation tests are available. The results are summarized as follows:

The test item FAT 40825/A was investigated for its ready biodegradability in a manometric respirometry test over 28 days according to OECD Guideline for Testing of Chemicals No. 301 F (1992).

The biochemical oxygen demand (BOD) of the test item FAT 40825/A in the test media was in the range of the inoculum controls throughout the entire 28-day exposure period. Consequently, FAT 40825/A was not readily biodegradable under the test conditions within 28 days.

The test item FAT 40825/A was investigated for its potential (inherent) ultimate biodegradability in a Zahn-Wellens / EMPA test over 28 days, based on the OECD Guideline for Testing of Chemicals, No. 302 B (1992). In the test flasks, containing the test item and activated sludge (inoculum), the mean concentration of DOC (dissolved organic carbon) varied between 94 and 101 mg/L over the 28-day exposure period, and was not significantly different from the initial mean DOC concentration of 101 mg/L, measured on Day 0 (starting value after 3 hours of exposure). Expressed as percentage DOC-removal, mean values in the range from 1 to 7 % were noted. Thus, FAT 40825/A was not biodegradable under the test conditions within 28 days.