Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Reactive Yellow 39 is neither readily nor inherently 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.

Nevertheless, biodegradability of Reactive Yellow 039 was tested in a Zahn Wellens test as well as couple of tests evaluating Biological Oxygen Demand (BOD5) and Chemical Oxygen Demand (COD). The BOD5 of FAT 40061/D was found to be 6 mg O2/g, while the COD was 800 mg O2/g. The resulting BOD5/COD quotient is 0.0075, indicating that FAT 40061/D is not rapidly biodegradable. In a Zahn-Wellens test, the bioelimination of the test substance FAT 40061/D after 28 days was observed to be 0 %. Therefore, FAT 40061/D is considered as not inherently biodegradable. In the supporting studies, the Chemical Oxygen Demand of FAT 40061/A was determined to be 789.91 mg/g O2, whereas the Biological Oxygen Demand was determined to be 56 mg/g O2 at 50 mg/l concentration. Thus BOD5/COD ratio was <0.5, indicating FAT 40061/A to be not rapidly biodegradable.