Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

The test substance is considered to be not biodegradable.

Additional information

By the nature of their design and use, disperse 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 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.

Neverthe less, tests were performed to measure BOD and COD for the test substance. BOD5 and COD value of 63 and 1135 mgO2/g test mat. was determined for the test substance. Based on the BOD5/COD quotient which is not >0.5, the substance is not considered to be biodegradable.

Taking the data from degradation test and BOD5/COD quotient into account, the test substance is considered to be not biodegradable.

Further this evaluation is supported by the study of inherent biodegradation conducted according the guideline OECD 302B. The mixture is the same of two first screening studies. After 28 days of test period 36 % biodegradation was recorded indicating the test substance not biodegradable.

Taking the data from all the three studies into account, the test substance is considered to be not biodegradable.