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Environmental fate & pathways

Biodegradation in water: screening tests

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Link to relevant study record(s)

Description of key information

The following studies are available to address the biodegradation end point:
Dr. Beimborn (2000). Determination of the Biodegradability of TZ 03498 the the Manometric Respirometry Test. Testing Laboratory: BASF Aktiengesellschaft, Ecology and Environmental Analytics, Laboratory of Ecology, D-67056, Ludwigshafen. Report Number: 99/0606/26/1. Owner Company: Dr. U. Gerigk, Witco GmbH, Ernst-Schering-Str. 14, Postfach 1620, D-59192 Bergkamen. Report Date: 2000-11-6
Von Schulthess. A (1992). Report on the test for ready biodegradability in the Modified Sturm Test of Irgastab T 22 M. Testing Laboratory: CIBA-GEIGY Limited, Product Safety, Ecotoxicology, CH-4002, Basle, Switzerland. Report Number: 928294. Owner Company: CIBA-GEIGY Limited, AD - Division, CH-4002, Basle, Switzerland. Report Date: 1992-09-18.
Von Schulthess. A (1993). Report on the test for ready biodegradability in the Modified Sturm Test of Irgastab 17 M. Testing Laboratory: CIBA-GEIGY Limited, Product Safety, Ecotoxicology, CH-4002, Basle, Switzerland. Report Number: 928310. Owner Company: CIBA-GEIGY Limited, AD - Division, CH-4002, Basle, Switzerland. Report Date: 1993-04-14.
The Beimborn was chosen as the key study on the basis that it was the only study performed on a substance (99.47% pure). The other two studies were performed on mixtures with 61.8 and 65 % Di-n-butyltin bis (2-ethylhexylthioglycolate) content. All studies were performed to GLP standard using recognised OECD or EU test methods. Based on this, the key study was designated a Klimisch score of 1 and the supporting studies Klimisch ratings of 2.

Key value for chemical safety assessment

Biodegradation in water:
inherently biodegradable

Additional information

With respect to the key study, the biodegradation after 28 days was 35.3% and the test substance could therefore not be classified as readily biodegradable. The study was extended to 74 days, for which the mean biodegradability was found to be 56%.The substance is classified as inherently biodegradable. The supporting studies agree with this classification, having mean biodegradability values of 28.5 % and 56.5 % after 28 days.