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EC number: 262-872-0
CAS number: 61617-00-3
Under the conditions of two studies, the substance was observed to be not readily biodegradable after 28 days (27 % (Safepharm Laboratories, 2003) and 0% (Bayer AG, 1992)).
Conducted under GLP conditions, ZMB2 attained 27% degradation after 28
days and therefore cannot be considered to be readily biodegradable
under the strict terms and conditions of OECD Guideline 301B (Safepharm
In accordance with OECD Guideline 301 F (Ready Biodegradability:
Manometric Respirometry Test), during the test period of 28 days ZMB2
provides a breakdown rate of 0%. ZMB2 is considered as "not readily
biodegradable" (Bayer AG, 1992).
Originally, a contract laboratory was contacted to initiate the conduct
of an OECD Guideline 302C Inherent Biodegradability: Modified MITI Test
(II) Study for the substance1,3-dihydro-4(or
5)-methyl-2H-benzimidazole-2-thione, zinc salt (ZMB2; CAS RN 61617-00-3;
EC 262-872-0), as per the original test plan proposal, to further assess
the inherent or ultimate biodegradability of the above substance. Upon
discussion with the laboratory and following theECHA
REACH Guidance Document, “Guidance on information requirements and
chemical safety assessment: Chapter R.7b: Endpoint specific guidance,”
it was determined thatan enhanced biodegradation screening test
based on OECD Guideline 301-B Ready Biodegradability: CO2Evolution
Test is more suitable to further investigate the potential degradation
of ZMB2 under optimized test conditions. In this study, the following
modifications/enhancements are proposed by the laboratory: extend the
study duration to 60 days; test volume will be increased from 3 liters
to 4 liters, and the concentration of
inoculum used will be increased from 30 mg suspended solids (ss)/L to 50
mg ss/L. As a result, the Lead Registrant is proposing to alter its
original test plan proposal and conduct an enhanced/modified OECD 301-B
Ready Biodegradability Study.
In an OECD 301-B Ready Biodegradability: CO2Evolution Test,
ZMB2 degraded 5% after 10 days, and degraded a further 22% to 27% after
28 days. This indicates that the substance could potentially degrade
above 60% within 60 days, and eventually biodegrade completely.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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