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Classification & Labelling & PBT assessment

PBT assessment

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PBT assessment: overall result

PBT status:
the substance is not PBT / vPvB
Justification:

When data are not available on the substance ZDBC, data from the close structural analog, Ziram (CAS number 137-30-4; EC number 205-288-3) are used to evaluate the PBT or VPvB properties.

Persistance:

The read-across substance Ziram is rapidly hydrolyzed (half-life 121 hours at pH 7), and has been shown to biodegrade 68% over 50 days in water and sediment. The key study shows that only 23% of the 14C labelled read-across substance was recoverable from soil after 50 days.

Based on analysis of the structural similarities between Ziram and ZDBC, ZDBC is likely to display similar effects as Ziram. ZDBC, therefore, is not expected to the persistent under the criteria of EC Regulation 1907/2006, Annex XIII, based upon reliable read-across data.

Bioaccumulation:

In a key study the Partition Coefficient of ZDBC was found to be log Pow >4.37 (Intertek, 2012) and in a read across key study, the BCFs of Ziram was 90 and 4.7 for Rainbow trout and Guppies (Van Leeuwen et al, 1986).

Based on analysis of the structural similarities between Ziram and ZDBC, ZDBC is likely to display similar effects as Ziram. ZDBC, therefore, is not expected to bioaccumulate under the criteria of EC Regulation 1907/2006, Annex XIII, based upon reliable data on ZDBC and read-across data.

Toxic:

The most sensitive aquatic species within the dataset was determined to be Daphnia magna (aquatic invertebrates). In a short term toxicity study on the read across substance Ziram the EC50(48 hour) was 0.048 mg/l, and in a long term study on the same substance, the 21 day NOEC was 0.0032 mg/l.

Based on analysis of the structural similarities between Ziram and ZDBC, ZDBC is likely to display similar effects as Ziram. ZDBC, therefore, is considered Toxic under the criteria of EC Regulation 1907/2006, Annex XIII, based upon reliable read-across data.