Registration Dossier
Registration Dossier
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EC number: 201-029-3 | CAS number: 77-47-4
PBT assessment
Administrative data
PBT assessment: overall result
- Name:
- Boundary composition
- Type of composition:
- boundary composition of the substance
- State / form:
- liquid
- Reference substance:
- Boundary composition
- PBT status:
- the substance is not PBT / vPvB
- Justification:
Persistence
An expert assessment was carried out to determine the biodegradability of Hexachlorocyclopentadiene. A weight of evidence approach was adopted to determine the endpoint in question, using available data on the substance from the EU Risk Assessment Report (2007) in addition to QSAR predictions using the BIOWIN model. It was concluded that the substance is not expected to be readily biodegradable in the aquatic environment. However, it is believed that the substance may be inherently biodegradable. Despite the uncertainties in the breakdown routes of Hexachlorocyclopentadiene in the environment, several metabolites (in particular photolysis products) were identified; however, the EU Risk Assessment considered the need for PBT assessment of the metabolites to be low, given the low environmental release of Hexachlorocyclopentadiene.
Hexachlorocyclopentadiene is potentially P. As the B-criterion of the PBT is not met (see below) further testing on P is not considered necessary.
Bioaccumulation
Based on the log Kow value of 5.04, Hexachlorocyclopentadiene would be considered to potentially fulfil the B-criterion. However, a substance only fulfils the bioaccumulation criterion when the bioconcentration factor (BCF) in aquatic species is higher than 2000. The BCF value for Hexachlorocyclopentadiene was found to be < 11 according to a toxicity and bioaccumulation study on larval and juvenile fathead minnow by Spehar et al. (1979).
Hexachlorocyclopentadiene does not meet the B-criterion of the PBT assessment.
Toxicity
The lowest short term aquatic toxicity value was found to be LC50 (48 hr) = 0.039 mg/L for freshwater species Daphnia magna, which meets the GHS criteria for classification as Aquatic Acute 1 and Aquatic Chronic 1. As the acute toxicity data is < 0.1 mg/L the substance is considered potentially T according to the screening criteria.
Hexachlorocyclopentadiene is potentially T. As the B-criterion of the PBT assessment is not met (see above), further testing on T is not considered necessary.
Overall, Hexachlorocyclopentadiene does not meet the PBT criteria.
Reference
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