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PBT assessment

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PBT assessment: overall result

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

Comparison with the Criteria of Annex XIII An assessment of the PBT status of MTBE has been made using all available data.

Persistence Assessment

A closed bottle test (OECD 301D) showed that TAME, the main component of this UVCB substance, is not readily biodegradable; The substance is therefore identified as being potentially persistent. Based on the proposed read-across approach (see Annex D of the CSR for details), this is also expected to apply to the other components of C5-6 branched alkylmethyl-ethers.

Bioaccumulation Assessment

No experimental BCF results are available for the substance as a whole. The potential for bioaccumulation was therefore assessed on the basis of the log Kow of the main component, which is 1.55. Using the QSAR BCFWIN™ (2000) a bioaccumulative potential for TAME of 4.14 l/kg is predicted. These values fall well below the screening criteria thresholds for bioaccumulation potential. Further testing in the scope of the PBT assessment is therefore not deemed necessary for the substance. Based on the proposed read-across approach (see Annex D for of the CSR for details), this conclusion will also apply for the other components of C5-6 branched alkylmethyl-ethers.

Toxicity Assessment

The acute effect concentrations for all three trophic levels are much higher than the screening criterion of 0.1 mg/l. It can therefore be expected that the substance is not potentially toxic towards aquatic organisms (see Section 7.1). The chronic effect concentrations for invertebrates and algae were higher then the definite criterion of 0.01 mg/l. In addition, the substance is not classified as being CMR and there is no evidence that C5-6 branched alkylmethyl-ethers are chronically toxic towards mammals. Therefore, the substance is not assigned as being toxic.

Conclusions

The overall conclusions, based on the present available data, are that the (screening) criteria for PBT/vPvB, as outlined in Annex XIII of Directive 2006/121/EC, are not met and that further testing in the scope of the final PBT assessment is not considered to be required.

Likely routes of exposure:

C5-6 branched alkylmethyl-ethers are not PBT/vPvB, therefore the emission characterisation need not be conducted.