2-methoxy-2-methylbutane

PBT assessment

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 is not readily biodegradable. TAME is therefore identified as being potentially persistent.

Bioaccumulation Assessment

No experimental BCF results are available. The measured logKow is 1.55 therefore the screening criteria are not met. The potential for bioaccumulation can be further assessed on the basis of the log Kow using the QSAR BCFWIN™ (2000). The model shows no bioaccumulative potential for TAME (based on an estimated BCF of 4.14 l/kg). Further testing in the scope of the PBT assessment is therefore not deemed necessary.

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 TAME is not potentially toxic towards aquatic organisms. The chronic effect concentrations for invertebrates and algae were higher than the criterion of 0.01 mg/l (lowest observed NOEC was 3.39 for invertebrates). In addition, TAME is not classified as being CMR and there is no evidence that TAME is chronically toxic towards mammals. Therefore, TAME 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:

Emission Characterisation TAME is not a PBT/vPvB substance, therefore an emission characterisation does need not to be conducted.