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PBT assessment

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PBT assessment: overall result

PBT status:
the substance is not PBT / vPvB


Dibutyltin methyl maleate is classified as not readily biodegradable. Although no hydrolysis study is available, in aqueous environments it is known to undergo hydrolysis to DBT oxide. DBT oxide is itself known to be stable to hydrolysis.

It is therefore concluded that DBT methyl maleate does not satisfy the persistence criteria, but that the hydrolysis product DBT oxide does.


No bioaccumulation data are available for dibutyltin methyl maleate, it is not possible to determine the LogKow experimentally and available QSARs are not appropriate for organometallic compounds. However, it is possible to read across from data on the similar compound dibutyltin chloride. In aquatic bioaccumulation studies dibutyltin chloride had BCFs of 5 to 135. These are significantly below 2000 and thus dibutyltin chloride and by read across, dibutyltin methyl maleate, can be considered not to satisfy the bioaccumulation criterion.


No chronic data are available. All the acute endpoints (EC/LC50s) are >0.1 mg/L. The NOEC obtained in the algal study was 0.88 mg/L (also considered a long term end point). Based on the environmental data dibutyltin methyl maleate is not considered to satisfy the T criteria.

However, dibutyltin methyl maleate is classified as a category 2 mutagen and as category 1B for toxicity for reproduction. Dibutyltin methyl maleate is therefore considered to satisfy the T criteria.

PBT/vPvB outcome:

Dibutyltin methyl maleate is classified T.

Dibutyltin methyl maleate is not classified as P or B or vPvB.