In a surprisingly swift response to civil society concerns about recent spills of PIB in the English Channel, the International Maritime Organisation (IMO) has agreed to reclassify the chemical and stop its routine discharge.

Polyisobutylene, alternatively polyisobutene or PIB, can, when discharged into the sea, coalesce into a glue-like consistency, coating birds’ wings and bodies and preventing them from feeding or flying. Thousands of birds were affected by two spills in the English Channel in the early part of 2013.

NGOs raised the issue at a meeting of the IMO’s Marine Environment Protection Committee in May this year, and the UK subsequently prepared a proposal to reclassify the substance.

This proposal was considered at a meeting of the IMO’s ESPH technical sub-group on October 21st. The UK had provided two options for tighter regulation and after an hour of debate and considerable industry pressure the less progressive option was agreed. But this still represents a very significant tightening of the regulations surrounding this substance.

In the new arrangements all PIB products greater than 224 molecular weight (MW) and all new highly reactive PIB products will become Category X products under MARPOL, banning their discharge at sea and requiring full pre-wash of cargo tanks before a ship goes to sea. PIBs lower than 224MW remain at Category Y. The PIBs involved in the recent spills were all over 1000MW, and the chemical profile of PIBs indicates that viscosity only increases about the 450MW mark so the limit is reasonably precautionary.

Picture courtesy of: WJ Strietman - St De Noordzee