Along the coasts of Belgium and southern England, birds began washing ashore coated in a thick white/transparent substance which caused their wings to stick to their bodies. Eventually the substance was identified as polyisobutylene or PIB, a component of many products, including sealants, chewing gum and adhesive tape. When combined with seawater PIB becomes glue-like, as it was when the birds were exposed to it. No source for the PIB was identified.
Polyisobutylene is used as a fuel and lubricant additive, as an adhesive (including medical adhesives), as a sealant in construction(e.g. double glazing), in products such as cling film and pipeline wrapping and as a base for chewing gum. Marpol (The International Convention for the Prevention of Pollution from Ships) lists PIB as Category Z, deemed to present a minor hazard tomarine resources and human health with regulation on the quantity and quality of PIB allowed to be discharged at sea.
Birds were pre-treated with margarine to loosen the sticky substance, which did not respond well to normal washing procedures used for oil removal.
Efforts have begun to have PIB reclassified under MARPOL, making it illegal to dump or spill the substance at sea. If, however, the polyisobutylene was dumped illegally the present regulations would cover these incidents, should a spiller be identified.
The RSPCA in the UK and VOC Ostend in Belgium rescued and cleaned affected birds. Of nearly 350 birds collected in the UK 53 died. In addition, approximately 200 birds were found dead within the first few weeks. In late April more than 170 more birds were brought into care at The RSPCA wildlife centre in West Hatch. It was not clear whether these birds were affected by the PIB spilled earlier or whether this was a separate incident. The product on the second group of birds did, however, appear to be from the same manufacturer, if not the same source.