Conservation organizations and shipping industry groups are seeking a review of international rules governing polyisobutene (PIB) releases from ships. The chemical, used as an additive for lubricants and fuel oils, was identified as the sticky substance coating seabirds along the southwest coast of England earlier this year. The Royal Society for the Protection of Birds (RSBP) estimates that more than 4,000 birds washed up on beaches along the English Channel in two incidents. PIB is not directly toxic to seabirds, RSPB says. But when in contact with water, the hydrophobic chemical coalesces into a waxy material. When PIB coats the plumage of seabirds, their movement is restricted, RSPB says. Under the International Convention for the Prevention of Pollution from Ships, vessels can legally discharge small amounts of PIB. British conservation and shipping organizations are calling for the International Maritime Organization to review PIB releases.