There is widespread concern about the potential dangers of the toxic chemicals being imported into islands in increasing amounts. Most governments lack adequate legislation controlling toxic chemicals. Pesticides or herbicides may be imported in bulk and then repackaged without adequate labelling, resulting in accidental poisonings. Chemicals brought in on a trial basis, or given on aid, may simply sit in a warehouse until the containers deteriorate and the contents spill out or seep down into the groundwater. Products considered too dangerous elsewhere are still in widespread use (and misuse) with no public awareness of the risks involved. Pesticides have been widely used in campaigns to control mosquitos and other insect pests with no monitoring of possible environmental effects. On one island, a warehouse containing barrels of Lindane was swept into the lagoon during a hurricane, killing a large area of reef; on others, drums of arsenic were spilled into the harbour, and toxic pesticides like Dieldrin have been used for fishing. Spraying equipment may simply be washed in the nearest stream, which may also serve as a village water supply. Accidents with toxic chemicals are that much more serious within the limited environment of small islands but few island doctors have experience in identifying poisoning by toxic chemicals, so most incidents probably go unreported. Monitoring for chemical residues in foods and the environment has hardly begun.
Oil pollution is only a minor problem in those small island countries that are not near major shipping routes, although the Caribbean has a problem with drifting tar balls. Oil spills have generally been restricted to small harbour accidents during fuelling or transshipment, and to spillage of fuel oil from wrecks. Even small accidents like these could be serious if they affect critical habitats such as mangroves or major fishing areas on a small island, but most spills to date have either been on remote reefs or in the already disturbed environment of harbours. There is always a slight chance of accidents involving tankers delivering petroleum products to island countries. If a major accident does occur, island countries are very poorly equipped to deal with it.