- guardian.co.uk, Sunday November 24 2002 08.54 GMT
At the beginning of investigations into the Exxon Valdez disaster, scientists thought they would find that the volatile components of the ship's crude oil - toluene and other chemicals - would be those that would cause most damage. To their surprise, it turned out to be the heavier components, the polynuclear aromatic hydrocarbons, or PAHs, that were the real danger. These chemicals persist in water for much longer, but until recently were not thought to be dangerous because they are relatively unreactive.
However, experiments subsequently showed that a suspension of less than half a part per billion of PAHs was enough to burst the cell membranes of fish, less than a hundredth of previous estimates of their danger.
The researchers suspect that PAHs kill fish - particularly young ones - by affecting the structure of their genes. 'Exposing an embryo to oil is like taking a shotgun to its DNA,' says Dr Ronald Heintz of the US National Maritime Fisheries Service.
The study - published in Environmental Toxicology and Chemistry - startled ecologists because it suggested that no coastal region could ever be protected from oil pollution and indicated these chemicals were likely to affect several future generations of fish, and therefore the rest of the food chain.
The effects of the sinking of the Prestige are likely to persist for decades, in other words.
