This week, the British oil company BP issued a controversial report on the cause of the massive oil spill in the Gulf of Mexico four months ago.

Regardless of who was at fault, the release of an estimated four million barrels of oil had a major environmental impact. But there has been relatively little scientific study of the long-term human health effect of this kind of event.

In a world dependent on petroleum fuels, oil spills seem inevitable. But Gina Solomon of the University of California San Francisco Medical School says the medical consequences don't get sufficient attention from scientists.

"Of the 35 or so major oil spills that have occurred in recent decades," says Solomon, "there's only some health study from eight of those spills, and most of those are just contemporaneous study."

Meaning there was no long-term study of the health effects.

One exception was a 2002 spill off the coast of Spain, where scientists documented DNA damage among volunteers doing cleanup along the beach.

Crude oil is full of toxic materials, and when oil from a leaking underwater well hits the surface, many of those materials can enter the air near where cleanup workers are breathing.

"The chemicals that evaporate off of the oil are quite toxic," says Solomon. "These are what are called volatile organic compounds that include cancer-causing chemicals like benzine, and chemicals that are linked to neurological effects, such as toluene."

Other chemicals enter the food chain - eaten by fish and seafood harvested for human consumption, but also consumed by smaller sea creatures that are more distant links in the human food chain.

Other threats from the Gulf oil spill include particulate matter generated by burning oil floating on the surface and from the large amount of chemical dispersants used.

Solomon says the BP spill was very disruptive to all three legs of the gulf economy - the oil business, tourism, and fishing - and it came as the region was still recovering from Hurricane Katrina five years ago. So the impact on emotional or psychological health is likely to be significant.

"One of the health effects that was studied after the Exxon Valdez disaster was psychological effects, and there were severe effects that were found even years later in the communities in Alaska affected by that oil spill," says Solomon. "So I think we can expect the same on the Gulf Coast."

The US National Institutes of Health is funding studies of the effects of the Gulf oil spill. Writing in JAMA, the journal of the American Medical Association, Gina Solomon says that, in the meantime, doctors and nurses in the area should be alert to the possibility that patients might be experiencing symptoms related to the oil spill.

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（来源：VOA 编辑：陈丹妮）