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DIGGING in the intertidal zone in Alaska's McClure Bay in 2004, scientists found a pocket of oil four inches below the surface. This was to be expected; the team was working with the Exxon Valdez Oil Spill Trustee Council studying lingering oil 15 years after the tanker grounded on a reef and spilled 11 million gallons of crude oil in Alaskan waters.

But the small pocket of oil did not feel or smell right to one of the scientists from the National Marine Fisheries Service Auke Bay Lab who requested it be tested. She was right. It was fuel oil spilled 25 years before the Exxon Valdez during the Great Alaskan Earthquake of 1964.

"Oil lasts a lot longer than we ever thought," says Katie Springman, a member of that 2004 team of scientists and now a researcher in Portland State's Chemistry Department.

Springman, a molecular toxicologist, has spent the past seven years exploring the aftereffects of the Alaskan North Slope crude oil that poured from the Exxon Valdez in 1989. Studies are funded from a government settlement made with Exxon.

Is this research now relevant for the Gulf of Mexico, where 18 times as much oil is estimated to have leaked from BP's well? You bet, says Springman.

She and her colleagues know the questions that need to be answered in the Gulf. Questions such as what does the oil's chemical profile do at different depths, how does it age, and the big unknown—how do dispersants affect it and the environment? Dispersants, which allow microbes to access oil more easily in the hopes of eventually breaking it down, were less important in the Valdez spill.

"Just looking at the quantity of oil alone is bad," says Springman, "and use of dispersants changes everything."

DATA STRONGLY SUGGEST, says Springman, that oil becomes more toxic by volume as it ages because its most toxic compounds—compounds that make the list of probable human carcinogens—linger while others dissipate.

Some oil from the Valdez has remained in a form that wildlife can absorb. Springman's research has shown that even small amounts of oil could strip animals of their immune systems.

In addition, sea ducks continue to be exposed to the oil because of how they eat, says Springman. "They root around in the mud looking for invertebrates for dinner. Sea otters do the same thing and get the oil on their paws, and ingest it when they clean themselves," she says.

Concerned over the toxicity of oil, Springman testified before a congressional committee last year about drilling on the outer continental shelf. In her testimony—that proved to be prophetic—she suggested that pre-drill environmental data be collected to serve as a basis for comparison after drilling. If an oil company harms the environment, even on a small scale, it can be known, she said.

Ocean oil drilling is not going away, says Springman, but "how about requiring—not zero release of oil—but zero effect, meaning not enough oil to make a fish sick."

Sea ducks (top photo) in Alaska continue to pick up oil from the 1989 Exxon Valdez spill, according to PSU toxicologist Katie Springman, pictured above bagging a devise that measures pollutants such as oil.