By Jan TenBruggencate
Advertiser Columnist

The Coast Guard hauled into Honolulu the stricken tanker Insiko — the one with the stranded dog on board — because of the fear that it would wreck and cause an oil spill at sea or on Johnston Atoll.

But oil spills at sea aren't the major cause of oil entering the ocean, according to a report by the National Research Council.

Most of the oil that ends up in the ocean comes from us, consumers, not from tankers.

The report says that 1.5 million gallons of fuel were dumped into the sea around North America from tanker spills, and another half a million gallons from pipeline spills.

But human activities in North America unrelated to the transport of oil put most of the 29 million gallons into the oceans every year.

The biggest chunk, 15.9 million gallons, is from runoff and rivers. Things like the sheen that escapes from oil on the road during a rain.

One of the reasons governments are trying to control older two-stroke engines is that they spray out unburned fuel with their exhaust. The report estimated that 1.6 million gallons of fuel enter the oceans in similar fashion.

"Oil spills can have long-lasting and devastating effects on the ocean environment, but we need to know more about damage caused by petroleum from land-based sources and small watercraft since they represent most of the oil leaked by human activities," said James M. Coleman, chairman of the committee that wrote the report, and a professor at the Louisiana State University Coastal Studies Institute.

The study indicated that large oil spills can be devastating to local environments, but that small amounts of oil can also have serious effects. One of the issues is that oil is not a single product, but a complex of different chemicals, and some of them are highly toxic to wildlife.

"The riskiest toxins are a class of organic compounds known as polycyclic aromatic hydrocarbons, or PAHs. Growing evidence suggests that PAHs and other toxic compounds can have adverse effects on marine species even at very low concentrations. This means chronic releases from runoff and recreational boating may inflict more damage than previously thought, and that the effects of large spills may last as long as residual oil persists in the area," the research council said.

The report calls on the federal government to conduct major research studies into the effects of chronic oil pollution, even at low levels. It suggested that regular, small-scale releases that occur at oil drilling sites may be a good place to conduct some of the research.

The National Research Council, an arm of the National Academy of Sciences, is a private scientific organization charted by the Congress to advise the government. The report, "Oil in the Sea III: Inputs, Fates, and Effects," is available for reading online.

Jan TenBruggencate is The Advertiser's Kaua'i bureau chief and its science and environment writer. Reach him at (808) 245-3074 or e-mail jant@honoluluadvertiser.com.