An estimated 210,000 gallons of oil a day continue to spew into the Gulf of Mexico from the sunken Deepwater Horizon rig, but the full environmental and economic impact of the accident is not yet clear.

Forecasts have been grim about the damage to fisheries, wetlands and the region's economy, and experts are carefully eyeing wind patterns as the slick threatens to creep toward the Atlantic Coast. But the spill is not yet among the worst oil accidents in history.

The complete effects of the spill depend on interlinked factors including the weather, ocean currents, properties of the oil involved and if efforts to stem the tide of oil and remediate its effects pay off. Yesterday the wind was pushing the slick away from the gulf's clockwise loop current, which had threatened to carry it toward the beaches and coral reefs of the Florida Keys.

While experts agree the spill is severe, and note that oil has already been found in some of the sensitive marshes at the tip of Louisiana, the effects are not yet comparable to some of the worst spills in history, and some experts are cautiously optimistic about addressing the spill.

"Right now what people are fearing has not yet materialized," said Edward Overton, a professor emeritus of environmental science at Louisiana State University and an expert on oil spills. "People have the idea of an Exxon Valdez, with a gunky, smelly black tide looming over the horizon waiting to wash ashore. I do not anticipate this will happen down here unless things get a lot worse."

Even if the spill continued at its current rate for years, it still could not measure up to the 36 billion gallons of oil spilled by retreating Iraqi forces when they left Kuwait in 1991. The spill also cannot yet compete with the 1979 Ixtoc I blowout in the Bay of Campeche, which gushed 140 million gallons of crude into the Gulf of Mexico, nor the Exxon Valdez accident of 1989, which contaminated 1,300 miles of largely untouched shoreline and led to the deaths of tens of thousands of seabirds, otters and seals along with 250 eagles and 22 killer whales.

Quenton Dokken, a marine biologist and the executive director of the Gulf of Mexico Foundation, said, "We've certainly stepped in a hole, and we're going to have to work ourselves out of it, but it isn't the end of the Gulf of Mexico" (Broder/Zeller, New York Times, May 3). -- DFM