New Orleans ? For days now, Dr. Damon Dietrich and other physicians have seen patients come through their emergency room at West Jefferson Medical Center with similar symptoms: respiratory problems, headaches and nausea.

In the past week, 11 workers who have been out on the water cleaning up oil from BP’s blown-out well have been treated for what Dietrich calls “a pattern of symptoms” that could have been caused by the burning of crude oil, noxious fumes from the oil or the dispersants dumped in the Gulf to break it up. All workers were treated and released.

“One person comes in, it could be multiple things,” he said. “Eleven people come in with these symptoms, it makes it incredibly suspicious.”

Few studies have examined long-term health effects of oil exposure. But some of the workers trolling Gulf Coast beaches and heading out into the marshes and waters have complained about flu-like symptoms — a similar complaint among crews deployed for the 1989 Exxon Valdez spill in Alaska.

BP and U.S. Coast Guard officials have said dehydration, heat, food poisoning or other unrelated factors may have caused the workers’ symptoms. The Louisiana Department of Health and Hospitals is investigating.

Brief contact with small amounts of light crude oil and dispersants are not harmful. Swallowing small amounts of oil can cause upset stomach, vomiting and diarrhea. Long-term exposure to dispersants, however, can cause central nervous system problems, or do damage to blood, kidneys or livers, according to the Centers For Disease Control and Prevention.