NEW ORLEANS (AP) — 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.

In the six weeks since the Deepwater Horizon rig exploded, killing 11 workers, an estimated 21 million to 45 million gallons of crude has poured into the Gulf of Mexico. Hundreds of BP contractors have fanned out along the Gulf, deploying boom, spraying chemicals to break up the oil, picking up oil-soaked debris and trying to keep the creeping slick out of the sensitive marshes and away from the tourist-Mecca beaches.

Commercial fisherman John Wunstell Jr. spent a night on a vessel near the source of the spill and left complaining of a severe headache, upset stomach and nose bleed. He was treated at the hospital, and sued — becoming part of a class-action lawsuit filed last month in U.S. District Court in New Orleans against BP, Transocean and their insurers.

Wunstell, who was part of a crew burning oil, believes planes were spraying dispersant in the middle of the night — something BP disputes.

‘‘I began to ache all over …’’ he said in the affidavit. ‘‘I was completely unable to function at this point and feared that I was seriously ill.’’

Dozens of complaints, most from spill workers, have been made related to oil exposure with the Louisiana Department of Health and Hospitals, said spokeswoman Olivia Watkins, as well as with the Louisiana Poison Center, clinics and hospitals. Workers are being told to follow federal guidelines that recommend anyone involved in oil spill cleanup wear protective equipment such as gloves, safety glasses and clothing.

Michael J. Schneider, an attorney who decided against filing a class-action lawsuit in the 1990s involving the Valdez workers, said proving a link between oil exposure and health problems is very difficult.

‘‘As a human being you listen to enough and you’ve got to believe they’re true,’’ he said. ‘‘The problem is the science may not be there to support them … Many of the signs and symptoms these people complained of are explainable for a dozen different reasons — it’s certainly coincidental they all shared a reason in common.’’

Similar to the Valdez cleanup, there have been concerns in the Gulf that workers aren’t being supplied with enough protective gear. Workers have been spotted in white jumpsuits, gloves and booties but no goggles or respirators.

‘‘If they’re out there getting lightheaded and dizzy every day then obviously they ought to come in, and there should be respirators and other equipment provided,’’ said LuAnn White, director of the Tulane Center for Applied Environmental Public Health. She added that most of the volatile components that could sicken people generally evaporate before the oil reaches shore.

BP PLC’s Chief Operating Officer Doug Suttles said reports of workers getting sick are being investigated but noted that no one has pinpointed the cause. Suttles said workers were being given ‘‘any safety equipment’’ needed to do their jobs safely.

Unlike with Exxon Valdez, in the Gulf, the oil has been lighter, the temperatures warm and humid, and there have been hundreds of thousands of gallons of chemicals used to break up the oil.

Court records showed more than 6,700 workers involved in the Exxon Valdez clean up suffered respiratory problems which the company attributed to a viral illness, not chemical poisoning.

Dennis Mestas represented the only known worker to successfully settle with Exxon over health issues. According to the terms of that confidential settlement, Exxon did not admit fault.

His client, Gary Stubblefield, spent four months lifting workers in a crane for 18 hours a day as they sprayed the oil-slicked beaches with hot water, which created an oily mist. Even though he had to wipe clean his windshield twice a day, Stubblefield said it never occurred to him that the mixture might be harming his lungs.

Within weeks, he and others, who wore little to no protective gear, were coughing and experiencing other symptoms that were eventually nicknamed Valdez crud. Now 60, Stubblefield cannot get through a short conversation without coughing and gasping for breath like a drowning man. He sometimes needs the help of a breathing machine and inhalers, and has to be careful not to choke when he drinks and eats.

Watching the Gulf situation unfold, he says, makes him sick.

‘‘I just watch this stuff everyday and know these people are on the very first rung on the ladder and are going to go through a lot of misery,’’ said Stubblefield, who now lives in Prescott, Ariz.