Gulf oil spill: human health effects debated
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There is broad disagreement on the potential health hazards of the spilled oil polluting the Gulf of Mexico and washing up onto its shores. Some scientists predict medical problems among workers involved in the cleanup and even the general public. Others expect safety precautions ordered by the federal government to protect cleanup workers and the public from harm.
One thing seems likely, though: The long-term health effects of this disaster probably will be monitored in more detail than the 1989 Exxon Valdez oil spill in Alaska and other previous spills, experts said Friday.
Concerns over the health effects of the spill grew this week as more workers and residents of the coastal areas reported symptoms such as headaches and problems breathing. So far, about 60 exposure-related complaints have been filed with the Louisiana Department of Health and Hospitals.
In one of the more publicized incidents, late last week seven workers performing skimming operations from boats were taken to hospitals due to sudden illness. An investigation of that situation is underway, but it appears the workers’ symptoms may have resulted from exposure to a cleaning substance, said Dr. David Michaels, assistant secretary of labor for the Occupational Safety and Health Administration.
“What OSHA is doing, along with other agencies, is monitoring exposures on the beaches and on the boats to determine what sort of protection workers should be receiving,” Michaels said. “At this point we see no evidence of exposure that would require respirators.”
A mobile public health clinic opened Tuesday in the town of Venice to serve those cleanup workers complaining of sickness. The clinic has not yet been overrun, said Rep. Charlie Melancon (D-La.), who helped establish the facility. “The volume of oil that has come in has not been enough to cause problems,” he said.
The clinic will be available for any health need of the workers, not just toxic exposures, Melancon added, but it also will be useful as a way to monitor workers’ reactions to the oil. “If we have stations to clean the birds, we ought to have stations to help humans,” he said.
There certainly is potential for hazard. Crude oil contains a brew of substances dangerous to human health, including chemicals such as benzene that are known to cause cancer in humans, and others that are toxic to the brain and central nervous system, such as polycyclic aromatic hydrocarbons.
“There is overwhelming evidence that many of the compounds found in crude oil are dangerous,” said James Giordano, director of the Center for Neurotechnology Studies at the Potomac Institute for Policy Studies in Arlington, Va. “It will be important to have a regional and national public health effort to assess the health impact.”
A lot of the hazard will depend on the degree of exposure — placing cleanup workers, not surprisingly, at the highest risk. Brief contact with crude oil is not considered harmful, but sustained exposure or high enough doses of the chemicals can sicken people rapidly, said Dr. Cyrus Rangan, assistant medical director for the California Poison Control System.
“If you breathe them or ingest them or absorb them through skin they can cause headaches, fatigue, dizziness, even changes in mental status,” Rangan said. “The severity depends on how much you are exposed to. The longer you out there and being exposed, the higher the risk.”
Although the flu-like symptoms reported by some of the cleanup workers in the Gulf in recent days have been dismissed by some Gulf area authorities as due to heat, fatigue or food poisoning, they are similar to what would be expected from crude oil toxicity, Rangan added.
“If these workers are complaining of these symptoms, they shouldn’t be dismissed,” he said. “You should pretty much presume these symptoms are from the crude oil before assuming otherwise.”
The timing of exposure can make a big difference to the health risk, said LuAnn White, a toxicologist and director of the Tulane Center for Applied Environmental Public Health in New Orleans.
“Oil changes over time,” she said. “When it’s first released, it comes up and sits on the water. Volatile compounds in the oil, such as those that would go into gasoline or solvents — the most toxic components — evaporate on top of the water.”
The oil that is drifting to beaches and wetlands, referred to as “weathered oil,” has lost most of the volatile components and therefore is not as toxic. The same goes for the tar balls — weathered oil that has been shaped by wind and waves into clumps.
“The workers on the beach picking up the tar balls and gooey stuff should wear gloves and boots and not let it come into contact with the skin. But they don’t need a respirator, based on what compounds are there,” White said.
Chemical dispersants, which are being used on a limited basis by BP, are of less concern than oil exposure, she said, because dispersants tend to keep the oil underwater and offshore. “The one being used has a short half-life and breaks down rapidly in the environment into harmless products. That happens in a matter of days,” she said.
One of the trickiest issues in assessing probable health effects is the poor record from prior spills.
A 2007 study following cleanup workers more than one year after a 2002 oil tanker spill off the coast of Galicia, Spain, showed that some workers experienced respiratory symptoms one to two years after exposure.
“Several people who worked on the Valdez spill complained of health problems,” added Dr. Stephen Cunnion, medical director for the Center for Health Policy and Preparedness at the Potomac Institute for Policy Studies. Skin and respiratory problems were the most common complaint from workers there, but little is known about longer-term effects. “There was no study,” Cunnion said. “Not following up on people in these situations has always been a problem.”
The Valdez spill and Gulf disaster are different, in any case, due to factors such as water temperature, weather conditions and density of human population along the coast — making them difficult to compare, experts said.
This time, several agencies, including Gulf state public health departments, the Centers for Disease Control and Prevention and the American Assn. of Poison Centers have said they will conduct long-term surveillance on health issues related to the spill, according spokesmen for these groups.
Predictions about what they will find vary depending on who you speak with. “This crisis will be an environmental crisis, not a public health crisis,” White said.
“This is a slowly evolving process,” Giordano said. “You may not see symptoms for weeks to months following exposures. It’s very insidious.”
-- Shari Roan