Oil-spill health risks under scrutiny
Scientists call for more research to monitor effects of oil exposure.
A plethora of health problems from exposure to chemicals threatens workers and volunteers involved in clean-up efforts for the Deepwater Horizon oil spill. People living in communities around the Gulf of Mexico are also at risk.
But more monitoring is needed to determine exactly how the vulnerable are being affected, said researchers and health officials at a workshop in New Orleans, Louisiana on 22–23 June.
The meeting was organized by the Institute of Medicine, a non-profit organization within the US National Academies in Washington DC, at the request of the US Department of Health and Human Services. Participants rallied local agencies and communities to pull together to address human health concerns and to avoid the mistakes made in the aftermath of previous spills.
Following the Exxon Valdez spill in 1989, "We didn't do the long-term longitudinal follow up that now we all wish we had data on," says Donald Williamson, state health officer for Alabama. "How do I tell my coastal communities it's going to be OK? Let's answer that question with the best possible science," he says.
Researchers and health officials said that samples such as cord blood, breast milk, blood and saliva should be collected from people living in the Gulf Coast region as soon as possible, to help to establish baseline data.
"Locally we're very impatient for action to happen, for the right science to be occurring and to be occurring now," says Maureen Lichtveld, an environmental-health scientist at Tulane University in New Orleans.
"It's already too late to collect some kinds of information that will become quite important. We don't know today what we might need to look for in years to come," adds John Bailar III, an epidemiology expert from the Department of Health Studies at the University of Chicago.
Potential health effects include respiratory symptoms and nausea — which have already been reported by some workers — as well as lower-respiratory-tract problems from inhalation of volatile organic compounds. Coastal communities could also experience more extreme health consequences, including long-term neurological effects on children and developing foetuses, and hereditary mutations.
Cleaners at risk
Workers on vessels close to where the oil plumes are surfacing are at the greatest risk of coming into contact with concentrated chemical dispersants and toxic vapours such as benzene, one of the volatile hydrocarbons in oil.
But researchers are finding it difficult to quantify levels of exposure to volatile compounds because the oil distribution in the Gulf is patchy and the oil is continuing to gush, says Edward Overton, an environmental chemist at Louisiana State University in Baton Rouge.
The thousands of volunteers and federal workers who are cleaning up oil that has already weathered and lost many of its most toxic volatile compounds may still be exposed to toxins — particularly if they remove protective gear or do not have sufficient training in handling toxic substances.
The Gulf states of Louisiana, Alabama, Florida, Mississippi and Texas each have their own systems for monitoring exposure. Reported symptoms are recorded in a local database that collates reports from hospitals, health clinics and first aid stations across the state. Louisiana is also looking for increases in reports of symptoms such as respiratory illnesses, compared to the last three years. So far they have seen no such increases, and measurements of air quality do not yet indicate that it is compromised.
The effects of past spills
Of 38 major oil spills involving supertankers worldwide to date, researchers have studied only seven for short- and long-term health effects1.
Blanca Laffon, a genetic toxicologist at the University of A Coruña in Spain, presented to the workshop results from studies following a spill in 2002, when the oil tanker Prestige sank off Spain's northwestern coast and polluted thousands of kilometres of Spanish and French coastline2,3. Laffon and her colleagues took blood samples from volunteers who were exposed to oil for only five days while handling oil-coated birds, and from workers hired by the government, who worked for several months to clean oil from rocks and beaches.
Laffon's team found that both groups had heightened DNA damage, with the amount of damage related to their exposure time. Whereas DNA damage was ultimately repaired in volunteers exposed for just five days, the damage became fixed in chromosomal DNA in workers exposed for months. The team is now analyzing samples collected in the last year to see whether the DNA aberrations are still present.
"That does not mean that people who have elevated parameters of this cytogenetic damage are going to develop cancer," says Laffon. "But they have an increased risk, similar to the risk that is present for people who live in highly polluted cities, or people who are smokers."
So far, no such studies have been organised in the Gulf, says Lichtveld: the workshop's aim was to start discussing what the research framework should be. Some experts said they would like a single, independent agency to act as a central command coordinating research in the area.
The dearth of research and answers about the health effects of oil exposure — and about what Gulf-Coast residents are now facing — was striking, even to the researchers and health officials themselves.
"There are a lot of unknowns," says Jimmy Guidry, Louisiana state health officer. "This is more than a spill. This is ongoing leakage of a chemical, and adding chemicals to stop the chemicals. We're feeling like we're in a research lab."
- Aguilera, F., Méndez, J., Pásaro, E. & Laffon, B. J. Appl. Toxicol. 30, 291-301 (2010).
- Pérez-Cadahía, B. et al. Environ. Health Insights 2, 83-92 (2008).
- Laffon, B., Fraga-Iriso, R., Pérez-Cadahía, B. & Méndez, J. Food Chem. Toxicol. 44, 1714-1723 (2006).