A new study has found a higher incidence of respiratory problems and chromosomal changes to white blood cells among fishermen who helped clean up a 2002 oil spill off the Spanish coast, providing a guide to potential flashpoints that may arise as federal scientists begin studying the long-term health of responders to this summer's Gulf of Mexico gusher.
The study, published in the latest issue of the Annals of Internal Medicine, followed 501 exposed workers and 176 nonexposed workers following the 2002 sinking of the tanker Prestige, which released an estimated 63,000 tons of oil -- a spill nearly twice the size of the Exxon Valdez in 1989.
The exposed workers were examined two years after their contact with spilled oil, when "a greater proportion" of that group was found to still experience respiratory symptoms such as wheezing and nighttime shortness of breath, the study's authors wrote. Chromosomal abnormalities in white blood cells, considered a potential marker for heightened cancer risk, was also detected at higher rates in fishermen who regularly came in contact with oil during cleanup work.
Joan Albert Barbera, a pulmonologist at the Hospital Clinic of Barcelona and one of the study's co-directors, noted that the research team had chosen "subjects we considered highly exposed" because they had spent at least 15 days on cleanup work for upward of four hours daily.
"It seems advisable," Barbera said in an interview, that oil-spill responders limit their cleanup work to those parameters and wear protective facial masks to limit their inhalation of hydrocarbons.
During the 86-day Gulf of Mexico oil disaster, fishermen who participated in BP PLC's "vessels of opportunity" program often worked shifts longer than four hours, but beach cleaners were often called on to rest for at least as long as they worked to mitigate the effects of heat stress.
Still, Barbera explained, the Prestige disaster differed in several notable ways from the Gulf leak, limiting the extent to which the new study can inform long-term monitoring of U.S. oil-spill responders.
The crude that spewed from the Macondo wellhead this year was lighter than the heavy bunker oil that came from the Spanish tanker, and the Prestige oil was also released on the water's surface rather than a mile beneath the sea, as was the case in the Gulf.
Hoses were also used to clean oiled shorelines following the Prestige spill, posing a greater risk of toxic aerosol inhalation, while no such tactics were used in the Gulf. Conversely, the use of chemical dispersants represents a variable introduced during this year's event but not in 2002.
"The bottom line is that we can't assume that all the findings of this study will necessarily apply to workers in the Gulf, but the study certainly raises serious concern about long term respiratory and cancer risks to oil spill clean-up workers," Natural Resources Defense Council senior scientist Gina Solomon blogged in a response to the new report.
Dearth of worker studies
The new study does, however, represent a significant addition to the previously meager catalogue of scientific research into the human health consequences of oil spills that was available in the wake of this year's gusher.
"We were surprised" to see how little literature was available on the subject, Barbera said. "There was a number of articles regarding effects on clamshells, on birds, on fish," but not workers.
One of the few studies already on the books, a 2006 analysis of Prestige cleanup workers, found evidence of DNA damage among cleanup workers, with the degree of genotoxicity varying depending on the type of task performed and the duration of work. The study, presented by Spanish researcher Blanca Laffon at a June meeting of the National Academies' Institute of Medicine, also found short-term DNA damage in subjects who cleaned oiled birds but did not see evidence of that genotoxicity lingering.
In her response to the Annals study, Solomon said that ensuring medical care for sickened locals and monitoring long-term health impacts should be top priorities during the ongoing Gulf response. Those goals are driving an ambitious Gulf worker study now in the works at the National Institute of Environmental Health Sciences (NIEHS), where officials have warned that their initial $10 million in federal funding is "just a deposit" on the full costs of a prospective evaluation (Greenwire, Aug. 19).
Aubrey Miller, a senior medical adviser to the NIEHS director, testified before a House committee in June that previous studies of health risks experienced by those exposed to oil from the Prestige and Valdez spills "remind us of the importance of keeping longer-term, less-obvious sequelae in mind, not just the immediate toxicity effects, when considering the overall health impact of this type of disaster."
An editorial accompanying the new Annals study -- co-written by Larry Engel, an epidemiologist at New York City's Memorial Sloan-Kettering Cancer Center who has joined the NIEHS study's investigative team -- expanded on the lessons that it might offer to scientists and officials tracking the health of Gulf workers.
"In the Deepwater Horizon spill, tension has already developed between the desire to fully investigate the health consequences of the spill and the desire to provide reassurance that will reinvigorate the region's tourism and seafood enterprises," the editorial says.
"In the face of such conflicts, results will inevitably be seen as supportive of one view and counter to another," it says. "Researchers need to be aware of this context and ensure that the scientific evidence is generated and disseminated in an objective, transparent manner."