Questions about the health risks posed by last year’s Gulf oil spill are unlikely to be resolved anytime soon, despite a recently initiated study involving 55,000 clean-up workers, according to public health officials.

The open-ended design and lack of specific endpoints are just two aspects of the study, currently underway at the National Institute of Environmental Health Sciences (NIEHS), that Bernard Goldstein, MD, of the University of Pittsburgh Graduate School of Public Health, and colleagues criticized in the April 7 issue of the New England Journal of Medicine.

The fact that the study was not funded until six months after the disaster poses another set of challenges including the potential for patient recall bias and inability to measure biologic markers of exposure that may not persist over time, they noted.

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“Despite a growing literature describing the impact of oil spills on health, it is difficult to respond to the many questions asked by clinicians and the public about this spill or the risk of future spills,” the researchers wrote.

Despite this complexity, they categorized the potential health consequences into four categories: those related to worker safety; toxicologic effects in workers, visitors and community members in the affected areas; mental health effects; and ecological impact.

“The interdependence of symptoms and preexisting clinical conditions, toxicologic effects and ecologic and economic concerns requires holistic, transdisciplinary clinical, mental health and public health studies and interventions,” the researchers wrote.

Two carcinogenic contaminants released in the spill are particularly worrisome — benzene polycyclic aromatic hydrocarbons (PAH). PAHs are more persistent, and are therefore more likely to accumulate in cells and cause skin and lung cancer in people living in affected communities. Benzene has a shorter half-life and is more of a concern among workers who were close to the oil source, according to the researchers.

Initial concerns regarding dispersants used in clean up have dissipated as one of the main ingredients, dioctyl sodium sulfosuccinate, has been identified as a commonly used stool softener and another, 2-butoxyethanol, is known to cause hemolytic anemia and hepatic angiosarcoma in rodents, but not humans.

Although few studies have examined the long-term health effects on workers, reports from earlier spills have documented problems with pulmonary function and bronchial hyper-responsiveness, the researchers noted.

Data from other reports have indicated that calls to mental health and domestic violence crisis centers in affected areas have increased since the oil spill.

Additionally, the researchers say the catastrophe still poses a “national seafood safety issue,” as PAHS are known to accumulate in seafood, and oil on marine rocks may increase the amount of arsenic that sea animals absorb.

“Several initiatives are urgently needed before similar disaster occur in the future: rapid development and implementation of protocols for baseline clinical evaluations, including respiratory function; biospecimen banking; short- and long-term medical surveillance and monitoring of workers; and development of psychosocial interventions,” the researchers wrote.

They added that developing clinical referral networks could help address immediate untreated existing health conditions and mental health symptoms.