People hired to clean up Gulf of Mexico beaches and marshes during the 2010 oil spill have significantly altered blood profiles that put them at increased risk of developing liver cancer, leukemia and other disorders, according to a report published Tuesday.
The study, conducted by doctors at Houston’s University Cancer and Diagnostic Centers and reported in the American Journal of Medicine, sheds new light on the potential health repercussions for the more than 170,000 people who worked in some capacity to clean up the 2010 spill.
Clean-up workers encountered oil that gushed from BP’s failed Macondo well but also may have come into contact with chemical dispersants used to help break up the crude. And while they were outfitted with protective suits and gloves, some workers may have removed the gear amid sweltering summer conditions or used diluents to scrub off any residue.
Oil contains benzene, a powerful carcinogen.
“Benzene is a very toxic substance. It’s easily absorbed through tissues, such as your skin,” said Mark A. D’Andrea, the lead author of the study and medical director for the University Cancer and Diagnostic Centers. “Once it enters your system, it affects several organs.”
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As blood carries chemicals through the body, it can go through bone marrow, which is the basis for production of blood cells. The liver also filters toxins.
D’Andrea’s study with colleague G. Kesava Reddy documented a wide range of abnormal values for enzymes in the blood of 117 former cleanup workers, compared to a control group of 130 patients not involved in sopping up the spill.
The workers had decreased levels of blood-clotting platelets, as well as lower numbers for blood urea nitrogen and creatinine, which are indicators of kidney health.
The amount of three liver enzymes — alkaline phosphatase, aspartate transaminase and alanine transaminase — in the cleanup workers’ blood also was higher than the non-exposed patients, a warning sign of liver dysfunction and damage.
D’Andrea said various studies show that patients with damaged bone marrow have higher incidence of possible leukemias, lymphoma and myelomas, and that liver damage increases risk of liver, pancreas and gallbladder cancer.
The study also documented a range of symptoms reported by the clean-up workers during clinical visits from 2010 to November 2012, including, most commonly, headaches and shortness of breath, followed by skin rashes and chronic coughs.
The doctors came to treat the oil spill cleanup workers on referral from a lawyer representing their potential claims.
While other studies have reported liver enzyme changes as a result of exposure to benzene, relatively little research has focused on the broad health changes in cleanup crews from previous oil spills.
“There are not a whole lot of studies of incident exposure in the United States, even though we have a big petrochemical industry,” D’Andrea said.
Under a settlement with BP, cleanup workers are entitled to some medical payments for certain ailments that they can prove were tied to the spill-related work and their exposure.
BP stressed that workers received safety training and personal protective equipment in coordination with government safety agencies.
“Based on extensive monitoring conducted by BP and the federal agencies, response worker and or public exposures to dispersants were well below levels that would pose a health or safety concern,” the company said.
Some research indicates risk depends on the type of exposure. Oil in the water near the spill site, for example, would be fundamentally different than tar balls that later washed ashore. A study for BP in 2011 found that tar balls contain mostly sand and most of the pollutants known as poly-aromatic hydrocarbons had already dissipated.
Researchers D’Andrea and Reddy noted limitations in their retrospective study of workers after their oil spill cleanup duties, chiefly that they had not collected health data on the patients before the April 20, 2010 blowout of BP’s Macondo well. As a retrospective study, the research fundamentally can’t say the oil spill caused the results — just document them among the studied cleanup workers.
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BP spokesman Jason Ryan faulted the study for its small sample — “fewer than 0.1 percent of the workers involved in the cleanup.” And he suggested there was selection bias in the study subjects, since they were “referred by their legal counsel, not randomly recruited.”
“This selection bias raises fundamental questions about the study,” he said. Beyond the methodological concerns, Ryan said, “the authors present no basis for assigning clinical significance to the non-specific biological markers they report.”
The researchers said long-term studies would be needed to understand the true clinical significance of oil spill exposure.
D’Andrea and Reddy are working on other studies examining the lung and respiratory function of people exposed to the oil spill.
The risks of oil cleanup work were known, even before the Gulf of Mexico spill. During the height of the spill, in June 2010, the Occupational Safety and Health Administration and other federal agencies issued a 124-page booklet schooling cleanup workers in precautions, given that they “face potential hazards from oil byproducts, dispersants, detergents and degreasers.”
Workers were advised to wear rubber shoes, wear oil-resistant gloves, don equipment to avoid breathing in possibly toxic gases and go through decontamination procedures whenever they stripped off the protective gear to eat.