Deepwater Horizon Oil Spill Led to 60% Higher Risk of Later Asthma for Cleanup Workers

An ongoing study of the tens of thousands of oil spill response and cleanup (OSRC) workers involved in the aftermath of the 2010 Deepwater Horizon oil spill in the Gulf of Mexico has discovered that they were 60% more likely to develop asthma in the years after the environmental disaster

The oil drilling rig exploded and sank April 20, 2010, killing 11 workers, and the spill was not capped for 87 days.

Until now, not much has been known about the effects of oil spills on respiratory health or on links between specific chemicals and lung health. Observational epidemiologic studies have found a higher risk of respiratory harm for oil cleanup workers, but quantitative measures have been lacking.

The Deepwater workers were exposed to airborne total hydrocarbons (THC); a subgroup of chemicals from crude oil (benzene, toluene, ethylbenzene, o-, m-, and p-xylenes and n-hexane, known collectively as BTEX-H) as well asPM_2.5 from burning/flaring oil and natural gas. These chemicals are classified as hazardous air pollutants according to the US Clean Air Act and are linked to other health issues.

The ongoing study that looks at their health, called the Gulf Long-term Follow-up Study (GuLF STUDY), led by the National Institutes of Health’s National Institute of Environmental Health Sciences (NIEHS), analyzed data from a subset of the 32,608 adults ≥ 21 years of age who participated in oil spill response and cleanup work (OSRC workers, n = 24,937) and those who were trained but not hired (non-workers, n = 7,671).

After excluding participants with missing data, researchers included 19,018 OSRC workers and another 5585 people who had completed required safety training, but did not work on the spill.

None of the participants had been diagnosed with asthma before the spill. For this study, asthma was defined as both self-reported wheeze and self-reported physician diagnosis of asthma, due to concerns about underreporting asthma due to lack of health care access by some of the participants.

The researchers estimated worker’s exposures to specific oil spill chemicals by looking at job class, THC, individual BTEX-H chemicals, BTEX-H as a mixture, and PM_2.5 from the burning/flaring oil and gas, and analyzed the relationship to asthma.

Exposure levels varied depending on the specific job and duration of exposure through the job.

Jobs varied from administrative support and environmental water sampling, to mopping up crude oil from aboard a sea vessel or shoreline vessel to decontaminating equipment or wildlife.

The 6 job categories, listed in order from highest to lowest exposure level, were: response, operations, cleanup on water, decontamination, cleanup on land, and support work.

In the current study, researchers found that the relative risk (RR) for asthma symptoms increased with rising levels of exposure to individual BTEX-H chemicals as well as the BTEX-H mixture.

The that 983 (5%) of the cleanup workers reported asthma and asthma symptoms, while only 196 (3%) nonworkers could report the same.

Overall, OSRC workers had greater asthma risk than nonworkers (RR, 1.60; 95% CI, 1.38-1.85), and the workers who were the most directly involved in the recovery effort, with positions in operating, maintaining, or refueling the heavy equipment, had the highest incidence of asthma, as compared with support and administrative workers.

Operations workers’ increased risk was nearly 330% higher and response workers’ risk was 280% higher.

In addition, higher estimated THC exposure levels were linked with increased risk in an exposure-dependent manner (linear trend test P < .0001),

Asthma risk also rose with increasing exposure to individual BTEX-H chemicals and the chemical mixture.

“This is the first study to ever look at specific chemicals from oil spills and link them to respiratory diseases,” Dale Sandler, PhD, chief of the NIEHS Epidemiology Branch and lead researcher for the GuLF STUDY, said in a statement.

There were some limitations to the study, some created by the singularly large scale and scope of the Deepwater spill. "The generalizability of our findings may be limited due to the unique exposures faced by the GuLF Study workers, though job-related health risks may inform future targeted interventions to further protect cleanup workers in a similar scenario," the authors said.

Reference

Lawrence KG, Niehoff NM, Keil AP, et al. Associations between airborne crude oil chemicals and symptom-based asthma. Environmental International; Volume 167; (PubMed).