BP Deepwater Horizon Oil Spill Elizabeth Rose Mayeda, MPH Student Case Study Presentation Environmental and Occupational Epidemiology University of California, San Francisco June 7, 2012
Outline • The event • Clean up • Possible health effects • Current studies • Future studies • Implications
Deepwater Horizon • Explosion on a BP offshore oil rig on April 20, 2010 11 workers died immediately • More than 30 workers seriously injured • Oil flowed unabated for 3 months • Wellhead capped July 15, 2010 • Oil continues to seep • Millions of barrels of oil released into the Gulf Goldstein, N Engl J Med, 2011
How did it happen? • National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling: • “Regulators failed to keep pace with the industrial expansion and new technology” • “Inexcusable shortfall in supervision of offshore drilling” http://www.oilspillcommission.gov
Unique oil spill • Magnitude • Duration of release • Source of emission (deep sea floor) • Management techniques (dispersants and controlled burns) Goldstein, N Engl J Med, 2011
Population • Vulnerable population • Communities with poor health indexes • Environmental justice concerns • Recurrent natural disasters • Communities still recovering from Hurricane Katrina Goldstein, N Engl J Med, 2011
Oil slick control • Dispersant • Used to dissipate oil slicks • Oil effectively spread throughout larger volume of water than surface • Controlled burns
Potential health consequences • Four broad categories: • Worker safety • Toxicologic effects in workers, community members, and visitors • Mental health effects from social and economic disruption • Ecosystem effects that affect human health • Acute and long term effects • Generally unknown! Goldstein, N Engl J Med, 2011
Worker health • Thousands of clean-up workers and volunteers • Health concerns: • Chemical exposures • Heat exhaustion • Degree of exposure depends on: • Job assignment • Duration of exposure • Extent of worker training • Use of personal protective equipment Goldstein, N Engl J Med, 2011
Toxicologic effects • Acute: • Respiratory and dermal irritation • Headaches • Eye irritation • Nausea • Long term • Pulmonary function • Endocrine disorders • Genotoxic effects
Contaminants of concern • Crude oil • >1,000 different hydrocarbons • Polynuculararomatic hydrocarbons (PAHs) • Trace metals • Sulfur • A lot of variability in composition depending on source • Dispersant Goldstein, N Engl J Med, 2011
Routes of exposure • All 5 elements of a complete exposure pathway present: • Sources of contaminants • Environmental media • Points of exposure • Routes of exposure • Receptor population Goldstein, N Engl J Med, 2011
Mental health effects • Anxiety • Depression • Post-traumatic stress
Ecosystem effects • National seafood safety-issue • Bioaccumulation and biomagnitifcation of crude oil components (esp. PAHs) in seafood • Controversy about FDA guidelines on Gulf seafood safety
Osofsky et al. 2011 1. What was the objective of this study?
Osofsky et al. 2011 1. What was the objective of this study? • To assess the mental health effects of the Deepwater Horizon oil spill on residents of areas of southeastern Louisiana affected by the spill. Osofsky et al., Disaster Med Public Health Prep. 2011
2. What methods did the researchers use? Do you these methods were appropriate for the study objective?
Osofsky et al. 2011 2. What methods did the researchers use? Do you these methods were appropriate for the study objective? • Cross-sectional study • Random and purposive sampling techniques • Correlation analyses to assess associations among occupation, proximity to spill, oil spill disruption, oil spill concerns, Katrina impact, place satisfaction, and rebound resilience with PCL-C (posttraumatic stress) and K6 scores (anxiety and depression symptoms). • Multiple regression analyses to assess the extent to which oil spill variables predicted posttraumatic stress scores and symptoms of depression and anxiety.
Osofsky et al. 2011 3. The researchers used both random and purposive sampling techniques. • Why did the researchers use these techniques? • How could these techniques have affected the results? • What implications do the sampling techniques have on the conclusions of the study?
Osofsky et al. 2011 • Purposive sampling was to allow for more detailed sampling of individuals from fishing, tourism, and oil drilling-related industries. • Difficult to identify study population—what population does the study population represent? • Some interviews over the phone and some in person---type of interview may have affected responses?
Osofsky et al. 2011 4. The telephone response rate was only 25%. • How could this have affected the study results? • How did the authors attempt to address the low response rate?
Osofsky et al. 2011 • Selection bias threat to internal validity of the study. • Data collection using landlines also excludes people from sample. • Purposive sampling techniques used to address the low response rate and increase representation of responses.
Osofsky et al. 2011 5. What did the authors report about the association between Hurricane Katrina and mental health effects of the oil spill?
Osofsky et al. 2011 • Losses from Katrina were highly associated with negative mental health outcomes.
Osofsky et al. 2011 6. What is the main conclusion from this study?
Osofsky et al. 2011 • The largest effect on mental well-being was the extent of disruption that the oil spill created in an individual’s life: work, family, social engagement. • This finding was consistent with findings from previous oil spills.
Osofsky et al. 2011 7. How can the findings of this study be used to improve public health?
Osofsky et al. 2011 • Gaining and understanding of the mental health effects will help determine directions of mental health services for people affected by the spill and future oil spills and disasters.
Grattan et al. 2011 • Objective: • Examine acute mental health effects of indirect and direct community oil exposure and income loss. • Methods: • Cross-sectional survey of two Gulf Coast communities • Indirect exposure group in Florida, (n=71) • Direct exposure group in Alabama, (n=23) Grattan et al. Environ Health Perspect, 2012
Grattan et al. 2011 • Results: • No significant differences in psychological impact between communities. • Individuals with income loss reported more psychological distress symptoms. • Conclusions: • Mental health effects may be underestimated in Gulf Coast communities that were not directly exposed to oil. • Income loss after the spill may have the greatest impact on mental health.
GuLF Study • GuLF (Gulf Long Term Follow-up) Study • Led by National Institute of Environmental Health Sciences (NIEHS) • Plans to follow 55,000 Gulf oil spill workers and volunteers for up to 10 years • Open-ended study—not focused on specific endpoints • Launched February 28, 2011 • Enrollment ongoing Goldstein, N Engl J Med, 2011, http://nihgulfstudy.org/reports.html; http://www.niehs.nih.gov/news/newsroom/releases/2011/february28/
GuLF study • All participants: telephone interview asking questions about: • The work they did with the oil spill cleanup • Health, lifestyle, and job history • Phase 2 (~20,000 participants): home visit and follow-up telephone interviews in subsequent years. • Samples of blood, urine, toenail clippings, hair, and house dust • Clinical measurements: blood pressure, height and weight, urine glucose, and lung function
GuLF Study • Largest study of it’s kind • One component of federal response to the disaster • Findings expected to: • Help inform policy decisions on health care and services in the region • Influence responses to future oil spills
Implications • Potential long-term health effects • Recovery • Future disasters • Future oil spills