Gulf Long-Term Follow-Up Study

The GuLF STUDY is a prospective cohort study of the potential health effects associated with response and clean-up related to the 2010 Deepwater Horizon oil spill. The cohort includes clean-up workers and others who completed clean-up safety training, but were not hired.
Participants were recruited between April 2011 and May 2013. At the time of enrollment, participants completed a comprehensive telephone interview that collected information on response and clean-up work history, health status, and lifestyle factors. A subgroup of participants was invited to complete a home visit following the enrollment interview where additional questionnaire data, clinical measurements, biospecimens, and environmental samples were collected.
A total of 32,608 participants enrolled in the study, and 11,193 completed a home visit. A team of experts in exposure assessment developed ordinal and quantitative estimates of spill-related exposures, including exposure to chemicals such as hydrocarbons, volatile organic compounds, particulate matter, and dispersants. The cohort represents the full range of spill-related jobs and includes vulnerable subgroups, such as those exposed to both environmental contamination and the socioeconomic effects of the spill.
The cohort will be followed for at least 10 years by telephone interview, in-person exams, and through public health records for major outcomes like cancer and mortality. The first follow-up telephone interview (n=21,256) and clinical exam (n=3,401) are complete and provide additional health information, biospecimens, and clinical measurements. As the largest and most comprehensive study of its kind, the GuLF STUDY offers researchers opportunities to examine a range of a priori and novel hypotheses.

Major study events include:

Enrollment Telephone Interview
At the time of enrollment, participants completed a computer-assisted, interviewer-administered telephone questionnaire. Participants were asked to provide demographic, socioeconomic, health, occupation, and lifestyle information. Workers were also asked, as part of the structured interview, to provide detailed information about each response or clean-up job or task they performed, including work locations and start and stop dates. Interviews were conducted in English, Spanish, and Vietnamese. The interviews generally took 30 to 60 minutes, depending on the extent and duration of participants' clean-up experience. An abbreviated version of the questionnaire was administered to Vietnamese-speaking participants.

Enrollment Home Visit
At the end of the telephone enrollment interview, participants residing in Florida, Alabama, Mississippi, Louisiana and east Texas were invited to participate in a home visit. The home visit interview collected additional information on clean-up work performed and use of any personal protective equipment, additional health, lifestyle, occupational, residential and family health histories, and standardized scales for depression, anxiety, and post-traumatic stress. Clinical measurements and biospecimens were collected during the visit as well.

A subset of participants who completed a home visit provided additional blood samples (n=1,061) during the home visit to be analyzed for the measurement of 46 different Volatile Organic Chemicals (VOCs), including BTEX, and metals. Additionally, 106 of these participants were asked to wear a personal environmental sampler to collect corresponding information on VOC’s for cross comparisons with blood measures and comparison with external environmental data.

Follow-up Telephone Interviews
We plan to follow GuLF STUDY participants via telephone interview every two to three years. The follow-up telephone interviews will allow study investigators to ascertain any changes over time in health status, occupational exposures, lifestyle factors, and residence. The first follow-up interview began in May 2013 and ended in April 2016. A total of 19,142 English-speaking participants completed this first interview. An additional 2,114 participants who were lost to the initial follow-up effort completed an abbreviated questionnaire to provide updates on their health status for a total of 21,256 completing this first follow-up effort. The second follow-up interview began in Fall 2018.

A subset of participants was also followed longitudinally by telephone interview to help us better understand mental health trajectories in the wake of a disaster and the impact of interactions with medical and social services. The subgroup included participants with signs of potential mental health distress at the time of the home visit, as well as others without any apparent issues. These interviews were conducted at the time of first follow-up interview and again 6, 12, and 24 months later. The mental health telephone interviews began in September 2013 and concluded in August 2016. Among 6,458 participants initially selected, 2,859 of those participants (65%) completed the baseline mental health interview, and became eligible for subsequent mental health follow-ups. 1,059 participants completed all four mental health waves.

Clinical Exam
Participants who completed a home visit and lived within 60 miles of study clinical sites in New Orleans, LA and Mobile, AL were eligible to take part in a clinical exam. Overall, 3,401 of the eligible participants completed exams between August 2014 and June 2016. The exam included health questionnaires, clinical measurements and biospecimen collections. In addition to repeated components from the home visit, the exam included lung function tests, neurological and neurobehavioral measures and more comprehensive mental health and substance abuse evaluations.

Biospecimen Analyses
A number of biomarkers have been measured in samples collected from the home visit and clinic exam to characterize clean-up related exposures and health effects, including biomarkers of kidney and liver injury and salivary cortisol.

Some of the additional ongoing analysis efforts include: mental health and disaster recovery work, mental health service utilization patterns among clean-up workers, impact of clean-up efforts on pulmonary function, association between blood BTEX concentration and hematologic parameters, respiratory symptoms associated with clean-up efforts, current exposure to VOCs among Gulf Coast residents, non-spill exposures related to pulmonary function, correlation between blood cell parameters and BTEX exposure, ambient and personal styrene exposure and adverse neurobehavioral outcomes, adverse mental health outcomes associated with oil-spill clean-up, oil spill exposure and cardiovascular disease, symptoms at the time of active oil spill clean-up in workers and non-workers, and acute symptoms related to dispersant use.