Repeated exposure to chemical spills leads to declining health, new study reports

Many studies have linked exposure to natural disasters and man-made hazards such as fires, floods and chemical spills with health outcomes, but to date, few studies have considered the nature of such exposures or the health effects of repeated exposures.

In addition, some studies have found that people who have experienced such an event are more aware of the potential risks and are more likely to heed warning systems, while other studies have found the opposite to be the case.

A new survey of nearly 1,100 residents of Houston, led by researchers from the Texas A&M University School of Public Health, helps fill these gaps. The study, published in Disaster Medicine and Public Health Preparedness, assesses whether repeat exposures to certain hazard events were correlated with a reduction in physical health scores.

“Houston is an excellent location for a study on the effects of natural and anthropogenic—man made—hazards,” said Garett Sansom, PhD, an assistant professor in the Department of Environmental and Occupational Health, who led the study. “It has received more flood insurance funds than any other community in the National Flood Insurance Program, resulting from nine tropical storms and six hurricanes since 2001, which caused 321 direct and indirect deaths and more than $155 billion in damages, as well as two tornadoes, one of which, in 1992, caused at least $500 million in damages.”

Sansom added that as the “Energy Capital of the World,” Houston has chemical spills or petrochemical fires that significantly impact the community, such as 2010’s Deepwater Horizon oil spill, roughly every six weeks.

For the study, the research team conducted a cross-sectional study from a representative sample of 1,094 residents in the Houston Metropolitan Statistical Area.

The survey was completed by 660 women and 434 men, with 564 identifying as non-Hispanic white and 223 as African American. Most—463—were between the ages of 25 and 44, and 123 were older than 65. The majority had completed a high school level education or higher. In addition, 223 of the respondents fell below an income level of $34,999, and slightly more than 382 were in the highest-earning bracket of $85,000 or more.

Most respondents reported experiencing many hazardous events over the past five years, including hurricanes and flooding (96.35 percent), tornadoes (79.82 percent), chemical spills (86.84 percent), and industrial fires (96.08 percent).

The study found that of all the hazards, only chemical spills showed a dose-response, meaning that physical health scores declined significantly with repeated exposures. In addition, respondents listed hurricanes above chemical spills in terms of their perceptions of physical vulnerability. Sansom said this could be because people perceive acute risks as more dangerous than the risks of exposures that take months or years to fully manifest and because most risk and disaster planning efforts focus more on natural hazards than man-made hazards.

“This new understanding of hazards, especially those that are repeated, could help improve efforts to prepare for, mitigate and recover from both natural and anthropogenic hazards,” Sansom said.

The research team for this study also included School of Public Health faculty Lindsay Sansom, PhD, and Benika Dixon, PhD, and graduate students Anna Glanzer and Lyssa Losa, as well as Courtney Thompson, PhD, of Texas A&M’s Department of Geography and a colleague from the University of Delaware.