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Leaking underground storage tanks: an emerging public health risk

by: Evelyn Talbott, DrPH, Professor of Epidemiology, GSPH and Jeanne Zborowski, PhD, Senior Research Specialist, Department of Epidemiology, GSPH, University of Pittsburgh

After World War II, the automobile became a fixture in the everyday life of Americans. The exponential growth of automobile sales resulted in the construction of thousands of gasoline stations across the country (2.2 million tanks!) Bare steel tanks, with an average tank life expectancy of 15 — 30 years, were installed underground to store gasoline. Since the 1980's, corrosion and faulty installation and operation have resulted in widespread ground water contamination by gasoline (benzene, toluene, ethylbenzene, xylenes (BTEX compounds) and methyl tertiary butyl ether (MTBE). Because fifty percent of all Americans rely on groundwater for their drinking water, these leaking underground storage tanks pose a significant public health hazard.

Leaking underground storage

Gasoline leaking from these tanks contaminates surrounding soil and groundwater causing both environmental and human health risks. Benzene, a component of gasoline, is categorized by the Environmental Protection Agency (EPA) as a proven human carcinogen and has been linked in occupational studies to increased cancer rates, particularly of the blood forming organs (leukemia, lymphoma, etc). While workers who regularly use benzene have been consistently found to have a number of serious health problems when compared to other workers without such exposures, few studies have examined the health effects of a community exposure to low-level benzene via gasoline or other spills.

In 2001 and 2002, our team of investigators from the University of Pittsburgh carried out an epidemiological study specifically examining the health effects of the Tranguch Gasoline Spill. The Tranguch Gasoline Spill has been characterized as a leakage of 50,000-900,000 gallons of gasoline from underground storage tanks in two municipalities located in northeastern Pennsylvania. As a result of the spill, it is believed that residents living within an EPA-defined remediation area were chronically exposed to low-levels of benzene sourcing from the gasoline since at least 1990. In response to community concerns, a study examined 663 individuals from 275 households that had been exposed to benzene to see whether they had a higher risk of cancer and other diseases, compared to others in Pennsylvania.

Using questionnaires, we collected personal information on health, jobs, and residence. Cancers that were reported in these questionnaires were verified by physicians and cross-referenced with the Pennsylvania Cancer Registry for the period January 1, 1990 to December 31, 2000. We calculated the rate of cancer in persons exposed to benzene from leaking gasoline tanks and found that they had nearly four times more leukemia than other persons in the state. In fact, the risk of all cancer in those exposed to benzene was not higher, but the risk of leukemia, a cancer known to be tied to benzene, was greatly elevated. Four incident cases of leukemia were reported (two acute myelogenous, one chronic myelogenous, and one chronic lymphocytic). The residential location of the acute myelogenous leukemia cases directly bordered the more concentrated areas of gasoline as projected by the US Army Corps of Engineer and EPA.

The results of our University of Pittsburgh study are consistent with what has been observed in workers who regularly use benzene but with eight hour exposures, which are considerably greater. We have found that chronic low-level benzene exposure is tied with an increased risk for leukemia among residents living near the Tranguch spill site. While acute myelogenous leukemia has been definitively linked to benzene exposure in workers, our study is one of the first to suggest such an association in residents from environmental exposures in their homes.

Scientists who worked on this study have met with the community to explain these results and suggested general precautions to lower personal environmental exposure to other sources of benzene, like cigarette smoke and pumping gasoline as well as housing cans of paint thinner, gasoline for lawn mowers and paint in close proximity to their living areas. Recommendations were made to public health agencies and the community based on the study's findings. They included screening the exposed community in the future to see whether they develop other health problems. Public health officials will be engaged in surveillance in the spill-affected area in order to determine the long-term impact of this low-level exposure to gasoline.

Our research is one of very few studies to extensively investigate exposures to gasoline/benzene in a community setting. Given the high prevalence of leaking underground gasoline tanks in the United States, this exposure is far from unique. Therefore, it is important for communities and public health agencies to cooperate to assess and address health effects potentially resulting from such leaks.

Contact the Center for Environmental Oncology at the University of Pittsburgh Cancer Institute (ceoinfo@upmc.edu) for updated information and evidence-based resources.


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