June 15, 2009 Evidence exists that people who lived or worked at Camp Lejeune Marine Base in North Carolina between the 1950s and 1985 were exposed to the industrial solvents tricholorethylene (TCE) or perchloroethylene (PCE) in their water supply, but strong scientific evidence is not available to determine whether health problems among those exposed are due to the contaminants, says a new report from the National Research Council.
The report adds that further research will unlikely provide definitive information on whether exposure resulted in adverse health effects in most cases. Therefore, policy changes or administrative actions to address and resolve the concerns associated with the exposures should not be deferred pending new or potential health studies.
"Even with scientific advances, the complex nature of the Camp Lejeune contamination and the limited data on the concentrations in water supplies allow for only crude estimates of exposure," said David Savitz, chair of the committee that wrote the report and professor in the department of community and preventive medicine at Mount Sinai School of Medicine, New York City. "Therefore, the committee could not determine reliably whether diseases and disorders experienced by former residents and workers at Camp Lejeune are associated with their exposure to the contaminated water supply."
In the early 1980s, two water-supply systems, Tarawa Terrace and Hadnot Point, on Camp Lejeune were found to be contaminated with various toxic industrial solvents, including PCE -- which entered the groundwater as a result of spills and improper disposal practices by an off-base dry cleaner -- and TCE from on-base spills and leaks from underground storage equipment. Considerable public controversy grew over the potential health consequences, such as various cancers, for former residents. To supplement the few studies that have been performed and to help inform decisions about addressing health claims, Congress asked the Research Council to examine whether adverse health effects are associated with past contamination of the water supply at Camp Lejeune.
The committee reviewed an extensive water modeling effort of the contamination of Tarawa Terrace, and for Hadnot Point they examined information on chemical contamination from records and disposal practices. PCE was the primary contaminant of the Tarawa Terrace water supply, but the water models could not overcome data gaps to provide accurate estimates of the concentrations of the contaminants. The committee concluded that in the Hadnot Point area, exposures to TCE and PCE occurred, and exposures to several other contaminants through the drinking water distribution system were likely. The ability to determine the levels of exposure at Camp Lejeune was complex, because people could have been exposed at home, school, daycare, or work.
In addition to reviewing the studies focusing specifically on Camp Lejeune, the committee examined data on exposures and available scientific research on associations between these chemicals and adverse health effects to determine which health problems might be associated with the Camp Lejeune contaminant exposure. The committee looked at data from two types of studies: epidemiologic and toxicologic. Epidemiologic studies examine whether a group of people with more exposure to particular chemicals have greater frequency of disease than people with lesser or no exposure. Toxicologic studies conduct tests on animals to observe the health effects caused by exposure to chemicals.
The epidemiologic studies of TCE and PCE, primarily conducted in workplace settings, contained insufficient evidence to justify causal inference for any health effects. However, the committee found "limited or suggestive evidence of an association" between chronic exposure to TCE, PCE, or a mixture of solvents, and some diseases and disorders, including cancers of the breast, bladder, kidneys, esophagus, and lungs. This categorization means these epidemiologic studies give some reason to be concerned that sufficiently high levels of TCE or PCE may have an adverse effect, but the studies do not provide strong evidence that they actually do.
The majority of the health outcomes reviewed in the epidemiologic studies was placed in the category of "inadequate or insufficient evidence," meaning that evidence was of insufficient quantity, quality, or inconclusive in results to make an informed assessment, but that an association between exposure to a specific agent and a health outcome cannot be ruled out. A summary of the conclusions drawn from the epidemiologic studies related to solvent exposure can be found in Box 2 on page 8 of the report. Some health outcomes reported by former residents of the base -- such as male breast cancer and second-generation effects -- are not cited because those specific outcomes were not investigated or the studies were too small or of insufficient quality.
The committee also compared information from epidemiologic studies with that from toxicologic studies and found similar health effects in both humans and animals for kidney cancer. Similar noncancerous diseases and disorders included adverse effects on the liver, kidneys, and nervous and immune systems. The findings are in Table 1 on page 10. The absence of other diseases and disorders from Table 1 indicate that the findings were inconsistent between the epidemiologic and toxicologic evidence or were not addressed in the available studies.
Studies specifically on the Camp Lejeune population have addressed only reproductive health outcomes, but the limited quality of exposure information restricts their value. The inability to study exposure and health outcomes accurately is a serious limitation in any future research. Thus, the committee concluded that the U.S. Department of the Navy, under which the Marine Corps operates, should not wait for the results of more research before making decisions about how to follow up on the evident contaminant exposures and their possible health consequences. They should undertake appropriate action in light of the available sparse information that indicate exposure to toxic contaminants occurred and may have affected the health of the exposed population.
The report was sponsored by the U.S. Department of the Navy. The National Academy of Sciences, National Academy of Engineering, Institute of Medicine, and National Research Council make up the National Academies.
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