Health effects of environmental contaminant exposure: an intrafile comparison of the Trichloroethylene Subregistry.

The establishment of the National Exposure Registry represents the first major effort toward longitudinal surveillance of general populations exposed long-term to low levels of specific substances in the environment. The authors investigated the National Exposure Registry's Trichloroethylene Subregistry intrasubregistry differences with respect to health outcomes and the possible relationships with types and levels of chemical exposure. Investigators divided the 4041 living members of the Trichloroethylene Subregistry into 4 subgroups, by type(s) of exposures (chemicals) and duration and level of exposures. The authors compared the reporting rates for 25 health outcomes across subgroups. The authors used logistic regression, in which age, sex, education, smoking history, and occupational history were the covariates. Statistically significant increases in reporting rates were seen with (a) increased maximum trichloroethylene exposures for the outcome stroke, (b) increased cumulative chemical exposure for respiratory allergies, and (c) duration of exposure for hearing impairment. Consistently elevated reporting rates across the exposure subgroups were seen for hearing impairment, speech impairment, asthma and emphysema, respiratory allergies, and stroke. Reporting rates for urinary tract disorders were related only to cumulative chemical levels. The authors noted that there appeared to be a relationship between trichloroethylene and reporting rates for speech impairment, hearing impairment, and stroke and between volatile organic compounds and asthma and emphysema, respiratory allergies, and urinary tract disorders.

The National Exposure Registry: analyses of health outcomes from the benzene subregistry.

The purpose of the National Exposure Registry is to assess the long-term health consequences to a general population from long-term, low-level exposures to specific substances in the environment. This study investigates the health outcomes of 1,143 persons (1,127 living, 16 deceased) living in south central Texas who had documented environmental exposure to benzene (up to 66ppb) in tap water. As with all subregistries, face-to-face interviews were used to collect self-reported information for 25 general health status questions. Using computer-assisted telephone interviewing, the same health questions were asked 1 year (Followup 1, F1) and 2 years later (Followup 2, F2). The health outcome rates for Baseline and Followup 1 and 2 data collections for the Benzene Subregistry were compared with national norms, that is, the National Health Interview Survey (NHIS) rates. For at least one of the three reporting periods, specific age and sex groups of the Benzene Subregistry population reported more adverse health outcomes when compared with the NHIS population, including anemia and other blood disorders, ulcers, gall bladder trouble, and stomach or intestinal problems, stroke, urinary tract disorders, skin rashes, diabetes, kidney disease, and respiratory allergies. Statistically significant deficits for the Benzene Subregistry population overall were found for asthma, emphysema, or chronic bronchitis; arthritis, rheumatism, or other joint disorders; hearing impairment; and speech impairment. No statistically significant differences between the two populations were seen for the outcomes hypertension; liver disease; mental retardation; or cancer. These results do not identify a causal relationship between benzene exposure and adverse health effects; however, they do reinforce the need for continued followup of registrants.

Benzene--a review of the literature from a health effects perspective.

A literature review of the impact on human health of exposure to benzene was conducted. Special emphasis in this report is given to the health effects reported in excess of national norms by participants in the Benzene Subregistry of the National Exposure Registry--people having documented exposure to benzene through the use of benzene-contaminated water for domestic purposes. The health effects reported in excess (p < or = .01) by some or all of the sex and age groups studied were diabetes, kidney disease, respiratory allergies, skin rashes, and urinary tract disorders; anemia was also increased for females, but not significantly so.

Trichloroethylene--a review of the literature from a health effects perspective.

This report reviews the literature on the impact of exposure to trichloroethylene (TCE) on human health. Special emphasis is given to the health effects reported in excess of national norms by participants in the TCE Subregistry of the Volatile Organic Compounds Registry of the National Exposure Registries--persons with documented exposure to TCE through drinking and use of contaminated water. The health effects reported in excess by some or all of the sex and age groups studied were speech and hearing impairments, effects of stroke, liver problems, anemia and other blood disorders, diabetes, kidney disease, urinary tract disorders, and skin rashes.

Methodology for selecting substances for the National Exposure Registry.

The National Exposure Registry was created in response to the pervasiveness of chemical contamination at the nation's waste sites and the relative lack of information on human health outcomes associated with long-term, low-level exposure to most of these substances. A ranking scheme was developed by the Agency for Toxic Substances and Disease Registry (ATSDR) to select the substances for which substance-specific subregistries of the National Exposure Registry would be developed. This scheme uses a general decision analysis approach that incorporates the most relevant and up-to-date data available on the substances found at sites known to ATSDR. There are currently four general subregistries (volatile organic compounds, dioxins, heavy metals, and radioactive substances) made up of persons exposed to specific primary contaminants, as selected by means of this ranking scheme.

The National Exposure Registry: procedures for establishing a registry of persons environmentally exposed to hazardous substances.

The Agency for Toxic Substances and Disease Registry has, as mandated in Superfund legislation, established the National Exposure Registry (NER). The purpose of the NER is to assess and evaluate the potential relationship between adverse health effects and environmental exposure for an exposed population, particularly the relationship between chronic health effects and long-term, low-level chemical exposures. The NER's primary goal is to facilitate epidemiology research by establishing multiple data bases (subregistries) that contain demographic, environmental, and health information on large populations exposed to selected chemicals. The Registry data mainly serve the purpose of being hypothesis-generating rather than hypothesis-testing. The NER is currently composed of subregistries of: (1) persons exposed to volatile organic compounds (VOCs)--a subset of registrants in whom trichloroethylene (TCE) is the primary VOC exposure, but others are present (N = 4,832), a subset in whom benzene is the primary VOC exposure (N = 1,142), and a subset in whom trichloroethane (TCA) and TCE are the highest VOC exposures (N = 3,666); and (2) persons with dioxin exposure (N = 250). Chromium and radioactive substances subregistries are planned.