Division of Health Studies

G. David Williamson, PhD, Director

The mission of the Division of Health Studies (DHS) includes six main elements. The Division:

1. Conducts clinical evaluations and medical follow-up of persons potentially exposed to hazardous substances to evaluate the relationships between exposure to toxic substances and health.

2. Develops methods and conducts studies to determine the background rate of the prevalence of specific health outcomes or biological measures of exposure or health effects to aid in the evaluation of health impacts of exposure to hazardous materials in specific communities.

3. Conducts epidemiologic studies designed to evaluate the causal nature of associations between exposure to hazardous substances and disease outcome by testing scientific hypotheses.

4. Conducts health surveillance programs of exposed populations (including medical testing and referral for treatment).

5. Establishes and maintains national registries of (1) persons exposed to hazardous substances, and (2) persons with serious diseases or illnesses.

6. Provides consultation and technical assistance to state and local governments on the design and merits of human health investigations related to exposure to hazardous substances.

Recent studies conducted by DHS have found positive associations between exposure to toxic materials in the environment and the occurrence of certain cancers, birth defects, mental retardation, and certain lung diseases. The following are two examples of studies conducted by DHS:

Bunker Hill, Idaho - Two studies found that people exposed to lead during the 1970s at the Bunker Hill NPL site in Idaho, have long-term health effects. As a result of their exposures as children and young adults more than 25 years ago, this population was found to be at increased risk for developing neurological disease, infertility, high blood pressure, and early onset of menopause.

Libby, Montana - From the 1920s until 1990, Libby was a location where extensive vermiculite mining was conducted. Vermiculite is a natural mineral used to make insulation materials and garden soil additives. It was discovered that vermiculite ore mined in the area was contaminated with asbestos and many people were exposed to this harmful contaminant. Non-occupational exposure to asbestos in Libby residents was significantly higher than national norms. A preliminary study has shown a higher than expected prevalence of lung diseases in Libby residents.

The Division of Health Studies has three branches. The Health Investigations Branch (HIB) conducts health studies in communities where citizens have possibly been exposed to hazardous substances released from hazardous waste sites or other environmental sources. The general types of studies conducted by HIB include descriptive studies of the prevalence of specific outcomes and analytic studies of the relationship between exposure to toxic substances and clinical measures of health effects. The Epidemiology and Surveillance Branch (ESB) is responsible for conducting analytic epidemiology studies that are designed to evaluate the causal nature of associations between exposure to hazardous substances and disease outcome by testing scientific hypotheses. The general types of surveillance investigations conducted by ESB are: state-based surveillance, site-specific surveillance, hazardous waste worker health surveillance, and hazardous substances emergency events surveillance. The Exposure and Disease Registry Branch (EDRB) develops and maintains the National Exposure Registry (NER). The NER is composed of substance-specific subregistries. These databases are used to facilitate epidemiologic research and to explore a wide range of possible adverse health effects.