Exposure Investigation

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What is an exposure investigation?

An exposure investigation is one way the Environmental Epidemiology Program can try to understand past, current and future human exposure to a hazardous substance in the environment. The Tennessee Department of Health, Environmental Epidemiology Program may perform an exposure investigation if people are actually exposed to a hazardous substance. There are three main ways information is gathered during an exposure investigation:

• Bio-medical tests, such as lab tests of blood or urine, are important sources of information gathered and evaluated during an exposure investigation. Bio-medical tests can show current (and sometimes past) exposure to a hazardous substance.
• Environmental samples of soil, water, or air are also important sources of information gathered and evaluated during an exposure investigation. Measurements of the amount of a hazardous substance at a site can be used to estimate risk to health. Environmental samples are often collected from where people live, work, play or otherwise might contact the hazardous substance under investigation. Evaluation of environmental samples is the most common way to evaluate potential health effects from exposure.
• Exposure-dose reconstruction analysis use environmental sampling data and computer models to estimate the amount of a hazardous substance that people may have been exposed to in the past or may be exposed to in the future. These complex models can sometimes be used to estimate how a person's health might be affected.

Who conducts exposure investigations?

A team of experts with knowledge in environmental sampling, toxicology, environmental sciences, risk, epidemiology, computer analysis, geographic information systems, medicine and community involvement is often assembled to work on an exposure investigation. The team uses information gathered during the exposure investigation to make public health decisions, prepare reports, involve the community and recommend appropriate actions to protect the public’s health.

How is the community involved?

The community is a very important part of an exposure investigation. So much so, that an exposure investigation cannot be done without community involvement. For an exposure investigation to be successful it needs to have:

• Community interest
• Community input
• Community members’ consent for testing
• Reasonable expectations from the community

While an exposure investigation tries to answer whether a community has been exposed to a hazardous substance, it cannot measure harm. It is important for a community to understand what the results of an exposure investigation may or may not tell them.

How do we decide to do an exposure investigation?

Before doing an exposure investigation, we consider:

1. If it is likely that people have been, are being, or might become exposed to a hazardous substance
2. If more information about how people are being exposed is needed
3. If an exposure investigation will provide new, useful information, and
4. If an exposure investigation will help in making public health decisions

What are some reasons for not conducting an exposure investigation?

There are some situations when an exposure investigation will not provide useful information about whether people have been exposed to a hazardous substance in the environment. For example, an exposure investigation would not be done when there is no exposure pathway to a hazardous substance. Another is when the exposure happened so long ago that the hazardous substance would be gone from the body. These situations may still be investigated using a different approach for responding to environmental public health concerns.