When Can You Request an EI?

A federal or state health agency usually requests an EI in coordination with ATSDR’s regional directors. The requestor provides the EI team with the information to answer the four questions below. If all four questions are answered with a “Yes,” ATSDR management will determine if an EI will be conducted. For more information, contact ATSDR’s Exposure Investigations Section Chief, whose contact information is at the end of this primer.

Can an exposed population be identified?

To see if there is a potentially exposed population, ask the following:

Is there a completed exposure pathway? This means that a contaminant is in a medium (for example, soil, water, air, plants, or animals) that a person contacts. In a completed exposure pathway, the following five elements are present: contaminant source, environmental fate and transport, exposure point, exposure route, and exposed or potentially exposed population.
Are people coming in contact with the suspected contamination?
Are activities, like playing, gardening, and using private well water, resulting in exposure to the contamination?
Are contaminants of interest still likely to be found at the site?
Are potential exposures recent enough to show up in biological samples?

Does a critical data gap exist that affects the ability to determine if there is a health hazard?

Determine if the data gap is critical, and whether an EI is the only option to fill this gap. In other words, determine if a public health call can’t be made without obtaining and analyzing the missing environmental or biological monitoring data specifically with an EI.
- For example, if a spill of a harmful contaminant occurred on the soil of a site, but no one has access to the area where the spill took place, then sampling of the soil is unnecessary to determine if people are exposed.
- Make sure to provide information to explain how the EI will fill the identified data gap(s).
Think about whether having ATSDR conduct an EI is the best way to gather the missing environmental or biological monitoring data.
Would another option, such as recommending environmental data collection by another agency, conducting modeling, or reviewing available biological monitoring data (for example, blood lead data), address the data gap?

Can an EI be designed to address this data gap?

ATSDR has standard methodology to collect both biological and environmental samples to fill data gaps at a site.
Ideally, the results of the data collection should be able to be evaluated using appropriate comparison criteria for biological samples (e.g., Blood lead reference value (BLRV) or the National Health and Nutritional Examination Survey (NHANES) values), and environmental samples (e.g., ATSDR comparison values).

Will the EI results impact the public health decision for the site?

Determine if the data collected would allow ATSDR to make better public health decisions, such as

making recommendations to regulatory agencies on how to reduce environmental contamination,
conducting additional environmental contaminant investigations,
recommending a health study, and
improving or expanding health education to reduce exposure.

If the data collected through the EI will not have an impact on public health decision-making, follow a different approach to fill the data gap(s).

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