A more thorough explanation:

The Agency for Toxic Substances and Disease Registry (ATSDR) is a part of the U.S. Department of Health and Human Services. Its main responsibility is to evaluate the impact of hazardous substances on public health and the environment. It also maintains a registry of contaminated waste sites and conducts research on the effects of hazardous substances on human health.

For example, if a factory releases toxic chemicals into a nearby river, the ATSDR would investigate the potential health effects on people who live in the area and may have been exposed to the chemicals. The agency would also work to identify the source of the contamination and take steps to prevent further exposure.

Another example is if a community is concerned about a landfill that may be contaminating their drinking water. The ATSDR would investigate the site, test the water, and determine if there is a health risk to the community. If necessary, the agency would work with local officials to develop a plan to clean up the site and protect public health.