When a hazardous substance release occurs in a community, public health nurses must consider whether community members have been exposed, and whether that exposure is sufficient to impact public health. 2. An exposure pathway is the process by which an individual is exposed to contaminants that originate from some source of contamination. The exposure pathway method is effective in determining whether community members are exposed to hazardous substances in their community. 3. After determining a completed exposure pathway, a toxicological analysis estimates the dose of hazardous substances community members may have received and whether that dose may increase risks for an adverse health effect. 4. The Agency for Toxic Substances and Disease Registry (ATSDR) provides information to health care professionals that can assist them in conducting exposure and toxicological analyses.