Toxic Exposure

The analysis may have to reconstruct conditions from product quantities, process or activity records, photographs, ventilation or site information, chemical properties, prior sampling, comparable measurements, witness accounts, and the duration and frequency of the activity. The expert should also identify assumptions and data gaps rather than present a reconstructed concentration as if it were directly measured. EPA recognizes indirect estimation or scenario evaluation as an approach to exposure assessment when direct measurements are unavailable or limited.

No. Detection establishes that a substance was present in the sampled medium under the conditions tested; it does not automatically establish that a particular person contacted it. The location and timing of the sample, contaminant concentration, person's activities, exposure route, frequency, and duration all matter. ATSDR similarly distinguishes environmental contamination from a completed pathway in which a person actually contacts, inhales, or ingests the contaminant.

Each route requires different evidence. Inhalation analysis may involve airborne concentrations, breathing-zone or area measurements, ventilation, and time spent in the affected space. Ingestion can involve concentrations in water, food, soil, or dust together with contact and intake assumptions. Dermal analysis considers skin contact with contaminated material and the circumstances and duration of contact. EPA treats these as separate exposure routes because the data and assumptions needed to estimate exposure differ.