Non-Discrete Incremental Sampling Methodology (ISM) Data: EPC Calculations

EPC Guidance Depending on Exposure Duration

Acute Exposures

Use the result of a single ISM or the average of multiple ISMs as EPCs under certain scenarios.

Intermediate or Chronic Exposures

Use the result of a single ISM or average of multiple ISMs as EPCs, as long as they adequately represent the exposure unit and were collected and analyzed in a manner consistent with data quality objectives (DQOs).

Refer to ATSDR’s Non-Discrete Sampling Guidance for more information on calculating EPCs for composite sampling and ISM data. Consult with the ADS group if you encounter site-specific scenarios or other conditions that are not covered in the guidance.

Note: ATSDR’s Non-Discrete Sampling Guidance does not apply to all contaminants and types of sampling.

Refer to SMEs when evaluating asbestos and lead.
Refer to ATSDR’s Toxic Equivalents Guidance for Dioxin and Dioxin-like Compounds for dioxins.
Refer to ATSDR’s Discrete Sampling Guidance for discrete sampling data (individual samples from a given point and time).
Refer to ATSDR’s Guidance for Calculating Benzo(a)pyrene Equivalents for Environmental Samples Analyzed for PAHs for PAHs.
Refer to the ADS group for EPC guidance when evaluating dependent data. These are instances where the results of one sample at least partially predict the results of another sample.
You can find all final guidance in the PHAGM Resources section.

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