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Human Health 2 Establishing Thresholds

This article discusses the process of setting water quality thresholds, examining factors such as exposure assessment, analytical methods, and fate and transport. It also delves into dealing with uncertainty and communicating risks, especially in relation to human health. Various scenarios like indirect potable reuse, bioaccumulation, and non-potable reuse are explored. The text covers how thresholds are dependent on exposure levels and addresses temporal issues like acute versus chronic exposure. Ongoing projects in toxicology and relevant research needs are highlighted. The importance of risk communication and managing uncertainty, as well as what steps to take if health reference levels are exceeded, are also discussed.

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Human Health 2 Establishing Thresholds

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  1. Human Health 2Establishing Thresholds

  2. Establishing Water Quality Thresholds (Q1) Epi Studies Toxicology Studies Analytical Methods Exposure Assessment Process Persistence (Fate and Transport) Uncertainty Occurrence Data (inc. degradates) Temporal Risk Communication THRESHOLD (Health Reference Level)

  3. Thresholds Depend Upon Exposure (Q2) • Indirect Potable Reuse - Groundwater • IPR - Surface Water Augmentation • Surface Water Discharge • Downstream Drinking Water • Bioaccumulation • Non-potable Reuse • Ocean Desalination b

  4. What Process For Establishing Water Quality Thresholds DLR HRL (PHG) Set DLR DLR<PHG DLR<PHG Set PHG CommunicateRIsk CommunicateRIsk b

  5. Thresholds Depend Upon Exposure (Q2) • Indirect Potable Reuse - Groundwater • IPR - Surface Water Augmentation • Surface Water Discharge • Downstream Drinking Water • Bioaccumulation • Non-potable Reuse • Ocean Desalination b

  6. Temporal Issues (Q2&Q3) • Acute Exposure vs. Chronic Exposure – compound specific • May have acute and chronic criteria • Acute criteria will drive monitoring frequency b

  7. Ongoing Projects Doing This Already • WRF/WRF Toxicological Relevance (05-005) • WRF Research Needs (Cotruvo/Bull) • WRF IEUA Health Based (Nellor) • Intertox Tox Relevance (WRF) • NRC Panel

  8. There are Known Knowns and Unknown Knowns Uncertainty & Conservatism = f(lack of information)

  9. Uncertainty Drives Threshold Conservatism (Q4) • Standard EPA Uncertainty Factors Can be Applied to Balance Lack of Data b

  10. Risk Communication • Uncertainty is Reality • Other Routes of Exposure? • Open Discussion with the Public • Work to Fix Problem • …try to avoid these issues through intermediate monitoring

  11. What if You Exceed HRL? • Retest, split samples, document outlier or repeated event. • Running averages to document risk • acute versus chronic

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