Development of NJ Human Health-based Criteria and Standards

Transcription

1 Development of NJ Human Health-based Criteria and Standards Gloria Post NJDEP Office of Science Presented to: Public Health Standing Committee October 18, 2010

2 Human Health-based Criteria and Standards developed by NJDEP Drinking water Groundwater - based on drinking water use Surface water based on drinking water and fish consumption for fresh waters based on fish consumption for saline waters Soil cleanup Incidental ingestion, dermal (if data available), inhalation, impact to groundwater (site specific) Air toxics - based on inhalation exposure

3 Human Health Criteria vs. Standards Human health criteria are values based on a risk assessment approach which consider toxicity and exposure Regulatory standards are enforceable values which may consider additional factors: Analytical quantitation limits (PQL) Other factors when applicable, for example: Natural background (e.g. arsenic in soil) Treatment removal capability - drinking water

4 Standard vs. Criterion Example Health-based criterion (Healthbased MCL) Practical Quantitation Level Regulatory Standard (MCL) 5 ug/l 1 ug/l 5 ug/l 5 ug/l 5 ug/l 5 ug/l 5 ug/l 10 ug/l 10 ug/l

5 General Considerations for Health-based Criteria Based on chronic exposure Based on reasonable upper percentile exposure assumptions, for example: Drinking water consumption (L/day) Incidental soil ingestion (mg/day) Fish consumption (g/day) Risk assessment approaches consistent with USEPA methodology

6 General Considerations for Health-based Criteria (continued) General approach determined by classification of compound as carcinogenic or non-carcinogenic, based on USEPA Risk Assessment Guidelines Non-carcinogen criteria based on Reference Dose (mg/kg/day) Carcinogen criteria based on slope (potency) factor (mg/kg/day) -1 and 10-6 lifetime cancer risk

7 Risk Assessment Approach for Non-carcinogenic Endpoints Threshold approach Identify Point of Departure for most sensitive appropriate endpoint from animal or human study No Observed Adverse Effect Level (NOAEL), Lowest Observed Adverse Effect Level (LOAEL), or Benchmark Dose Apply appropriate uncertainty factors to derive Reference Dose Abridged definition of Reference Dose: Daily oral dose to humans (including sensitive subgroups) likely to be without appreciable risk of deleterious effects during a lifetime.

8 Uncertainty Factors in Reference Dose Development Default values are 10. Other value, such as 3, may be used when appropriate Intra-individual (susceptible human subgroups) Interspecies (animal-to-human) NOAEL-to-LOAEL Duration of Exposure (subchronic-to-chronic) Studies of less than subchronic duration normally not used as basis for chronic Reference Dose (except developmental) Not used for developmental endpoints of short duration because exposure takes place during relevant period. Database deficiencies or other unaddressed uncertainty

9 Risk Assessment Approach for Carcinogenic Endpoints Default approach based on non-threshold assumption. Threshold approach may be used if threshold Mode of Action is established. Linear low dose extrapolation from experimental data through low dose range to derive slope (potency) factor (mg/kg/day) -1 Risk level is a policy choice, not a scientific decision. NJ criteria are based on one-in-one million (10-6 ) lifetime cancer risk. This risk level is specified in the NJ Safe Drinking Water Act.

10 Sources of Toxicity Factors Used in Health-based Criteria Consistent for all NJ criteria based on oral exposure Toxicity factors developed for NJ drinking water standards by the NJ Drinking Water Quality Institute USEPA Integrated Risk Information System (IRIS) database Peer reviewed values used by all USEPA programs Other USEPA programs Developed by NJDEP Office of Science For contaminants of high priority (e.g. hexavalent chromium) or when no toxicity factor otherwise available When basis for IRIS factor not scientifically supportable (e.g. important new data has not been considered.)

11 If you have questions or would like more information: Gloria Post NJDEP Office of Science (609) Thank you!