1. Human Health Risk Assessment and Chemical Safety Stephanie Simstad The Ohio State University Extension Clermont County AFCEE, 2002

2. Acknowledgements U.S. EPA risk assessment documents including: U.S. EPA risk assessment documents including: –Risk Assessment Guidance for Superfund –Presenter’s Manual for “Superfund Risk Assessment and How You Can Help”

3. What if.. Your private water well has been sampled and results show that a commonly used pesticide is present in your drinking water. Your private water well has been sampled and results show that a commonly used pesticide is present in your drinking water. How would you determine whether this contaminant could be a health problem for your family? How would you determine whether this contaminant could be a health problem for your family? Ohio EPA

4. Overview Description of risk assessment and how it is used Description of risk assessment and how it is used Use of human health risk assessment process to evaluate a contaminated family well Use of human health risk assessment process to evaluate a contaminated family well Group exercise to identify source and pathways of pesticide into well Group exercise to identify source and pathways of pesticide into well Consideration of exposure pathway analysis to identify Best Management Practices for protection of drinking water sources Consideration of exposure pathway analysis to identify Best Management Practices for protection of drinking water sources

5. Human Health Risk Assessment A formalized process to evaluate risk posed to humans from exposure to an identified hazard A formalized process to evaluate risk posed to humans from exposure to an identified hazard –Evaluation of both cancer and noncancer effects –Evaluation of risk to adult, child, or even prenatal populations

6. Hazard versus Risk Hazard Hazard –Potential to do harm tornado tornado hazardous chemical hazardous chemical Risk Risk –Likelihood of defined harm to occur from specific hazard 1 additional cancer per 10,000 people exposed 1 additional cancer per 10,000 people exposed Individual Lifetime Risk of Developing Melanoma is 1 in 75. (OEPA) (NOAA) (NIH)

7. How is Risk Assessment Used? To set drinking water standards for public water supplies To set drinking water standards for public water supplies Licensing and regulation of pesticides Licensing and regulation of pesticides Identification and clean-up of hazardous waste sites Identification and clean-up of hazardous waste sites Identification of special handling requirements for chemicals Identification of special handling requirements for chemicals

8. Back to the Well... You’ve found that the family well is contaminated and you use this water for drinking, cooking, and bathing. You’ve found that the family well is contaminated and you use this water for drinking, cooking, and bathing. How would the risk to those who use water from the well be evaluated? How would the risk to those who use water from the well be evaluated?

9. Risk Assessment is a 4-Part Process Hazard Identification Hazard Identification –What chemicals are present and are they likely to be toxic? Exposure Assessment Exposure Assessment –Who is exposed, at what concentration, how often, and for how long? Toxicity Assessment Toxicity Assessment –How is it toxic and at what exposure levels? Risk Characterization Risk Characterization –What does the risk assessment tell us about this situation?

10. Risk Assessment Process (U.S. EPA) Hazard Identification Exposure Assessment Toxicity Assessment Risk Characterization

11. Step 1:Hazard Identification Collect data on presence of chemical Collect data on presence of chemical –Sampling –Modeling –Chemical fate and transport Determine if chemical may be toxic Determine if chemical may be toxic Develop model of how chemical may move through environment Develop model of how chemical may move through environment –Conceptual Site Model is used to organize information regarding chemicals and potential transport to people © Vermont DPS, 2000 AFCEE, 2002

12. Input for Conceptual Site Model Modified from Oak Ridge (2002) Conceptual Site Model Who may be exposed? How may they be exposed? How are chemicals transported to receptors? How does exposure change through time? What information is missing?

13. Modeling of Chemicals in the Environment Chemical characteristics Chemical characteristics –More or less soluble in water? Soil and connections to surface and ground water Soil and connections to surface and ground water –Type of soil –Likely paths to and through water sources General Concept General Concept –Based on knowledge of the chemical, the soils, and local water sources; predictions can be made about how that chemical will move through the environment.

14. Conceptual Site Model (Oak Ridge National Lab, 2002)

15. Step #2: Exposure Assessment Who is Exposed? Who is Exposed? –Adult, Child, Special Populations How Are They Exposed? How Are They Exposed? –Ingestion, Inhalation, Skin Contact What is the Concentration of Chemical to Which They are Exposed? What is the Concentration of Chemical to Which They are Exposed? –ppm in Water or Soil How Often Are They Exposed? How Often Are They Exposed? –Days per year, Number of years

16. Exposure Pathway Definition: The steps that a chemical takes from the source to an exposed individual Definition: The steps that a chemical takes from the source to an exposed individual –Exposure is contact with a chemical through either swallowing, breathing, or direct contact on skin Spilled Container SoilGroundwater Well Individual Using Well SOURCE Exposed Individual Path Traveled by Chemical

17. Exposure Pathway Diagram (ATSDR, 2002)

18. Complete Exposure Pathways Key to Risk Assessment is Identifying Complete Exposure Pathways Key to Risk Assessment is Identifying Complete Exposure Pathways –Individual must have contact with chemical for it to cause a health effect ChemicalReceptor Contact

19. Complete Exposure Pathway Steps in Complete Exposure Pathway Steps in Complete Exposure Pathway –Source –Chemical Transport and Transformation –Exposure Point –Receptor and Exposure Route Spilled Container SoilGroundwater Well Individual Drinks Water SOURCE RECEPTOR AND EXPOSURE ROUTE CHEMICAL TRANSPORT EXPOSURE POINT

20. Exposure Point and Exposure Route Exposure Point defines the place that an individual comes into contact with the chemical Exposure Point defines the place that an individual comes into contact with the chemical –Home with lead-contaminated paint Exposure Route describes the way a chemical enters the body Exposure Route describes the way a chemical enters the body –Ingestion (Eating and Drinking) –Inhalation (Breathing) –Dermal (Skin Contact)

21. Exposure Pathways All exposure pathways are not obvious All exposure pathways are not obvious –Ingestion of contaminated soil Children during play (200 mg soil /day) Children during play (200 mg soil /day) Children who deliberately ingest soil (1 gram soil/day) Children who deliberately ingest soil (1 gram soil/day) Incidental ingestion by adults (100 mg soil/day) Incidental ingestion by adults (100 mg soil/day) –Inhalation of chemical vapors During showering with contaminated water During showering with contaminated water –Volatile chemicals will vaporize into the air from the shower water, they can then be inhaled by person showering Vapor migration into homes from contaminated ground water or soil under homes Vapor migration into homes from contaminated ground water or soil under homes

22. Identify Source and Potential Exposure Pathways (Oak Ridge National Lab, 2002)

23. Back To Contaminated Well Example... Who is exposed when family farm well is contaminated? Who is exposed when family farm well is contaminated? What are their routes of exposure? What are their routes of exposure? Drinking Water Well ? Receptors Routes of Exposure ?

24. Exposure Assessment Purpose is to calculate dose that individual receives Purpose is to calculate dose that individual receives –Dose represents a daily average intake per unit of body weight Use information from conceptual site model and sampling to identify complete exposure pathways Use information from conceptual site model and sampling to identify complete exposure pathways Calculate dose for each exposure pathway by using exposure assumptions Calculate dose for each exposure pathway by using exposure assumptions Sum goes across all pathways to get total dose Sum goes across all pathways to get total dose

25. Exposure Assumptions Answer “how much” and “how often” people may be exposed to chemical in air, water, soil or dust Answer “how much” and “how often” people may be exposed to chemical in air, water, soil or dust Examples Examples –How much water does an adult drink in one day? –How many days per year is someone at their home? –How many years does someone live in the same house?

26. Why Calculate Dose? Paracelsus (15 th century scientist) Paracelsus (15 th century scientist) – “Dose makes the poison” For most chemicals, there is a threshold below which health effects are unlikely to occur For most chemicals, there is a threshold below which health effects are unlikely to occur –HOWEVER for some cancer-causing chemicals, a threshold is not assumed to exist Toxicity data can then be compared with dose to determine if health effect likely to occur Toxicity data can then be compared with dose to determine if health effect likely to occur Courtesy of the National Library of Medicine

27. Dose-Response Curve Dose – Chemical concentration per unit body weight Response – Level of measured adverse effect

28. Putting it all together... Intake Equation for Drinking Water Example Intake Equation for Drinking Water Example C= Chemical Concentration (Obtain from sampling) CR= Contact Rate (2 liters water/day) EF= Exposure Frequency (350 days/year) ED= Exposure Duration (30 years) BW=Body Weight (70 kg.) AT= Averaging Time (10,950 days)

29. Special Concerns During Exposure Assessment Children Children –Children will often have a higher dose than adults when exposed to the same chemical concentration in the environment Differences in children’s activities Differences in children’s activities –Playing in dirt, infant mouthing of toys, formula- dominated diet of young infants Water, food, and air intake per pound of body weight can be higher for children than adults Water, food, and air intake per pound of body weight can be higher for children than adults

30. Step #3: Toxicity Assessment What toxicity data are available? What toxicity data are available? –Acute or chronic effect? Or both? –Cancer or noncancer effect? Or both? Consider effects of multiple chemicals Consider effects of multiple chemicals –Similar to “Mode of Action” concept in pesticides but broader since multiple nonlethal effects can still have an adverse impact on human health Consider route of exposure Consider route of exposure – Effects can be route of exposure specific

31. Sensitive Subpopulations Children Children –Rapid development and differing physiologies of young children can result in potentially greater sensitivity to contaminants Lead exposure and the developing brain Lead exposure and the developing brain –Exposure to lead during prenatal or early childhood can cause irreversible intelligence losses –What are potential sources on the farm for lead exposure to children?

32. Sensitive Subpopulations Children or adults with health problems Children or adults with health problems –Compromised immune systems Undergoing chemotherapy Undergoing chemotherapy Organ transplant patients Organ transplant patients Diseases affecting immune system Diseases affecting immune system –Other diseases that affect body system that chemical exposure may target Children or adults with “hidden” sensitivities Children or adults with “hidden” sensitivities –Genes can increase or decrease susceptibility to environmental factors and can therefore modify risk

33. Distinction between Cancer and Noncancer Effects Calculation of dose and some exposure assumptions differ Calculation of dose and some exposure assumptions differ Large number of carcinogenic contaminants are assumed to have no threshold Large number of carcinogenic contaminants are assumed to have no threshold What would dose- response curve look like if we did not assume a threshold existed? Hint: An effect would be seen at any dose level.

34. Step #4: Risk Characterization The risk characterization combines the information obtained on toxicity with the calculated exposure to provide an estimate of risk. Purdue, 1997

35. Risk Characterization Answers What is the likelihood of harm following exposure to this chemical in this specific situation? What is the likelihood of harm following exposure to this chemical in this specific situation? –Provides a numerical estimate of risk –Identifies key uncertainties in this estimate –Compares numerical estimate of risk with a previously determined risk goal

36. Risk Goal Most environmental programs have a specified risk goal which has gone through review Most environmental programs have a specified risk goal which has gone through review Risk goal is a policy determination Risk goal is a policy determination –Risk goal is numerical estimate of acceptable risk for cancer or noncancer effects. 1 in 1,000,000 for cancer or the level of reference dose (threshold + uncertainty factor) for noncancer effect. 1 in 1,000,000 for cancer or the level of reference dose (threshold + uncertainty factor) for noncancer effect. Compare numerical estimate of risk with risk goal Compare numerical estimate of risk with risk goal If risk goal is exceeded, risk management decision necessary If risk goal is exceeded, risk management decision necessary

37. Risk Assessment is One Part of Decisionmaking Process to Manage Hazards Science determines likelihood of effect but risk management determines whether and how the risk should be addressed Science determines likelihood of effect but risk management determines whether and how the risk should be addressed Policy decision Policy decision

38. What Does Risk Assessment Not Tell Us? Whether risk is “acceptable” Whether risk is “acceptable” Whether risk is equitably distributed across population Whether risk is equitably distributed across population Predictions regarding personal or individual risk Predictions regarding personal or individual risk

39. Summary Risk assessment is a 4-part process to evaluate risk from suspected hazards. Risk assessment is a 4-part process to evaluate risk from suspected hazards. –Hazard Identification –Exposure Assessment –Toxicity Assessment –Risk Characterization For a hazard to have an adverse impact on health, there must be contact between the receptor and the hazard. Exposure must occur. For a hazard to have an adverse impact on health, there must be contact between the receptor and the hazard. Exposure must occur. Children and other sensitive subpopulations can have greater exposure and toxicity to the same environmental conditions than other adults. Children and other sensitive subpopulations can have greater exposure and toxicity to the same environmental conditions than other adults.

40. Summary contd. Risk goals are used as a comparison point with calculated risk values. These are policy, or nonscientific, determinations. Risk goals are used as a comparison point with calculated risk values. These are policy, or nonscientific, determinations. Risk characterization Risk characterization –defines the risk relative to the risk goal, –identifies uncertainties, and –identifies receptors and exposure pathways of most concern.

41. Summary contd. Risk management is the decisionmaking process to determine whether to take action for an identified risk. Risk management is the decisionmaking process to determine whether to take action for an identified risk.

42. Case Study Scenario Smith family well was found to have “herbex” contamination Smith family well was found to have “herbex” contamination Both neighboring farms have used or stored herbex Both neighboring farms have used or stored herbex Handouts Handouts – Risk Assessment Case Study Map – Pesticide Application Worksheet – Participant worksheet to complete – Herbex label

43. Case Study Map

44. Pictures of Storage Sheds Mr. Ulright’s Shed Mr. Sorong’s Shed

45. Hints Examine map closely Examine map closely Environmental information from herbex label Environmental information from herbex label Review Pesticide Application Worksheets Review Pesticide Application Worksheets Complete participant worksheet to aid in identifying all parts of exposure pathway Complete participant worksheet to aid in identifying all parts of exposure pathway

46. Case Study Answers Working back from the contaminated well Working back from the contaminated well –What are some possible sources and associated pathways? –Which source and pathway do you believe to be the most likely cause? Why?

47. Pesticide Selection? Pesticide Selection? Pesticide Storage? Pesticide Storage? Pesticide Application Practices? Pesticide Application Practices? Well Placement? Well Placement? Well Maintenance? Well Maintenance? Well Abandonment? Well Abandonment? BMP’s to Prevent Potential Well Contamination?

48. And How Can You Use Your New Risk Assessment Knowledge? Think about the possible ways that chemicals stored or used at your farm could reach receptors, especially through drinking water pathways. Think about the possible ways that chemicals stored or used at your farm could reach receptors, especially through drinking water pathways. X

49. Consider Drinking Water Sources Be aware of drinking water sources that could be affected by your use of agricultural chemicals Be aware of drinking water sources that could be affected by your use of agricultural chemicals –Private family wells? Public Water Supply wells? –Nearby reservoirs used as public water sources? –Drinking water intakes in rivers or streams? Take necessary steps to protect them Take necessary steps to protect them

50. Consider Local Conditions When Selecting Pesticides Be aware of geologic and hydrologic conditions when selecting pesticides Be aware of geologic and hydrologic conditions when selecting pesticides –Type of soils Sand versus clay? Sand versus clay? –Location of surface water bodies and runoff pattern of surface water –Location and depth of ground water Think: If you have shallow groundwater and sand/gravel soils, what should you be concerned about if you choose to apply a highly water soluble pesticide?

51. Consider Local Surface Water Quality Conditions Be aware of local water quality conditions when selecting pesticides Be aware of local water quality conditions when selecting pesticides –Are there any identified problems with pesticides in water, sediment or fish in local streams or rivers? See Ohio EPA’s web site and associated reports See Ohio EPA’s web site and associated reports –Join your local watershed group! Most watersheds in the state have a watershed coordinator and group working to improve water quality Most watersheds in the state have a watershed coordinator and group working to improve water quality OEPA

52. Consider and Use Appropriate BMPs Be aware of BMPs when storing and applying pesticides Be aware of BMPs when storing and applying pesticides –Store properly and be prepared for spills –Read and follow the label! Drinking and surface water advisories (e.g., Atrazine) Drinking and surface water advisories (e.g., Atrazine) –Use buffer strips and maintain streamside areas in natural state U.S. EPA NRCS University of Arizona