Outline: risk assessment. What kind of environmental risks do we commonly consider? 11/19/2013. Why do we need chemical risk assessment?

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Griselda Haynes
6 years ago
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Outline: Human health h and ecological l risk

quantifying risk Case study: Children s exposure to As

New directions SWS 6262 Ky Gress What kind of

Potential for adverse consequences from: Residential

Food and body products Activities Why do we need

Over 70,000 synthetic chemicals in use >700 more

1 Outline: Human health h and ecological l risk assessment Purpose of risk assessment Methodology for quantifying risk Case study: Children s exposure to As from CCA wood staircases Issues practical and political New directions SWS 6262 Ky Gress What kind of environmental risks do we commonly consider? Potential for adverse consequences from: Residential location Household chemical use Drinking water quality Food and body products Activities Why do we need chemical risk assessment? Over 70,000 synthetic chemicals in use >700 more introduced yearly Burden of testing on government No relevant toxicological data on most Americans exposed to >5,000 chemicals/day 1

2 Drivers behind risk assessment: Environmental degradation Social burden of morbidity and mortality Cancer epidemic Reproductive effects Rate of species extinctions Financial priorities Decline in quality of life What does risk assessment attempt to quantify? Effects on health and well-being of individuals and groups Impact of specific behaviors Vulnerabilities (HEI) Variability and uncertainty Impact of regulations Typical uses of RA: Hazardous waste sites Changed land use Industrial accidents Unusual disease incidence Evidence of increased exposure Changes in regulations Legal challenges Important for assessing common, low-dose exposures: Arsenic in rice, mercury in fish, BPA in plastics, pthalates in body products, PBDEs in mattresses, chromium(vi) in drinking water, pesticides in food, growth hormones, endocrine disruptors, PAHs, lead dust, dioxins HEI = 2

The role of risk assessment in environmental crisis: The role of RA in setting regulatory limits: Nuclear meltdowns at Fukushima Where is it safe to live? What can I eat and drink?

What about animals living in the forest?

Susceptible to political influence Soil clean-up target levels for arsenic (mg/kg): California: 0.07 Florida: 2.

3 The role of risk assessment in environmental crisis: The role of RA in setting regulatory limits: Nuclear meltdowns at Fukushima Where is it safe to live? What can I eat and drink? Is my child going to develop cancer? Is it safe to work on the site? Can we fish in the ocean? Can the farmland be remediated? Is it safe to get pregnant? What about animals living in the forest? Purpose is to estimate likelihood of adverse health effects from exposure 1x10-6 for 95% of exposed population considered acceptable risk Based on assumptions Art within a Science Susceptible to political influence Soil clean-up target levels for arsenic (mg/kg): California: 0.07 Florida: 2.1 Texas: 24 England: 32 Australia: 100 Japan: 150 (rice growing regions 15) These SCTLs have serious economic consequences and each one is set taking into account the likelihood of health effects. Risk assessment at your site: Who was exposed to the contaminants at your site? What were the routes and pathways of exposure? How does the remediation impact exposures? What more can be done to protect people/animals? 3

4 Risk assessment methodology: Hazard Identification Is it known to be hazardous? Dose-Response Assessment What known health effects at different doses? Exposure Assessment What dose are people/animals exposed to? Risk Characterization What type of effects are likely? How do we identify a hazardous chemical? Epidemiologic data Animal studies (NOEC, LD 50 ) Bioassays cell cultures QSAR compare molecular structure of new chemicals to others with known biological activity x.asp Dose-response assessment: What effects occur at different doses? Is there a NOAEL? Typically based on animal studies Often no human toxicity data Complicated by mixtures and cumulative exposures Setting a reference ( safe ) dose for non-carcinogen: Determine most sensitive endpoint Find concentration where no observed adverse effect Reference dose = NOAEL/ uncertainty factors Interspecies & population variability = UF of 100 4

Evaluating toxicological studies to set a reference dose:

is most sensitive endpoint with NOAEL of 5 mg/kg-bw/day

no safe dose Chemical-specific cancer slope factor reflects

contaminant has both cancer and non-cancer effects? http://www.epa.

NERL) International Agency for Research on Cancer (IARC) Exposure

5 Evaluating toxicological studies to set a reference dose: threshold Dose (mg/kg bodyweight) Liver damage is most sensitive endpoint with NOAEL of 5 mg/kg-bw/day Dose-response assessment for carcinogens: For many carcinogens, is no safe dose Chemical-specific cancer slope factor reflects potency Cancer risk = Cancer slope factor x dose What if a contaminant has both cancer and non-cancer effects? Who is working to codify hazard identification and doseresponse data? National Toxicology Program US Public Health Service USEPA (IRIS, NERL) International Agency for Research on Cancer (IARC) Exposure assessment: what constitutes an exposure? Direct contact with tissue Bioaccessibility versus bioavailability Role of biomarkers of exposure NERL - USEPA 5

11/19/2013 Calculating an exposure dose: Routes of exposure: ingestion, inhalation, dermal

(exposure factors) Exposure dose (mg/kg-d) = Concentration x Duration x Frequency USEPA Exposure

IR x B x EF x ED x CF BW x AT C = concentration in soil; IR =ingestion ingestion rate; B =

bodyweight; AT = averaging time (6 years) Risk (HQ) = Actual dose/ Reference dose Estimating a

= concentration in soil IR = ingestion rate EF = exposure frequency ED = exposure duration B =

6 11/19/2013 Calculating an exposure dose: Routes of exposure: ingestion, inhalation, dermal Pathways of exposure: air, water, soil, sediment,, food,, dust How much, how long and how often (exposure factors) Exposure dose (mg/kg-d) = Concentration x Duration x Frequency USEPA Exposure Factors Handbook, 2011: Calculating an average daily dose for non-carcinogen: ADD (mg/kg-d) = C x IR x B x EF x ED x CF BW x AT C = concentration in soil; IR =ingestion ingestion rate; B = bioavailability; EF = exposure frequency; ED = exposure duration; CF = conversion factor; BW = bodyweight; AT = averaging time (6 years) Risk (HQ) = Actual dose/ Reference dose Estimating a lifetime average daily dose for a carcinogen: LADD (mg/kg-d) = C x IR x EF x ED x B x CF BW x AT C = concentration in soil IR = ingestion rate EF = exposure frequency ED = exposure duration B = bioavailability CF = conversion factor (1 10-6) BW = bodyweight AT = averaging time (70 years) Risk = Dose x Cancer slope factor 6

7 Issues with exposure assessment: Accurate sampling Use of averages, assumptions Variability unaccounted for Able to manipulate data, modeling Case study: Children s exposure to arsenic from CCA wood HEI, 3 years old Background: Chromated copper arsenate (CCA) used to preserve lumber Found in public places and around homes Arsenic leaches from wood, contaminates soil Hazard identification: arsenic Naturally-occurring and anthropogenic sources, ubiquitous Group A human carcinogen Non-cancer effects stance.asp?toxid=3 7

Dose-response assessment: Exposure assessment: Acute minimal risk level: 0.

00030003 mg/kg-d Cancer slope factor of 1.5 (adults) and 4.

Children contact soil, wood and objects Soil sampling in uniform grid

risks Soil arsenic concentrations under staircases (mg/kg): 70 60 50 As,

2 ): 160 120 As (mg/kg g) 40 30 20 10 DA (µg/100 cm²) 80 40 20 0 A-1 A-2

8 Dose-response assessment: Exposure assessment: Acute minimal risk level: mg/kg-day NOAEL: mg/kg-d Reference dose: mg/kg-d Cancer slope factor of 1.5 (adults) and 4.5 (children) RfD is exceeded by many through ingestion of food and water Children contact soil, wood and objects Soil sampling in uniform grid Dislodgeable As (DA) on wood and objects Calculate doses Estimate cancer risks Soil arsenic concentrations under staircases (mg/kg): As, <2 mm As, <250 µm Bioaccessible As Dislodgeable As on railings (µg/100 cm 2 ): As (mg/kg g) DA (µg/100 cm²) A-1 A-2 A-3 B-1 B-2 B-3 C-1 C-2 C-3 D-1 D-2 D-3 10 Staircases at complexes A-D 0 A-1 A-2 A-3 C-1 C-2 D-1 D-2 D-3 D-4 D-5 non-cca 8

Dislodgeable As (DA) on objects (µg/100 cm 2 ): g/100 cm²) As (µg 2.5 2 1.5 1 0.

method developed to sample lead dust on hard surfaces.

9 mg/kg) IR = Ingestion rate (100 mg/day) EF = Exposure frequency (350 days/year) ED = Exposure duration (6 years) CF =

0 10-5 to 8.1 10-6 from combined DA and soil 1.2 10-5 to 4.

9 Dislodgeable As (DA) on objects (µg/100 cm 2 ): g/100 cm²) As (µg grip-a seat-a grip-b seat-b Grill top Toy car Toy car Amount of DA on object surface seat-c seat control Assessed using wipe method developed to sample lead dust on hard surfaces. seat control ADD from ingestion of soil: ADD (mg/kg/d) = C x IR x EF x ED x CF BW x AT C = Bioaccessible As (6.9 mg/kg) IR = Ingestion rate (100 mg/day) EF = Exposure frequency (350 days/year) ED = Exposure duration (6 years) CF = Conversion factor (1x10-6 ) BW = Mean bodyweight child 1-6 yo (14.6 kg) AT = Averaging time (2190 days) ADD = mg/kg-d HI = 0.15 No acute risk LADD and cancer risk from DA and soil ingestion: LADD (mg/kg/d) = C x HT x EF x ED x B x CF BW x AT to from combined DA and soil to cancer risk Estimated cancer risk is above regulatory threshold of level of acceptable risk. Of 100,000 children having exposure to CCA wood staircases, 1-5 of them likely to develop cancer as a result. Risk characterization: Under some circumstances, there is an increased risk of cancer in children living in apartment complexes with CCA wood staircases Describe assumptions made Indicate factors that may lead to increased or decreased risk Make recommendations 9

Commonalities between HHRA and ecological RA: Collect samples

target population(s) p Assess multiple pathways of exposure

important consideration Differences between HHRA and ERA:

species Lack of understanding about animal

protection Out of sight, out of mind Importance of soil

protocols Bioaccessibility and bioavailibility Mitigation of

New directions for risk assessment: Focus on cumulative

10 Commonalities between HHRA and ecological RA: Collect samples from environmental media Focus on adverse health effects of target population(s) p Assess multiple pathways of exposure air, water, sediment/soil Impact on reproductive outcomes important consideration Differences between HHRA and ERA: Serious limitation in the toxicological data on diverse species Lack of understanding about animal behavior,,population p numbers, ecology Weak regulatory protection Out of sight, out of mind Importance of soil science in RA: Fate and transport of toxic substances Sampling protocols Bioaccessibility and bioavailibility Mitigation of risk Guidance to affected residents, policy makers and lawyers New directions for risk assessment: Focus on cumulative exposures Effects of multiple stressors Emphasis on vulnerable subgroups Increasing chemical tox data REACH, QSAR GIS 10

11 Use of RA to assist consumers in making informed choices: 11

Development of NJ Human Health-based Criteria and Standards

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