1. Introduction to Exposure Investigations
Susan W. Metcalf, MD
Kenneth Orloff, PhD
Greg Zarus

2. Assessing Human Exposure to Environmental Contamination
Exposure Investigations
Assessing Human Exposure to Environmental Contamination

3. Today’s Agenda Introduction 20 min How We Decide 25 min
Who we are
Purpose/Mission
What we do
How We Decide min
Four questions
Bio Markers min
How they’re used
Limitations
Quality Assurance 55 min
Limiting uncertainty
Altered methods
Site Example min
Community specific sampling
Biologic and Environmental samples

4. Agency for Toxic Substances and Disease Registry

5. What is ATSDR ?
A Federal public health agency that addresses human health issues that might arise from exposure to hazardous substances in the environment

6. Site Specific Evaluations
Public Health Advisories
Public Health Assessments
Health Consultations
Exposure Investigations

7. Public Health Assessments Evaluate
Environmental data
Health outcome data
Community concerns
Environmental data-
Bulk of the PHA usually concerns environmental data
available environmental data collected by EPA or state environmental agencies.
which may be inadequate to evaluate pathways of exposure to contaminants of concerns and for making a public health determination
may be out-of-date

8. Rationale for Exposure Investigations
“Virtually no information about actual exposure to the public is derived from personal sampling, direct exposure of individuals, or total exposure assessment modeling.”
National Academy of Sciences, 1991
In 1991 ATSDR requested that the National Research Council convene the Committee on Environmental Epidemiology to review current knowledge about the health effects of hazardous substances and to suggest ways to improve the scientific bases for evaluating the effects of exposure to these substances.
they came to the not-to startling conclusion that exposure assessment is crucial for carrying out environmental epi studies.
And in the course of addressing appropriate approaches to measuring exposure, they specifically looked at the public health assessments
The slide sums up what the report said about the information provided in PHA about off-site contamination

9. Objective of Exposure Investigation
To gather and analyze site-specific information to determine if human populations have been exposed to hazardous substances
1. Fill data gap in pathway for a contaminant
Site-specific- not a study and are not generalizable
Focus on those that have the likelihood of the highest exposure.\
often the purpose of an EI is to provide information to transition to a follow up activity
Health study
To get partners (EPA, state agencies) to take action

10. The EI Section: Multidisciplinary
Engineer
Industrial hygienist
Epidemiologist
Environmental scientist
Toxicologist
Atmospheric scientist
Physicians

11. Environmental Health Continuum1 2 3 4 5
Exposure Assessment
Epi studies
Pathway Transport

12. Types of Exposure Investigations
Bio-medical testing (blood, urine, hair)
Environmental testing (air, water, soil, house dust)
Exposure-Dose Reconstruction (ground water/air modeling)

13. Bio-medical Testing Biomarkers of exposure Biomarkers of effect
Blood serum dioxins
Urine mercury
Biomarkers of effect
IgE antibodies to diisocyanates
Urine RBP
Biomarkers of susceptibility
α1-antitrypsin deficiency

14. Biological Sampling
Blood
Urine
Hair
Expired air
Saliva
Fat

15. Environmental Sampling
Air
Water
Soil
House dust
Food

16. Dose Reconstruction Air Modeling for Concentrations
Water Modeling for Concentration
Dose Calculations

17. Exposure can be defined as contact over time between a person and one or more biologic, chemical or physical agents.
Conceptually, Exposure would seem to be a simple concept.

18. Exposure Parameters Agent Environmental media/transport Concentration
Source
Point of exposure
Route of exposure
A LARGE number of parameters that need to be described to define an exposure and need to be considered if you want to measure exposure
Agent
Biologic Single Agent
Chemical
Physical Mixtures
Sources
Anthropogenic/Non anthropogenic
Area/Point
Stationary/Mobile
Indoor/Outdoor
Environmental Media and Transport
Air Water Soil Dust
Food- subsistence fishing; locally group vegetables
Point of Exposure- location that contact with media occurs
Residence /Non residential
Indoors/Outdoors
Occupational/non occupational
Route of Exposure
inhalation ingestion dermal contact
Concentration

19. Exposure Parameters (Continued)
Frequency
Population
Time frame
Duration
Geographic scope
Duration- how long does the exposure last
minutes hours days weeks months lifetime
Frequency- may partly be determined by individual activity pattern
continuous intermittent rare
cyclic random
Geographic Scope
Site specific Local Regional National
International Global
Exposed Population
General population
Subgroups (specific groups/ susceptible groups)
Window of vulnerability
Time Frame
Past Present Future Trends

20. Characteristics of an Exposure Investigation
Site-specific
Public health-oriented
Involves community
Exposure investigations are a public health service activity
not meant to be research
(but we can learn from them)
Frequent collaboration with Community Involvement Branch
Health Education

21. Exposure Investigations
Fill specific data gaps
Are completed in a relatively short time period
Support a collaborative public health process by involving stakeholders
Provide a scientific basis to support public health actions

22. Limitations of Exposure Investigations
Exposure does not mean effect
Source of the exposure may not be identified
May represent only current conditions
Relevant biomarkers are limited to certain contaminants
Lead and Hg?
Most of our investigations that involve biomarkers deal with metals and persistent organic compounds

23. ATSDR Exposure Investigations (since late 1997)
53 Sites where we collected Biological and Biota samples
54 Sites where we collected Environmental samples (

24. ATSDR Exposure Investigations Biological and Biota
53 Biological and Biota (e.g.)
Urine; mercury
Blood; dioxin
Hair; arsenic
fish, crabs, eggs; metals, pesticides

25. ATSDR Exposure Investigations Environmental
54 Environmental (e.g.)
Air: hydrogen sulfide
Water: lead
Soil: PCBs
Dust: arsenic
(PM)
(PM)

26. Requestors of Exposure Investigations
State/County/Tribal health departments
Citizens/residents (Petitioned Health Assessments)
Elected representatives
Environmental action groups

27. How to get our help
Requesters submit answers to four questions designed to evaluate if an exposure investigation can help (discussed later).
An inter-disciplinary panel of scientists interview the requester to determine the best course of action.