Exposure Science (5)

Question 1

What is exposure science?

Answer 1

The study of human contact with chemical, physical, or biological agents occurring in their environments

Can address past, present, or expected exposures

Question 2

Examples of exposure pathways?

Answer 2

1. Groundwater contamination
2. Radiation
3. Multi-pollutants

Question 3

What are the objectives of exposure science?

Answer 3

1. Follow trends/status (identify pollutants of concern)
2. Risk assessment
3. Epidemiologic studies (exposure assignment, exposure validation)
4. Examine disease etiologies

Question 4

What are the four steps of risk assessment?

Answer 4

1. Hazard ID
2. Exposure Assessment
3. Dose Response Assessment
4. Risk Characterization

Question 5

How can we quantify exposures?

Answer 5

1. Direct measurements (at point-of-contact)
2. Scenario modeling/evaluation (hypothetical exposures)
3. Biomonitoring (biomarkers, excretion levels, historical exposures)

These approaches are independent of each other

Question 6

What are some issues in planning risk assessments?

Answer 6

1. Cost
2. Statistical power (generalizability, detecting significance)
3. Time
4. Uncertainty

Question 7

Applications of direct measurement

Answer 7

Environmental air/water pollutants, radiation, pesticides

Question 8

Advantages of direct measurement

Answer 8

Direct measurement, accurate

Question 9

Disadvantages of direct measurement

Answer 9

Expensive, time-consuming, cumbersome, limited range of pollutants

Question 10

Applications of modeling/evaluation

Answer 10

Groundwater, indoor air, soil sampling at waste sites

Question 11

Advantages of modeling/evaluation

Answer 11

Inexpensive; can be prospective

Question 12

Disadvantages of modeling/evaluation

Answer 12

Assumptions; validation required

Question 13

How can we measure ambient concentrations?

Answer 13

Dispersion models

Question 14

How can we measurer ground level PM?

Answer 14

Remote sensing

Question 15

Applications of biomonitoring

Answer 15

Lead, dioxin, VOCs (volatile organic compounds)

Question 16

Advantages of biomonitoring

Answer 16

Gives idea of internal dosage; biologically-relevant exposure; historical exposures

Question 17

Disadvantages of biomonitoring

Answer 17

Requires pharmacokinetic info; potentially expensive & invasive

Question 18

What is the exposome?

Answer 18

The measure of all the exposures of an individual in a lifetime and how those exposures relate to health.

Question 19

How can we characterize the exposome?

Answer 19

Top-Down and Bottom-Up

Question 20

Advantages of “Bottom-Up” characterization

Answer 20

1. Focus on external, familiar sources & products

2. Direct policy and intervention implications

Question 21

Disadvantages of “Bottom-Up” characterization

Answer 21

1. Many, many pathways
2. Unknown exposures
3. How do we evaluate mixtures/synergistic relationships?

Question 22

Advantages of “Top-Down” characterization

Answer 22

1. Efficient (both endogenous & exogenous)
2. Represents totality of exposure
3. Hypothesis-generation
4. Focus on unknown causes of disease

Question 23

Disadvantages of “Top-Down” characterization

Answer 23

1. Hard to define “normal”
2. Inter-individual variability
3. Agnostic, not hypothesis-driven

Question 24

What is the “Top-Down” approach?

Answer 24

Untargeted method utilizing biological systems methods

Question 25

What is the “Bottom-Down” approach?

Answer 25

1. Corresponds to traditional EH practice

2. Identifies key exogenous exposures