Human Health Risk Assessment and Environmental Public Health Tracking

Question 1

Definition of risk

Answer 1

• The chance of harmful effects to human health resulting from exposure to an environmental Stressor
• Any physical, chemical, or biological entity that can induce an adverse response

Question 2

Definition of risk assessment

Answer 2

The process to estimate the nature and probability of adverse health effects to people who may be exposed to hazardous substances in contaminated environmental media Soil, groundwater, air, etc.

Question 3

Aspects of human health risk assessments conducted by the Agency for Toxic Substances and Disease Registry or by the U.S. Environmental Protection Agency

Answer 3

https://docs.google.com/document/d/1fsmRmza58qLBfgz6TQwp85vV4QdgA25KEvVa4xRBSJ4/edit?usp=sharing

Question 4

Major pre-step and steps (and definitions) of the U.S. Environmental Protection Agency’s Human Health Risk Assessment process

Answer 4

1. Hazard Identification
   -What health problems are caused by the
   pollutant?
2. Dose-Response Assessment
   -What are the health problems at different
   exposures?
3. Exposure Assessment
   -How much of the pollutant are people exposed
   to during a specific time period? How many
   people are exposed
4. Risk Characterization
   -What is the extra risk of health problems in the
   exposed population?

Question 5

Definition of toxicokinetics

Answer 5

Absorption - lungs
Distribution - blood
Metabolism - liver
Excretion - urine

Question 6

Definition of toxicodynamics

Answer 6

Cellular, organ, and organismal responses

Question 7

Non-linear dose-response assessment

Answer 7

Used when ‘mode of action’ data suggests a threshold for toxicity

Question 8

NOAEL: no observed adverse effect level

Answer 8

Denotes the level of exposure of an organism, found by experiment or observation, at which there is no biologically or statistically significant increase in the frequency or severity of any adverse effects

Question 9

LOAEL: lowest observed adverse effect level

Answer 9

The lowest concentration or amount of a substance found by experiment or observation that causes an adverse alteration

Question 10

Definition and examples of uncertainty factors

Answer 10

Full or partial order-of-magnitude values that help quantify our understanding of the uncertainty in a dose-response relationship
• Differences between animals and humans
• Variability within human populations
• Use of a LOAEL
• Use of a short-term study
• Database inadequacy (e.g., missing data on
certain effects)

Question 11

Reference dose and formula

Answer 11

An estimate of a daily exposure in humans, including sensitive populations, that is likely to be without appreciable risk of adverse effects during a lifetime.
𝑅𝑓𝐷 = 𝑒𝐷𝑜𝑠𝑒 / |-| (𝑈𝑛𝑐𝑒𝑟𝑡𝑎𝑖𝑛𝑡𝑖𝑒𝑠)
-Where – eDose is the effect dose –
Uncertainties
-Type of dose (NOAEL, LOAEL)
-Differences between animals and humans •
-Variability within human populations •
-Exposure duration (acute, subchronic, and
chronic exposure)
-Database inadequacy (e.g., missing data on
certain health effects)

Question 12

Linear dose-response assessment

Answer 12

-Used when the ‘mode of action’ data indicates no
toxicity threshold exists
-Often found when assessing carcinogenicity
-Theoretically, there is no level of exposure that
does not pose a small but real possibility of
generating a carcinogenic response
UFs are not used; a cancer slope factor is derived

Question 13

Exposure assessment estimation methods

Answer 13

Estimating the magnitude, frequency, and duration of human exposure to a substance in the environment

• Intake of water and selected liquids
• Non-dietary ingestion factors
• Ingestion of soil and dust
• Inhalation rates
• Dermal exposure factors
• Ingestion of foods
• Activity factors

Question 14

Definition of risk characterization

Answer 14

Goal: summarize and integrate information from the prior steps to develop an overall conclusion about risk (answer the “So what does it mean?” question)
  -Conveys the assessor’s professional judgement 
   regarding
  -Presence or absence of risks
  -Methodology
  -Assumptions
  -Uncertainties
  -Recommendations for action

Question 15

Environmental Public Health Tracking Network (and potential uses of EPHTN data)

Answer 15

http: //epht.health.utah.gov/
https: //ephtracking.cdc.gov/