11.6: Risk Assessment
- Page ID
- 485488
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Learning Objectives
After completing this lesson, you will be able to:
- Identify the basic steps in the risk assessment process.
- Explain the framework for risk-based decision-making.
- Describe methods for identifying hazards.
- Explain methods for toxicity assessment, including dose-response and exposure.
In this section...
Topics include:
What We've Covered
This section made the following main points:
- A hazard is the capability of a substance to cause an adverse effect.
A risk is the probability that the hazard will occur under specific conditions. - Risk assessment is the process of determining hazard, exposure, and risk.
Risk management is the process of weighing policy alternatives and deciding on the most appropriate regulatory action. - There are four basic steps to risk assessment:
- Hazard Identification
- Identify or develop information suggesting or confirming whether a chemical poses a potential hazard to humans.
- (Quantitative) Structure Activity, or (Q)SAR methods, including computer models, help consider closely related chemicals as a group or category.
- Read-across involves estimating what a chemical may be like, including the presence or absence of certain properties or activities, based on one or more other chemicals.
- Adverse Outcome Pathways (AOPs) involve in vitro methods that evaluate changes in normal cellular signaling pathways.
- Other emerging methods include (Quantitative) in vitro to in vivo extrapolation, or (Q)IVIVE, Integrated Testing Strategies, and Integrated Approaches to Testing and Assessment (IATA).
- Dose-Response Assessment
- Carcinogenic (cancer) risk assessment involves two steps:
- Perform qualitative evaluation of all epidemiology studies, animal bioassay data, and biological activity.
- Quantitation of the risk for substances classified as definite or probably human carcinogens.
- Non-carcinogenic risk assessment includes:
- Acceptable Daily Intake (ADI), which divides the NOAEL by uncertainty/safety factors.
- Reference Dose (RfD), which divides the NOAEL or LOAEL by uncertainty/safety factors.
- Benchmark Dose Method (BMD), which extrapolates data to determine a point of departure (POD) that accounts for study quality.
- Assessments for noncancer toxicity effects, acute or short-term exposures, and occupational exposures.
- Carcinogenic (cancer) risk assessment involves two steps:
- Exposure Assessment
- People are exposed to mixtures of hundreds of chemicals in everyday life.
- An exposure pathway describes the:
- Route a substance takes from its source to its endpoint.
- How people can be exposed to the substance.
- The three steps of exposure assessment are to:
- Characterize the point of exposure setting and exposure scenario.
- Identify exposure pathways.
- Quantify the exposure.
- Exposure models are commonly used because actual exposure measurements are often not available.
- Risk Characterization
- This final phase predicts the frequency and severity of effects in exposed populations.
- Biological and statistical uncertainties are described.
- For carcinogenic risks, the probability of a person developing cancer over a lifetime is estimated by multiplying the cancer slope factor for the substance by the chronic, 70-year average daily intake.
- For noncarcinogenic effects, the exposure level is compared with an ADI, RfD, or MRL derived for similar exposure periods.
- Hazard Identification