overview of human health risk assessment
TRANSCRIPT
Office of Research and DevelopmentCenter for Public Health and Environmental Assessment
Overview of Human Health
Risk Assessment
Office of Research and DevelopmentCenter for Public Health and Environmental Assessment
RISK ASSESSMENT TRAINING & EXPERIENCE
RASS Syllabus - 101
Disclaimer:
The views expressed are those of the speakers and do not necessarily
represent the views or policies of the U.S. Environmental Protection Agency.
RASS 101
Overview of Human Health
Risk Assessment
Goals and Objectives
• Review risk assessment process
• Discuss components of risk assessment
• Review types of data used in risk assessment
• Discuss benefits and limitations
of risk assessment process
• (Briefly) discuss Risk Characterization
1
Photo credit: flickr user Oldmaison
RASS 101
Engineering/
Structural
“Risk and Risk Assessment” is
Contextual
Financial/
Business
Security:
Vulnerability
and Threat
Ecological
Human
Health
Office of Research and DevelopmentCenter for Public Health and Environmental Assessment
RISK ASSESSMENT
TERMINOLOGY
RASS 101
EPA’s Definition of Risk
Assessment
Risk assessment:
“….qualitative and quantitative evaluation
of the risk posed to human health and/or
the environment by the actual or potential
presence and/or use of specific pollutants”
From EPA’s “Terms of Environment” Glossary
RASS 101
Risk Assessment Definitions
Hazard: A potential source of harm.
Hazard identification: The process of
determining whether exposure to an agent can
cause an increase in the incidence of a
particular adverse health effect (e.g., cancer,
birth defect) and whether the adverse health
effect is likely to occur in humans
EPA’s IRIS Glossary
RASS 101
Risk Assessment Definitions
Exposure: Contact made between a chemical, physical, or biological agent and the outer boundary of an organism. Exposure is quantified as the amount of an agent available at the exchange boundaries of the organism (e.g., skin, lungs, gut).
RASS 101
Risk Assessment Definitions
Exposure Assessment: An identification and evaluation of the human population exposed to a toxic agent, describing its composition and size, as well as the type, magnitude, frequency, route and duration of exposure.
Guidelines for human exposure assessment: https://www.epa.gov/sites/production/files/2020-
01/documents/guidelines_for_human_exposure_assessment_final2019.pdf
RASS 101
Risk Assessment Definitions
Potential dose:
Ingested, inhaled,
applied to skin
(μg / kg–day)
Applied dose:
Available for
absorption
(μg / m3)
Internal dose:
Amount absorbed
and available for
interaction
(μg / kg)
Dose
RASS 101
Risk Assessment Definitions
Dose Response Assessment: A determination of
the relationship between the magnitude of an administered,
applied, or internal dose and a specific biological response.
Response can be expressed as
• measured or observed incidence or change in level of
response,
• percent response in groups of subjects (or populations),
or
• the probability of occurrence or change in level of
response within a population.
Benchmark dose response guidance: https://www.epa.gov/sites/production/files/2015-
01/documents/benchmark_dose_guidance.pdf
RASS 101
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RE
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: F
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f p
op
ula
tio
n a
ffe
cte
d
DOSE:mg/kg-day
Example Dose-Response
Curves
RASS 101
Risk Assessment Definitions
Reference Dose: An estimate of a daily oral exposure
to the human population that is likely to be without an
appreciable risk of deleterious effects during a lifetime.
Reference Concentration: An estimate of a
continuous inhalation exposure to the human population that
is likely to be without an appreciable risk of deleterious
effects during a lifetime.
A review of reference dose and reference concentration process.
https://www.epa.gov/sites/production/files/2014-12/documents/rfd-final.pdf
RASS 101
Risk Assessment Definitions
Risk Characterization: The integration of
information on hazard,
exposure, and dose-
response to provide an
estimate of the likelihood
that any of the identified
adverse effects will occur in
exposed people.
https://www.epa.gov/sites/production/files/2015-
10/documents/osp_risk_characterization_handbook_2000.pdf
RASS 101 13
Overview of Human Health
Risk Assessment
Information
DECISION
Ban
More research
Standards:air, water, food
Priorities:research,
regulation
Risk char
Social
Economic
Legal
• Epidemiology
• Clinical Studies
• Animal Studieso Species, exposure, etc.
• S.A.R. (Structure Activity
Relationships)
• Modeling
RESEARCHRISK
ASSESSMENT
Hazard Identification
Dose-Response
Assessment
Exposure Assessment
Information
Research
Needs
Assessment Needs
Planning & Scoping
RISK
MANAGEMENT
National Research Council, 2014
RASS 101
Risk Assessment and
Risk Management
• Risk assessors and risk managers need to have a good sense of when a decision is scientific judgment versus when it is a policy decisioninformed by science.
• Opinions vary on how separated risk assessment and risk management should be.
• The most current frameworks recommend an iterative process.
• Transparency is key.
Risk
Assessment
Risk
Management
SCIENCE POLICY
RASS 101
Decision
Synthesis
Characterization
Analysis
Planning and ScopingScientific Factors
(Risk Assessment)
Economic
Factors
Public Values
Political Factors
Technological
Factors
Social Factors
Legal Factors
Risk Management
Decision Framework
Source: EPA’s Risk Characterization Handbook (2000)
RASS 101 16
NRC Risk Assessment/
Risk Management Paradigm
Source: NRC 2014, adapted from NRC 1983
IRIS
TSCA
RASS 101 17
Dose-Response Assessment• Characterize
exposure-response relationships
• Account for extrapolations
Risk Characterization• Integrate hazard,
dose-response and exposure assessments
Hazard Identification• Which effects are
credibly associated with the agent?
• Which are relevant to human health?
Exposure Assessment• How are people
exposed to the agent?• How much are they
exposed to?
Risk Management• Develop, analyze,
compare options• Select appropriate
response
Activities of public health agencies
EPA Offices, Regions, States, Tribes, etc
EPA’s IRIS Program
Other EPA Offices, some States
ATSDR Tox Profiles (non-cancer)
NTP RoC, WHO/IARC
EPA Offices, Regions, States, Tribes, etc.
HBA 201 18
COMPONENTS OF RISK
ASSESSMENT:
PLANNING AND
SCOPING
RASS 101 19
Planning and Scoping
Identify the Problem
• Where does the problem exist?
• Who or what is affected?
• What causal agents should be considered?
• What are the system boundaries?
• What are risk management needs?
• What are stakeholder needs?
• What are the scientific questions specific to the
assessment?
RASS 101
Scoping and Problem
Formulation: IRIS example
20
https://www.epa.gov/iris/basic-information-about-integrated-risk-information-system#process
RASS 101
Systematic Review
“… systematic review is a scientific
investigation that focuses on a
specific question and uses explicit,
pre-specified scientific methods to
identify, select, assess, and
summarize the findings of similar but
separate studies. The goal of
systematic review methods is to
ensure that the review is complete,
unbiased, reproducible, and
transparent.”
IOM (Institute of
Medicine). 2011.
Finding What Works in
Health Care: Standards
for Systematic Reviews.
Washington, DC: The
National Academies
Press.
https://www.nap.edu/c
atalog/13059/findingwhat-
works-in-healthcare-
standards-forsystematic-
reviews
21
A structured and documented process for transparent literature review
RASS 101
PECO Statement
PECO =
• Populations
• Exposures
• Comparators/Controls
• Outcomes
Defines the criteria used in a systematic approach
to identify strengths and limitations regarding
individual attributes for each study that can affect
the confidence in the study results.
22
U.S. EPA. ORD Staff Handbook for Developing IRIS Assessments (Public Comment Draft, Nov 2020).
U.S. EPA Office of Research and Development, Washington, DC, EPA/600/R-20/137, 2020.
https://cfpub.epa.gov/ncea/iris_drafts/recordisplay.cfm?deid=350086
RASS 101 23
Development of the Supporting
Literature Database
Literature search strategy:
1. Develop list of search terms
2. Conduct individual searches of relevant databases
3. Conduct searches of relevant websites for other applicable documents, for example:
▪ Gray literature
▪ International Agency for Research on Cancer (IARC) Reports
4. Produce annotated reference outline for the toxicological review
RASS 101
SWIFT Review
Problem formulation and
screening prioritization
HAWC (manual)
Distiller* (manual, but also has
machine learning)
SWIFT Active* (machine learning)
Reference screening and tagging
*supports multiple screeners
Qlik Sense, Tableau, Power BI
Interactive visualization of
screening results and literature
inventory
Database of SR software tools:
http://systematicreviewtools.com/
24
Systematic Review Tools
24
RASS 101 25
•Broad surveys to assess extent
and nature of evidence, level of
effort, type of expertise required
•Surveys inform decisions on
targeted focus, e.g., evidence
streams to consider core-PECO
(versus supplemental), health
outcomes likely covered in
assessment
•Surveys may be developed
based on other assessments,
manual review of studies, or
through use of specialized
software applications
Literature Surveys
Outcomes
Human Studies Animal Studies
Occ
up
atio
nal
ep
idem
iolo
gy
Gen
eral
po
pu
lati
on
ep
idem
iolo
gy
Co
ntr
olle
d e
xpo
sure
Cas
e re
po
rts
and
case
ser
ies
rep
ort
s
Ch
ron
ic
Sub
chro
nic
Sho
rt-t
erm
Acu
te
Mu
lti-
gen
erat
ion
al
Ges
tati
on
al
Cancer 60 13
Cardiovascular 1 1 3
Dermal and ocular 1
Developmental 14 2 6
Endocrine(thyroid) 6 1 4 3 1
Gastrointestinal 1 7 5 1
Hematological 25 3 10 4 6 3 1
Hepatic 3 2
Immunological
Metabolic disease 8
Musculoskeletal
Neurological and sensory 1 6 1 1 1
Renal 1
Reproductive 3 2 2 1
Respiratory
Other 9 2 1 1
The numbers represent the numbers of studies that investigated a particular
health effect, and not the number of studies that identified a positive
association with exposure.
Nitrate/Nitrite (survey based on IARC
2010 and ATSDR 2017 assessments)
RASS 101
2nd Public Release: Protocol
• Protocol: Assessment method documents to establish
assessment-specific criteria that will be used for:
▪ Literature search strategy
▪ Literature screening strategy
▪ Study evaluation strategy
▪ Study results extraction
▪ Evidence integration framework
• The protocol will be updated and revised throughout assessment
development process to reflect knowledge gained during
implementation and to focus on the best available evidence26
Scoping
Initial Problem Formulation
Literature Search, Screen
Literature Inventory
Study Evaluation
Organize Hazard Review
Data Extraction
Evidence Analysis and Synthesis
Evidence Integration
Select and Model Studies
Derive Toxicity Values
Systematic Review Protocol
Assessment
Initiated
Assessment
Developed
Protocol: How the assessment will be conducted (specific)
Refined Evaluation Plan
26
HBA 201 27
COMPONENTS OF RISK
ASSESSMENT:
HAZARD
IDENTIFICATION
RASS 101 28
Hazard Identification
Gather Data
Identify
Toxicity
Identify
Adverse
Effects
Identify
Uncertainties
RASS 101 29
Gathering Data: Literature Search and Screening
Database
Searches
Inventories
• Identify peer-reviewed and
“gray” (unpublished) literature
• PubMed, ToxLine, and Web of
Science are standard (others
can be included as needed)
• Conduct regular search
updates
• Details of search strategy,
dates, and retrieved records
are presented in protocols
and assessments
Screening
1. Title/abstract
2. Full text
Health Outcome &
PBPK Studies
Supplemental
Studies*
• Tag studies by line of
evidence and outcome
• Distribute to disciplinary
experts for review
• May include in vitro and
other mechanistic evidence
(e.g., non-PECO exposure
route; non-PECO animal
model; toxicokinetic data)
• Use manual and automated approaches
• ≥ 2 screeners
• Tag studies as excluded, meeting PECO
criteria, or supplemental information
• Screening decisions available in HERO
• Typically do not apply language-restrictions
• Review reference list of included studies
and relevant reviews to identify studies
missed from database searches
• Share list of included studies with public to
further ensure all relevant studies included
• Inventories contain basic
study methods for evaluation
and prioritization decisions
RASS 101 30
Gather Data
▪ What is the chemical of interest?
▪ Which populations might be affected?
▪ What toxicity data are available?
▪ Human Data
• Epidemiology studies
• Controlled human exposure studies
▪ Animal Bioassay Data
▪ Other Data
• In Vitro and Mechanistic Data
• Structure-activity relationships
• Metabolic data
• Genomics
Gather Data
RASS 101 31
Identify Toxicity
▪ Effects – What effects are observed from the data collected?
▪ Toxicokinetics – What does the body do to the chemical?
▪ Toxicodynamics – What does the chemical do to the body?
▪ Mode of action – How does the chemical act to produce an effect?
▪ Weight of evidence – How likely is this chemical to cause non-cancer effects or cancer and under what conditions?
▪ Causality Framework – A way to organize and evaluate toxicity information to assess causality given those data.
How toxic is the chemical?
RASS 101 32
Identify Types of Effects
▪ What are the affected organs or tissue systems?
▪ What is the severity of effects?
▪ Who is more sensitive or susceptible?
▪ What factors affectsusceptibility?
What are the adverse effects?
▪ Adaptive
▪ Compensatory
▪ Adverse
▪ Critical
▪ Frank
Types of Effects
RASS 101 33
Review of Key Terminology
Reference ValueEstimate of exposure to the human population likely
to be without an appreciable risk of
adverse health effects over a lifetime.
Adverse EffectA biochemical change, functional impairment, or pathologic lesion
affecting an organism’s performance and reducing its ability to
respond to environmental challenges
(also called a response).
Dose-Response RelationshipQualitative relationship between dose and biological response in
which the incidence or severity of the response is affected with
increasing dose (or exposure).
Margin of Exposure (MOE) Ratio of the toxicity level (point of departure) to the estimated
exposure dose
RASS 101
Example: Cadmium
Hazard Identification
IRIS Hazard ID for Cadmium (Noncancer Effects)
Oral Exposure Inhalation Exposure
Data available –
human or animal?
• Human – chronic exposure
• Animal data availableNot available
Effects Significant proteinuria Not available
Uncertainty Intrahuman variability Not available
Confidence in
studyBased on multiple studies Not available
Confidence in
databaseHigh Not available
Confidence in
reference valueHigh Not available
34
RASS 101
Example: Cadmium
Hazard Identification
IRIS Hazard ID for Cadmium (Cancer)
Oral Exposure Inhalation Exposure
WOE classification Not available B1; probable human carcinogen
Data available –
human, animal?
• Human – not available
• Animal data available
• Human – occupational
• Animal data available
Mode of action Not available
Interference with spindle
formation resulting in
aneuploidy in germ cells
Effects No evidence of carcinogenicityDeath from lung, trachea, and
bronchus tumors
Confidence
DiscussionNot available
• Large cohort
• Smoker confounding addressed
• Human data deemed more reliable
than animal data
35
RASS 101 36
IRIS Values: A Comparison to
Other Noncancer Values
IRIS RfD/RfC (Reference
dose/concentration) ATSDR MRL (minimum risk level)Cal-REL (reference exposure
level)
Route •Oral/Inhalation •Oral/Inhalation •Oral/Inhalation
Duration •Chronic (lifetime) •Acute (1-14 days)
•Intermediate (>14-364 days)
•Chronic (> 365 days)
•Acute (1 and 8 hours)
•Chronic (lifetime)
Data used for
derivation
•Epidemiological or animal
or human toxicological data
•Epidemiological or animal or
human toxicological data
•Epidemiological animal or
human toxicological data
Preferred dose-
response method
for selecting POD
•BMD/BMC •NOAEL (but BMD/BMC
sometimes preferred)
•BMD/BMC
Uncertainty factors
UFA (animal to human) 1, 3, 10 1, 3, 10 1, 3, 10
UFH (human-human
variability)
1, 3, 10 1, 3, 10 1, 3, 10
UFS (subchronic to
chronic)
1, 3, 10 Not typically applied 1, 3, 10
UFL (LOAEL to NOAEL) 1, 3, 10 1, 3, 10 1, 10
UFD (database
deficiencies) IRIS ONLY
1, 3, 10 Not typically applied 1, 3
HBA 201 37
COMPONENTS OF A
RISK ASSESSMENT:
DOSE-RESPONSE
ASSESSMENT
RASS 101
The Critical Effect
Critical effect: The adverse effect that occurs at the lowest
dose, or its known precursor, that occurs to the most
sensitive species as the dose rate of an agent increases
• Criteria for Critical Effect:
▪ Adverse or precursor to adverse
▪ Dose- or concentration-dependent at
low doses or concentrations
▪ Can occur in humans
38
https://iaspub.epa.gov/sor_internet/registry/termreg/searchandretrieve/gl
ossariesandkeywordlists/search.do?details=&vocabName=IRIS%20Glo
ssary
RASS 101 39
Dose-Response Assessment:
Non-Cancer
Evaluate Data
Animal or human
Exposure route
Exposure duration
Age
Gender
Confounders
Species and strain
Characterize Dose-Response
Relationship
Identify a NOAEL or LOAEL.
If possible, Conduct dose-response
modeling (e.g. BMD modeling). Uncertainty
Factors Identify Sources of
Uncertainty and Apply
Uncertainty Factors
Calculate
Reference Value
RfD
RfC
Identify critical effect(s) and
level(s)
Identify point of departure (POD).
Calculate human equivalent
concentrations (HEC) or doses
(HED).
RASS 101 40
Exposure Durations
Evaluate Data
Animal or human
Exposure route
Exposure duration
Age
Gender
Confounders
Species and strain
Acute:Less than 24 hours
Short-Term:Up to 30 days
Sub-Chronic:Up to 10% of the organism’s lifespan
Chronic:Up to a lifetime
US EPA (2002) “A Review of Reference Dose and Reference Concentration Processes”
RASS 101 41
Dose-Response Terminology
Characterize Dose-Response Relationship
Identify a NOAEL or LOAEL
Conduct dose-response modeling and BMD Modeling.
LOAELLowest-Observed-Adverse-Effect Level.
Lowest dose at which significant
adverse effects are observed.
BMDBenchmark Dose. An exposure to a low
dose of a substance that is linked with a
low (ex. 1-10%) risk of adverse health
effects, or the dose associated with a
specific biological effect.
NOAELNo-Observed-Adverse-Effect Level.
Highest dose at which no significant
adverse effects are observed.
BMDLA lower, one-sided confidence limit on
the BMD.
ED10
Dose that produces an adverse effect
in 10% of exposed, relative to control. https://www.epa.gov/bmds
RASS 101 42
Terminology and Key Concepts
Benchmark Dose/
Concentration Lower
Confidence Limit
(BMDL/BMCL)
Dose or Concentration
% R
esp
on
se
Point of Departure
(POD)
Benchmark Dose/Concentration
(BMD/BMC)
No-Observed-Adverse-
Effect Level (NOAEL)
Lowest-Observed-
Adverse-Effect Level
(LOAEL)
Benchmark
Response
(BMR)0
0
RASS 101 43
Dose-Response Assessment:
Cancer
Evaluate Data
Animal or human
Exposure route
Exposure duration
Age
Gender
Confounders
Species and strain
Characterize Dose-Response
Relationship
Identify a NOAEL or LOAEL (for
nonlinear) or an LED10 (for linear)
Conduct dose-response modeling
and BMD Modeling
Identify critical effect(s) and
level(s)
Identify point of departure
Calculate Risk
Values
IUR
OSF
RASS 101
Example: Noncancer
Cadmium Dose Response
44
IRIS Noncancer Dose-Response Assessment for Cadmium
Reference Value Units
Oral RfD (water) 0.0005 mg/kg-day
Oral RfD (food) 0.001 mg/kg-day
Dermal RfD Not reported
Inhalation RfC Not available
RASS 101
Example: Cancer Cadmium
Dose Response
45
IRIS Cancer Dose-Response Assessment for Cadmium
Risk Value Units
Inhalation unit risk
(IUR)
1.8E-3 per
1 µg/m3 airNone
Oral slope factor
(OSF)Not available
Drinking water unit
riskNot available
HBA 201 46
COMPONENTS OF A
RISK ASSESSMENT:
IDENTIFYING
UNCERTAINTIES
RASS 101 47
Identify Uncertainties
▪ Human variability
▪ Using animal data
▪ Extrapolating the study duration
▪ Extrapolating the exposure effect level
▪ Relevance to target context (human exposures)
▪ Strength of database
▪ Quality of data
▪ Risk characterization
What introduces uncertainties?
RASS 101 48
IRIS Uncertainty Factors
•UFH – Human variability
•UFA – Animal-to-human extrapolation
•UFS – Subchronic-to-chronic extrapolation
•UFL – LOAEL-to-NOAEL extrapolation
•UFD – Database deficiencies
•UF – “Composite” or “Total” uncertainty (UFH× UFA× UFS×
UFL× UFD)
HBA 201 49
COMPONENTS OF A
RISK ASSESSMENT:
EXPOSURE
ASSESSMENT
RASS 101 50
Exposure Assessment
Who is exposed?
• Characteristics of the
population?
• Size of the
population?
How are they exposed?
• Route?
• Magnitude?
• Frequency?
• Duration?
Quantify Exposure
Descriptive:
• Point of contact
measurement
Predictive:
• Dose reconstruction
• Scenario evaluation
https://www.epa.gov/expobox/about-exposure-factors-handbook
US EPA Exposure Factors Handbook (2011)– more recent updates by Chapter
RASS 101 51
Quantify Exposure
Point of
Contact
MeasurementReconstruction of
Dose
Scenario
Evaluation
RASS 101 52
Quantify Exposure
Point of Contact Measurement
(Field Measurements)
• Measure chemical
concentrations over time
• At or near point of contact for
exposure in question
• Various sampling methods
RASS 101 53
Quantify Exposure
Reconstruction of Dose
(Clinical Measurements)
• Attempt to quantify internal
dose based on physiological
data
• Using measurements from
the body, tissues
• Biomarkers of exposure,
metabolites – involves
extrapolation. Predictive
estimate.
RASS 101 54
Quantify Exposure
Scenario Evaluation
(Predictive Estimate)
• Measure or estimate the
amount of substance
contacted at site
• Use equations and
assumptions about behavior
and exposure rates
• Mathematical estimation of
exposure; predictive
estimate
RASS 101 55
Exposure Assessment Equation –
Concentration
Co
nce
ntr
atio
n
Time
Exposure Concentration vs. Time
RASS 101 56
Exposure Assessment Equation –
Mass
HBA 201 57
RISK
CHARACTERIZATION
RASS 101 58
Risk Characterization
Risk characterization is the integration of information on
hazard, exposure, and dose-response to provide an
estimate of the likelihood that any of the identified adverse
effects will occur in exposed people. (IRIS Glossary Definition)
Risk characterization requires:
▪ Transparency
▪ Clarity
▪ Consistency
▪ Reasonableness
RASS 101 59
Elements of Risk
Characterization
•Key Information
• Context
• Sensitive Populations
• Scientific Assumptions
• Policy Choices
• Key Conclusions
• Alternatives Considered
• Variability
• Uncertainty
• Bias and Perspective
• Strengths and Weaknesses
• Confidence Statements
• Research Needs
RASS 101 60
Risk Characterization:
Outcome
Noncancer Risk
Hazard Quotient (HQ): Ratio of estimated exposure to
reference level at which no adverse health effects are
expected (e.g, oral RfD or inhalation RfC).
Margin of Exposure (MOE): Ratio of the point of
departure (POD) to the estimated exposure.
Cancer Risk: Incremental probability of developing cancer
for an individual exposed to a given chemical over a lifetime.
Risk assessment is an iterative process: The results of
risk characterization inform decisions on next steps,
including further analysis or risk management actions.
RASS 101 61
Risk Characterization:
Non-cancer Quantitative Results
Noncancer Effects
Where:
ADD = Average Daily Dose (Oral or Dermal)
RfD = Reference dose
EC = Exposure Concentration (Inhalation )
RfC = Reference Concentration
𝑯𝑸 =𝑬𝑪
𝑚𝑔𝑚3
𝑹𝒇𝑪𝑚𝑔𝑚3
RASS 101 62
Risk Characterization:
Non-cancer Quantitative Results
Noncancer Effects
• MOE (unitless): Ratio of the point of departure to the
estimated level of exposure.
• Inhalation PODs and exposures are in mg/m3 or ppm
• Oral PODs and exposures are in mg/kg-d
• The MOE approach is not recommended for some
endpoints (e.g., genotoxicity, sensitization)
RASS 101 63
Risk Characterization:
Cancer Quantitative Results
Cancer
Where:
Risk = Excess Cancer Risk (Unitless)
Human Exposure = Exposure estimate (µg/m3 or mg/kg-d)
Slope Factor = Inhalation unit risk (per µg/m3) or
Oral slope factor (per mg/kg-d)
Historically, EPA considers cancer risks ranging from 1×10-4 to 1×10-6
to be acceptable.
RASS 101 64
Risk Characterization:
Cancer Quantitative Results
Cancer
Where: LADD = Lifetime Average Daily Dose
RASS 101 65
Conclusion
Risk assessment integrates qualitative and quantitative
information on:
• Toxicity
• Severity of Effects
• Geographic Extent
Scientific estimates of hazard and exposure inform environmental
and public health risk management decisions
Hazard assessment is more than dose-response assessment alone.
Different organizations/disciplines conduct different parts of an
assessment (e.g., hazard and exposure)
Risk Characterization combines hazard and exposure estimates
into information usable for decision-making
• Exposure
• Magnitude of Response
• And many other factors