overview of human health risk assessment

Office of Research and DevelopmentCenter for Public Health and Environmental Assessment

Overview of Human Health

Risk 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


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


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


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


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


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


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

https://www.epa.gov/sites/production/files/2015-01/documents/benchmark_dose_guidance.pdf

RASS 101

0

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: F

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DOSE:mg/kg-day

Example Dose-Response

Curves

RASS 101


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 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


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

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

http://systematicreviewtools.com/

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

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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


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


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


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

https://iaspub.epa.gov/sor_internet/registry/termreg/searchandretrieve/glossariesandkeywordlists/search.do?details=&vocabName=IRIS%20Glossary

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”

https://www.epa.gov/sites/production/files/2014-12/documents/rfd-final.pdf

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

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

https://www.epa.gov/expobox/about-exposure-factors-handbook

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


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


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


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


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

overview of human health risk assessment

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