An Overview of Risk Assessment

Bernard D. Goldstein, MD

University of Pittsburgh

Graduate School of Public Health

An Overview of Risk AssessmentObjectives of this Lecture

• The student will have an understanding of:– The definition of risk assessment and its four

components, including their scientific basis.

– The basic issues in environmental policy that are responsible for the genesis and use of risk assessment.

– The key strengths and weaknesses of risk assessment as a public policy tool

– The role of risk assessment as an interface between environmental science and public policy

What Are the Components of Risk Assessment?

• Hazard identification

• Dose-response evaluation

• Human exposure evaluation

• Risk characterization

Better Things Through Chemistry

5,000,000 known chemicals (1,000,000 in 1945)

70,000 chemicals in widespread use

1,500 new chemicals in use yearly

Annual bioassay capability about 500/year

Scientists manipulate formulae to match the real world.

Policymakers manipulate the real world to match formulae.

Comparative Risk of Death

Number of

Deaths / Year Lifetime Risks

Motor vehicle accidents

46,000 1/65

Home accidents

25,000 1/130

Lung cancer deaths in smokers

80,000 1/12

Risk

Assessment

Risk

Management

Research and

Data Collection

The Three Laws of Toxicology

• The dose makes the poison

• Chemicals have specific effects

• Humans are animals

Hazard Identification

The determination of whether a particular chemical or agent is or is not causally linked to a particular health effect.

Probably Not Carcinogenic4

Not Classifiable3

Possibly Carcinogenic2B

Probably Carcinogenic2A

Carcinogenic to Humans1

Weight of Evidence

IARC Overall Evaluation of Carcinogenicity to Humans

Dose Response Evaluation

The determination of the relation between the magnitude of exposure and the probability of occurrence of the health effect in question.

Dose-Response Curve

ResponseObservable Range

Range of Inference

Dose

Structure of DNA

Human Exposure Evaluation

• How many people will be exposed?

• Through which routes?

• Who is exposed?

• What is the magnitude, duration, and timing of the exposure?

Continuum for the Emission of and Exposure to a Contaminant and the Expression of a Health Effect

P.J. Lioy, Env. Sci. & Tech. Submitted 1990

SourceEmission

Transport andTransformation

Accumulationin

Environment

HumanContact

Exposure

Potential Doseto the Body

Health EffectEarly

Expression ofDisease

BiologicallyEffective Dose Internal Dose

EliminationAccumulation

TransformationBioavailability

Risk Characterization

The description of the nature and often the magnitude of the human risk, including attendant uncertainty.

Risk Assessment

Dose-Response Assessment

Risk Characterization

Exposure Assessment

Hazard Identification

Dose-Response

Assessment

Risk Characterization

Exposure Assessment

Hazard Identification

Regulatory Decision

Control Options

Non-Risk Analysis

Risk Assessment Risk Management

The Three Laws of Toxicology

• The dose makes the poison

• Chemicals have specific effects

• Humans are animals

Uses of Risk Assessment for Management Decision Making

• National Regulations:– Environmental standards (air, water, hazardous waste,

etc.)– Food safety (chemical contaminants, additives, pathogens)– Manufacturing and production (pharmaceuticals,

pesticides, etc.)

• International Trade / WTO SPS Agreement:– Food products (Safety Assessment and Acceptable Daily

Intake [ADI])– Animals and animal products– Plants and plant products

Range of Expert Judgment

X XX XX X

Range of Expert Judgment

XXX XXX

Communication of Science

In the presence of uncertainty, the technique usually relied upon to ascertain the current state of knowledge is:

CONSENSUS by SCIENTISTS

BALANCE by JOURNALISTS

CONFRONTATION by LAWYERS

CATNIP PRINCIPLE

Cheapest Available Technology Not Involving Prosecution

Margin of Safety

Is it Risk Assessment or Risk Management?

Components of decision:

What is strength of positive data?

What is strength of negative data?

Is uncertainty qualitative or quantitative?

What is the clinical significance of risk?

Problems and Limitations of Risk Assessment

1. The process by which policy and science are mixed together in a risk assessment is poorly understood.

2. Its ability to provide a “Bright Line” has been overstated by risk assessors and overused by regulators and lawmakers.

Problems and Limitations of Risk Assessment

(continued)3. The data quality objective for the different goals

and types of risk assessment is poorly understood.

4. There is often a substantial gap between the data quality objective of the decision maker and the degree of complexity of the assessment, with unnecessary analyses confusing and delaying response.

Problems and Limitations of Risk Assessment

(continued)5. Risk assessment often obscures the substantial

gap between the data needs for good public health decision making and the paucity of available data.

6. Risk characterization should be extended beyond a probabilistic statement of cancer risk to include considerations of other health and non-health endpoints.

Problems and Limitations of Risk Assessment

(continued)

7. Risk assessment is secondary prevention rather than primary prevention.

Risk Assessment and Risk Management is a 3 Step Process

• Science Policy producing Risk Assessment Guidelines

• Risk Assessment

• Risk Management

Risk Assessment Guidelines:Use and Intent

• Provide consistency

• Establish data quality objectives

• Assure technical quality

• Clarify scientific assumptions

• Allow flexibility to be transparent

• Provide public with “Road Map”

Precautionary Principle Described

in the Rio Declaration:Nations shall use the precautionary approach

to protect the environment. Where there are

threats of serious or irreversible damage,

scientific uncertainty shall not be used to

postpone cost-effective measures to prevent

environmental degradation.

Definition of the Precautionary Principle

(Cynical Version)

The Precautionary Principle is a nebulous doctrine developed by Europeans as a means to erect a trade barrier against any item that can be produced more efficiently elsewhere

RISK ASSESSMENT AND THE PRECAUTIONARY PRINCIPLE

Three different views• The Precautionary Principle is already

incorporated in Risk Assessment

• The Precautionary Principle should be incorporated into Risk Assessment

• The Precautionary Principle and Risk Assessment are completely antithetical

Framework is Conducted:

• In collaboration with stakeholders.

• Using iterations if new information is developed that changes the need for or nature of risk management.