The New Millennium: Values, Perceptions of Risk and the Key

Roles of Science and Technology

Ionizing Radiation Science and Protection In the 21st Century

Gilbert S. Omenn, MD, PhD

Executive Vice President for Medical Affairs and CEO, University of Michigan Health System

National Council on Radiation Protection and Measurements

April 5-6, 2000 Arlington, Virginia

AMERICAN VALUES FOR THIS MILLENNIUM

• Sustainable development: Robust economy,

environmental protection, inter-dependent world

• Freedom of speech, freedom of religion, freedom from

want, freedom from fear (FDR, 1941)

• Transparency of decision-making in an internet-

informed or misinformed, more empowered populace

• High expectations and benefits and tolerance for risks

from science and technology

SOURCES OF IONIZING RADIATION EXPOSURES

• Nature background; radon progeny• Medical Diagnostic and Therapeutic Uses• Industrial Radionuclides• Radioactive Liquid and Solid Wastes• Nuclear Power Plant Operations /

Emissions Risk• Decommissioning of Nuclear Reactors

“I know no safe depository of the ultimate powers of society but the people themselves; if we think them not enlightened enough to exercise their control with a wholesome discretion, the remedy is not to take it away from them, but to inform their discretion.”

- Thomas Jefferson

NOT OBSERVABLE

• Unknown to those exposed

• Effect delayed• New risk• Risks unknown to

science

OBSERVABLE

• Known to those exposed

• Effect immediate• Old risk• Risks known to

science

RISK PERCEPTION

CONTROLLABLE

• Not dread• Not catastrophic• Not fatal• Equitable• Low risk to future

generations• Easily reduced• Risk decreasing• Voluntary

UNCONTROLLABLE

• Dread• Global catastrophic• Consequences fatal• Not equitable• High risk to future

generations• Not easily reduced• Risk increasing• Involuntary

FRAMEWORK FOR REGULATORY DECISION-MAKING

Epidemiology

Hazard Identification Lifetime rodent bioassays Short-term, in vitro tests Structure / activity

Potency (dose/response)

Risk Characterization Exposure analysis Variation in susceptibility

Information

Risk Reduction Substitution Regulation / Prohibition

Objectives of Risk Assessment

1. Balance risks and benefitsDrugs Pesticides

2. Set target levels of riskFood contaminantsWater Pollutants

3. Set priorities for program activitiesRegulatory agenciesManufacturersEnvironmental/Consumer organizations

4. Estimate residual risks and extent of risk

Reduction after steps are taken to reduce risks

BIOLOGICAL END-POINTS

• Cancers

• Mutations

• Birth Defects

• Reproductive Toxicity

• Immunological Toxicity

• Neurobehavioral Toxicity

• Organ-Specific Effects

• Endocrine

Modulation/Disruption

• Ecosystem Effects

Major Toxic Chemical Laws

EPA: Air pollutants Clean Air Act 1970, 1977, 1990 Water Pollutants Fed WP Control Act 1972,

1977 Safe Drinking Water Safe DW Act 1974 Pesticides FIFRA 1972 Ocean Dumping Marine Protection Act Toxic Chemicals TSCA 1976 Hazardous Wastes RCRA 1976 Hazardous Waste Cleanup CERCLA (Sperfund) 1980, 1986

CEQ: Envvlt Impacts NEPA

OSHA: Workplace OSH Act

FDA: Foods, Drugs, Cosmetics FDC Acts

CPSC: Dangerous Consumer Products CPS Act

DOT: Transport of Haz Materials THM Act

MANDATE

Uses and limitation of risk assessment in decision-making

Appropriate exposure scenarios

Uncertainty and risk communication

Risk management policy issues

Consistency across agencies

EXPOSURE

• Sources

• Pathways

• Environmental transformations

• Routes of entry

• Time course of exposures

• Concept of total exposure

• Need for translation from ambient levels to target

tissue effective dose

• New methods for tissue burdens and dosimetry

MIXTURES

Test real world mixturesdiesel exhausturban smogactual effluentspesticide combinationsworkplaces

Assume additivity of risks as default; use mechanisms, if known

Pay attention to radiation and microbial exposures/risks

PUTTING ENVIRONMENTAL RISKS INTO CONTEXT

• Multi-Source

• Multi-Media

• Multi-Chemical / Multi-Agent

• Multi-Risk

CONTEXT

Multi-Source

Multi-Media

Multi-Agent

Multi-Risk

Public Health

Status/Trends

Ecological Health

Social & Cultural

Environmental Justice Considerations

Reducing risk by orders of magnitude is not equivalent to linear reductions

0

200

400

600

800

1000

1 x 10-3 1 x 10-4 1 x 10-5 1 x 10-6

Level of risk

Risk Commission, Final Report, 1997

RISK COMMISSION RECOMMENDATION (1997 REPORT, p. 82)

A concerted effort should be made to evaluate and relate the methods, assumptions, mechanisms, and standards for radiation risks to those for chemicals to clarify and enhance the comparability of risk management decisions, especially when both types of hazards are present.

LACK OF COLLABORATION ON CHEMICAL AND RADIATION

HAZARDS

• Different models of carcinogenesis• Different regulatory laws and

agencies• Different disciplines and scientific

meetings• Smaller margin of exposure tolerated

for IR• Despite common waste streams and

co-existing contamination

POLICY AND PUBLIC INTEREST IN COMPARISONS OF RISK

Discrepancy between levels of risk considered negligible forradiation exposures and for chemical exposures

Workers General Population Comments

Chemicals 10-3 10-6 Single chemicals

Radiation 50 mSV/yr 1mSV/yr Integrated Dose 10-1 / 10-2 Ratio of 50 vs 300+

Importance of interactions of radiation and chemicals, of

radiation and infectious disease risks.

BEIR VII - Phase 1 Letter---21 January, 1998

• Continued reliance on epidemiological studies• Lots of laboratory studies• OPPORTUNITY FOR REALLY BIG BREAKTHROUGH

- Patterns of gene expression on microarray

and protein expression in proteomics

readouts that reflect carcinogenesis: key to

resolving long-festering questions about risks of

low-level exposures

OUR GENETIC FUTURE

“Mapping the human genetic terrain may rank with the great expeditions of Lewis and Clark, Sir Edmund Hillary, and the Apollo Program.”

--Francis Collins, Director

National Human Genome Research Institute, 1999