Session 2: Chemical Policy Issues and Strategies

1
Health, Risk and Science

• Session 2 Chemical Policy Issues and Strategies
• American Nurses Association

Daryl Ditz, Ph.D., Senior Policy AdvisorCenter
for International Environmental Law April 27,
2006
2
Preview

• Risk-based and Health-based Approaches
• New Science about Exposures and Effects
• The (Many) Problems with Risk Analysis

3
Risk is a Familiar Concept for Health Care
Providers

• Weighing drug efficacy against side effects
• Setting priorities for primary prevention
• Emergency triage

4
The Traditional Risk Paradigm

• Risk, the potential for harm, has many meanings.
  In general it combined the concepts of exposure
  and effects.

Intrinsic properties of chemicals in biological
systems, also with many complexities.
The chemical dose (with many additional
complexities for environmental exposures)
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LD50 Acute Toxicity
100
Observed Effect
50
0
Dose
LD50
Lethal Dose 50
6
No Observed Effects Level
100
Observed Effect
50
0
Dose
NOEL
Threshold
0
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Extrapolating to Low Doses
1 in a1,000
1 in a10,000
Observed Effect
1 in a100,000
1 in a1,000,000
Dose
Assume No Threshold
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A Typical Risk Analysis
3) EstimatedImpact (individual or population)
1) Exposure Pathways
Water
Dermal
Food
Dose-Response
Air
Other
2) EstimatedBody Burden
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How much risk is too much?

• 1 in a million chance of mortality
• The queasy moral world of acceptable risk
• No such thing as zero
• Actuarial statistics (what risks do people
  voluntarily accept)?
• Economic approaches (what does society spend to
  save a life?)

10
Risk is about Uncertainty

• We rarely know about REAL human exposures
  (biomonitoring is reality check)
• We rarely know enough about human effects
  biological mechanisms, interactions,
  vulnerabilities, etc., in people

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The Public Health Paradigm

• An Ounce of Prevention
• The Precautionary PrincipleDont wait for 100
  certainty before taking prudent action.
• Opt for safer substitutes, based on intrinsic
  properties of substances.

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Intrinsic Properties PBTs

• P Persistence (half-life, kinetics)
• B Bioaccumulation (lipid solubility)
• T Toxicity (biological impacts)
• vPvB very P, very B (biological impacts)

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2. Risk and Emerging Science

• Dose
• Toxicity
• Multiple endpoints
• Differential response

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Dose and Toxicity

• Amount, timing, pattern, duration
• Health effects
• depend on exposure and susceptibility of the
  individual or population.
• depend on interaction of genetics, nutrition,
  social environment, cumulative exposures.
• one chemical may have a variety of health effects
  that occur at different doses, timing, and
  patterns of exposure (dose-response)

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Mechanisms of Toxicity

• Many different ways that a chemical can cause
  toxicity or a health effect
• Direct damage to parts of cells or organs (e.g.
  mercury)
• DNA damage or mutation (e.g. benzene)
• Interfere with gene expressionmultiple impacts
  (e.g. dioxin)
• Endocrine disruption (e.g some pesticides,
  phthalates)
• Interfere with normal enzyme levels, affecting
  metabolism (e.g. dioxin, solvents)

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Endocrine disruptors

• Interfere with normal hormone (or other signaling
  molecules) levels or function
• Exposures during development can have life-long
  impacts at levels of exposure that have no
  discernable impacts in adults
• Multiple mechanisms of action NOT through
  typical toxicity mechanisms

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Multiple Health Endpoints

• Organ toxicity (e.g. nervous system, liver,
  hematologic, etc.)
• Reproductive/developmental toxicity infertility,
  miscarriage, low birth weight, prematurity, birth
  defects (structural or functional)
• Immune system toxicity
• Cancer

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3. The Many Problems with Risk Analysis for
Chemicals

• As commonly practiced, risk analysis ignore
  almost ALL these scientific subtleties
• Persistence and bioaccumulation lead to chronic,
  increasing exposures
• Toxicity data is the exception, so we dont know
  real effects on real people.
• Latency of effects, synergistic effects,
  sensitive subpopulations, etc.

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3. The Many Problems with Risk Analysis for
Chemicals (cont.)

• The expense and time required to analyze risk
  slows decisions (favors the status quo)
• Often prepared by expert consultants on behalf
  of interested parties
• Language and style carries an air of scientific
  credibility
• Technocratic style tends to exclude public
  involvement (you wouldnt understand)

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Conclusions

• Risk is a vital concept for environmental health
  and relevant to precaution.
• Risk analysis is a poor tool for protecting
  public health, especially in the wrong hands.
• Emerging scientific evidence challenges the way
  that chemicals are regulated.