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Regulation of Carcinogens: historical disasters

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Regulation of Carcinogens: historical disasters . Toothpaste & Spas X-Ray Techs & Radium Workers. The Modern landscape. EPA: Environmental Regulation dates mainly from 1970s Uses the linear model, for lack of a better alternative An alternative: the hockey-stick model

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slide1
Regulation of Carcinogens: historical disasters

Toothpaste & Spas

X-Ray Techs & Radium Workers

The Modern landscape

EPA:

Environmental Regulation dates mainly from 1970s

Uses the linear model, for lack of a better alternative

An alternative: the hockey-stick model

Regulation by tort law

slide2
Bruce Ames: a Skeptic
  • Questions:
  • How do we know what to regulate?
    • (50% of tested chemicals are carcinogens)
    • What about that hazing accident where a student died of an overdose of water?
  • How do we know what the lethal dose is?
    • (linear versus hockey stick)
  • How do we set priorities?
    • How do natural pesticides and chemicals enter the problem?
  • Framework: HERP, a normalized risk indicator.
    • Find dosage that reduces survivorship of test animals to 50%.
    • Calculate human equivalent (by relative weight)
    • Figure out how much of that dose the human is getting.
slide3
Contra:

Bruce Ames

  • Is the issue only about science? What about social science?
    • For example, aflatoxins are made by mold, which is partially preventable. Should we ban peanut butter? Celery?
  • “Physicist-sociologists of risk need to note that some of the recent work in the study of economic behavior has provided a framework for a more complex analysis of consumer choice in the marketplace in place of simple comparisons of marginal benefit and cost.
  • - Ellen K. Silbergeld
  • Environmental Defense Fund
slide4
Contra:

Bruce Ames

“The proposal by Bruce N. Ames et al for ranking risk of carcinogens, while elegant in structure, is not realistic or implementable. First, as a basis for the HERP (human Exposure dose/Rodent potency dose), it relies heavily on the assumption that there are reliable data on exposure . . . When this lack of data is factored into an equation already burdened by the range of unresolved issues and uncertainties of risk assessment, it is doubtful how much practical use the approach of Ames et al. can be.”

- Ellen K. Silbergeld

Environmental Defense Fund

slide5
Contra:

Bruce Ames

Second, any comprehensive system ranking risk should be capable of devolution to deal with risk control decisions at the margin. That is, it is important to be able to determine how to deal with, for instance, risks of dioxin from incinerator emissions in populations who smoke, eat certain foods, sunbathe, or otherwise engage in risky business. It is hard to know how to use the approach of Ames et al. for this critical assessment.

- Ellen K. Silbergeld

Environmental Defense Fund

slide6
Contra:

Bruce Ames

Finally, the approach of Ames et al. and much of the discussion of risk assessment in Science and elswhere continues to confine our national debate to one end point – cancer risk. While evaluating the potential risks of chemicals and as carcinogens is important, the human disease and dysfunction that can reasonably be associated with impacts of chemical exposure and environmental modifications are likely to be expressed in many other outcomes.”

- Ellen K. Silbergeld

Environmental Defense Fund

slide7
Dioxin (the active ingredient in Agent Orange)
  • “A powerful Litigen” following Vietnam
  • The science of dioxin: very toxic to animals

What about to humans? What is the mechanism?

  • The science in humans:

Dioxin stays in fat cells, so we know exposure.

Dioxin needs receptors, but at what exposures?

Can dioxin cause congenital disorders in offspring?

slide8
Dioxin (science and epidemiology)
  • Returning soldiers sued the US government and producers sued health effects.

EPA regulates.

  • How do we know who was harmed? What kinds of epidemiological studies were done?
  • The politics: National Academies of Sciences (Institute of Medicine) issued a somewhat discredited report. This is a big deal for NAS.
  • Gough at OTA, a big critic: Says IOM issued an unsubstantiated report. What is Gough’s argument about conflict of interest?
  • Should I be afraid of Weed-b-Gone?
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