Methods and goals of environmental toxicology

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Methods and goals of environmental toxicology

• Topic 2

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Concepts to learn

• Environmental toxicology as an integrative
  discipline
• The role of science in validating perceptions
  about pollutants in the biosphere

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Environmental toxicology Scientific goals

• Goal to organize knowledge (about pollutants in
  the biosphere and their effects) based on
  explanatory principles
• How Methodology of modern science developed by
  Karl Popper
• Product explanatory paradigms and theories (most
  probable reflection of truth not the absolute
  truth)

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Environmental toxicology Technological goals

• Goal to develop and apply tools and methods to
  acquire a better understanding of contaminant
  fate and effects in the biosphere
• Product analytical instrumentation, standard
  methods, tests and approaches, computational
  methods
• The link between science and practice

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Environmental toxicology Practical goals

• Goal to apply available knowledge, tools and
  procedures to solving or documenting specific
  problems
• Uses technology to solve or document a particular
  environmental situation
• Products criteria, standards and guidelines for
  practice, clean-up and pollutant containment
  solutions, etc.

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Environmental toxicology Amalgam of science,
technology and practice
Long
Time to benefit
Short
Local
Global
Value
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Common perceptions about pollutants What can
science contribute?

• Does environmental pollution pose a serious
  threat to human or ecosystem health?
• Answer this question as it applies to your own
  experience and the experience of people close to
  you
• Answer this question from your knowledge about
  other communities, countries and habitats on
  Earth
• Are man-made chemicals more toxic than natural
  ones?
• Do costs of controlling pollution outweigh
  benefits?

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Clash of perceptions

• Pro
• Pollution is a significant contributor to cancer
  and cancer rates are soaring
• Contra
• Life expectancy is increasing in industrialized
  countries
• Cancer (non-smoking) death rates are steady or
  going down

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Cancer Death Rates, All Sites Combined, All
Races, US, 1973-1999
Rate Per 100,000
Males
Both Sexes
Females
Age-adjusted to the 2000 US standard
population. Source Surveillance, Epidemiology,
and End Results Program, 1973-1999, Division of
Cancer Control and Population
Sciences, National Cancer Institute, 2002.
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Cancer Death Rates, for Men, US, 1930-1999
Rate Per 100,000
Lung
Prostate
Stomach
Colon and rectum
Pancreas
Leukemia
Liver
Age-adjusted to the 2000 US standard
population. Source US Mortality Public Use Data
Tapes 1960-1999, US Mortality Volumes 1930-1959,
National Center for Health
Statistics, Centers for Disease Control and
Prevention, 2002.
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Clash of perceptions

• Pro
• Human exposure to carcinogens and other toxins
  are nearly all due to synthetic chemicals
• Contra
• Amount of synthetic pesticide residues in plant
  foods used by humans is insignificant compared to
  the amount of natural plant pesticides (10,000
  times more natural than synthetic)
• 5,000-10,000 of natural pesticides (1500 mg/day)
  consumed by humans

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Human exposure/rodent potency ratio (HERP) of
different carcinogens
Ames, B.N., R. Magaw, and L. Gold. (1987).
Ranking Possible Carcinogenic Hazards. Science
236271-80.
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Lets have another cup ocoffee?

• Acetaldehyde
• Benzaldehyde
• Benzene
• Benzofuran
• Benzoapyrene
• Caffeic acid
• Catechol
• 1,2,5,6,Dibenzanthracene
• Ethanol
• Ethylbenzene
• Formaldehyde
• Furan
• Furfural

• Hydrogen peroxide
• Hydroquinone
• Limonine
• Styrene
• Toluene
• Xylene

Overall gt1000 chemical compounds
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Coffee is there more to come?
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Caffeine a good guy or a bad guy?
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Is trouble just a bubble?

• Sub-lethal and sub-toxic effects
• Developmental effects
• Endocrine effects
• Genetic effects
• Bioaccumulation/biomagnification
• Sensitive populations, species and life stages
• Local populations/groups at risk (near sites of
  release, workplace exposure in humans)
• Multiple exposures
• Scientific uncertainty Unknown effects

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Role of science

• Science is first of all a set of attitudes
  Science is a willingness to accept facts even
  when they are opposed to wishes Scientists have
  simply found that being honest with oneself as
  well as with others is essential to progress.
  Experiments do not always come out as one
  expects, but the facts must stand and the
  expectations fall. The subject matter, not the
  scientist knows best.
• B.F.Skinner (1953) Science and Human Behavior

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Precautionary principle

• In order to protect the environment, the
  precautionary approach shall be widely applied by
  States according to their capabilities. Where
  there are threats of serious or irreversible
  damage, lack of full scientific certainty shall
  not be used as a reason for postponing
  cost-effective measures to prevent environmental
  degradation.
• Principle 15, Rio Declaration on Environment and
  Development, 1992.

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Take-home messages

• Environmental toxicology is a synthesis of
  science, technology and practice
• The role of science is to provide hard data about
  the potential risks associated with exposure to
  natural and synthetic chemicals
• Science does not pass judgment, only informs
• When scientific evidence is insufficient,
  precautionary principle can be applied