ENVIRONMENTAL HEALTH RISK ASSESSMENTS

1
ENVIRONMENTAL HEALTH RISK ASSESSMENTS

• SCIENCE OR VOODOO?
• Ron Pearson, M.S., CIH
• Environmental Health Safety, Inc.
• St. Paul MN

2
The Nature of Risk

• 200 people die annually in U.S. from
  electrocution (risk level 10-6 per year)
• should I replace the wiring in my old house?

3
The Nature of Risk

• 7000 people die annually in U.S. from falls in
  their homes
• but ... most are over age 65, so should the rest
  of us ignore this?
• It's all about CHOICES

4
Estimating Risk

• Probabilities are fine until it happens to me
• Some of the uncertainty is due to chance, some of
  it isn't

5
Estimating Risk

• Historical risks are easily understood - e.g. car
  accidents
• What kind of car do you drive?
• Does it have airbags?
• Do you drive fast?

6
Comparing Risks

• action annual risk uncertainty
• all cancers 3 in 1,000 10
• pack-a-day 4 in 1,000 150
  smoker
• mountain 6 in 10,000 50
  climber
• car accident 24 in 10,000 10
• drinking MCL 6 in 1,000,000 1,000 of
  chloroform
  in water

7
Comparing Risks

• Human nature dictates that we tend to worry more
  about risks that are severe and abrupt, as
  opposed to something that has some "probability"
  of occurring down the road
• Many say that we cant compare unlike risks,
  but in fact, we do it all the time

8
The Costs of Risk Reduction

• Location Risk Reduction Cost per
  
  (geog.)
  means life saved
• Indonesia Death Immunization 100
  countries (infection)
• U.S./ Cancer Pollution 1,000,000
  other prevention

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Why do we need Risk Assessment?

• "Emerging" risks - e.g. hormonal analogues
• Shifts in perception
• information overload - the "health studies"
  results that we are bombarded with daily
• ability to measure minute amounts of substances
• many traditionally severe health risks (e.g.
  smallpox) are gone

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Environmental Health Risk Assessment

• health risk the likelihood that an adverse
  effect will occur to a person (or group of
  persons) in a chemical exposure situation
• Usually, a higher exposure causes more serious
  effects or makes them more likely
• At some low exposure level, the risks become
  insignificant

11
Estimates of Risk

• Estimates of risk are needed to assist in making
  decisions
• Only in extreme cases will risks estimates alone
  drive decision making
• zero risk compels no action, while a great risk
  may compel immediate action
• IN REALITY, risk estimates lie somewhere in
  between

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Environmental Health Risk Assessments use two
types of Risk Estimates

• for carcinogens, the increased probability of
  individuals' getting cancer from a particular
  exposure
• for other toxicants, a comparison of expected
  exposure to an exposure that is assumed to be
  insignificant

13
Environmental Health Risk Assessments use two
types of Risk Estimates

• Why? Because they are most often used in USEPA
  risk assessments
• In general, effects on systems such as the
  reproductive or immune system are not scrutinized
  nearly as much as carcinogenic effects

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What DONT risk assessments estimate?

• total number of people affected
• relative incidence of an adverse effect in
  populations known to be exposed with those not
  exposed
• the ratio of the expected risk with the exposure
  to that expected without it
• reduced life expectancy associated with the
  effect
• lost income potential, costs to society

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Uncertainties in Risk Assessments

• Dose Effect relationship between the amount of
  a chemical exposure and the nature and/or
  severity of the toxic effect
• Data on toxic chemicals usually come from
• laboratory experiments on animals NOT
  epidemiology studies of humans
• moreover, many are inferences based on bacterial
  and/or human cells

16
Uncertainties in Risk Assessments

• Dr. Bruce Ames, (Ames salmonella microsomal
  screening test developer), stated repeatedly that
  he never intended for his "tool" to be applied as
  it is today

17
Uncertainties in Risk Assessments

• both of these sources of data cause problems
  because
• an animal or cell is not a human being
• most animal toxicity data is short-term
• relatively high exposures are used
  experimentally, to cause statistically
  significant effects

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Uncertainties in Risk Assessments

• many species are homogeneous (purposely, to limit
  variability in response)
• By contrast, humans are diverse in their response
  to chemicals due to

• genetic make up
• age
• habits
• occupation
• health status
• diet, etc.

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Uncertainties in Risk Assessments

• some argue that extrapolations from animals to
  humans are more reliable than epidemiology
  studies, due to
• small study populations (lack of "statistical
  significance")
• confounding variables
• lack of exposure data
• differences between study populations and the
  population to be protected

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Uncertainties in Risk Assessments

• When no effect is seen in lab animals, is there
  negligible risk to humans exposed at such a
  level?
• a 1 incidence of any disease would be impossible
  to detect in a study of 25 animals, but would
  represent more than 2 million cases if the entire
  U.S. population were exposed
• HOW DO WE ANSWER THIS QUESTION???

21
Uncertainties in Risk Assessments

• In risk assessment, it is often assumed that
• for cancer there is no safe dose, and
• at low doses, the relationship between
  dose-effect is directly proportional (linear)
• for other health effects there is a safe dose

22
Public Perception and Public Demands

• The "vicious circle"
• public perception -gt
  media reporting -gt
  congressional action -gt
  agency regulation in response to public demands

23
Public Perception and Public Demands

• Are we (in the U.S.) better off now than before
  the "skyrocketing" industrial use of chemicals?
• Since 1940 - life expectancy has increased nearly
  15 years
• Since 1970 - infant mortality has decreased by
  1/2
• Since 1970 - heart disease has dropped by nearly
  1/3

24
Public Perception and Public Demands

• Cancer deaths have increased...or have they?
• Many feel the this is due simply to
• smoking (increases lung, pharyngeal, pancreatic
  and bladder cancer incidence)
• sun exposure (malignant melanoma has increased
  eight-fold)
• the increase in life expectancy (you have to die
  of something...)

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Where has this all brought us?

• Many times, the science of epidemiology simply
  confirms the obvious - rarely has an
  epidemiological study drawn attention to an agent
  that was not already recognized by an astute
  observer in the field (e.g. Fen-Phen)

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Where has this all brought us?

• We fear carcinogens in our drinking water ... but
  what about Milwaukee's public water supply and an
  outbreak of cryptosporidium? Would we better off
  taking some of our money from the former and
  spending it on the latter?
• Asbestos we won't even get into it ...

27
Regulatory Reform

• What agencies conduct health risk assessments?
• OSHA
• EPA
• FDA
• USDA

28
Regulatory Reform

• 1983 - the NAS published the "Red Book" - "Risk
  Assessment in the Federal Government Managing
  the Process"
• defined four steps of risk assessment, but more
  importantly, discussed how to separate the
  "science" from the "policy"

29
Regulatory Reform

• 1987 EPA published "Unfinished Business" -
  ranked items such as pesticides in food and radon
  as higher health risks than items such as
  groundwater contaminants or hazardous waste sites
  BUT...failed to rank airborne lead as a high risk
  - again, it was driven by carcinogens....essential
  ly we have no scientific methods for comparing
  cancer with non-cancer risks

30
Regulatory Reform

• 1991 - Federal Focus, Inc. called for an
  executive order (16 CRR 171), essentially
  prohibiting the use of overly conservative
  assumptions
• Risk Assessment has been represented by many as a
  "value free" process, when in fact it is full of
  judgements
• Risk Assessment and Risk Management are, and
  should remain, separate processes

31
Regulatory Reform

• Risk Assessment produces very precise numbers of
  questionable accuracy

32
Regulatory Reform

• Federal Trend legislators pursuing risk
  assessment as means of telling us what the "real"
  risks are, so we can spend our money accordingly
  - represents another easy answer for attacking
  what ails us - after all, what politician in
  their right mind would outright oppose
  legislation that is supposedly "good for the
  environment"?

33
Regulatory Reform

• State Trends decreasing funding for public
  health/environmental health programs but
  increasing environmental regulatory spending - in
  1994 we spent 4.09 per capita on the former and
  18.87 per capita on the latter
• In the Republican party's "Contract with America"
  a bill called the "Job Creation and Wage
  Enhancement Act" bolstered risk assessment and
  cost benefit analyses requirements

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Cost-Benefit Analysis

• A good example of cost-benefit analysis and the
  fallacies that can be put forth
• OSHA's proposed IAQ rule estimated that a
  facility manager would spend an average of 15
  minutes documenting each complaint

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"Advancements" in the Science of Environmental
Health Risk Assessment

• ASTM RBCA - Risk Based Closure Assessment
  methodology
• many states have jumped on the bandwagon for this
  approach to screening UST sites, especially as
  state funds have become more scarce

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• ASTM RBCA - Risk Based Closure Assessment
  methodology
• uses a tiered approach
• Tier I "lookup tables"
• Tiers 2 - 4 incorporate more site specific
  values for
• ground water
• soil types
• specific information on receptors
• Still, much of the conclusions depend on
  mathematically modeled results - "garbage in -
  garbage out" still applies

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Conclusion Where do we go from here?

• Most environmental problems are extremely
  complicated technically

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Conclusion Where do we go from here?

• We live in the age of entitlement we want the
  government to provide us a risk-free society, and
  we want it now!
• We MUST decide how much minuscule reductions in
  risk we are willing to pay for
• We MUST question our legislators AND regulators
  motives and actions

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Conclusion Where do we go from here?

• We live in the age of technology, and science can
  solve all of our ills modern science has it's
  limitations, particularly when it comes to the
  analysis of living systems - it may never suffice
  in accurately predicting health effects or their
  potential from low level exposures
• We MUST decide how much uncertainty we are
  willing to tolerate

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Conclusion Where do we go from here?

• We live in the age of the sound byte most of the
  public gets the lion's share of this information
  from the media
• We MUST improve communication of these issues
  dramatically

41
Conclusion Where do we go from here?

• We live in the age of cancer paranoia most of
  the EPA's regulatory efforts focus on cancer
• We MUST shift the emphasis equally to non-cancer
  endpoints

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• "Security is mostly a superstition. It does not
  exist in nature, nor do the children of men as a
  whole experience it. Avoidance of danger is no
  safer in the long run than outright exposure.
  Life is either a daring adventure, or
  nothing."... Helen Keller
• DON'T WORRY - BE HAPPY ... Bobby McFerrin