The%20Epidemiology%20of%20Human-Animal%20Interactions%20Part%20III:%20Animals%20as%20Sentinels%20of%20Environmental%20Hazards - PowerPoint PPT Presentation

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The%20Epidemiology%20of%20Human-Animal%20Interactions%20Part%20III:%20Animals%20as%20Sentinels%20of%20Environmental%20Hazards

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Provide a rationale for using pet animals ... bladder cancer and commonly used insecticides for flea & tick control ... tick & flea dips, sprays. Conclusions ... – PowerPoint PPT presentation

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Title: The%20Epidemiology%20of%20Human-Animal%20Interactions%20Part%20III:%20Animals%20as%20Sentinels%20of%20Environmental%20Hazards


1
The Epidemiology of Human-Animal Interactions
Part IIIAnimals as Sentinels of Environmental
Hazards
  • Larry Glickman, VMD, DrPH
  • and
  • Nita Glickman, MS, MPH
  • Purdue University
  • School of Veterinary Medicine

2
The Epidemiology of Human-Animal Interactions
Animals as Sentinels of Environmental Health
Hazards
  • Larry Glickman
  • and
  • Nita Glickman

3
Instructional Objectives
  • Describe the risk assessment process
  • Explain the sentinel concept
  • Provide a rationale for using pet animals in risk
    assessment
  • Explain how pet animals can be used as sentinels
    for environmental causes of human disease

4
Risk Assessment
  • The process by which scientific evidence is
    accumulated and used to define the health effects
    resulting from the exposure of individuals or
    populations to hazardous chemicals or situations

5
Usual Sources of Data for Risk Assessment
  • Human epidemiological studies
  • Laboratory animal toxicological studies

6
Suggested Complementary Approach to Risk
Assessment
  • Naturally occurring diseases in animals
  • Epidemiological studies of animal populations
  • In situ studies

7
Sentinel
  • Sentinel is derived from the French word
    sentinelle meaning watch tower
  • Sentinels provideearly warning
  • A sentinel is like a guard dog on patrol

8
Classical Example of Animals as Sentinels
  • Canaries in the coal mines - 1916
  • Canaries were taken into the coal mines to warn
    of noxious gases
  • Canaries are more sensitive to the effects of
    odorless coal gas than humans

9
Modern Example of Animals as Sentinels
  • Bioterrorism in Japan in 1995
  • A Japanese cult released poisonous gas into the
    subway system
  • Japanese policeused canaries asdetectors
    forpoisonous gasduring a raid on the cults
    premises

10
An Example of a Potential Animal Sentinel That
Was Overlooked
  • Mercury poisoning at Minamata, Japan (1956)
    Niigata, Japan (1965)
  • Strange, erratic behavior of local cats that
    consumed mercury contaminated fish
  • This behavior in cats preceded similar changes
    in humans
  • Unfortunately, the valueof this animal sentinel
    was not recognized early enough to prevent
    significant human morbidity
  • Supercourse Lecture on Minamata disease

11
One Approach to Environmental Monitoring Animal
Sentinel Systems
  • Systems in which health information on animals
    exposed to environmental contaminants are
    regularly and systematically analyzed to identify
    potential hazards to other animals or humans.

12
Primary Objectives of Animal Sentinel Systems
  • Facilitate assessment of human exposures to
    environmental contaminants
  • Facilitate assessment of health hazards resulting
    from such exposures
  • Indicate relationships between exposure hazard,
    eg., dose-response

13
Animal Sentinel Systems Can Be Classified By
  • 1) What is being monitored, i.e., exposure or
    effect
  • 2) Species of animals used
  • 3) Environment in question
  • 4) Natural habitat (observational) vs. purposely
    placed (experimental orin situ)

14
Selection of an Animal Species
  • An ideal animal sentinel species for human health
    risk assessment is one that is exposed to
    chemical contaminants in habitats shared with
    humans or comparable with human habitats and at
    similar concentrations(e.g., pet animals)

15
Desirable Features of Animal Sentinel Species
  • Abundance availability
  • Example pet animals

16
Selected Diseases in Household Dogs Associated
with Environmental Hazards
17
Example of a Veterinary Sentinel Event Lead
Poisoning
BLC blood lead concentration
18
Example of a Veterinary Sentinel Event Lead
Poisoning (cont)
  • Family dogs can be sensitive sentinels of lead
    poisoning in children.
  • Veterinarians diagnosing lead poisoning in dogs
    have a responsibility to protect public health as
    well.

19
Example of a Veterinary Sentinel Event Asbestos
Mesothelioma
  • Mesothelioma is a highly fatal cancer of humans
    and dogs caused by asbestos exposure
  • The latency period between asbestos exposure and
    mesothelioma may be gt25 years in humans
  • Pet dogs with spontaneous mesothelioma were used
    to identify environmental exposures that might
    increase their owners risk of asbestos-related
    diseases

20
Example of a Veterinary Sentinel Event Asbestos
Mesothelioma (cont)
  • Dogs share their owners home environment but do
    not have occupational exposures that could
    confound interpretation of human epidemiologic
    studies

21
Summary of a Veterinary Sentinel Event Asbestos
Mesothelioma
Mesothelioma
5 years
ALERT
Preventive Action
Asbestos Exposure
Mesothelioma
25 Years
22
Example of a Veterinary Sentinel Event
Insecticides Bladder Cancer in Pet Dogs
  • Pet dogs were used to test for an association
    between spontaneous bladder cancer and commonly
    used insecticides for flea tick control

23
Example of a Veterinary Sentinel Event
Insecticides Bladder Cancer in Pet Dogs (cont)
  • Risk of bladder cancer was significantly
    increased by topical insecticide use followed a
    dose-response pattern

24
Further Implications of a Veterinary Sentinel
Event Insecticides Bladder Cancer in Pet Dogs
  • Pet owners and dog groomers are often heavily
    exposed to topical insecticides during their
    application
  • The latent period for bladder cancer is lt 10
    years in dogs, but probably gt 25 years in humans
  • Question Is canine bladder cancer a sentinel
    health event?

25
Summary of a Veterinary Sentinel Event
Insecticides Bladder Cancer
Bladder Cancer
8 years
ALERT
Insecticide exposure- tick flea dips, sprays
Preventive Action
Bladder Cancer
25 Years
26
Conclusions
  • Pet animals can serve as valuable sentinels for
    hazards in the home environment
  • Diseases of animals only make useful sentinels if
    they are recognized reported in a timely manner
  • Sentinel systems require cooperation between
    human and veterinary health specialists
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