1. Ecotoxicology & Environmental Toxicology
Tee L. Guidotti
GWUMC

2. Comparison: infectious disease, chemical exposure

3. Ecotoxicology Fate and disposition Ecosystem health
Release into medium
Pathways of migration, accumulation
Biomodification
Removal, degradation or precipitation
Ecosystem health
change in population structure
health of individual species
damage to ecosystem

4. Substances move around and change in the ecosystem
Once released into media: partition
Pathways of movement, exposure
Metabolism and biomodification
Exposure of “receptors”
Effects on individuals
Effects on populations
Recycling and uptake

5. Example: A “typical” water contamination issue

6. How do we judge the risk of this incident?
Exposure assessment
pathway
magnitude
duration
Characterize the population exposed
Risk assessment
formal/informal risk assessment
identify subpopulations at risk

7. Concerns in Environmental Toxicology
Air
ambient
indoor
occupational airborne
Water
surface
ground
Soil
contact
uptake and migration
Food
Consumer products
commercial
drugs
cosmetics
“Toxics”
hazardous substances
waste disposal
Environmental security

8. Human Toxicology Toxicokinetics Toxicodynamics Absorption Distribution
Metabolism
Excretion
Toxicodynamics
mechanisms
exposure-response
susceptibility

9. Essentials of Toxicology

10. Absorption

11. Distribution

12. Metabolism and Excretion

14. Toxicodynamics

15. Toxicology and Ecotoxicology are similar but not identical.

16. There are also differences.
Toxicology
Host defense mechanisms
Individual susceptibility states
Single effects
Cumulative exposure
Ecotoxicology
Bioaccumulation
Bioconcentration (in water)
Biomagnification
Never single effects
Movement between media (air, water)

17. Broad generalizations in toxicology!
The dose makes the poison
The most susceptible are the very young, the very old and the infirm
Interaction and multiple effects may occur
Occupational and environmental exposures never go away - they reappear in other settings.

18. Toxic effects are related to age of life.

19. The risk to the next generation.
First period of risk: embryo
peak period of risk is first trimester, first ten weeks, during organogenesis
severe damage is likely to result in spontaneous abortion
Second period of risk: fetal development
some late developing organs
neurological development and behaviour
cancer risk

20. The risk to the next generation.
After birth:
lactation and exposure through breast milk
environmental exposure
Toddlers and young children
accidental exposures
inquisitive behaviour
compulsive ingestion

21. Children and Toxic Exposures
Children are different
Higher minute ventilation
More active, behaviourally and metabolically
Growing
Incomplete defenses and physiological barriers

22. Physiological Aspects of Exercise
Increased minute ventilation increases exposure to airborne hazards
Bypass of host defense mechanisms
Reduces athletic performance
Increased metabolic rate
Airways reactivity
Increased cardiovascular risk with some exposures

23. How do we manage the risk of this incident?
Risk characterization - what is the risk?
Risk assessment - how big is it?
Risk perception - how do people see the problem?
Risk communication - talking about risk
Risk management - doing something about it

24. Exercise and Environmental Health
Exercise and ecosystem preservation
wilderness, climbing
hiking, orientiering, cross-country skiing
parks and open space
water sports, sailing
Extreme environments
heat stress
cold stress

25. Exercise and Environmental Health - 2
Environmental health and risk
water quality
water supply
microbial contamination
chemical contamination
bathing facilities
air quality
air pollution, health risk and performance
asthma

26. Exercise and Occupational Health
Ergonomics
Occupational health risk
Fitness to work
Preplacement screening
Return to work
Rehabilitation, impairment
musculoskeletal
cardiovascular and endurance

27. Exercise and Air Pollution
Heavily studied area of environmental physiology
Increased delivery of oxidant air pollutants (e.g. ozone) to lower respiratory tract)
Ozone has a direct effect on J-receptors in lung, inhibits deep inspiration
Older people show less effect
Tolerance developed, lost quickly

28. Example: Air Pollution
A complex set of issues
Recognition that PM, ozone associated with increased mortality
Concern that this reflects cardiovascular risk, esp. elderly
Exhaustion of susceptibles = “harvesting”
not proven
Triggering effect for asthma

29. Air pollution The major issues: reducing photochemical air toxics
stratospheric ozone layer depletion,
enhanced greenhouse effect
occupational
indoor air quality

30. Ambient Air Pollution Reducing Photochemical Industrial activity
Mostly sulfur
High coarse and fine particulate levels
Characteristic of developing countries
Bronchitis, most lethal AQ incidents
Photochemical
Vehicular traffic
Mostly oxidants
Fine particulates
Developing and developed countries
Population health effects

31. Health Issues Associated with Modern Ambient Air Pollution
Mortality, associated with PM, ozone
Morbidity
aggravating lung disease, cardiovascular disease
eye irritation
increased risk of URI
increased frequency of asthma attacks
Not cancer!

32. Secondary Issues in Air Pollution Management
Secondary ambient air quality standards may be set for:
plant life
materials
visibility
Loss of amenity is a major issue
loss of natural beauty
loss of enjoyment