Ecotoxicology

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Ecotoxicology Environmental Toxicology

• Tee L. Guidotti
• GWUMC

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Comparison infectious disease, chemical exposure
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Ecotoxicology

• Fate and disposition
• 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

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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

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Example A typical water contamination issue
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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

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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

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Human Toxicology

• Toxicokinetics
• Absorption
• Distribution
• Metabolism
• Excretion
• Toxicodynamics
• mechanisms
• exposure-response
• susceptibility

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Essentials of Toxicology
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Absorption
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Distribution
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Metabolism and Excretion
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Toxicodynamics
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Toxicology and Ecotoxicology are similar but not
identical.
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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)

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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.

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Toxic effects are related to age of life.
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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

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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

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Children and Toxic Exposures

• Children are different
• Higher minute ventilation
• More active, behaviourally and metabolically
• Growing
• Incomplete defenses and physiological barriers

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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

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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

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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

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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

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Exercise and Occupational Health

• Ergonomics
• Occupational health risk
• Fitness to work
• Preplacement screening
• Return to work
• Rehabilitation, impairment
• musculoskeletal
• cardiovascular and endurance

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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

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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

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Air pollution

• The major issues
• reducing
• photochemical
• air toxics
• stratospheric ozone layer depletion,
• enhanced greenhouse effect
• occupational
• indoor air quality

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Ambient Air Pollution

• Reducing
• 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

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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!

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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