Ecotoxicology & Environmental Toxicology Tee L. Guidotti GWUMC.
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Transcript of Ecotoxicology & Environmental Toxicology Tee L. Guidotti GWUMC.
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
Substances move around and change in the ecosystem
Once released into media: partitionPathways of movement, exposureMetabolism and biomodificationExposure of “receptors” Effects on individualsEffects on populationsRecycling and uptake
How do we judge the risk of this incident?
Exposure assessment pathway magnitude duration
Characterize the population exposedRisk assessment
formal/informal risk assessment identify subpopulations at risk
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
Human ToxicologyToxicokinetics
Absorption Distribution Metabolism Excretion
Toxicodynamicsmechanismsexposure-responsesusceptibility
Toxicology and Ecotoxicology are similar but not identical.
Toxicology Ecotoxicology
Absorption Release into theenvironment
Distribution Fate and Disposition
Metabolism Metabolism
Elimination No counterpart!
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)
Broad generalizations in toxicology!
The dose makes the poisonThe most susceptible are the very
young, the very old and the infirm Interaction and multiple effects may
occurOccupational and environmental
exposures never go away - they reappear in other settings.
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
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
Children and Toxic Exposures
Children are differentHigher minute ventilationMore active, behaviourally and
metabolicallyGrowing Incomplete defenses and
physiological barriers
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
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
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
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
Exercise and Occupational Health
ErgonomicsOccupational health riskFitness to work
Preplacement screening Return to work
Rehabilitation, impairment musculoskeletal cardiovascular and endurance
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
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
Air pollution
The major issues: reducing photochemical air toxics stratospheric ozone layer depletion, enhanced greenhouse effect occupational indoor air quality
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
Health Issues Associated with Modern Ambient Air Pollution
Mortality, associated with PM, ozoneMorbidity
aggravating lung disease, cardiovascular disease
eye irritation increased risk of URI increased frequency of asthma attacks
Not cancer!