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

Example: A “typical” water contamination issue

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.

Toxic effects are related to age of life.

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!

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