Ecotoxicology & Environmental Toxicology

1. Ecotoxicology & Environmental Toxicology Tee L. Guidotti GWUMC

2. Comparison: infectious disease, chemical exposure

3. 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

4. Substances move around and change in the ecosystem • Once released into media: partition • Pathways of movement, exposure • Metabolism and biomodification • Exposureof “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. 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 Concerns in Environmental Toxicology

8. Human Toxicology • Toxicokinetics • 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. 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) There are also differences.

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. 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 Ambient Air Pollution

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