1. Chapter 14: Environmental Health and Toxicology

2. Environmental Health
assesses environmental factors that influence human health and quality of life
natural
human-caused

3. Physical Hazards natural disasters earthquakes volcanic eruption fires
floods
blizzards
landslides
hurricanes
droughts
UV radiation
difficult to predict
areas of high risk can be determined

4. Chemical Hazards synthetic chemicals society produces
disinfectants (Lysol products)
pesticides (DDT)

5. Biological Hazard ecological interaction between organisms
infectious diseases
swine flu: virus
tuberculosis: bacteria Mycobacterium tuberculosis
malaria: parasite Plasmodium sp.
cholera: bacteria Vibrio cholerae

6. Cultural Hazards behavioral choices location we live in
smoking, sunbathing, drug use
location we live in
near an active volcano
Alaskan volcano 2006
apod.nasa.gov/apod/ap html

7. socioeconomic status occupation Cadillac Heights hazardous work or
lack of safety equipment
Dallas Flood June 2007

8. Disease
major factor of environmental health

9. Indoor Health Hazards radon lead highly toxic gas
seeps up from the ground in certain areas
lead
water from lead pipes and lead paint in homes and toys
damages brain, liver, kidney and stomach
learning disabilities
behavioral abnormalities
anemia
hearing loss
death

10. Indoor Health Hazards asbestos PBDEs form long thin microscopic fibers
used in insulation (sound, heat)
resists fire
dangerous when inhaled: asbestosis & cancer
PBDEs
fire-retardant
used in electronics, plastics and furniture
evaporates at very low rates
accumulates in tissues
may affect nervous system and cause cancer
banned in the EU

11. Toxicology study of poisonous substances
environmental toxicology deals with toxics discharged in the environment
on humans
other animals
ecosystems

12. Environmental Toxicology
natural toxins
radon, arsenic, mercury
exuded substances from plants and animals
human-made toxins
wastewater contaminants
pesticides & herbicides
Silent Spring by naturalist Rachel Carson
effect of DDT on humans, animals and ecosystems
DDT is still in use in tropical areas to control diseases

13. Types of Toxicants carcinogens mutagens teratogens causes cancer
causes mutations in fetus
teratogens
affects fetus during gestation causing birth defects
Thalidomide

14. Types of Toxicants allergens neurotoxins weakens immune system
increase in asthma
neurotoxins
inorganic: heavy metals (lead, mercury)
Minamata case
organic: pesticides (DDT, mothballs, nerve gas)
some are very stable and can last decades, others may only last hours

15. Types of Toxicants endocrine disruptors
interfere with hormones
affects growth, reproduction, behavior, brain function
similar to hormones so they "mimic" them
certain pesticides→ feminization of males
possible cause of human sperm count drop worldwide
possible cause of increase rates of
testicular cancer
undescended testicles
genital birth defects in men
female breast cancer

16. Effects of Endocrine Disruptors

17. Other Effects of Endocrine Disruptors
brain functioning
PCB contamination of food (fish)
lower birth weight of babies
smaller heads
weak and jerky reflexes
tested poorly in intelligence tests

18. Means of Toxins' Disperse
water
many are soluble in water
runoff
concentrates toxins in surface waterways
enters tissue through drinking or contact
air
pesticide drift
toxins appeared in tissues of arctic polar bears and antarctic penguins
thought to be due to global atmospheric circulation

19. Distribution of Toxins

20. Toxins in the Food Chain
Bioaccumulation
stored in tissues according to its solubility
Biomagnification
increase in toxin concentration up in the food chain
Bald eagle case related to DDT
population decrease of polar bears

21. Epidemiology Studies
application of experimentation due to conditions in the environment
effect of a contaminant in the air to a population already established
drawback
takes too long
many other factors may affect the health of the subjects
statistical association between health hazard and effect but it does not confirm it as the cause of the problem

22. Dose-responce Toxicity
effect of toxins according to amount in the system/body
LD50→ lethal dose for 50%
low LD50 means high mortality
high LD50 means low mortality
ED50→ effective dose for 50%
half of the population gets sick but doesn't die
Threshold
toxin level above which a responce is observed

23. Exposure vs Responce acute responce chronic responce
responce to a high exposure during a short period of time
Union Carbide accident in India
chronic responce
responce to a low concentration of a toxin but during a long period of time
exposure to Teflon
synergistic effect
unpredicted consequences of mixing toxins
sum
cancel
multiply or exacerbate

24. Risk Assessment & Risk Management
Assessment: collection and interpretation of scientific data identifying outlining problems
expressed in probability
risk of crashing if driving too fast
Management: formulation of policy to minimize risk
influenced by political pressure
considers economics and ethics
EPA, CDC, FDA
banning of Seldain D
banning of DDT
containing cholera

25. Philosophical Approaches
innocent-until-proven-guilty
innovation goes ahead
doesn't slow down technology
can result in disasters
recall
Vioxx (short period of testing)
vitamins & herbs (unregulated)

26. Philosophical Approaches
harmful until proven otherwise
precaution principle
experimentation has to be done thoroughly
long process]
regulated medications

27. EPA
Federal Insecticide, Fungicide and Rodenticide Act of 1947 assured the effectiveness of the product
EPA was created to protect the public and environment from toxic chemicals using risk assessment and management
EPA examines the data from the manufacture
assesses the possible risks to humans and environment
approves, denies or sets limits to use

28. Toxic Substances Control Act (1976)
regulation of synthetic chemicals by the EPA
criticized as too weak
screening of industry is minimal
EPA needs to show proof of toxicity and not the other way around
only 10% have been tested for toxicity
only 2% have been tested for carcinogens
fewer than 1% are government regulated
none have been tested for endocrine, nervous or immune system damage

29. International Regulation
Stockholm Convention on persistent Organic Pollutants of 2004
"dirty dozen"
guidelines to phase off these chemicals
REACH pushes innovation of new chemicals to do the same job but be less toxic

30. Dirty Dozen
The End