Download Ch 14 Env Health 2013 - Pendleton

Chapter 14
Environmental Health,
Pollution & Toxicology
Categories of Pollutants
• Biological Hazards
– Viral: HIV, Hantavirus, Dengue Fever, Ebola,
Smallpox, chicken pox
The stylets (needle-like structures) and proboscis (elongated mouth) of an
Aedes aegypti feeding.
Dengue viruses are transmitted during the feeding process.
Biological Hazards
– Bacterial: Anthrax, Lyme disease, Salmonella
– Parasitic: Legionellosis (Legionnaires’
Disease), Giardiasis, Malaria, Cryptosporidosis
• Vector: insect or organism that can
transport and transmit infectious agent
• Reservoir: organism that carries
infectious agent but does not have
symptoms of the disease
• Chemical Hazards
-Toxic Heavy Metals
– Include Hg, Pb, Cd, As, Se, Cr
– By-products of mining, industry,
refining
– Biomagnifies
Mercury & Minamata, Japan
• From 1932-1968, Chisso Corp. dumped Hg into
•
•
local bay; didn’t believe inorganic Hg would
enter food chain
Hg converts to methyl mercury [CH3Hg]+, easier
to absorb
Symptoms occurred at exposure of 500ppb; first
in cats
-Organic Compounds
– Compounds of C, including synthetics
– Do not easily break down, fat soluble, travel
long distances
– Include dioxins, PCBs (polychloro-biphenols),
pesticides (DDT, Aldrin, Dieldrin)
DDT
PCB general formula
Times Beach, Missouri 1982
– Dioxin: one of the most toxic synthetic
chemicals; byproduct of herbicide production
– Oil sprayed on roads contained 2000x higher
dioxin level than in Agent Orange
– Town has since been evacuated, purchased
by gov’t.
– Superfund $ to clean up site through
incineration
Former Ukranian President Victor
Yushchenko, a victim of intentional dioxin
poisoning, 2004
Physical Hazardous
-Radiation
– Workplace Exposure
– Byproduct of Nuclear
Energy production
– Natural sources such
as Radon
-Particulates
– Dust, soot, asbestos
– Can be coupled with
Heavy Metals & other
toxics
– Much $ has been
spent on asbestos
removal; much
unnecessary
-Thermal Pollution
– Heating of water or air
– Natural Events: Fires,
volcanoes
– Man-made: Cooling towers for
electric power plants; cools
turbines
– Eutrophication, fish migration,
spawning cycles disrupted,
stress on fish
-Electromagnetic Fields
–
–
–
–
Produced by all electrical appliances, power lines
Natural fields around us
Possible link to childhood leukemia
Cell phone use?
-Noise Pollution
– Any unwanted sound
– Measured in decibels; home interior = 45 dB
– >140 dB = pain
– >80 dB potentially damaging
– Airports, mechanical equipment, workplace
machinery
• Lifestyle/Cultural Exposure
-Voluntary
– Tobacco, Alcohol
– Drug Use (OTC, prescription, illegal)
– Driving (texting & cell use)
-Involuntary Exposure:
-Secondhand smoke
-Living near pollution sources
-correlates w/socioeconomic
Toxicology
• Toxicity: measure of how harmful a
substance is
• Dosage: Amount of substance ingested,
inhaled or absorbed through skin
• Harmfulness depends on:
1.
2.
3.
4.
Size of dosage over certain period of time
How often exposure occurs
Who is exposed (ex: child vs adult)
How well body’s detoxification systems work
(kidney, liver, lungs)
5. Genetic makeup that determines one’s
sensitivity to a particular toxin
Threshold Effects
• Level below which no effect occurs; above
which effects begin to occur
• How much is “safe” vs how much is
“realistic”
Dosage
• LD50: dose that kills 50% of a population
(usually mice & rats)
• LC: lethal concentration; amt in local env.
• ED50: dose effective for 50% of the
population
• TD50: dose toxic to 50% of population
Fig 15.14 In this hypothetical toxic doseresponse curve, toxin A has no threshold.
© 2003 John Wiley and Sons Publishers p. 300
Toxicity Ratings and Average Lethal Doses for Humans
Toxicity Rating
LD50 (mg per kg
bodyweight)
Average LD
Examples
Supertoxic
< 0.01
< 1 drop
Nerve gas,
botulism, dioxin
Extremely Toxic
<5
< 7 drops
Potassium
cyanide, nicotine,
heroin, parathion
Very Toxic
5-50
7 drops- 1 tsp
Hg salts,
morphine
Toxic
50-500
1 tsp – 1 oz
Pb salts, DDT,
caffeine, CCl4
Moderately Toxic
500-5000
1 oz to 1 pt
Methyl alcohol,
ether, speed,
aspirin
Slightly Toxic
5000-15000
1 pt to 1 qt
Ethyl alcohol,
soap
Essentially
nontoxic
>15000
> 1 qt
Water, glycerin,
sugar