Download Chapter 17 Human Health and Environmental Risks

CHAPTER 17
HUMAN HEALTH AND
ENVIRONMENTAL RISKS
THREE CATEGORIES OF HUMAN
HEALTH RISKS
 PHYSICAL
– EXCESSIVE EXPOSURE TO UV
RADIATION OR RADON
 BIOLOGICAL
- ASSOCIATED WITH
DISEASE
 CHEMICAL
– NATURALLY OCCURRING AS
WELL AS SYNTHETICALLY PRODUCED
LEADING CAUSES OF DEATH IN THE WORLD
BIOLOGICAL RISKS
 INFECTIOUS
DISEASES- THOSE CAUSED BY
INFECTIOUS AGENTS, KNOWN AS PATHOGENS.
 CHRONIC DISEASE- SLOWLY IMPAIRS THE
FUNCTIONING OF A PERSON’S BODY.
 ACUTE DISEASE- RAPIDLY IMPAIRS THE
FUNCTIONING OF A PERSON’S BODY.
 EPIDEMIC – RAPID INCREASE
 PANDEMIC – EPIDEMIC OVER A LARGE
GEOGRAPHIC AREA
LEADING HEALTH RISKS
HISTORICAL DISEASES

PLAGUE – AKA BUBONIC PLAGUE OR BLACK DEATH
CAUSED
MOST

BY BACTERIA SPREAD BY FLEAS
RECENT PANDEMIC IN ASIA IN EARLY 1900’S
MALARIA
CAUSED
BY A PARASITIC PROTIST CARRIED BY
MOSQUITOES

TUBERCULOSIS
CAUSED
BY AIRBORNE BACTERIA
SERIOUS
PROBLEM TODAY IS DRUG-RESISTANT
STRAINS
EMERGENT DISEASES

HIV/AIDS – SPREAD BY CONTACT WITH
INFECTED BODILY FLUIDS

EBOLA – EXTREMELY HIGH DEATH RATE

MAD COW DISEASE – CAUSED BY PRIONS;
SPREAD TO HUMANS THROUGH INGESTION OF
INFECTED MEAT

BIRD FLU – AKA H1N1; SPREAD FROM INFECTED
DOMESTICATED BIRDS

WEST NILE VIRUS – SPREAD FROM WILD BIRDS
TO HUMANS VIA MOSQUITOES
TRANSMISSION OF PATHOGENS
CHEMICAL RISKS
NEUROTOXINS- CHEMICALS THAT DISRUPT THE NERVOUS
SYSTEM – SOME INSECTICIDES, LEAD, MERCURY
 CARCINOGENS- CHEMICALS THAT CAUSE CANCER –
ASBESTOS, RADON, FORMALDEHYDE, TOBACCO
 TERATOGENS- CHEMICALS THAT INTERFERE WITH THE
NORMAL DEVELOPMENT OF EMBRYOS OR FETUSES –
THALIDOMIDE, ALCOHOL
 ALLERGENS- CHEMICALS THAT CAUSE ALLERGIC
REACTIONS – PEANUTS, MILK, PENICILLIN, CODEINE
 ENDOCRINE DISRUPTORS- CHEMICALS THAT INTERFERE
WITH THE NORMAL FUNCTIONING OF HORMONES IN AN
ANIMAL’S BODY - HORMONES

DOSE-RESPONSE STUDIES
 LD50-
LETHAL DOSE THAT KILLS 50% OF THE
INDIVIDUALS
STUDIES
ARE CONDUCTED ON ANIMALS AND
EXTRAPOLATED TO HUMANS
 ED50-
EFFECTIVE DOSE THAT CAUSES 50% OF THE
ANIMALS TO DISPLAY THE HARMFUL BUT
NONLETHAL EFFECT
SUBLETHAL
EFFECTS – IS THE CHEMICAL A
TERATOGEN, CARCINOGEN, NEUROTOXIN?
LD50 STUDY
 SYNERGISTIC
INTERACTIONS- WHEN
TWO RISKS COME TOGETHER AND
CAUSE MORE HARM THAT ONE WOULD.
EXAMPLE:
THE HEALTH IMPACT OF A
CARCINOGEN SUCH AS ASBESTOS CAN
BE MUCH HIGHER IF AN INDIVIDUAL
ALSO SMOKES TOBACCO.
ROUTES OF CHEMICAL
EXPOSURE
BIOACCUMULATION
 AN
INCREASED CONCENTRATION OF A
CHEMICAL WITHIN AN ORGANISM OVER TIME
 USUALLY
OCCURS WITH FAT-SOLUBLE
SUBSTANCES
 CLASSIC
EXAMPLE: DDT
BIOMAGNIFICATION
IN THE FOOD CHAIN
- DDT
PERSISTENCE
 HOW
LONG A CHEMICAL REMAINS IN THE
ENVIRONMENT
RISK ANALYSIS
PROBABILITY OF DEATH IN U.S.
QUALITATIVE RISK
ASSESSMENT
 MAKING
A JUDGMENT OF THE RELATIVE
RISKS OF VARIOUS DECISIONS
 PROBABILITY-
THE STATISTICAL LIKELIHOOD
OF AN EVENT OCCURRING AND THE
PROBABILITY OF THAT EVENT CAUSING
HARM
QUANTITATIVE RISK
ASSESSMENT
 THE
APPROACH TO CONDUCTING A
QUANTITATIVE RISK ASSESSMENT IS:
 RISK=
PROBABILITY OF BEING EXPOSED TO A
HAZARD X PROBABILITY OF BEING HARMED
IF EXPOSED
STOCKHOLM
CONVENTION

IN 2001, A GROUP OF 127 NATIONS GATHERED IN
STOCKHOLM, SWEDEN, TO REACH AN AGREEMENT
ON RESTRICTING THE GLOBAL USE OF SOME
CHEMICALS

12 CHEMICALS WERE TO BE BANNED, PHASED OUT,
OR REDUCED

THESE INCLUDE DDT, PCBS, AND CERTAIN
CHEMICALS THAT ARE BY-PRODUCTS OF
MANUFACTURING PROCESSES.