Environmental Life Sciences: Chapter 14

Causes cancer, nerve damage, and miscarriages.
-hundreds of products, cans, utensils
-93% of it in their bodies
-mimics estrogen

1. Physical hazards- earthquakes, floods, etc. Cannot prevent them, increase vulnerability by deforestation

2. Chemical hazards- synthetic chemicals such as pharmaceuticals, disinfectants, pesticides. Harmful natural chemicals also exist (venom).

3. Biological Hazards- result from ecological interactions. Viruses, bacteria, & pathogens. Cannot avoid, but can reduce infection

4. Cultural hazards- result from where we live, socioeconomic status, occupation, & behavioral choices. Smoking, drug use, diet, etc. Health factors.

Radon- highly toxic, radioactive gas that is colorless & undetectable. Builds up in basements.

Asbestos- mineral that insulates, muffles sounds & resists fire.
Asbestosis- scarred lungs that cease to function

Lead poisoning- caused by lead. Damages brain, liver, kidney, etc. Causes learning problems, behavioral abnormalities, and death. Exposure is from drinking water that flows thru lead pipes, and lead paint

PBDE's- fire retardant properties. Used in computers, plastics, furniture, etc. Concentrations rising in breast milk

Disease is a major focus.
- kills most of us- cancer, heart disease, respiratory
-Poverty & poor hygiene foster illness

Best way is to improve basic living conditions
-food security, sanitation, clean water

-expanded access to health care
-Education campaigns

Toxicology: the study of the effect of poisonous substances on humans and other organisms.
Toxicity: the degree of harm a toxicant can inflict
Toxicant: any toxic substance (poison)
"The dose makes the poison"
Environmental toxicology: deals with toxic substances that come from or are discharged into the environment
- studies health effects on humans, animals and other organisms

Written by Rachel Carson (1962)
-depicted the risks of DDT exposing people, wildlife, & ecosystems
-chemical companies challenged the book
DDT was banned in 1973- yet is still exported

Carcinogens- cause cancer
Mutagens- cause DNA mutations (can cause cancer)
Teratogens- cause birth defects in embryos
Neurotoxins- assault the nervous system
Allergens- overactivate the immune system
Endocrine disruptors- affect the endocrine (horomone) system

Pesticide drift- airbone transport of pesticides
breakdown products- simpler products that toxicants degrade into
Bioaccumulation- toxicants build up in animal tissue
Biomagnification-concentrations of toxicants become magnified

Case history approach- studies individual patients
-autopsies tell us about the lethal doses
-don't tell about probability/risk or rare, new toxins

Epidemiological studies- large scaled comparisons between exposed and unexposed groups
-studies can last for years
-not necessarly the cause/effect

The amount of toxicant required to kill (afffect) 50% of the subjects

the level where certain responses occur

The response varies based on; genetics, location, poor health sensitivity, age, sex, weight, infants clearly more sensitive

set for adult responses

Acute exposure- high exposure to a hazard for short periods of time
-easy to recognize stem from discreate events

Chronic Exposure- low exposure for long periods of time
- more common- harder to detect
-affects organs gradually

Risk- the probabilty that some harmful outcome will result from a given action, event, or sub.

Probability- the likelihood of a certain outcome

Innocent-until-proven-guilty approach
-assumes a substance is harmless

Precautionary- assumes a substance is harmful until it is proven harmless