Environmental Science Chapter 8
1 g/kg of body wt to be lethal
A moderately harmful toxin
The Bill and Melinda Gates Foundation has pledged $200 million for medical aid to help fight _____, _____, and _____
AIDS, TB, and malaria
_____ are caused by a single exposure to the toxin and result in an immediate health crisis.
Acute effects
_____ matters and _____ matters: healthy adults, for example, may be relatively insensitive to doses that are very dangerous to young children or to someone already weakened by other diseases.
Age; general health
_____ generally cause more ill health than any other exposure source. But, food, water, and skin contact can also expose us to a wide variety of hazards.
Airborne toxins
substances that activate the immune system. Some allergens act directly as antigens
Allergens
_____ is complicated by differences in toxic sensitivity between individual animals
Animal Testing
proteins produced by our bodies that recognize and bind to foreign cells or chemicals
Antibodies
substances (pollen, bacteria, etc.) recognized as foreign by WBCs and stimulate production of antibodies
Antigens
_____, _____, _____, and _____ could eliminate most of diseases.
Better nutrition, clean water, improved sanitation, and inexpensive inoculations
organisms selectively absorb and store toxins in their bodies
Bioaccumulation
occurs when the toxic burden of a large number of organisms at a lower trophic level is accumulated and concentrated by a predator at a higher trophic level
Biomagnification
substances that cause cancer
Carcinogens
_____ are long-lasting, perhaps permanent. Can result from a single dose of a very toxic substance, or a continuous/repeated sub-lethal exposure.
Chronic effects
_____ diseases account for about 1/3 of all disease-related mortality.
Communicable
_____ attempts to understand how our environmental changes threaten our own health as well as that of the natural communities.
Conservation medicine
_____, _____, etc., once thought to occur only in rich countries are rapidly becoming factors everywhere.
Depression, heart attacks
_____, _____, _____, _____, _____ & others kill ~11 M children/yr.
Diarrhea, acute respiratory illnesses, malaria, measles, tetanus
_____ in humans and ecological diseases are similar in that environmental change upsets normal ecological relationships.
Emergent diseases
those not previously known or that have been absent for at least 20 years. (H1N1, Ebola)
Emergent diseases
Chemicals that interrupt normal hormone functions
Endocrine Disrupters
deals with the effects of toxins in the biosphere or environment
Environmental toxicology
1/100 as much (only a few drops)
Extremely toxic
a state of wellbeing, not just the absence of disease
Health
In the case of a lethal dose (LD), this is called the _____
LD50
_____ is the most common toxin in children.
Lead
one of the most prevalent remaining infectious diseases. About 500 M new cases/yr and about one M die
Malaria
_____ have become the leading killers almost everywhere in the world
Modern lifestyles
chemicals/radiation, that damage or alter genetic material (DNA) in cells
Mutagens
poisons that specifically effect nerve cells
Neurotoxins
_____ are often misleading. Not personally experiencing a bad outcome, we feel it is rare.
Personal experiences
probability of harm times the probability of exposure
Risk
headaches, allergies, and chronic fatigue caused by poorly vented indoor air contaminated by various contaminants
Sick building syndrome
extremely potent; for some, a few micrograms (millionths of a gram) are lethal
Supertoxic chemicals
an interaction in which one substance exacerbates the effects of another
Synergism
chemicals or factors that cause abnormalities during embryonic growth and development
Teratogens
study of the adverse effects of external factors on an organism or a system
Toxicology
______ can be harmful even if dilute. Billionths, even trillionths, of a gram can cause irreversible damage.
Toxins
_____ virus shows how fast new diseases can travel. (absent from N. Am. until 1999!)
West Nile
Very toxic:
about 1/10 of that amount.
Public perception of hazards can disagree with _____
actual risks
Other materials are _____ when they occur together in exposures.
additive
People downplay risks to emphasize their own _____
agendas
Difficult to assess specific health risks of chronic exposures due to other factors, like _____ or _____
aging or normal diseases
Some materials produce _____ reactions. That is, they interfere with the effects or stimulate the breakdown of other chemicals.
antagonistic
Taken in small doses, however, most toxins can be _____ or_____ before they do much harm. Some damage from toxins can be repaired by _____
broken down or excreted; cells
100 cups of strong coffee, 100 aspirin tablets, 10 kg (22 lbs) of spinach or rhubarb, or a liter of alcohol would be _____
deadly all at once
Mortality means
death
Some toxins _____ quickly, others _____ for years (Pb, Hg, PVC)
degrade; persist
90% of all disease occurs in _____ countries (WHO)
developing
Even if we know how toxic a specific chemical is in laboratory tests, it is still _____
difficult to determine risk
4 Factors affecting toxicity:
dose (amount) route of entry timing of exposure sensitivity of the organism
Wildlife also experience widespread epidemics, which are sometimes called _____. (Botulism causes die offs in birds)
ecological diseases
West Nile Virus belongs to a family of mosquito-transmitted viruses that cause _____ (brain inflammation).
encephalitis
These chemicals are sometimes called _____ or _____, because they often cause reproductive health problems in females or feminization of males.
environmental estrogens or androgens
We have an exaggerated view of our own abilities to control our _____.
fate
Some of the most insidious effects of persistent chemicals, such as DDT and PCBs, are that they interfere with normal _____, _____, and _____ of a variety of animals at very low doses.
growth, development, and physiology
Morbidity means
illness
Diseases still kill millions of people, but _____
infections, birth issues, and nutritional deficiencies are still significant.
The greatest loss of life from an individual disease in a single year was the great _____
influenza pandemic of 1918
Toxicology includes chemicals, drugs, diet & physical factors, such as _____, _____, and _____
ionizing radiation, UV light, and electromagnetic forces
Each of us consumes _____ of many chemicals during our life.
lethal doses
A complication is that the effects of some toxins and health hazards can be _____
nonlinear
Toxins move between _____ and the _____
organisms and the environment
Wide variety of _____: viruses, bacteria, protozoans (single-celled animals), parasitic worms, and flukes.
pathogens
Better measurments today may lead us to believe that toxic materials are more _____ but maybe we are just better at finding trace amounts.
prevalent
Antibiotic/pesticide resistance is _____ (MRSA)
rising
"The dose makes the poison" almost everything is _____ at very high levels. This is a basic principle of toxicology, how a material is delivered and at what rate.
toxic
A convenient way to describe _____ of a chemical is to determine the dose to which 50 percent of the test population is sensitive.
toxicity
There are many routes for _____ to enter our bodies
toxins
Wealthy nations pursue drugs to _____ and _____, _____, and _____ while billions of people are sick or dying from treatable infections and parasitic diseases.
treat baldness and obesity, depression in dogs, and erectile dysfunction