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