Environmental Science Chapter 10

Physical hazards occur naturally in the environment. Other examples include tornadoes, floods, volcanoes, and fires.

Most people spend upward of 90% of their time indoors. Without proper ventilation, many pollutants can accumulate indoors. Cigarette smoke and radon are the leading indoor hazards.

Almost 75% of deaths worldwide are caused by communicable diseases (those that can be passed from person to person) and diseases with a genetic or behavioral cause (e.g., cardiovascular disease, cancer).

smoking cigarettes. This is a choice that people make that exposes them to significant health hazards.

These organisms include rats, mosquitos, fleas, ticks, and even human beings.

lead poisoning. Many older homes have lead-based paint. When young children are exposed to lead, the symptoms described above can occur.

infectious diseases. Biological hazards are many times communicable and can be spread from one human to another. Because we can travel worldwide very quickly, our biological hazards can as well.

Silent Spring. Rachel Carson wrote this book in 1962. It exposed the dangers to birds from widespread use of DDT.

allergen. not universally considered toxins, because a given allergen will not necessarily affect any given person.

They mimic or block hormones that direct reproductive and developmental processes. Endocrine disruptors interfere with the normal hormonal communication system that controls, among other things, the normal patterns of development and reproduction. Reread the section called "Toxic substances come in different types."

Chronic means a long time of developing a condition at low exposure over a long period of time.

through drinking water and through water consumed by nonhuman biota, which, in turn, are consumed by human beings

Teratogens are a type of toxin that causes harm to developing fetuses.

in the North Pole and South Pole, because of prevailing ocean currents, as well as the fact that deposition exceeds evaporation at the poles. Once deposited, these toxins and pollutants enter the food web.

long persistence. The rate at which PCBs break down in the environment is very slow.

Toxicants are carried by the wind as well as the waters of streams and the oceans. Toxic substances are released into the air and can travel far from where they were manufactured or used. They can also be transported by water over large distances because of water's inherent cohesion.

It is the increase in toxicant concentration as it moves up to the top trophic levels in the food chain. DDT (still used in Africa and South America) is more concentrated in top predators than in lower levels of the food chain (trophic pyramid).

Epidemiological studies track the fate of exposed and unexposed groups for long periods to provide data that will allow the detection of observable differences between the groups.

high. The LD50 indicates the dose of a toxicant that is lethal to 50% of people. If the number is high, then a high dose of the substance is required to kill people.

Two gases chemically combine to become a different pollutant with new, unique properties.

manipulative. This type of experiment is most useful for establishing cause and effect but is often unethical to perform on humans.

by graphing the response of model systems or organisms to specific doses of toxicants. The response is generally quantified by measuring the proportion of animals exhibiting negative effects at a range of toxicant concentrations.

the dosage in which a response is first elicited. Reread the section called "Dose-response analysis is a mainstay of toxicology."

The low LD50 means that it does not take much toxicant to cause the death of 50% of the subjects exposed to it.

Following individuals with exposure to toxicants or mutagens allows for the calculation of the rates at which health problems are likely to develop. Epidemiology is based on a large sampling of people who have been exposed to a given toxicant, mutagen, disease-causing organism, radiation, and so on.

The levels of a given toxicant increase more or less exponentially at each successive trophic level. Reread the section called "Toxic substances may accumulate and move up the food chain."

Animals can serve as an early warning to the damage of environmental toxins. Much like the proverbial canary in the coal mine, studies on wild animal populations can detect the effects of toxins on wildlife before they show up in humans.

probability. The risk of exposure is measured in terms of probability that those exposed will suffer a harmful outcome.

policy. Policy is how management decisions based on risk assessment are implemented.

Housing and Urban Development (HUD). The types of policy decisions covered in this chapter are not part of this agency's directive covers.

This is a description of the likelihood of a given thing happening. This description is quantitative.

pre-market testing by industry, government, and academic scientists utilizing the precautionary principle approach. This is only the second stage in the sequence of events for marketing the product. Doing this saves taking any of the other steps.

The main idea of the precautionary principle approach is that products go through extensive testing before being allowed to reach consumers.

The use of this principle places the responsibility of harm to the environment and humans on the manufacturer of the chemical instead of on the government.

European nations tend to use the precautionary principle, whereas the United States follows the innocent-until-proven-guilty approach. In the United States, powerful corporate interests have been able to ensure that the responsibility of determining whether a chemical is safe is placed on the government instead of on the manufacturer.