Pollution 2 Vocabulary

carcinogen

chemicals, ionizing radiation, and viruses that cause or promote the development of cancer

dioxins

family of 75 chlorinated hydrocarbon compounds formed as unwanted byproducts in chemical reactions involving chlorine and hydrocarbons, usually at high temperatures

dissolved oxygen content

amount of oxygen gas dissolved in a given volume of water at a particular temperature and pressure, often expressed as a concentration in parts of oxygen per million parts of water

dose response curve

plot of data showing the effects of various doses of a toxic agent on a group of test organisms

dose

amount of a potentially harmful substance an individual ingests, inhales, or absorbs through the skin

hazardous chemical

chemical that can cause harm because it is flammable or explosive, can irritate or damage the skin or lungs, or can cause allergic reactions of the immune system

hazardous waste

any solid, liquid, or containerized gas that can catch fire easily, is corrosive to skin tissue or metals, is unstable and can explode or release toxic fumes, or has harmful concentrations of one or more toxic materials that can leach out. these substances are usually byproducts of manufacturing processes.

leaching

process in which various chemicals in upper layers of soil are dissolved and carried to lower layers and in some cases groundwater

median lethal dose (LD50)

amount of a toxic material per unit of body weight of test animals that kills half the test population in a certain time

neurotoxin

chemical that can harm the human nervous system

open dump

fields or holes in the ground where garbage is deposited and sometimes covered with soil. they are rare in developed countries, but are widely used in many developing countries, especially to handle wastes from megacities.

polychlorinated biphenyls (PCBs)

group of 209 toxic, oily, synthetic chlorinated hydrocarbon compounds that can be biologically amplified in food chains and webs

precautionary principle

when there is a significant scientific uncertainty about potentially serious harm from chemicals or technologies, decision makers should act to prevent harm to humans and the environment

radioactive waste

waste products of nuclear power plants, research, medicine, weapon production, or other processes involving nuclear reactions

risk

probability that something undesirable will result from deliberate or accidental exposure to a hazard

risk analysis

identifying hazards, evaluating the nature and severity of risks associated with hazards, ranking risks, using this and other information to determine options and make decisions about reducing or eliminating risks, and communicating information about risks to decision makers and the public

risk assessment

process of gathering data and making assumptions to estimate short- and long-term harmful effects on human health or the environment from exposure to hazards associated with the use of a particular product or technology

risk management

use of risk assessment and other information to determine options and make decisions about reducing or eliminating risks

secondary pollutant

harmful chemical formed in the atmosphere when a primary air pollutant reacts with normal air components or other air pollutants

secondary recycling

a process in which waste materials are converted into different products; for example, used tires can be shredded and turned into rubberized road surfacing

secondary sewage treatment

second step in most waste treatment systems in which aerobic bacteria decompose as much as 90% of degradable, oxygen-demanding organic wastes in wastewater. it usually involves bringing sewage and bacteria together in trickling filters or in the activated sludge process.

septic tank

underground tank for treating wastewater from a home in rural and suburban areas. bacteria in the tank decompose organic wastes and the sludge settles to the bottom of the tank. the effluent flows out of the tank into the ground through a field of drainpipes.

smog

originally a combination of smoke and fog but now used to describe other mixtures of pollutants in the atmostphere

solid waste

any unwanted or discarded material that is not a liquid or a gas

sulfur dioxide

colorless gas with an irritating odor. about 1/3 of the SO2 in the atmosphere comes from natural resources as part of the sulfur cycle. the other 2/3 comes from human sources, mostly combustion of sulfur-containing coal in electric power and industrial plants and from oil refining and smelting of sulfide ores.

synergistic interaction

interaction of two or more factors or processes so that the combined effect is greater than the sum of their separate effects

teratogen

chemical, ionizing agent, or virus that causes birth defects

toxic waste

form of a hazardous waste that causes death or serious injury

toxicity

measure of the harmfulness of a substance

toxicology

study of the adverse effects of chemicals on health