A Small Glossary





The process by which an agent is taken into an organism's cells or blood supply

Absorption of nicotine by the lungs

Acute exposure

Exposure of a single or very limited number of doses

One alcoholic drink

Acute response

The response associated with acute exposure

Drunk from an evening drinking alcohol

Acute toxicity

Undesirable effects of an acute exposure

Hangover from drinking alcohol


Decreased ability of blood to transport oxygen

Fewer or damaged red blood cells (can be caused by lead)


A progressive, non-cancerous disease due to asbestos exposure that causes shortness of breath from scarring of the lung

Asbestos workers


The ability of some organisms to accumulate specific compounds

Fish accumulate methyl mercury in muscle; DDT and PCBs accumulate in fat (among other chemicals)


The changing of one substance into another by an organism, often to increase excretion or reduce toxicity

Bacteria changing mercury into methyl mercury

Carcinogen or carcinogenic

Any substance that causes cancer


Chelating agent

An agent that binds other agents to facilitate their excretion

Used to treat elevated lead or mercury levels


Parts of cells responsible for heredity characteristics (DNA)

Most humans have 46 chromosomes

Chronic toxicity

Causes health effects from long-term exposure

Smoking cigarettes


Causes burns to the skin or other body tissue

Lye, strong cleaning agents

Detoxification or Biotransformation

The biochemical process to neutralize (i.e. metabolize) or excrete a toxicant

The metabolism of alcohol


How a chemical agent distributes throughout the body

PCBs and pesticides accumulate in fat


A measured amount of exposure, usually in terms of body weight or sometimes surface area

10 mg/kg

Dose / response

The effect or response is related to the dose or amount of exposure

One cup of coffee is ok but two or three results in unpleasant effects


Sunburn and skin inflammation; dilation of the blood vessels causes redness and heat

UV radiation


How the body removes agents from its cells or the entire body

Mercury is excreted in the urine.


Duration and type of contact with an agent


  • Route of exposure

How the agent gained access to the organism: dermal (skin), inhalation (lung), or stomach (ingestion)

Cigarette smoke: lung

Lead: ingestion

  • Frequency of exposure

How often the exposure occurs, and the time between exposures

Consider 4 beers in 1 hour vs. 4 beers over 4 days

  • Duration

How long the exposure occurs (see acute and chronic exposure)

Acute exposure to gas fumes at a gas station, or lifetime exposure to food additives

Fetal Alcohol Syndrome (FAS)

Pattern of physical, developmental, and nervous system disabilities seen in babies born to mothers who consumed alcohol during pregnancy

1 to 3 per 1000 infants effects world wide

Fetal Alcohol Effect (FAE)

Similar to FAS: learning and nervous system disabilities without the obvious physical deformities

Incidence unknown


A measure of time to reduce the amount of agent by one half

The half-life of caffeine in the blood is 3-4 hours


An agent or situation capable of causing an adverse effect or harm.

Loud noise (can cause  deafness)

Lead (can reduce IQ)


Lethal dose that will kill 50% of a group of animals

The LD-50 of nicotine is 1mg/kg


Cancer of the blood-forming organs of the bone marrow

Caused by benzene


A rare cancer of the thin membranes lining the lungs, almost always related to asbestos exposure

Asbestos workers (increases with smoking)


The change of one substance into another, which usually aids excretion or reduces toxicity

Caffeine being changed to less active compounds

Milligram (mg)

One thousandth of a gram

1 mg

Minimal Risk Levels (MRLs)

ATSDR definition: “An MRL is an estimate of the daily human exposure to a hazardous substance that is likely to be without appreciable risk of adverse noncancer health effects over a specified duration of exposure.”

Inorganic mercury in air; MRL by inhalation: 0.2 µg/m3

Mutagen or Mutagenic

Any substance that causes alterations in cellular DNA


Production of an adverse change in the structure or function of the nervous system following exposure to a chemical or physical agent

Neurotoxic agents include mercury, lead, pesticides, heroin, and alcohol


A chemical used to communicate between cells of the nervous system

Dopamine, serotonin


Polychlorinated biphenyls: used as cooling agent in transforms because of low flammability; now banned because of their environmental persistence and bioaccumulation in the fat of many species, including whales and humans



“… any substance or mixture of substances intended for preventing, destroying, repelling or mitigating any insects, rodents, nematodes, fungi, or weeds or any other form of life declared to be pests. … and any substance or mixture of substances intended for use as a plant regulator, defoliant or desiccant.” - Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA, 1947)

DDT, atrazine, carbofuran


The study of the beneficial and adverse effects of drugs

Benefits of aspirin or caffeine


An agent, often released by human activity, that adversely affects the environment

DDT, PCBs, mercury, lead

Reference Dose (RfD)

A daily exposure level (dose) that is not expected to cause any adverse health effects in humans

EPA's RfD for methyl mercury: 0.1 µg/kg-day


The reaction to an exposure to, or dose of, an agent

Stomachache from eating too many green apples


The probability of injury, disease, loss of function, or death for an individual or population exposed to a hazardous substance (Risk = Hazard X Exposure)


Risk assessment

The process by which the nature and magnitude of risks are identified


Risk communication

Strategies for effectively communicating information about hazards and risk


Risk management

The process of determining whether or how much to reduce risk through our actions



Factors that can increase or decrease the adverse effects of an agent



The young and elderly are often more susceptible to the effects of an agent

Lead is far more toxic to infants than adults


Disease can increase susceptibility to an agent

Liver disease can increase susceptibility


The many physiological changes that occur during pregnancy alter susceptibility

Greater absorption of lead, longer half-life of caffeine.


Man and women differ in their response to agents due to hormonal influences

Female birth control pill is the most obvious

Teratogen or Teratogenic

Any substance that cause defects in the developing embryo or fetus (birth defects)

Alcohol can cause facial deformities (FAS)


The branch of science that deals with the causes, mechanisms, manifestations, and prevention of congenital defects; from the Greek teras, meaning abnormal form


Therapeutic index

Measure of a drug's benefit and safety; a wide index indicates that a drug has few toxic effects at high dose levels

Wide index: antibiotics

Narrow index: lithium

Toxic substance (regulatory term)

Any substance that can cause acute or chronic injury to the human body or is suspected to do so

US NIOSH publishes a list of toxic substances

Toxicant (poison)

An agent cable of causing toxicity; a poison

DDT, lead, noise, solvents, food additives, ozone

Toxic effect

The adverse reaction to an agent

Soft egg shells, reduced IQ, cancer

Toxicokinetics or Pharmacokinetics

The study of the absorption, distribution, and excretion of an agent

The period of time alcohol stays in the body


The study of the adverse effects of chemical and physical agents on living organisms

Study of lead's effects on the developing nervous system


A scientist that studies the adverse effects of agents on biological systems



A natural biological agent (from plants, animals, bacteria, or fungi) that causes toxicity

Domoic acid in shellfish, caffeine


A foreign compound, i.e. one that is not naturally found in an organism

Caffeine in humans

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