Term

Definition

Example

Absorption

The process by which an agent is taken into the blood supply or cells of an organism.

Absorption of nicotine by the lungs.

Acute exposure

A singe 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

Hang over from alcohol

Anemia

Decreased ability of blood to transport oxygen

Fewer or damaged red blood cells (lead)

Asbestosis

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

Asbestosis workers

Bioaccumulate

The ability of some organisms to accumulate specific compounds.

Fish accumulate methyl mercury; DDT or PCB’s accumulate in fat

Biotransformation

An organism changing one substance into another form often to increase excretion or reduce toxicity

Bacteria changing mercury into methyl mercury

Carcinogen or carcinogenic

Any substance that causes cancer

Asbestos

Chelating Agent

An agent that binds other agents to facilitate their excretion

Used to treat elevated lead or mercury levels

Chromosome

Parts of cells responsible for heredity characteristics -- DNA

Most humans have 46 chromosomes

Chronic Toxicity

Causes health effects from long-term exposure

Smoking cigarettes

Corrosive

Causes burns to the skin or other body tissue

Lye, strong cleaning agents

Detoxification or Biotransformation

The biochemical process to neutralize a toxicant (i.e. metabolism) or excretion.

The metabolism of alcohol.

Distribution

How a chemical agent distributes throughout the body.

PCB's and pesticides accumulate in fat.

Dose

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 to an agent.

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

Erythema

Sunburn – inflammation – dilation of the blood vessels thus the redness and heat.

UV radiation

Excretion

How the body removes agents from the body or even cells.

Mercury is excreted in the urine.

Exposure

Duration and type of contact with an agent

Route of exposure

How the agent gained access to the organism - dermal (skin), inhalation (lung), 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 life time 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 with learning and nervous system disabilities without the obvious physical deformities

Incidence unknown

Half-life

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

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

Hazard

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

Loud noise - deafness
Lead - reduced IQ

Inhalation

Exposure to and absorption of a compound via the lung

Cigarettes (nicotine)

Marijuana (THC)

Ingestion

Exposure to and absorption of a compound via the stomach or intestines

Food, coffee (caffeine), lead

LD-50

Lethal dose that will kill 50% of a group of animals (little used)

Nicotine (1 mg/kg)

Leukemia

Cancer of the blood-forming organs of the bone marrow

Caused by benzene

Mesothelioma

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

Asbestos workers (increased with smoking)

Metabolism

Change one substance in another which usually aids excretion or reduces toxicity

Caffeine into less active compounds

Milligram (mg)

One thousands 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 - Inhalation 0.2 µg/m³

Mutagen or Mutagenic

Any substance that causes alterations in cellular DNA

Many cancer causing agents, radiation

Neurotoxicity

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

Mercury, Lead, pesticides, heron, alcohol etc...

Neurotransmitter

A chemical used to communicate between cells of the nervous system

Dopamine, serotonin

PCBs

Polychlorinated biphenyls – used as cooling agent in transforms because of low flammability. Now banned because of their environmental persistence and bioaccumulation in fat of many species including whales and humans.

Memory lose

Pesticide

“… 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

Pharmacology

The study of the beneficial and adverse effects of drugs.

Benefits of aspirin or caffeine

Pollutant

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

DDT, PCBs, mercury, lead, etc….

Reference Dose (RfD)

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

EPA RfD for methyl mercury - 0.1 µg/kg-day

Response

The reaction to an exposure to or dose of an agent

Stomach ache from eating too many green apples

Risk

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

Evaluating the dose of lead or mercury that causes developmental effects in children

Risk assessment

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

Reference dose (RfD) or acceptable daily intake (ADI)

Risk Communication

Strategies for effectively communicating information about hazards and risk.

Town meetings, pamphlets, the World Wide Web

Risk management

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

Hazardous waste site clean up, removing lead from gasoline

Skin Absorption

Exposure to and absorption of a compound via the skin

Nicotine patch, solvents

Susceptibility

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

Developing organism, childhood, genetics

Age

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

Lead is far more toxic to infants than adults.

Health

Disease can increase susceptibility to an agent.

Liver disease can increase susceptibility.

Pregnancy

The many physiological changes that occur during pregnancy alter susceptibility.

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

Sex

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).

Teratology

From the Greek word teras meaning abnormal form, the branch of science that deals with the causes, mechanisms, manifestations and prevention of congenital defects.

Thalidomide (caused limb deformities in children)

Therapeutic index

Measure on a drugs benefit and safety. A wide index indicates that a drug as few toxic effects at high 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

Toxicity or Toxic effect

An adverse reaction of the organism.

Soft egg shells, reduced IQ, cancer

Toxicokinetics or Pharmacokinetics

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

How long alcohol stays in the body.

Toxicology

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

Study of affects of lead on the developing nervous system.

Toxicologist

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

Toxin

A natural biological agent (from plants, animals, bacteria or fungus) that cause toxicity.

Domoic acid found in shell fish, caffeine

Xenobiotic

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

Caffeine in humans