Resources - Toxicology

Glossary of Terms

accelerator. A chemical used to increase the speed of a chemical reaction in the production of rubber or plastics.

ACGIH. American Conference of Governmental Industrial Hygiene.

acute-moderate syndrome. The onset is acute, but not life threatening. For chemicals, the length of exposure is less than 24 hours. The patient is likely to be seen in a clinic or emergency room, but not admitted to the hospital.

acute-severe syndrome. The onset is acute, severe, and life threatening. For chemicals, the length of exposure is less than 24 hours. The patient is likely to be admitted to the hospital.

aerosol. Small particles, usually in the range of 0.01 to 100 micrometers, dispersed in air; includes liquid (mist) and solid particles (dust).

AIHA. American Industrial Hygiene Association.

alveoli. Tiny sacs at the ends of bronchioles in the lungs; oxygen and carbon dioxide gas exchange takes place here with red blood cells in adjacent capillaries.

anemia. Decreased hemoglobin or number of red blood cells.

anesthesia. Temporary loss of consciousness induced by high concentrations of organic solvents.

antibiotic. A drug used in medicine to inhibit or kill microorganisms.

antibody. Proteins produced by the body's immune system in response to specific antigens.

antigen. A foreign substance that can induce the body to produce antibodies.

aplastic anemia. One type of anemia caused by injury to blood forming tissues and associated with occupational exposure to TNT, benzene, and ionizing radiation.

aromatic. An organic chemical (hydrocarbon) characterized by the presence of a benzene ring.

asthma. Reversible bronchoconstriction (narrowing of bronchioles) initiated by the inhalation of irritating or allergenic agents.

BEI. Biological Exposure Indices (ACGIH)

benign. 1) Refers to a tumor that does not invade other tissues and does not metastasize to other parts of the body. 2) Refers to an interstitial lung disease without any apparent symptoms or detectable changes in pulmonary function, e.g., siderosis caused by iron oxide.

bioaccumulation. Progressive increase of a poison in the body; occurs because the rate of intake exceeds the rate of elimination.

bronchiole. Bronchioles are the narrowest airways that branch from the bronchi of the trachea.

bronchitis. Chronic bronchitis is a persistent cough and the production of phlegm for at least 3 months out of the year for at least two successive years. (American Thoracic Society)

burn. Burns are characterized by: 1st degree-- redness; 2nd degree-- blisters; and 3rd degree--ulcers that heal by scarring.

carbamates. The carbamate insecticides are poisons that interrupt nerve conduction. These compounds cause the accumulation of acetylcholine at nerve endings by reversibly binding with the acetycholinesterase enzyme.

carcinogen. A chemical that can increase the incidence of cancer in exposed populations. Chemicals are classified by the International Agency for Research on Cancer (IARC) as known; probable, and possible human carcinogens based on available epidemiologic and toxicological evidence.

CAS #. Chemical Abstracts Service registry number, a unique number for each chemical in the format xxx-xx-x.

CBD. Chronic Beryllium Disease.

Ceiling. "The concentration that should not be exceeded during any part of the working exposure." (ACGIH)

CFR. Code of Federal Regulations.

chemical asphyxiant. A poison that blocks either the transport or use of oxygen by living organisms.

chloracne. A skin disease resembling acne that is caused by exposure to dioxin, pentachlorophenol, PCBs, and other chlorinated hydrocarbon compounds.

chronic syndrome. The onset of symptoms is gradual over a period longer than 2 months. A chronic syndrome induced by chemicals may represent 1) A cumulative exposure with a long latency, or 2) Adverse effects that persist two months or longer after a brief high exposure.

CNS. Central Nervous System.

CNS solvent syndrome. Organic solvents can affect the central nervous system both acutely (increased reaction time and anesthesia) and chronically (permanent brain damage).

confined space. "A space that is large enough and so configured that an employee can bodily enter and perform work. Confined spaces have limited or restricted means for entry or exit and are not designed for continuous occupancy. Confined spaces include storage tanks, bins, boilers, ventilation and exhaust ducts, pits, manholes, vats, and reactor vessels."

contact dermatitis. Dermatitis caused by contact with irritating or allergenic chemicals or biological agents.

corrosive. Pertaining to chemicals that can induce severe burns at the site of contact.

CWP. Coal Workers’ Pneumoconiosis.

dermatotoxin. A chemical that can cause skin disease.

dose-response relationship. Relationship between the dose of a toxic chemical and the incidence of an adverse effect. This is a fundamental law of toxicology expressed as, "The dose makes the poison." For any poison, there exists a threshold dose below which adverse effects do not occur.

edema. Increased intercellular fluid in tissues. In pulmonary edema, there is increased fluid in lung tissues.

EEGL. Emergency Exposure Guidance Level. (NRC)

elastomer. A plastic or synthetic rubber with elastic properties at room temperature.

engineering controls. Methods put in place (engineered) to control the source of worker exposure, e.g., exhaust ventilation systems or glove-box enclosures.

EPA. Environmental Protection Agency.

fibrogenic. Inducing tissue injury and fibrosis (scarring).

flammability. NFPA flammability code: 0 = will not burn; 1 = must be preheated; 2 = high ambient temp required; 3 = may ignite at ambient temp; 4 = burn readily.

gastrointestinal. Pertaining to the organs of the digestive system, including the stomach, liver, and intestines.

half-life. Time required to reduce by one half the amount of a chemical absorbed by the body. Half-life can be calculated accurately only for those substances eliminated linearly, independent of concentration. For linearly eliminated substances, it takes approximately 3.5 half-lives to eliminate 90% of the substance. [LaDou, p.174]

hard metal disease. Interstitial lung disease caused by repeated inhalation of cobalt dusts or fume. Exposure may occur during the manufacturing or use of hard metal tools containing cobalt and tungsten carbide.

hematotoxin. A chemical that is toxic to blood or blood-forming tissues.

hemoglobin. Proteins in red blood cells that carry oxygen.

hemolytic anemia. One type of anemia induced by chemicals in which the red blood cell membrane becomes fragile and lyses.

hepatotoxin. The chemical is toxic to the liver: 1) occupational hepatotoxin (principal effect); 2) secondary hepatotoxin (a) from occupational exposure (secondary effect) or (b) in animal studies or in humans after ingestion.

High-resolution computerized tomography (HRCT). An x-ray procedure used to diagnose lung diseases.

histopathological. Pertaining to the microscopic study of diseased cells and tissues.

hypersensitivity pneumonitis. An interstitial lung disease caused by repeated inhalation of organic dusts, e.g., Farmer’s lung.

hypoxia. Deficiency of oxygen available to living tissues.

IARC. International Agency for Research on Cancer; classifies chemicals as established (1), probable (2a), or possible (2b) human carcinogens.

IDLH. Immediately Dangerous to Life or Health.

inhalation fever. An acute, flu-like illness that begins a few hours after a heavy inhalation exposure to the causative dust or mist, e.g., zinc oxide fumes (metal fume fever) or organic dusts (organic dust toxic syndrome).

interstitial pulmonary fibrosis. Asbestos, coal, and silica dusts induce scar formation in interstitial lung tissue. The interstitium is the supporting lung tissue adjacent to pulmonary airways and blood vessels.

isomers. Chemicals with the same composition and molecular weight but different physical or chemical properties.

known carcinogen. Human carcinogen: sufficient evidence of carcinogenicity. [IARC]

lachrymator (lacrimator). A substance that irritates the eyes and induces the flow of tears.

latency. The latency for an occupational disease is the time lag between exposure to the toxin and detection of the disease.

LC50. Lethal concentration in 50% of animals tested.

Lower Explosive Limit (LEL). Lower Explosive Limit; the minimum concentration below which combustion will not occur.

Lowest-Observed-Adverse-Effect Level (LOAEL). "The lowest exposure level of a chemical in a study, or group of studies, that produces statistically or biologically significant increases in frequency or severity of adverse effects between the exposed population and its appropriate control." [ATSDR]

lung cancer. Cancer of the lung caused by occupational exposures-all of these agents are in the IARC Group 1 (known human carcinogens).

MAC (MAK). Maximum Allowable Concentration (Federal Republic of Germany).

methemoglobinemia. The presence of increased methemoglobin in the blood; chemicals are classified as either Primary (Methemoglobinemia is the primary toxic effect.) or Secondary.

mg/m3. Milligrams per cubic meter of air.

mmHg. Millimeters of mercury; at sea level the earth's atmosphere exerts a pressure of 760 mmHg. 1 mmHg = 1 Torr.

mppcf. Millions of particles per cubic foot of air.

MSDS. Material Safety Data Sheet.

MSHA. Mine Safety and Health Administration.

NAERG. North American Emergency Response Guidebook.

narcosis. Temporary sleepiness induced by high concentrations of organic solvents.

nephrotoxin. The chemical is toxic to the kidneys in the occupational setting; this is a primary toxic effect of the chemical.

neuropathy. Impairment of sensory and/or motor nerve function (slowing of conduction) caused by injury to peripheral nerves.

neurotoxin. Toxic to nerve cells; includes peripheral neuropathy (predominantly motor or sensorimotor), Parkinsonism, solvent syndrome (acute or chronic), and other CNS neurotoxins. [Rom, p. 697-707; LaDou, p. 366-74]

NFPA/ National Fire Protection Agency; see “flammability.”

NIOSH. National Institute for Occupational Safety and Health.

No-Observed-Adverse-Effect Level (NOAEL). "The dose of a chemical at which there were no statistically or biologically significant increases in frequency or severity of adverse effects seen between the exposed population and its appropriate control." [ATSDR]

NRC. National Research Council.

NTP. National Toxicology Program

odor threshold. The lowest concentration at which a substance can be detected or recognized using the sense of smell.

organochlorines. The organochlorine insecticides, including DDT and chlordane, persist in the environment and in animal tissues.

organophosphates. The organophosphate insecticides are poisons that interrupt nerve conduction. These compounds cause the accumulation of acetylcholine at nerve endings by irreversibly binding with the acetycholinesterase enzyme.

OSHA. Occupational Safety and Health Administration.

other CNS neurotoxin. Cyanide, organic tin, and other chemicals can cause a type of central nervous system injury different from neuropathy, Parkinson's syndrome, and solvent syndrome.

PACD. Photoallergic contact dermatitis.

paresthesia. Tingling or numbness.

Parkinson's syndrome. A degenerative central nervous system disorder with 4 characteristic features: slowness and poverty of movement, muscular rigidity, resting tremor, and postural instability.

PEL. Permissible exposure limit. (OSHA)

personal protective equipment. Respirators, gloves, eye protection, and other equipment used to protect workers from hazards when engineering controls fail to completely eliminate the potential for exposure.

pesticide. A substance used to kill pests including: algae (algicide), aphids (aphicide), fungi (fungicide), plants (herbicide), insects (insecticide), larvae (larvacide), molluscs (molluscicide), eggs (ovicide), rodents (rodenticide), and slime-producing organisms (slimicide).

photoallergic contact dermatitis (PACD). A type of allergic contact dermatitis caused by skin contact with an allergen that becomes active only after it absorbs UV light.

photoirritant contact dermatitis (PICD). A type of irritant contact dermatitis caused by skin contact with an irritant that becomes active only after it absorbs UV light.

pleura. A thin membrane that covers the lungs (visceral pleura) and thorax adjacent to the lungs (parietal pleura).

pneumoconiosis. Chronic scarring lung disease caused by the accumulation of asbestos, coal, silica, and other fibrogenic dusts.

pneumonitis. Inflammation of the lungs induced by inhalation of metal fumes or toxic gases and vapors.

possible carcinogen. Possible human carcinogen: limited epidemiological evidence and the absence of sufficient evidence in experimental animals. [IARC]

PPE. Personal protective equipment.

ppm. Parts per million.

probable carcinogen. Probable human carcinogen: limited epidemiological evidence, but sufficient evidence in experimental animals. [IARC]

pulmonary. Pertaining to the lung.

RD50. Concentration producing a 50% decrease in respiratory rate in experimental animals following a 10-minute exposure.

REL. Recommended exposure limit. (NIOSH)

renal. Pertaining to the kidneys.

reproductive toxin. A chemical that is toxic to the reproductive system, including defects in the progeny and injury to male and female reproductive function.

Restricted Use. Regulations that have banned or restricted the use of the agent.

route of exposure. Route of entry. For occupational exposures, poisons are usually absorbed through inhalation or skin contact. Significant occupational lead absorption can occur through ingestion.

sensitizer. An agent that can induce an allergic reaction in the skin or lungs.

serum. "Watery proteinaceous portion of the blood that remains after clotting." [Glossary for Chemists of Terms Used in Toxicology,"]

sign. Objective evidence of a disease as determined by laboratory results, an x-ray finding, or the physician's physical examination.

simple asphyxiant. A gas or vapor that can cause asphyxiation by displacing oxygen, but has no other significant adverse effects.

skin designation. "Danger of cutaneous absorption." (ACGIH)

SPEGL. Short-term public emergency guidance level. (NRC)

STEL. Short-term exposure limits. (ACGIH)

subacute syndrome. The onset of symptoms is gradual over a period of time less than 2 months. The syndrome may be a cumulative exposure with short latency, e.g., lead poisoning.

threshold limit value. "Concentration in air of a substance to which it is believed that most workers can be exposed daily without adverse effect (the threshold between safe and dangerous concentrations). These values are established (and revised annually) by the American Conference of Governmental Industrial Hygienists and are time-weighted concentrations for a 7 or 8-hour workday and a 40-hour workweek. For most substances the value may be exceeded, to a certain extent, provided there are compensatory periods of exposure below the value during the workday (or in some cases the week). For a few substances (mainly those that produce a rapid response) the limit is given as a ceiling concentration (maximum permissible concentration - designated by "C") that should never be exceeded." [Glossary for Chemists of Terms Used in Toxicology," ]

TIH. Toxic inhalation hazard. (NAERG)

TLV. Threshold limit value. (ACGIH)

TWA. Time-Weighted Average, the concentration of a chemical averaged or weighted over an 8-hour workday.

uncoupler. A chemical like pentachlorophenol that can cause a hypermetabolic state by poisoning cellular respiration (uncoupling oxidative phosphorylation).

vapor pressure (VP). A measure of a chemical’s volatility at 68 degrees F.

Source: National Institutes of Health (NIH)

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