Z94.13 - Occupational Health & Safety

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TEMPORARY THRESHOLD SHIFT (TTS). The hearing loss suffered as the result of noise exposure, all or part of which is recovered during an arbitrary period of time when one is removed from the noise. It accounts for the necessity of checking hearing acuity at least 16 hours after a noise exposure.

TEMPORARY TOTAL DISABILITY. The classification for any injury which does not result in death or permanent total or permanent partial disability, but which renders the injured person unable to perform a full day's work. This means that the injured employee cannot perform all the duties of a regularly established job which is open and available; or unable to perform such duties during the entire time interval corresponding to the hours of the regular shift on any one or more days including weekends, holidays, and other days off, or plant shutdown, subsequent to the date of the injury.


TENOSYNOVITIS. Inflammation of a tendon sheath.  Causes are varied, but commonly seen in industry associated with repetitive motion in an awkward or strained position. Commonly occurs about the wrist, the extensor tendons of the thumb, or in the fingers. 

TERATOGEN. Any agent or substance capable of producing a permanent alteration in the structure and/or function of cells, tissue and organs in the developing embryo or fetus when a pregnant female is exposed to that substance.

THEORY. A system of assumptions, accepted principles and rules of procedure devised to analyze, predict, or otherwise explain a specified set of phenomena.

THERP. This is an acronym for Technique for Human Error Prediction, a means for quantitatively evaluating the contribution of human error to the degradation of product quality. It is often combined with failure mode and effect and fault free methods to identify failures of the human components in a system.

THRESHOLD (HEARING). The point at which a person just begins to notice the tone is becoming audible. The level where the first effects occur.

THRESHOLD DOSE. The minimum dose of radiation which will produce a detectable biological effect.

THRESHOLD LIMIT VALUES (TLVS®). Exposure guidelines that have been established by the American Conference of Governmental Hygienists (ACGIH).  TLVs represent conditions under which it is believed that nearly all workers may be repeatedly exposed day after day without adverse health effects.  The ACGIH cautions that individuals may experience health problems at the specified levels, and that there may be harmful effects from the interactions of the specified exposures with exposures to other agents, such as tobacco smoke or other chemicals.  The guidelines are intended only as recommendations for the control of contaminants in the professional practice of industrial hygiene.

THRESHOLD LIMIT VALUE-CEILING (TLV-C).  The ceiling exposure limit-the concentration that should not be exceeded, even instantaneously.

THRESHOLD LIMIT VALUE-TIME-WEIGHTED AVERAGE (TLV-TWA). The allowable time-weighted average concentration of an air contaminant for a normal 8-hour workday or a 40-hour workweek.

TIME-WEIGHTED AVERAGE (TWA). An average over a given (working) period of a person's exposure as generally determined by integrative monitoring techniques.

TINNITUS. A ringing sound in the ears.

TOEBOARDS. A guard commonly installed around flywheels and other equipment in open pits and on overhead catwalks. The installation of toeboards should conform to the ANSI Standard A-1264.1, Safety Requirements for Workplace Floor and Wall Openings, Stairs and Railings. Toeboards should be at least 4 inches high and should be made of wood, metal, or metal grille not exceeding 1-in. mesh. Toeboards at flywheels should be placed as close to the edge of the pit as possible. Wood toeboards for permanent installations should be of 1" x 4" stock or heavier.

TOLERANCE. The ability of a living organism to resist the usually anticipated stress. The upper and lower limits of permissible variability. The limits of permissible inaccuracy above and below design specifications.

TOLERANCE (DRUG). The progressive diminution of susceptibility to the effects of a drug resulting from its continued administration.

TONGS, SAFETY.  A device for feeding objects to and removing them from a danger area.

TOTAL LOSS. Loss of all the insured property. Also a loss involving the maximum amount for which a policy is liable.

TOTAL REACTION DISTANCE (MOTOR VEHICLE). The distance traveled between the point at which the driver perceives that braking evasive action is required and the point at which the contact is made with the braking controls.

TOTAL REACTION TIME (MOTOR VEHICLE). The time required for a vehicle to move the total reaction distance.

TOTAL STOPPING DISTANCE (MOTOR VEHICLE). The distance in which the vehicle comes to rest after the driver discovers a hazard which requires stopping. Includes driver reaction time, brake reaction time, and braking time.

TOXEMIA. Poisoning by way of the blood stream.

TOXIC. Of, pertaining to, or caused by poison. Poisonous, harmful.

TOXIC SUBSTANCE. A substance that demonstrates the potential to induce cancer, to produce short- and long-term disease or bodily injury, to affect health adversely, to produce acute discomfort, or to endanger life of human or animal resulting from exposure via the respiratory tract, skin, eye, mouth or other routes in quantities which are reasonable for experimental animals or which have been reported to have produced toxic effects in humans.

TOXICANT. A substance that causes a degenerative alteration in any anatomic, physiologic, or biochemical system of a formed organism.

TOXICITY. A relative property of a chemical agent with reference to a harmful effect on some biologic mechanism and the condition under which this effect occurs.

TOXICOLOGY. That branch of medical science which deals with the nature and effects of poisons.

TOXICOLOGY, INDUSTRIAL. Study of the nature and action of toxic agents that may cause health impairment to workers.

TRAFFIC ACCIDENT. Any accident involving one or more motor vehicles in motion on a roadway. A traffic accident may involve more than one unit if each unit comes in contact with some other unit involved while part or either is in contact with the road or sidewalk.

TRANSMISSION LOSS (SOUND). The ratio, expressed in decibels, of the sound energy incident on a structure to the sound energy that is transmitted. The term is applied both to building structures (walls, floors, etc.) and to air passages (muffler, ducts, etc.).

TRAUMA. An injury, wound, or shock resulting from an accident or outside force.

TREMOR. Involuntary shaking, trembling, or quivering.


TSCA. Toxic Substances Control Act.

TUMOR. Any neoplasm.

TUNNEL VISION. Inability to see toward the sides. A narrow field of vision.

TWO-HAND CONTROLS. Tripping devices for a machine which require simultaneous application of both hands to operate the control, so that the hands of the operator are kept out of the point-of-operation area while the machine is operating.

TYPE OF ACCIDENT. The classification of an accident  according to the manner of contact of the injured person with the agency. Involves movement of object, material, or person and association with an agency; such as fall, struck by, struck against, etc.

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