Environmental Health and Safety

MSDS Glossary

Reaction
A chemical transformation or change. The interaction of two or more substances to form new substances.
Reactivity
Chemical reaction with the release of energy. Undesirable effects — such as pressure buildup, temperature increase, formation of noxious, toxic or corrosive byproducts — may occur because of the reactivity of a substance to heating, burning, direct contact with other materials, or other conditions in use or in storage.
RCRA
Resource Conservation and Recovery Act is environmental legislation aimed at controlling the generation, treatment, storage, transportation and disposal of hazardous wastes. It is administered by EPA.
Reducing Agent
In a reduction reaction, which always occurs simultaneously with an oxidation reaction, the reducing agent is the chemical or substance which combines with oxygen, or loses electrons to the reaction. See Oxidation.
REL
The NIOSH REL (Recommended Exposure Limit) is the highest allowable airborne concentration which is not expected to injure workers. It may be expressed as a ceiling limit or as a time-weighted average (TWA).
Reproductive Toxin
Substances that affect either male or female reproductive systems and may impair the ability to have children. See also Mutagen.
Respiratory Protection
Devices that will protect the wearer's respiratory system from overexposure by inhalation to airborne contaminants. Respiratory protection is used when a worker must work in an area where he/she might be exposed to concentration in excess of the allowable exposure limit.
Respiratory System
The breathing system that includes the lungs and the air passages (trachea or "windpipe," larynx, mouth, and nose) to the air outside the body, plus the associated nervous and circulatory supply.
Routes of Entry
The means by which material may gain access to the body, for example, inhalation, ingestion, and skin contact.

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