Safety glossary

59 terms and acronyms that appear on Safety Data Sheets, GHS labels and workplace exposure records. Cross-referenced to OSHA HazCom 2012, EU CLP and the UN GHS Rev. 10.

A

ACGIH: American Conference of Governmental Industrial Hygienists. Private body that publishes the TLV occupational exposure recommendations used across North America.
ADR: European agreement on the international carriage of dangerous goods by road. Defines the orange plates and hazard class diamonds you see on trucks.
Aerosol: Suspension of solid or liquid particles in a gas. On an SDS, refers to pressurised spray products classified under GHS category Flammable Aerosol.
Asphyxiant: Gas that displaces oxygen (simple asphyxiant, e.g. nitrogen) or blocks its transport (chemical asphyxiant, e.g. carbon monoxide).
Autoignition temperature: Lowest temperature at which a substance ignites in air without an external spark or flame.

B

BEI: Biological Exposure Index. ACGIH reference value for a chemical or its metabolite measured in blood, urine or exhaled air.
Boiling point: Temperature at which the vapour pressure of a liquid equals atmospheric pressure. Section 9 of the SDS.

C

CAS number: Unique numeric identifier assigned by the Chemical Abstracts Service to every substance. Example: 67-64-1 is acetone. Read more →
Carcinogen: Substance shown to cause cancer. Classified by IARC (groups 1, 2A, 2B, 3, 4) and by GHS (categories 1A, 1B, 2).
CLP: EU Regulation (EC) No 1272/2008 on Classification, Labelling and Packaging. European transposition of GHS.
Combustible liquid: Liquid with a flash point at or above 37.8 °C (100 °F). Below that, it is flammable.
Corrosive: Substance that destroys living tissue or corrodes metals on contact. GHS pictogram GHS05.

D

DNEL: Derived No-Effect Level. Exposure level above which humans should not be exposed. Used in REACH chemical safety reports.
DOT: US Department of Transportation. Sets the hazardous materials transport rules in 49 CFR.

E

ECHA: European Chemicals Agency. Manages REACH, CLP and biocide legislation for the EU.
EPI / PPE: Personal Protective Equipment. Gloves, goggles, respirators, coveralls listed in SDS section 8.

F

Flash point: Lowest temperature at which a liquid gives off enough vapour to form an ignitable mixture with air.

G

GHS: Globally Harmonised System of Classification and Labelling of Chemicals. UN framework that standardises hazard classes, pictograms and statements worldwide. Read more →

H

H-statement: Hazard statement code (H2xx physical, H3xx health, H4xx environmental). Example: H225 Highly flammable liquid and vapour. Read more →
HazCom: OSHA Hazard Communication Standard, 29 CFR 1910.1200. The US worker right-to-know rule that mandates SDS and labels.

I

IDLH: Immediately Dangerous to Life or Health. NIOSH airborne concentration threatening life or causing permanent damage within 30 minutes.
IARC: International Agency for Research on Cancer. Publishes the monographs that classify carcinogens (group 1 to 4).
IUPAC name: Systematic chemical name defined by the International Union of Pure and Applied Chemistry. Example: propan-2-one for acetone.

L

LC50: Lethal Concentration 50. Airborne concentration killing 50% of a test animal population within a set exposure time.
LD50: Lethal Dose 50. Oral or dermal dose killing 50% of test animals. Lower LD50 = more acutely toxic.
LEL / LFL: Lower Explosive (or Flammable) Limit. Minimum vapour concentration in air that will ignite in the presence of an ignition source.

M

MSDS: Material Safety Data Sheet. Legacy name replaced by SDS in 2012 when GHS harmonised the 16-section format. Read more →
Mutagen: Substance that induces heritable genetic changes. GHS classes 1A, 1B and 2.

N

NFPA 704: US placard system with a red/blue/yellow/white diamond rating flammability, health, instability and special hazards from 0 to 4.
NIOSH: US National Institute for Occupational Safety and Health. Publishes RELs, IDLHs and the NIOSH Pocket Guide.

O

OEL: Occupational Exposure Limit. Umbrella term for TWA, STEL, PEL, REL, MAK and similar workplace limits.
OSHA: US Occupational Safety and Health Administration. Enforces HazCom, PELs and workplace safety rules.
Oxidiser: Substance that yields oxygen to support combustion of other materials. GHS pictogram GHS03.

P

P-statement: Precautionary statement code (P1xx general, P2xx prevention, P3xx response, P4xx storage, P5xx disposal). Read more →
PEL: Permissible Exposure Limit. OSHA legally enforceable 8-hour time-weighted average concentration in US workplaces.
pH: Measure of acidity from 0 to 14. Values ≤ 2 or ≥ 11.5 usually trigger corrosive classification.
Pictogram: Red-bordered white diamond with a black hazard symbol required on GHS labels and SDS. Nine pictograms in total.
PNEC: Predicted No-Effect Concentration. Environmental threshold below which no adverse effect is expected. REACH parameter.
PubChem: Free open chemistry database maintained by the US National Library of Medicine. Primary source for CIDs, structures and properties.
Pyrophoric: Ignites spontaneously in air at or below 54 °C. Example: white phosphorus.

R

REACH: EU Regulation (EC) No 1907/2006 on Registration, Evaluation, Authorisation and Restriction of Chemicals.
REL: Recommended Exposure Limit. NIOSH advisory workplace exposure limit, often lower than the OSHA PEL.

S

SDS: Safety Data Sheet. Standardised 16-section document describing the hazards and safe handling of a chemical product. Read more →
SDS section 8: Exposure controls and personal protection. Lists exposure limits (TWA, STEL) and required PPE. Read more →
Sensitiser: Substance that causes allergic reaction after repeated exposure. Respiratory (H334) or skin (H317) sensitisers.
Signal word: Danger (severe hazard) or Warning (less severe). Only one appears per label. Read more →
SDS section 16: Other information. Includes revision date, abbreviations, references and disclaimers.
STEL: Short-Term Exposure Limit. 15-minute time-weighted average that should not be exceeded, typically no more than four times per shift.
STOT: Specific Target Organ Toxicity. Single (STOT-SE) or repeated exposure (STOT-RE), GHS categories 1 to 3.

T

TDG: Transportation of Dangerous Goods. Canadian equivalent of ADR / DOT hazmat regulations.
Teratogen: Substance causing birth defects. Reported under GHS Reproductive Toxicity (H360, H361).
TLV: Threshold Limit Value. ACGIH airborne concentration below which nearly all workers can be exposed daily without adverse effects.
TWA: Time-Weighted Average. Average airborne concentration over a normal 8-hour workday, 40-hour workweek.

U

UN number: Four-digit code assigned by the UN Committee of Experts identifying dangerous goods in transport. Example: UN 1090 = acetone.

V

Vapour density: Ratio of the mass of a vapour to that of an equal volume of air. > 1 means the vapour sinks and accumulates in low points.
Vapour pressure: Pressure exerted by a vapour in equilibrium with its liquid at a given temperature. Higher pressure = more volatile.
VOC: Volatile Organic Compound. Organic chemical with high vapour pressure at room temperature; regulated for air quality.

W

WHMIS: Workplace Hazardous Materials Information System. Canadian hazard communication standard aligned with GHS.
Water-reactive: Substance that emits flammable gases on contact with water. GHS category 1 to 3, statements H260 / H261.

Results are indicative and for educational use. Verify against your institution's protocols and the manufacturer's SDS before any real-world use. Not valid as a regulatory label. Terms of use.