IARC
International Agency for Research on Cancer.

IDLH
Immediately Dangerous to Life and Health. An atmospheric concentration of any toxic, corrosive or asphyxiant substance that poses an immediate threat to life or would cause irreversible or delayed adverse health effects or would interfere with an individual’s ability to escape from a dangerous atmosphere.

Ignition source
Anything that provides heat, spark or flame sufficient to cause combustion or explosion.

Ignition temperature
The minimum temperature to initiate or cause self-sustained combustion in the absence of any source of ignition.

Impervious
A material that does not allow another substance to pass through or penetrate it. Frequently used to describe gloves.

Inches of mercury column
A unit used in measuring pressures. One inch of mercury column equals a pressure of 1.66 kPa (0.491 psi).

Inches of water column
A unit used in measuring pressures. One inch of water column equals a pressure of 0.25 kPa (0.036 psi).

Incompatible
Materials which could cause dangerous reactions from direct contact with one another.

Ingestion
Taking in by the mouth.

Inhalation
Breathing of a substance in the form of a gas, vapor, fume, mist, or dust.

Insoluble
Incapable of being dissolved in a liquid.

Irritant
A chemical, which is not corrosive, but which causes a reversible inflammatory effect on living tissue by chemical action at the site of contact.