Hazard not otherwise classified (HNOC)

The GHS classification system, as used in HazCom, covers many hazard classes, but no list can capture every effect. HNOC fills the gap. If a chemical manufacturer has valid evidence of a hazard that fits no existing class, such as a particular effect on workers that is not covered, the hazard should not be ignored just because it has no category.

OSHA added the HNOC concept when it aligned HazCom with GHS Rev. 3 in 2012. It is a US addition. The GHS itself does not have a general hazard-not-classified category in the same way, so an HNOC will not appear in the same form in other countries' labelling systems.

Where an HNOC applies, the manufacturer or importer must include it in the hazard identification section of the SDS. It is not required on the label, which keeps the label focused on classified hazards. Do not confuse HNOCs with simple asphyxiants and combustible dust: OSHA defines those hazards specifically and does require label elements for them (the signal word Warning and a set hazard statement, with no pictogram).

Examples of the type of hazard that might be an HNOC include effects that do not match a class because of their nature, such as a hazard evident only in a certain use. The details depend on the evidence, and judgement is needed. The standard sets out that HNOCs relate to hazards found through scientific evidence, not rumor.

For workers, the main lesson is not to treat a missing pictogram as proof of safety. Read section 2 of the SDS for any statements about other hazards.