CA-ATU · WHMIS Label element[Insert the total concentration in percentage of ingredients with unknown acute toxicity] % of the mixture consists of an ingredient or ingredients of unknown acute toxicity

WHMIS, no GHS code · supplemental label elementHealth

CA-ATU is a WHMIS supplemental label element from the Hazardous Products Regulations: “[Insert the total concentration in percentage of ingredients with unknown acute toxicity] % of the mixture consists of an ingredient or ingredients of unknown acute toxicity”. The Regulations give it no code; CA-ATU is the ID used on this site. It is used for Acute toxicity, mixture with ingredients of unknown acute toxicity (s. 8.1.6(b)). Listed in US OSHA and Canada. The Canadian French wording is in the table below.

Maintained by Valenc. Data checked 2026-10-20.

Heading text: Canada HPR. Wording can differ by jurisdiction; see the table below.

Wording by jurisdiction

UN GHS Rev.11

Not in UN

GHS Rev.11 (2025), Annex 3

WHMIS element with no GHS code, not part of the UN GHS.

US OSHA HCS

Different wording

HCS 2024 · primarily GHS Rev.7, some Rev.8

X% of the mixture consists of ingredient(s) of unknown acute toxicity (oral/dermal/inhalation)

29 CFR 1910.1200 App. C, C.3.3

Required on the label and SDS when an ingredient of unknown acute toxicity is present at 1% or more and the mixture is not tested as a whole (App. C, C.3.3).

EU CLP

Not adopted

EU_CLP_2025 · consolidated 1 Jul 2026

Not listed in EU CLP Annex III or IV.

Canada (EN)

No GHS code

WHMIS_2022 · GHS Rev.7 (Rev.8 for chemicals under pressure)

[Insert the total concentration in percentage of ingredients with unknown acute toxicity] % of the mixture consists of an ingredient or ingredients of unknown acute toxicity

HPR s. 3(1)(e)

Canada (FR)

No GHS code

WHMIS_2022 · SGH Rév.7, texte officiel

[Insérez la concentration totale en pourcentage d’ingrédients ayant une toxicité aiguë inconnue] % du mélange consiste en ingrédients de toxicité aiguë inconnue

HPR s. 3(1)(e)

Mexico (ES)

Not adopted

NOM-018-STPS-2015 · GHS 5th revised edition

Not listed in NOM-018-STPS-2015.

Hazard classes and categories

Acute toxicity, mixture with ingredients of unknown acute toxicity (s. 8.1.6(b))

Canada HPR

Related codes

CA-PYR-a CA-PYR-b CA-BIO1

Change in UN GHS Rev.11

Not part of the UN GHS, so Rev.11 does not apply.

Notes

Canada-specific HPR wording with no GHS code. The HPR does not assign a code; "CA-ATU" is a lookup ID used on this page only.

Sources

Each cell in the table names the official table and page for CA-ATU. Full citations, links and revision notes for UN GHS Rev.11, US OSHA, EU CLP, Canada and Mexico: Sources and revision notes.

These are regulatory phrases for labels and safety data sheets. Check them against the official source for your jurisdiction before use.