Formaldehyde COSHH data sheet: hazards, exposure limit and SDS summary

A category 1B carcinogen that also sensitises skin, is fatal if inhaled and harmful if swallowed. Under COSHH it requires the highest level of control and health surveillance. Some keratin hair treatments release it when heated.

Hazard data from the HSE GB MCL, the ECHA C&L Inventory and HSE EH40, checked 8 September 2026. Classification checked automatically against the HSE GB mandatory classification list (version 8) and the ECHA C&L inventory on 9 September 2026. Confirm the concentration and form against the supplier data sheet for the product you use.

Identification

CAS number	50-00-0
EC number	200-001-8
Physical form	liquid
Signal word	DANGER
Pictograms	GHS05 Corrosive; GHS06 Acute toxicity; GHS08 Serious health hazard
Routes of exposure	inhalation, skin, eyes, ingestion

Hazard classification

Harmonised classification from the GB mandatory classification list (index 605-001-00-5). GB classification revised on 15 January 2025, with full compliance required by 15 August 2026. Acute toxicity category 2 is by inhalation (fatal if inhaled) and category 4 by ingestion. Skin Corr 1B and EUH071 apply at 25% and above; 5 to 25% solutions are skin and eye irritants. Older data sheets still show H301, H311 and H331.

Carcinogenicity, category 1B
Germ cell mutagenicity, category 2
Acute toxicity, category 2
Acute toxicity, category 4
Skin corrosion, category 1B
Skin sensitisation, category 1A

Hazard statements

H350 May cause cancer.
H341 Suspected of causing genetic defects.
H330 Fatal if inhaled.
H302 Harmful if swallowed.
H314 Causes severe skin burns and eye damage.
H317 May cause an allergic skin reaction.
EUH071 Corrosive to the respiratory tract.

Workplace exposure limit

Reference period	ppm	mg/m³
Long term (8 hour TWA)	2	2.5
Short term (15 minute)	2	2.5

Common uses

Laboratory preservation
Some hair smoothing treatments
Resin manufacture

First aid

Inhaled: fresh air, medical attention. Skin: wash with plenty of water. Eyes: rinse for 15 minutes, medical attention. Swallowed: call 999.

In an emergency call 999. For advice call NHS 111. Always follow section 4 of the safety data sheet for the product you have.

Storage

Enclosed, ventilated, locked, away from oxidisers and acids.

Sources

HSE GB mandatory classification and labelling list (GB MCL), Index 605-001-00-5. Checked 8 September 2026.
ECHA C&L Inventory, CAS 50-00-0, ECHA 100.000.002. Checked 8 September 2026.
HSE EH40/2005 Workplace exposure limits (2020 edition), Table 1. Checked 8 September 2026.

We do not host or copy manufacturer safety data sheets. Ask your supplier for the current sheet for the product you use.