At a glance
| Chemical family | Organophosphate — thiophosphoric acid ester insecticide (cholinesterase inhibitor) |
| CAS number | 333-41-5 |
| Classification | IARC Group 3 (not classifiable as to carcinogenicity, Monographs Vol. 30/Suppl 7). Acetylcholinesterase inhibitor. EPA cancelled all residential and indoor uses in 2004 (children's risk). WHO Class II (moderately hazardous) |
| Where you encounter it | Formerly the #1 home insecticide in the US; still used in agriculture; persists in house dust in homes treated before 2004; garden/lawn use (phased out in US) |
| Sleep micro-environment relevance | Persists in house dust in older homes that were treated before the 2004 residential ban. Children crawling on treated carpets were the population of concern that drove the ban |
Regulatory & certification status
| European Union | Not approved as a plant protection product. Not authorised for biocidal use. Effectively prohibited. Regulatory |
| United States | EPA cancelled all residential and indoor uses (2004, voluntary agreement with manufacturer). Some agricultural uses remain. The residential phase-out was driven by risks to children from house dust exposure. Regulatory |
| Canada | PMRA re-evaluation completed. Most residential uses cancelled. Some agricultural uses remain. Regulatory |
| International | IARC Group 3 (not classifiable, Monographs Vol. 30/Suppl 7). WHO Class II (moderately hazardous). US residential ban (2004) was the landmark regulatory action. Regulatory |
What it is
Diazinon is a thiophosphoric acid ester that inhibits acetylcholinesterase — the enzyme that breaks down the neurotransmitter acetylcholine at nerve synapses. When cholinesterase is inhibited, acetylcholine accumulates, causing overstimulation of muscarinic and nicotinic receptors (salivation, lacrimation, urination, defecation, muscle fasciculation, and in severe cases respiratory failure). At the sub-acute levels found in residential exposure, the concern was chronic low-level cholinesterase depression in children. IARC classified diazinon as Group 3 in its Monographs Vol. 30 and reaffirmed this in Supplement 7. The EPA cancelled diazinon's residential uses in 2004 through a voluntary agreement with the manufacturer, citing risks to children from crawling on treated surfaces and mouthing objects contaminated with diazinon residues.
Where it shows up in bedding
Diazinon is no longer applied to bedroom surfaces in the US (all residential uses cancelled in 2004). However, it persists in house dust in homes where it was previously used — particularly in carpet dust, which acts as a long-term reservoir for semi-volatile pesticides. Studies have detected diazinon in dust samples from homes years after the last known application. For the sleep environment, this means that bedrooms in pre-2004 homes with original carpeting may still contain diazinon in floor dust, which can be tracked onto bedding. The concentrations are declining over time but remain detectable. Replacing old carpet eliminates this reservoir.
Citations
- IARC (1987). Diazinon. IARC Monographs Supplement 7. Source Peer-reviewed
- EPA (2004). Diazinon — Revised Risk Assessment and Agreement with Registrant. Source Regulatory
- Whyatt, R.M. et al. (2003). Residential Pesticides and Risk of Childhood Leukemia. Environmental Health Perspectives, 111(5): 659-665. Source Peer-reviewed
Frequently asked questions
Is diazinon still in my house dust?
If your home was treated with diazinon before the 2004 residential ban (particularly if the original carpet is still in place), diazinon may still be detectable in carpet dust. Carpets act as long-term reservoirs for semi-volatile pesticides. Concentrations decline over time but can persist for years. Replacing old carpet is the most effective way to remove this legacy contamination.
Why was diazinon banned for home use?
The EPA cancelled residential uses of diazinon in 2004 because of risks to children. Young children crawl on floors, mouth objects, and have hand-to-mouth behaviour that leads to higher pesticide ingestion from treated surfaces relative to body weight. The EPA risk assessment concluded that residential use could cause unsafe levels of cholinesterase inhibition in children.
Related compounds
Embr is a sleep environment company researching and addressing the chemistry of the bedroom. Research and product development in progress.
Last reviewed 2026-07-08. If you find a factual error, contact us.