![Benz[a]anthracene — Embr Bedroom Chemistry Atlas](../assets/atlas/benz-a-anthracene.jpg)
At a glance
| Chemical family | Polycyclic aromatic hydrocarbon (PAH) — four-ring alternant structure with a bay region |
| CAS number | 56-55-3 |
| Classification | IARC Group 2B (possibly carcinogenic to humans, Monographs Vol. 92, 2010). EU CLP Carc. 1B (H350). One of the 8 EU REACH Entry 50 restricted PAHs |
| Where you encounter it | Combustion products (tobacco smoke, wood smoke, vehicle exhaust, coal tar); found in household dust; grilled/smoked food; coal tar pitch |
| Sleep micro-environment relevance | Found in household dust from combustion sources. One of the carcinogenic PAHs that contributes to the cancer risk from PAH mixtures in indoor environments |
Regulatory & certification status
| European Union | CLP Carc. 1B (H350). REACH Annex XVII Entry 50 restricts 8 priority PAHs (including BaA) to 1 mg/kg in rubber and plastic components with prolonged skin contact. Regulatory |
| United States | EPA Priority Pollutant. Clean Water Act listed. California Proposition 65 listed (cancer). Regulatory |
| Canada | CEPA Schedule 1 (toxic substance) as part of the PAH group. Regulatory |
| International | IARC Group 2B (possibly carcinogenic, Monographs Vol. 92, 2010). One of the 8 EU priority PAHs restricted in consumer articles. Regulatory |
What it is
Benz[a]anthracene (BaA) is a four-ring PAH with an angular structure that creates a bay region — a concave area in the molecule that is structurally associated with carcinogenic activity in PAHs. IARC evaluated BaA in Monographs Vol. 92 (2010) and classified it as Group 2B based on sufficient evidence of carcinogenicity in animals and inadequate evidence in humans. The EU takes a more precautionary approach, classifying BaA as Carc. 1B. BaA is formed during incomplete combustion of organic matter and is found in tobacco smoke, wood smoke, vehicle exhaust, and coal tar. It is one of the 8 priority PAHs restricted in rubber and plastic components of consumer articles under REACH.
Where it shows up in bedding
Benz[a]anthracene is not an ingredient in bedding products. It enters the bedroom as a component of combustion-derived particulate matter that settles in dust. Sources include tobacco smoke (both secondhand and thirdhand residue on surfaces), fireplace and wood stove emissions, and outdoor vehicle exhaust that infiltrates through windows and ventilation. BaA is one of several carcinogenic PAHs that co-occur in these combustion mixtures. The EU restricts BaA to 1 mg/kg in rubber and plastic components of consumer articles with prolonged skin contact under REACH Entry 50.
Citations
- IARC (2010). Some Non-Heterocyclic Polycyclic Aromatic Hydrocarbons and Some Related Exposures. IARC Monographs Vol. 92. Source Peer-reviewed
- ATSDR (1995). Toxicological Profile for Polycyclic Aromatic Hydrocarbons (PAHs). Source Regulatory
- EU REACH Annex XVII, Entry 50 — PAHs in consumer articles. Source Regulatory
Frequently asked questions
Is benz[a]anthracene as dangerous as benzo[a]pyrene?
No. While both are carcinogenic PAHs, benz[a]anthracene has lower carcinogenic potency than benzo[a]pyrene. BaP is classified IARC Group 1 (carcinogenic) while BaA is Group 2B (possibly carcinogenic). In PAH mixture risk assessments, benzo[a]pyrene typically drives most of the estimated cancer risk, with BaA contributing a smaller fraction.
What is a bay region in a PAH?
A bay region is a concave area in the molecular structure of a PAH, formed by the angular arrangement of fused rings. This structural feature is important because PAHs with bay regions can be metabolised to bay-region diol-epoxides — reactive intermediates that bind to DNA and initiate carcinogenesis. Not all PAHs have bay regions, and those that do tend to be more carcinogenic.
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.