Benzo[a]pyrene – a carcinogen in smoke
You need to read this article if:
- you work as a volunteer bushfire fighter
- you work in a smoky environment
- you work in the commercial compost industry
- you work with recycled soils or in soil remediation
- you are exposed to tar, pitch, asphalt, soot, carbon black, crude paraffin, coal or coke
- you work regularly with a char grill or a charcoal barbecue.
Such work can expose you to benzo[a]pyrene (abbreviated BaP), a naturally occurring dangerous chemical that forms as a result of incomplete combustion of both fossil fuels and bushland. BaP is mutagenic and highly carcinogenic: that is, it causes cancer. In fact, BaP was recognised in 1933 to be the component of coal tar responsible for cancers of the scrotum suffered by chimney sweeps in 18th century England.
Sources of BaP
BaP is a product of the incomplete combustion of most organic materials at temperatures between 300 and 600 °C. Hence, it is a normal component of bushfire smoke, diesel exhaust, old urban soils, barbecue smoke, cigarette smoke and the smoke from spontaneously igniting commercial compost windrows. It is also present in roofing tar, pitch and asphalt.
If you work in any of these areas, then you need to protect yourself from BaP.
Exposure routes
BaP enters the body through the skin, in the air you breathe and in any contaminated food ingested. The most common route of exposure is in smoke.
Long-term effects of BaP exposure
- BaP causes skin, lung, bladder and scrotal cancers.
- The presence of BaP on the skin enhances the risk of skin cancer from UV in sunlight.
- Repeated exposure to BaP can cause thickening, reddening and darkening of the skin.
- Bronchitis is a possible consequence.
- Immune system function is depressed, leading to reduced ability to fight disease.
- Numerous studies have shown a clear association between inhalation of gases containing BaP and other related chemicals (e.g. coke oven emissions, roofing tar emissions, cigarette smoke) and increased risk of lung cancer and other cancers.
Symptoms of acute BaP exposure
- A skin rash with redness or a burning sensation. Exposure to the UV in sunlight can exacerbate these effects.
- Eye irritation.
Ways of reducing exposure
Commonsense measures will help protect you against harm from BaP:
- Wear protective clothing and respirators.
- Wash thoroughly after exposure.
Working safely
- Ventilate enclosed work areas.
- Wear respirators and protective equipment.
- Change contaminated clothing immediately.
- Wash your skin at the end of each work day.
- Wash contaminated work clothes at work, not at home.
- Provide eye wash fountains in the immediate work area for emergency use.
- Do not eat, smoke or drink where BaP may be present. Wash hands before eating or smoking.
- Do not dry-sweep: use a vacuum cleaner or a wet method to reduce dust.
If someone has been exposed
- Eyes: Immediately flush with large amounts of water for at least 15 minutes, occasionally lifting lids.
- Skin: Quickly remove contaminated clothing. Immediately wash skin with large amounts of soap and water.
- Inhalation: Remove the person from exposure.
Health checks
- If you are concerned that you might be exposed regularly to BaP, see your GP. Ask the GP to check you for skin cancers and lung function.
- Routine sampling of air and surfaces in the workplace will reveal potential hazards.
Workplace exposure limits
- An annual average concentration in air of 0.30 ng/m3 or higher requires investigation.
- In the USA, the airborne permissible exposure limit is 0.2 mg/m3 averaged over an 8-hour work shift.
- As BaP is a known carcinogen, there may be no safe level of exposure, so reduce all contact to the lowest possible level.
BaP and SESL
BaP is a fundamental component of the NSW EPA’s Site Auditor Scheme and Contaminated Land Assessment legislation. It is also measured in both the waste classification process and the resource recovery testing.
SESL tests for BaP and is happy to discuss contamination issues and potential and appropriate remediation strategies.
Further information
New Jersey. 2007. Benzo(a)pyrene. Hazardous Substance Fact Sheet 0207. Department of Health and Senior Services, NJ, USA.
Wikipedia: Benzo[a]pyrene.