Combustion and coal-tar compounds
PAHs
Also known as Polycyclic aromatic hydrocarbons
PAHs form during incomplete combustion and occur in coal tar, coke-oven waste, creosote, petroleum, soot, and contaminated sediment.
Environmental behavior
Persistence and movement
Heavier PAHs bind to soil and sediment and may persist for decades, while lighter PAHs evaporate or degrade more readily.
Pathways
How exposure may occur
- Breathing smoke, soot, or contaminated dust
- Eating contaminated food or ingesting soil
- Skin contact with coal tar, creosote, soot, or contaminated sediment
People
Potential long-term human effects
- Some PAHs can damage genetic material and increase cancer risk.
- Long-term exposure may also affect reproduction, development, immunity, skin, and lungs depending on the mixture and route.
Other living systems
Potential ecological effects
- PAHs in sediment can affect fish and bottom-dwelling organisms.
- Some PAHs become more toxic to aquatic life when exposed to sunlight.
Limits
Important uncertainty
PAH results should identify the individual compounds or mixture because toxicity varies substantially.