The effects of environmental factors such as ultraviolet light or air pollution (wood stoves; fossil fuels; volatile carcinogenic compounds formed during cooking) are ill-defined but they may act via the production of free radicals that elicit DNA mutations. The occupations with an increased risk of oral squamous cell carcinoma (OSCC) mostly involve blue collar workers, and they may include;
- Benzene exposure
- Blacksmithing
- Building industry
- Carpet installation
- Construction work
- Driving
- Electricity working
- Fossil fuel exposure
- Furniture industry
- Grain production
- Machinery operations
- Masonry
- Metal working
- Painting
- Pesticide exposure
- Petroleum industry
- Plumbers
- Railway working
- Textile industry
- Woodworkers.
Other possible risk factors for OSCC include;
- Diseases
– Chronic candidosis
– Diabetes
– Discoid lupus erythematosus
– Dyskeratosis congenital
– Fanconi anaemia
– HIV/AIDS
– Li Fraumeni syndrome
– Plummer-Vinson syndrome
– Scleroderma
– Xeroderma pigmentosum
- Iatrogenic causes
– DXR (radiotherapy)
– Drugs
– Anti-hypertensives
– Immunosuppressives
– Marijuana
- Social deprivation
- Dietary factors.
The consumption of adequate portions of fruit and vegetables (five a day) is associated with a reduced risk of OSCC suggesting a diet deficient in antioxidants predisposes to oral pre-cancer and cancer. One study from the USA showed an inverse association between total fruit and vegetable intake and incidence of head and neck cancer. The Mediterranean diet has been shown to be particularly associated with a reduced oral and pharyngeal cancer risk. No single dietary factor alone appears responsible; foodstuffs or drinks containing antioxidants are believed to have anti-carcinogenic effects, though a Cochrane review concluded the evidence is conflicting and insufficient. Similarly, any role of polyphenols and reports of a protective effect of coffee need confirmation.