The study concludes that cancer-causing hazards besides smoking have been introduced into the US population in the past several decades, and into other industrialised countries as well. Better diagnosis explains some but not all of the increase, JAMA says, because the rise in cancers started before improved diagnostics became available. This is important bad news. The recently introduced causes of cancer in Sweden and the US remain largely unidentified. The study suggests that something useful might be learned by studying farmers.
Farmers smoke less and are more active than most people.
They are also exposed to more engine exhausts, chemical solvents, pesticides, fuels, animal viruses and sunlight than most people.