Increased exposure to pesticides has been linked with the continual rise in non Hodgkin's lymphoma in the US.
The study looked at blood concentrations of DDT and PCBs in 74 people who subsequently developed the disease and in 147 matched controls. No significant link was found between DDT levels and non Hodgkin's lymphoma. But PCB levels were significantly higher in sufferers than in controls (Lancet, 1997; 350: 240-4).
For more information on pesticides see WDDTY vol 6 no 3 and vol 7 nos 8 and 11; for non Hodgkin's lymphoma see vol 6 no 5.