Pesticides are widely used in agriculture and have been linked to various types of cancers including breast cancer, bowel cancer, leukaemia, and lymphomas. High doses of some of these chemicals can cause cancer in animals, but the levels found in foods are much, much lower.
Fruit and vegetables sometimes contain very small amounts of pesticides. Because of this, you are recommended to rinse fruit and vegetables before eating them. But there is no evidence that these small amounts can increase cancer risk. In fact, eating lots of fruit and vegetables can reduce your risk of several cancers, despite any pesticide residues on them.
Some potentially dangerous pesticides such as DDT are now banned but were used in the past. These chemicals break down slowly so they can accumulate in the environment. They could eventually find their way up the food chain and be stored in our fatty tissues. Even so, scientists have not found a link between these chemicals and cancer. These studies have been very consistent across different research groups and countries, so their results are likely to be accurate.
A pesticide called Lindane was investigated as a cause of cancer. In 2000, The European Union Standing Committee on Plant Health banned the use of Lindane for all agricultural and gardening purposes. Government laboratories routinely monitor for Lindane in milk but it has not been found in recent years.
Workers exposed to higher levels of pesticides in industry or farming, may be at higher risk of certain cancers, particularly leukaemias and lymphomas. Some scientists think that these chemicals could suppress the immune system in people who are regularly exposed to them. This could increase their risk of cancer, but more research is needed to make sure. The current evidence is inconclusive but suggests that any possible risks would be very small.