With phytopharmaceutical products, farmers have effective means to combat the various parasite attacks on crops, which secures harvests. These products make an important contribution to meeting the immense food challenge announced for 2050 when the world population is expected to reach 9 billion people. However, the means of use of these products, their dissemination and persistence in the environment, their residual presence in food, and their effects on health are issues of concern for many citizens. The main problem faced by scientists in assessing the harmful effects of exposure to pesticides results from the multiplicity of other factors that can cause identical symptoms. While toxicologists can easily identify the cause of acute poisoning, the same does not apply for epidemiologists who address the effects on health of long-term exposure to low doses of pesticides. Some epidemiological studies show that farmers, the main users of pesticides, have overall less cancers than the general population. On the other hand, they develop more types of cancers (brain tumours, prostate cancer, hemopathies) and other diseases: respiratory diseases, reproductive disorders, neurological disorders (Parkinson's and Alzheimer's diseases). Surprisingly, biological analyses prove that the exposure level to pesticides does not depend on the quantity of pesticides used or on the surface area treated but on the application method and user protection level. In France, the Mutualité sociale agricole (agricultural social protection body), insists that its members use individual protection equipment.