In Britain, a detailed study found some carrots on sale in shops with not twice, not four times, but 25 times the allowed pesticide residue (what's left after harvest) in them. These organophosphate (OP) insecticides are highly dangerous nerve poisons. No one knows the long term effects of consuming low levels of OPs or any other substance, nor how they react with preservatives, colourings and stuff in the food you eat [1].
More than 1 in 10 people who are regularly exposed to OP pesticides (like farmers) will suffer irreversible physical and mental damage [2].
Many popular pesticides seem to damage the body's ability to fight infection. They could be a hidden killer in poor countries where infections are a leading cause of death [2].