[4] Prior to 1940, pesticides consisted of inorganic compounds (copper, arsenic, mercury, and lead) and plant derived products.
Since World War II pesticides composed of synthetic organic compounds were the most important form of pest control.
[8][9] Because the half life in soil is long (for DDT 2–15 years[10]) residues can still be detected in humans at levels 5 to 10 times lower than found in the 1970s.
[11] Each country adopts their own agricultural policies and Maximum Residue Limits (MRL) and Acceptable Daily Intake (ADI).
The level of food additive usage varies by country because forms of agriculture are different in regions according to their geographical or climatical factors.
[12] Likewise, restricted entry intervals are the amount of time to allow residue concentrations to decrease before a worker can reenter without protective equipment an area where pesticides have been applied.
Pesticide tolerances are set by the Ministry of Health, Labour and Welfare through the Drug and Food Safety Committee.
Accidental or inadvertent poisoning of agricultural workers due to exposure to pesticides is a very serious matter resulting in many deaths and hospitalizations.
However the maximum residue limits of pesticides in food are low, and are carefully set by the authorities to ensure, to their best judgement, no health impacts.
[30] The ACA advises washing fruit and vegetables before eating to remove both pesticide residue and other undesirable contaminants.
In August 1994, a serious incident of pesticide poisoning of sweet potato crops occurred in Shandong province, China.
Also, there was a case where a large number of students were poisoned and 23 of them were hospitalized because of vegetables that contained excessive pesticide residues.
Infants and children consume higher amounts of food relative to their body-weight, and have a more permeable blood–brain barrier, all of which can contribute to increased risks from exposure to pesticide residues.