The definition of pesticide covers about 1 00 000 different chemicals, inorganic and organic, that are grouped according to their function or their chemical structure. Evidence is growing about long-term health effects following high-level, long-lasting exposure to some pesticides, including asthma and other allergic diseases, immunotoxicity, endocrine disruption, cancer, and central and peripheral nervous system effects. Identifying such specific chemicals is of paramount importance in preventing ill health in farmers, while preserving the benefits of plant protection against pests.Methods
An extensive review of the literature was conducted.Result
Currently, the International Agency for Research on Cancer classifies three obsolete agrochemicals as Group 1 human carcinogens (Arsenic compounds, lindane, and 1,2-dichloropropane); six are classified as probable human carcinogens, including captafol, DDT, diazinon, glyphosate, ethylene dibromide, and malathion, generating a vast controversy among the International Health and Safety Agencies and the media about the need to phase them out as some were widely used worldwide. Possibly human carcinogen pesticides are 20, and for 32 there is inadequate scientific evidence to classify their potential human carcinogenicity. The endocrine disrupting effects of numerous pesticides have also been extensively studied, but evidence of hormonal effects comes mainly from animal studies, either laboratory or wildlife animals; such results are difficult to refer to the low level long term exposure in humans. Other chronic effects repeatedly reported among users of specific pesticides include asthma and chronic bronchitis, immunosuppression, and neurodegenerative diseases, with the classical example of paraquat, but also other pesticide classes, and Parkinson’s disease.Discussion
Major reasons for uncertainty in interpreting epidemiological findings of long term pesticide effects include the complex pattern of overlapping exposure due to multiple treatments applied to different crops and their frequent changes over time to overcome pest resistance. Further research will have to address specific agrochemicals with well-characterised exposure patterns.