To elaborate that thinking: when absorbed in the quantities experienced by a farm worker in this context, some pesticides can have irritant or toxic effects. They (or rather their application methods and cocktails) are designed not to permeate the food products of the plant, although some do with some foods and this is ongoing research. Farmers need to consistently produce healthy produce people can afford, and want to do as little harm as possible to people in the process.
To elaborate that thinking: when absorbed in the quantities experienced by a farm worker in this context, some pesticides can have irritant or toxic effects. They (or rather their application methods and cocktails) are designed not to permeate the food products of the plant, although some do with some foods and this is ongoing research. Farmers need to consistently produce healthy produce people can afford, and want to do as little harm as possible to people in the process.