The use of a chemical becomes hazardous (irrespective of its toxicity) if it is formulated or used in such a way that human exposure is increased and poisoning occurs.
The relative hazard of pesticides can be readily judged from the signal words that appear at the top of the principal panel of the label of the pesticide container. These words must appear on pesticide labels.
There are three main ways chemicals can enter our bodies:
Skin absorption (dermal)
Skin absorption is responsible for the majority of occupational poisonings. Spraying without protective clothing and general carelessness when mixing and spraying are responsible for most poisoning cases in this group.
No protective equipment, mixing chemicals in a badly ventilated space, and working downwind when spraying is responsible for inhalation of chemicals.
By mouth (oral)
Chemicals may be swallowed when eating with contaminated hands, smoking and blowing or sucking to clear blocked nozzles on the spray unit.
Children sometimes poison themselves by drinking chemicals left within their reach. All chemicals should be properly stored.