In the first of two articles on pesticides, Frances Northall and Grainne Cullen discuss the clinical features and management of herbicide poisoning

Apesticide is any substance or mixture of substances intended for preventing, destroying, repelling or mitigating any pest (insect, rodent, nematode, fungus, weed) (Hayes and Laws 1991). Herbicides are used for the control of weeds and their use has increased over the past 40 years. They may be formulated for professional (agricultural) or amateur (domestic) use with professional formulations likely to be much more concentrated. A wide variety of herbicides is available with various modes of action and different uses. Contact herbicides will kill only those parts of the plant which have been sprayed, whereas systemic herbicides are translocated to all parts of the plant and damage leaf-tissue and roots.