Abstract

Pyrethroid insecticides and naturally occurring pyrethrins arecommonly used for insect control in households and in agri-culture.1 Reasons for this are increasing restrictions in the use of organophosphate and organochlorine insecticides, the greater selectivity of pyrethroids for certain target species,2 their moderate acute oral toxicity in vertebrates and humans,3 and relatively low levels of environmental residues due to rapid degradation out-doors.1 While pyrethroids have received both scientific2 and regu-latory4,5 attention, questions remain as to their safety, especially for residential applications. What are pyrethroids? Natural pyrethrins are present in pyrethrum extracts obtained from flowers of some species of chrysanthemum. Because pyrethrins degrade easily under the influence of water and sunlight, more sta-ble alternatives – the synthetic pyrethroids – have been developed, allowing for longer intervals between applications.1 Pyrethroids and pyrethrins act on the nervous system of flying insects by disrupt