The same classes of pesticides are used all over the world, but conditions of use vary widely, and public perceptions of risk vary more widely still. Within Western Europe pesticide residues in commercially traded foodstuffs are subject to international standards and are closely monitored. Hence risks to consumers from such foods are negligible. The major hazards are poisoning associated with high acute/chronic operator exposures due to occasional pesticide misuse. In addition pesticides provide a convenient means of attempting suicide in agricultural areas. In contrast, public perception of risks from pesticides centres on low level exposures, and is heightened by several factors. These are: poisonings associated with pesticide misuse; the indirect nature of the benefit to the consumer (cf. medicines or public health uses); and commercially motivated marketing of pesticide-free produce. In press reports pyrethroid insecticides have been linked to "Multiple Chemical Sensitivity" in Germany, and organophosphates to "Chronic Fatigue Syndrome" in the UK. A number of pressure groups are actively campaigning to ban all uses of organophosphorus pesticides. Unfortunately evaluation of the real risks of pesticide exposure is rendered less certain by the lack of any very useful retrospective exposure measures with which biological effects of uncertain aetiology might be correlated. This means that although we can be sure that pesticides pose no gross threat to health in the general population, subtle effects on more highly exposed sub-populations are, as yet, more difficult to rule out.

Attitude↗

PubMedDate not supplied

The contrasting actions of two pyrethroids (deltamethrin and cismethrin) in the rat.

Deltamethrin and cismethrin are representative members of the two classes of pyrethroid insecticide which can be distinguished on the basis of the symptoms which they produce in mammals. This paper reviews the relevant literature together with some new findings. The motor symptoms produced by the deltamethrin class are a complex but distinctive sequence of co-ordinated movements which are accompanied by EEG spiking, increased brain blood flow, increased brain glucose utilization in some regions, salivation, hyperglycaemia and, in vitro, increased cardiac contractility. The cismethrin class produces a different pattern of uncoordinated tremor accompanied by increased brain blood flow and regional glucose utilization, but without EEG spiking, salivation, hyperglycaemia or cardiac actions. Both compounds produce regional dissociations between brain blood flow and glucose utilization. It is concluded that most of these actions are attributable to prolongation of membrane sodium currents, and that the more widespread actions of deltamethrin are due to the much greater sodium current prolongation which it produces.

Animals↗