WHO Pesticide Evaluation Scheme (WHOPES)

WHOPES: WHO Pesticides Evaluation Scheme

Why is the use of pesticides for public health such an important issue?

Insecticide-treated mosquito nets

Vector-borne diseases and those with intermediate hosts are among the major causes of illness and death in many tropical and subtropical countries. Such diseases, which include malaria, Chagas, dengue, leishmaniasis, lymphatic filariasis and African trypanosomiasis, significantly impede economic and social development.

Vector control plays a key role in prevention and control of major vector-borne diseases such as malaria, dengue and Chagas disease and often constitutes the first line of activity in case of epidemics of vector-borne diseases. Chemical control (use of pesticides) is still the most important element in the integrated approach to vector control.

Safe, cost-effective and operationally acceptable pesticides are required for public health use. The highly developed pesticides of today, which are formulated for a particular use pattern, require selection and usage of the most appropriate active ingredients and formulations for the target pest and intended application.

Why quality pesticide products are essential?

Good product quality is essential for effective and safe pesticide use. Impurities formed during manufacture of the pesticide or by interaction in unstable formulations can increase product toxicity to humans and the environment. Applying products that are lower in active ingredient content than declared could result in monetary loss and application of a sub-lethal dose of pesticide, leading to ineffective control and promotion of the development of resistance. Products or formulations with inferior physiochemical properties, such as suspensibility, emulsification or particle size characteristics, can also result in inadequate application and possibly increase the degree of risk for personnel who may come into greater contact with the pesticide and/or pesticide contaminated application equipment.

WHOPES develops specifications for pesticides as part of the International Code of Conduct on the Distribution and Use of Pesticides for quality control and international trade.

What about the arsenal of public health pesticides?

Public health programmes are faced with a depleting arsenal of safe, efficient and cost-effective insecticides. This is mainly due to the resistance of major vectors to common insecticides which have been misused and overused in agriculture. In addition, the withdrawal or abandonment of certain pesticides for reasons of safety or high cost of re-registration has further reduced the available options.

Considering that very few new insecticide compounds are coming to the market for vector control, judicious, more selective and targeted use of available compounds is essential not only to increase their effective life span, but also for economic and environmental reasons.

WHOPES and its partners promote the development of alternative pesticides and their safe and judicious use in public health.