[DDT and public health]

The availability of DDT led to a revolution in insect pest control. However, in the 1970's it was banned or its use restricted in many countries because it was accumulating in the environment. It was suggested that this could have a deleterious effect on human health. However, these effects, particularly carcinogenesis, have never been clearly proved in humans. Furthermore, accumulation is significantly lower in the tropical than temperature environment. DDT can therefore be continued to be used as a spray in houses, where it is sequestrated by mud walls. It is mainly used against anopheles (mosquitoes) for malaria control and phlebotomus (sand flies) for control of leishmaniasis. However, the value of DDT is restricted by the resistance of many vector species; and its excitatory-repellent effect which does not allow interruption of malaria transmission in highly endemic areas (for example Northern Cameroun).