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September 2006. The following are the views of one of PestNet’s members in Samoa; they are not necessarily the views of the organisation. [The postion of the WHO 2005 can be found at: http://www.who.int/malaria/docs/WHOpositiononDDT.pdf]
DDT and Malaria Control
It is good to see that some sanity has finally returned with the possible reintroduction of the insecticide DDT into malaria control programmes, after a hiatus of 30 odd years, although I see that some countries in Africa continued to use it for insect vector control during this period.
My experience with DDT/malaria control was gained in PNG in the 1960s/1970s when I and others of the Ministry of Agriculture???s Entomology Section investigated some of the side effects of DDT usage resulting from the Ministry of Health???s Malaria Control Programme (spraying of indoor structures ??? walls, roofs, etc ??? with DDT. This was but a part, a very important part, of the total Malaria Control Campaign). Dr David Parkinson was in charge of the Ministry of Health???s Malaria control section in those days.
Certainly, some of the side effects of DDT usage ??? e.g., the death of cats from ingesting insects and geckos killed by the spraying, reduced life of roof thatching, DDT resistance in bed-bugs in sprayed houses, etc. ??? were of concern, but these had to be compared with the thousands, probably millions of people over the years who were protected from catching malaria (and some other mosquito borne diseases).
Worldwide, the benefits from using DDT in insect vector control programmes over many, many years, before its use was frowned on, was immense. For DDT to be done away with in such programmes when no real evidence was produced to support the claims made by some that it was harmful to humans (no doubt it was, if they ate nothing but DDT), caused all sorts of problems in birds (never substantiated), was very short-sighted and resulted in thousands, probably millions of unnecessary deaths from mosquito and other insect borne diseases.
In the West Sepik Region of PNG, when villages withdrew from the DDT malaria control programme in the mid-1970s, the incidence of and deaths from falciparum malaria increased rapidly within the first 6 to 12 months and continued to increase.
DDT, to my knowledge, directly, has not resulted in the death of one person, worldwide. But then, perhaps it has, but the number must be very, very small indeed, compared with the probably hundreds of millions it has protected and saved from death from insect borne diseases.
Certainly, because of trade, pesticide resistance and residue and other problems, DDT had to be replaced in agriculture. It was not a problem of safety to applicators and consumers, but more one of trade protectionism.
Let us not be hard on Rachel Carson. Her book came at a very timely time and put the many problems associated with incorrect pesticide usage before the public and led to a better approach to pesticide usage and solution of some of the problems usage has created.
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