This is the long-awaited part 2 of my response to Roger Bate’s reply to the article on DDT in Prospect by John Quiggin and me. (Part 1 is here.) In this part I look at Bate’s false history of DDT and malaria.
Here’s Bate’s history:
But while there were serious concerns about the bioaccumulation of DDT up the food chain, and it was rightly phased out for use in agriculture, it still had a valid role in combating public health menaces, notably disease-bearing mosquitos. Not satisfied with having DDT outlawed for agriculture, environmentalists increased pressure for a total ban in the late 1980s and early 1990s.
By 1997, the World Health Assembly had bowed to this pressure, passing a resolution to restrict the use of insecticides in public health, and the United Nations Environment Programme was beginning negotiations towards what would become the Stockholm convention to phase out global use of DDT and 11 other chemicals. Several major environmental organisations were demanding a total ban on DDT by 2007.
But look at what the 1997 World Health Assembly resolution actually said about DDT:
to ensure that the use of DDT is authorized by governments for public health purposes only, and that, in those instances, such use is limited to government-authorized programmes that take an integrated approach and that strong steps are taken to ensure that there is no diversion of DDT to entities in the private sector;
Do you think that it is accurate to for Bate to claim that this is bowing to environmentalist pressure for a total ban on DDT?
And in Bate’s history he did not mention that it was insect resistance, not environmentalist pressure that was the big factor in reducing DDT use in public health, as this 28 July 1997 Wall Street Journal Europe article relates:
It’s widely acknowledged that DDT spraying rid large areas of Asia and Africa of insect-borne diseases such as typhus and malaria, saving millions of lives. Moreover, DDT replaced older extremely toxic arsenic-based pesticides and increased agricultural productivity in the process.
But DDT was so effective and resilient as a pesticide that it accumulated in the tissue of living organisms. Studies showed that the higher the animal was on the food chain, the more DDT remained in its system, affecting reproduction and killing off predators, especially eagles. After a decade or so, other effects emerged. DDT led to serious pest infestation, as it was often more effective at killing off the larger insects that fed on the pests themselves. Pests also developed resistance to DDT’s effects, and it was being phased out for this reason when the international outcry against it began.
And guess who wrote this article? Roger Bate, that’s who. So what changed his mind between 1997 and today? Well, in 1998 he came up with his plan to drive a wedge between environmentalists and public health people by blaming environmentalists for banning DDT and causing malaria. You can read his pitch to Philip Morris. So he rewrote the history of malaria and DDT to eliminate the fact that:
Pests also developed resistance to DDT’s effects, and it was being phased out for this reason when the international outcry against it began.
Bate’s rewritten (with Richard Tren) history is When Politics Kills: Malaria and the DDT Story. They rely heavily on Gordon Harrison’s Mosquitoes, malaria, and man: A history of the hostilities since 1880, (read an extract here), citing him over twenty times, but when they write about the Sri Lankan experience, they conspicuously fail to mention that DDT spraying in Sri Lanka failed because of resistance, instead claiming that
pressure not to use DDT may have been applied by western donors using resistance as a convenient argument. Recent evidence shows that even where resistance to DDT has emerged, the excito-repellancy of DDT causes mosquitoes not to enter buildings that have been sprayed (Roberts et al., 2000). Under test conditions (see Grieco et al., 2000), for at least one type of malarial mosquito in Belize (the only country in which these tests have so far been conducted),DDT is far more successful than the most favoured vector control pesticide Deltamethrin. Hence it is unlikely that malaria rates would have increased (significantly) even if resistance were found.
But malaria rates did increase because of resistance even though DDT was extensively used. Harrison has an entire chapter on this, which Bate could not possibly have missed. Bate’s history is false.