Thanks for some informative comments. Clearly, I should have said the WHO rather than the WTO. I apologize for this carelessness that is especially disturbing to me since I often write about the WTO.
I also regret that I probably exaggerated how many lives could have been saved over the years by extensive use of DDT spraying in houses. However, I am not guilty of saying that DDT spraying alone would do the job, for I did say that mosquito nets and drugs are also useful. A combination is the best approach, but these other methods are just not a good enough substitute for DDT spraying. So I do stand behind a claim that opposition to DDT spraying by many organizations caused a very large number of needless deaths from malaria.
Does the recent WHO statements supporting the use of DDT in homes reflect a change in attitudes toward DDT home use by this organization? One strong critic of my discussion points out several errors in what I said, and I am indebted to him for these corrections. However, he is inconsistent on this issue of whether the WHO has "changed" its position. On the one hand, he says that "The WHO‚Ä¶has always supported its use" (that is, DDT spraying), but then quotes with approval a statement by another critic of DDT spraying that "The World Health Organization's new (!) stance on DDT" (my parenthesis). "New" or not new, that is the question? I was wrong to say that the WHO had banned the use of DDT in homes until recently. However, it is accurate to say I believe that the WHO had not strongly endorsed its use until a few weeks ago, and that many donor agencies were for this reason reluctant to finance purchases of DDT for household spraying.
One commenter challenged me (and his challenge was very well answered by another commenter) as to whether DDT house spraying does pass a relevant benefit-cost criterion. Accepting his assumptions, DDT spraying would cost $12 per year per person. That amount seems to be a highly worthwhile expenditure if we relate it to estimates of the value of saving the lives of young persons even in very poor countries. Of course, a full analysis would require knowing the money value placed on their utility by people in poor countries (my paper with Rodrigo Soares and Tomas Philipson in the March 2005 issue of the American Economic Review on declines in mortality in poor countries tries to measure utility value of improved life expectancy, not improvements in GDP alone), the probabilities that such spraying would save lives or significantly improve the quality of lives, the productivity of alternative uses of these funds, such as to find an effective vaccine, and so forth. I, have not, nor has any one else to my knowledge, made these calculations, but if spraying only costs $12 per year, and it is effective in significantly cutting deaths from malaria (some commenters dispute that), to me that seems like a great use of private or public funds.