DDT, Malaria, and the Environment--Posner's Comment

I am a strong environmentalist, and support the ban on using DDT as a herbicide. Although Rachel Carson's belief that DDT causes cancer has not been substantiated, there seems little doubt that its widespread use as a herbicide, if continued, would have caused a significant reduction in biodiversity because of its lethal effect on many fish and bird species. In my book Catastrophe: Risk and Response 63 (2004), I quote a responsible estimate that the combined effect of human population growth (and resulting contraction in animal habitats), herbicide use, global warming, and other factors is causing 10,000 species to become extinct every year. Of course, there have always been extinctions--without which there would be no room for new species to evolve--but the fossil record suggests that the background (i.e., pre-human) average annual number of extinctions is only one. Even the fierce environmental skeptic Bj√∏rn Lomborg estimates that the current annual extinction rate is 1500 times the background rate. And these figures greatly understate the loss of genetic diversity, because much genetic diversity is intraspecies (e.g., birds of the same species but a different color; or imagine if there were only one breed each of dogs and cats). That diversity has been plummeting as well, in part because of selective breeding, which reduces the number of strains of each crop to the best, the others being abandoned. The decline in genetic diversity--to which spraying crops with DDT would be contributing significantly if it were permitted--is alarming even from a purely selfish anthropocentric perspective because such diversity, like other forms of diversification, performs an important insurance function. This is most obvious when one considers plant diversity; if there were only one strain of wheat, predator evolution would concentrate on it and once the strain was eliminated a significant part of the human food supply would be destroyed. But with animals too, the elimination of a species (or even a breed) can have a ramifying effect throughout the food chain, as when the exctinct species was the major food source of another species, which in turn was a major food source of still another species, and so on. All this said, the quantities of DDT used in spraying indoor houses in Subsaharan Africa (where 90 percent of malaria deaths occur) are so minute that the environmental effects are inconsequential. The Stockholm Convention on Persistent Organic Pollutants (2001) bans DDT but with an exception for its use against malaria, and the puzzle is why the exception is so rarely invoked, South Africa being a notable exception. An even greater puzzle is why the Bill and Melinda Gates Foundation, which is the world's largest foundation and has made the eradication of malaria a priority, is spending hundreds of millions of dollars searching for a vaccine against malaria but nothing (as far as I know) to encourage indoor spraying with DDT. Of course, spraying can't eradicate malaria, because it just kills malaria-bearing mosquitoes that happen to get inside a house, but it appears to be extremely effective in minimizing malaria infection, as well as being cheap. So it is difficult to understand why the Gates Foundation doesn't divert some of its resources to promoting and if necessary financing the spraying, pending the discovery of a vaccine. As we know in the case of AIDS, the search for a vaccine against a particular disease can be protracted. Not that eliminating childhood deaths from malaria (I have seen an estimate that 80 percent of malaria deaths are of children) would be a completely unalloyed boon for Africa, which suffers from overpopulation. But on balance the case for eradicating malaria in Africa, as for eradicating AIDS (an even bigger killer) in Africa, is compelling. Malaria is a chronic, debilitating disease afflicting many more people than die of it, and the consequence is a significant reduction in economic productivity. Considering how much cheaper and easier it would be to (largely) eliminate malaria than to eliminate AIDS (which would require behavioral changes to which there is strong cultural resistance in Africa), the failure of the African countries, the World Health Organization, the World Bank, and private foundations and other nongovernmental organizations to eliminate most malaria by means of indoor spraying with DDT is a remarkable political failure.

Comments

[DJS]

A quick read of the Gates Foundation website reveals plenty of PR-orientated rhetoric that sounds like they would support DDT distribution and use as part of their wider efforts to eradicate malaria in sub-saharan Africa. Here's the reference:

http://www.gatesfoundation.org/GlobalHealth/Pri_Diseases/Malaria/Malaria_Grantmaking.htm

[Grumpy Old Man]

"Not that eliminating childhood deaths from malaria (I have seen an estimate that 80 percent of malaria deaths are of children) would be a completely unalloyed boon for Africa, which suffers from overpopulation."

Economic analysis of social problems can be useful and even compelling. The foregoing, however, seems a bit cold-blooded even for an economist. I suspect and hope Posner doesn't really mean it.

It's probably oversimplified, too. For one thing, an expectation that more children will survive to adulthood seems to lead to a decline in the birth rate (now below replacement levels in Europe and Japan). It also seems highly wasteful to spend resources on children who end up dying or hopelessly lethargic.

[Tim Lambert]

The answer is that the people in the Gates foundation know more about malaria control than you do. If DDT spraying could eliminate malaria it would have done so in the 60s when there was a massive world-wide program using DDT spraying that tried to eliminate malaria. A vaccine is the most promising approach, but we also need to develop new insecticides and drugs because the mosquitoes and malaria parasites keep evolving resistance to the ones we have.

[Lawrence Indyk, University of Kansas School of Law]

DDT use could actually be helpful to the environment of Subsaharan Africa by reducing the need for those most menaced by malaria to engage in less effective and environmentally damaging alternatives.

DDT may be banned, but in its absence there is widespread use of other pesticides with their own associated risks to health and the environment. A relatively novel and promising technique has been to soak the fur of mosquito-attracting cattle with pesticides. This has shown some success fighting malaria, but creates a workplace of constant chemical exposure for African cowboys.

Without a cheap and effective method of killing/repelling mosquitos near human dwellings, the mosquito population at large will be targeted which usually involves the draining of swamps, marshes, and other wetlands. The destruction of this habitat could be detrimental not only to other species but to humans through erosion and other land effects.

So besides the overwhelming (in my opinion) argument in favor of saving human lives, the economic-environmental question of whether to use DDT should not consider the costs of the pesticide vs. doing nothing, but compared to the existing and future environmental costs of the employment of even less satisfactory substitutes.

[Speed]

Tim Lambert: "If DDT spraying could eliminate malaria it would have done so in the 60s when there was a massive world-wide program using DDT spraying that tried to eliminate malaria."

The Economist, Dec 14, 2000: "The widespread use of DDT in the 1950s and 1960s all but eliminated malaria in several developing countries and saved an estimated 500m lives by 1970."

And for Richard Posner, I believe DDT is a pesticide, not a herbicide although if you poured enough on your lawn, it would likely kill the grass.

[Mike]

Posner states that "Not that eliminating childhood deaths from malaria (I have seen an estimate that 80 percent of malaria deaths are of children) would be a completely unalloyed boon for Africa, which suffers from overpopulation."
I am curious as to the basis for the assertion that Africa "suffers from overpopulation." To be sure, the standard of living in many parts of that continent is appalling. However, it strikes me that the likely culprit is underdeveloped (and poorly adapted) economic institutions, not an excess of people. Given the amorphous markets, the lack of stable commercial institutions (and law), and the antipathy toward medium- and large-scale free enterprise that exist in many parts of Africa, the standard of living would likely be no better if population were only 90, 50 or even 10 percent of what it is today. Indeed, it might well be much worse -- it is difficult to know how many palliative innovations would have been forgone (because the innovator would never have been born), had the population been some fraction smaller over some interval. (Obviously, I am taking a page from Julian Simon here.)

[Chuck]

Re: Lambert's statement regarding " If DDT spraying could eliminate malaria it would have done so in the 60s"

The CDC reports that DDT was an important element of the eradication of malaria in the United States. See the quote below. Source: http://www.cdc.gov/malaria/history/eradication_us.htm

In 1920 in the United States there was about one case of domesically-acquired malaria per 300 people.

Eradication of Malaria in the United States (1947-1951)

The criteria for eradication as put forth by the National Malaria Society was: "Malaria may be assumed to be no longer endemic in any given area when no primary indigenous case has occurred there for three years".

The National Malaria Eradication Program, a cooperative undertaking by State and local health agencies of 13 Southeastern States and the Communicable Disease Center of the U. S. Public Health Service, originally proposed by Dr. L. L. Williams, commenced operations on July 1, 1947. The program consisted primarily of DDT application to the interior surfaces of rural homes or entire premises in counties where malaria was reported to have been prevalent in recent years. By the end of 1949, over 4,650,000 house spray applications had been made. Total elimination of transmission was slowly achieved. By 1951, CDC gradually withdrew from active participation in the operational phases of the program and shifted to its interest to surveillance, and in 1952, CDC participation in operations ceased altogether.

[Barry]

Chuck, IIRC, massive DDT spraying was combined with drainage and sanitation programs in the US, along with things like window screens, and a climate which is generally not tropical.

[Barry]

It's worth piling on: Posner: "I am a strong environmentalist, and support the ban on using DDT as a herbicide.".

Basic facts, like herbicide vs pesticide, and the nature of the DDT ban, are relevant to the real world. To the world of propaganda, of course....

[ompus]

Tim Lambert wrote, "If DDT spraying could eliminate malaria it would have done so in the 60s when there was a massive world-wide program using DDT spraying that tried to eliminate malaria." Several responses have attempted to rebut Lambert by turning to statements such as that found in the Economist. Specifically, "The widespread use of DDT in the 1950s and 1960s all but eliminated malaria in several developing countries and saved an estimated 500m lives by 1970."

Those following the DDT debate will see no contradiction between Lambert's comment and the words written in the Economist. DDT did have a profound affect on malaria. In some places, it was even eliminated. Millions of lives wer saved. BUT...tolerance quickly reared its ugly head. IN AND OF ITSELF, DDT COULD NOT ELIMINATE MALARIA.

I think Posner clearly recognizes that DDT is not a cure-all when he writes "spraying can't eradicate malaria." He asks simply if it is being sufficiently used. And to that point, it seems most prudent to conclude that those people in the field of public health have a much firmer grasp of why the exception is so rarely invoked, than economist Posner or statistician Lambert.

[Lawrence Indyk, University of Kansas School of Law]

Perhaps "overpopulation" should be the topic next week, it seems to have sparked enough interest and touched a few nerves. I don't know if it's useful to talk about the population density of Africa at large since conditions vary so greatly among 54 countries across a vast and diverse continent. But one of the measures of wealth is average resources availble per individual - which includes water and arable land (not just total land mass, which is misleading when there are expansive deserts with low carrying capacities). Ethiopia, for example, only has 10% arable land.

Certainly, I think most people will agree, at some point, the growth of a human population can put so much pressure on the environment and natural resources as to make further increase detrimental (even dangerous) to the wealth and quality of life of a nation's citizens. Or the world's; a small percent of environmentalists in the US, not typically a conservative crowd, have sided with the fervently anti-immigration groups on the theory that, once in the US with our exeptionally high per capita resource consumption rate, new arrivals will only put more intense pressure on the local and global environment.

And then there's also the Solow theory effect of a population that grows faster than the capacity of the economy to equip new entries into the workforce with at least as much capital and infrastructure as that enjoyed by their predecessors - which hurts the productivity of those new workers. Many countries in Africa have low initial capital, low life expectancy but high fertility and so a great fraction of the population is below 18. That mass of youth has to rely on their few elders to supply them with the capability of leading richer lives, an objective that those significantly outnumbered adults may find impossible to accomplish. This can be a problem even when there is plenty of room for expansion, and is only exacerbated by conditiones of already stretched-thin resources.

So I think Judge Posner's point is that if you were to solve the Malaria problem (which kills large numbers of children) in parts of Africa, you may have torn down one wall only to find that the increase in population growth causes those societies to run into another - potentially worse - catastrophe.

[N.E.Hatfield]

DDT or for the bio-chemists in the group, Dichlorodiphenyl trichloroethane. Great stuff, its cheap, functions as a superb pesticide, that is when the application is as a pesticide and not as a herbicide. Although, if it works great on bugs it ought to also work great on weeds which is what the untrained have thought and done. ;)

It just has a couple of problems, it's a "persistent organic pollutant" (doesn't biodegrade well) and has a great tendency to bioaccumulate in the food chain. As for its toxicity it functions as a central nervous system disrupter at the proper dosage level. The question is, where is the critical dosage level for disruption to occur? No one knows, but we do know that more than four billion pounds of this stuff has already been dumped into the environment, but no one is really sure about that either. There is a huge black market application around the globe. It has another problem too, the development of bug resistance to the compound.

With these types of problems inherent in the pesticide, wouldn't it be better to use safer more environmentally friendly alternatives? Alternatives do exist in the pesticide arsenal, but they aren't as cheap.

[Andrew]

To me it seems like there has to be a way to keep a house "mosquito free" that is better than repeatedly spraying it full of toxic chemicals. What about placing "mosquito screens" on the windows and doors? Perhaps someone could devise a homemade indoor "mosquito trap" (like using a dish full of soapy water to kill fleas)?

[happyjuggler0]

Lawrence Indyk,

You raise some good points about overpopulation. At the risk of appearing too stubborn, I remain unconvinced however.

Is the island of Manhattan overpopulated? How about Hong Kong or Singapore? High population density does not equal impossible to eradicate poverty, or even merely equate to any kind of poverty.

I do agree though that countries need to have a significantly larger amount of economic growth to overcome added population growth on infrastructure broadly defined.

I picked India as my counterexample to Africa simply because "everyone" once thought that India was going to be hopelessly mired in poverty and possibly/probably mass starvation due to "overpopulation". Similarly China. Both countries are showing, or should I say have shown(?), that huge populations per "fixed" resources are not predestined for interminable poverty.

Overpopulation, without accompanying significant qualifiers, ought to be a word permanently discarded to the trash bin.

[happyjuggler0]

I almost forgot. No country needs to grow its own food in the modern economy, and many rich countries are in fact net importers of food.

Poverty really is about poor institutions, not population density or natural "resources".

[mike]

I do not think that any metric based on a per capita ratio of "water" or "arable land" (or any other resource) communicates anything useful about "overpopulation" or the possibility that there is binding contraint on population in any particular physical space.
Water and arable land (and any resource) can be increased substantially without limit through technology (albeit, of course, at a cost). Waste water can be recycled (and sea water can be desalinized) to increase the usable quantity of clean water without increasing the "natural" supply. Similarly, advancements in agricultural technology allow one to grow what once was "an acre's worth" of any given crop on less than an acre. (If that seems too facile, then it is also true that hydroponics allow for the growth of crops indoors, i.e., on unarable plots.)
The proposition can be generalized to any resource -- that is why the world's known oil/coal/gas/bauxite/iron ore/copper reserves do not decline unit-for-unit with consumption of each. Thus, I do not accept that a maximum sustainable human population of any particular country or continent can be determined -- unless one is willing to indulge the assumption that technology is fixed, which I view as thoroughly unrealistic.
I come down on the side of those who conclude that poor countries have a low standard of living, in large part, because they have poorly adapted economic institutions, not because they have too many people.

[Dmitri]

I do not think that overpopulation in Sub Saharan Africa will pose a serious threat. In the short run it will be a problem. In the long run however, as birth rates level off, and children develop into able-bodied men, production and productivity will increase. It is important to note that malaria does not have the mere effect of killing people. Deaths in the family have the added effects on worker productivity. In any case, the question of malaria must be addressed for Africa to have any chance of emerging from poverty. And at the moment, it makes no sense to watch productive future workers die just to preserve a species or two.

[Lawrence Indyk, University of Kansas School of Law]

The comments of Happyjuggler0, Mike, and Dmitri convince me more than ever of the need for population to get its own economic discussion on this blog. To make a few things clear though:

1. I never said that any part of Africa *is* overpopulated or such overpopulation is the source of any of it's poverty as opposed to poor institutions. I didn't even touch on *why* so much of Africa is poor beyond the Solow theory, which is only a part of the picture.

2. I also never said that technology and trade couldn't dramatically increase the carrying capacity of a bit of terrain. Both have been doing so since (or indeed creating) the development of civilization, and in fact, mutual exchange of things with alternating respective surplus and scarcity is how economically efficient allocation of resources to the benefit of total wealth works.

3. Nevertheless, the nature of the physical universe is not infinite and limits the practical amount of "stuff" each of use can have or afford. Even if we're not poor, we're not infinitely rich either, and population is part of what constrains us. Especially when resources are depletable (like fossil Energy) increase in population exacerbate problems of scarcity.

4. Finally, it's worth asking, what should we maximize? Do you value more human beings quantitatively, or do you place more value on the quality of their lives and their relative wealth.

[W]

In my quick read of Posner's post, the gist seems to be that a massive increase in the spraying of DDT as a pesticide would cause a massive decrease in intraspecies genetic diversity among birds and fish, with chaotic ripple effects shivering throughout the food chain. Posner uses that as a springboard to attack the resource allocation of the Gates Foundation, whose focus on reducing malaria by investing in vaccination is doubly wrong; first, because widespread vaccination would obstruct malaria's knack for killing off suprlus African population; second, because the level of DDT spraying required to extirpate malaria (or, rather, the mosquitoes transmitting it) is so minimal that the harm to birds and fish is effectively nil, Melinda and Bill would more wisely invest in spraying DDT than vaccination. But it seems Posner could just as easily fault American and European immigration policy for not admitting more Africans, who then wouldn't be in Africa to contribute to its overpopulation or to be exposed to African mosquitoes carrying malaria. Bill and Melinda, Posner could just as reasonably argue, should invest in changing American immigration policy to favor Africans from countries where malaria is rampant and overpopulation is persistent.

[happyjuggler0]

W,

:]

I'd just add though that the reason that the US is malaria-free, and therefore safe to migrate to, is because of US spraying of DDT....

Perhaps we could swap African immigrants, inexchange those malaria infested countries have to take US convicts. The taxpayers of the US get a lower prison bill, the African countries get both remittances from their overseas workers as well as a small stipend for keeping guard over our prisoners. Sounds like another free trade example of comparative advantage. :o

[W]

Perhaps we could swap African immigrants, inexchange those malaria infested countries have to take US convicts. The taxpayers of the US get a lower prison bill

Actually, I think this would be disastrous for the American economy, at least in those states where the corrections sector is a sizeable share of the economy. We want more prisoners in those states: more prisoners means more cops and more guards; more cops and guards mean more trainers for cops and guards; and more manufacturers and suppliers of equipment and educational materials for cops and guards means more workers preparing those materials and producing that equipment.

As a legal matter, divesting an American citizen of all citizenship rights for, say, identity theft or possession of marijuana, is quite different from extending citizenship rights to non-Americans to advance our foreign policy goals by fostering goodwill with trading partners.

I would note that America is malaria-free in great part to its geography, e.g., the most of it does not consist of coastal mud that is a seasonal breeding ground for mosquitoes. Add to that our supply lines and medical care infrastructure and ample roads make it quite easy to distribute and stock vaccines, not to mention administering them with relative ease to vast swaths of the population at once. I fail to see in your analysis a cost comparison between installing similar infrastructure in African nations where malaria is rampant and spraying DDT in such nations.

[owinok]

Is Judge Posner right that Africa is overpopulated? I wonder what measure he uses to reach this conclusion because I do not agree. More importantly though, he and Prof. Becker are right that prudent use of DDT in certain areas in the African continent would definitely improve the malaria situation remarkably but again it cannot be a panacea because it is not appropriate for use in all regions in that large continent.

[ben]

Posner wrote:

Not that eliminating childhood deaths from malaria ...would be a completely unalloyed boon for Africa, which suffers from overpopulation. But on balance the case for eradicating malaria in Africa...is compelling.

I have thought about this comment for a week and it is disturbing. In what sense is Africa made better by a citizen's death? Ignoring the disutility of the citizen and his relations, then Africans might well feel better off. But how can Posner justify ignoring the disutility of the victim himself, or consider even the possibility that the benefit to Africa overall outweighs his loss?

Other posters have pointed out that the idea of overpopulation is wrongheaded except in the very narrowest sense that, other things being equal, less people would be better. But, again, why even consider this possibility when the fundamental source of African poverty is to do with institutions rather than too many people.

As I said a year ago, I believe Posner has a real blind spot when it comes to the environment. I sense a willingness to put the environment ahead of (other people's) lives, which I find quite distasteful. I think arguments using genetic diversity are close to silly: humans rely on only a tiny fraction of the world's genetic diversity to survive. The possibility that a reduction in that diversity could have long term implications for the survival of people must be weighed against the fact that many people are dying right now. Furthermore, Posner, as with all environmentalists, ignores the role of innovation and the fact that these environmental costs, if they exist at all, will arrive into a world that is far wealthier than it is today and better able to deal with those problems.

[ben]

The first para in my last post incorrectly implies Posner thinks malaria a good thing in Africa, which he makes clear he does not. My point was simply that his even considering a trade off implies some dangerous thinking. The para should read:

"I have thought about this comment for a week and it is disturbing. In what sense might Africa made better by a citizen's death? Ignoring the disutility of the citizen and his relations, then Africans might well feel better off. But how can Posner justify discounting the disutility of the victim himself, or consider even the possibility that the benefit to Africa overall outweighs his loss?"

[Anonymous]

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