Paul Bissex points us to a provocative article, What the World Needs Now Is DDT, claiming that DDT is the best available tool to prevent up to 2 million malarial deaths (and hundreds of millions of cases of long incapacitation) a year. Methinks we can come up with much better tools than persistant pesticides (such as a malaria vaccine), but it did get me thinking.
This is hardly a new claim.
DDT revisionism has been a conservative / anti-regulation shibboleth for at least a decade. It's usually couched in scolding, self-righteous "these environmentalists love animals more than people!" language.
If you want to find out who they really love, find out what they think about, say, mercury in smokestack emissions or arsenic in water supplies.
Or just follow the damn money.
Then again, DDT is an extremely effective pesticide whose toxicology is well known. Try not to politicize or emotionalize the argument.
Fact: Malaria shamefully still kills or incapacitates more people each year than most other diseases combined.
Fact: In certain use cases, DDT is extremely effective in combatting the persistence and spread of malaria.
Fact: It is currently strictly controlled by convention.
So why not carefully use it? With the care and oversight of clued-in greens? It is a tool, with no intrinsic good or evil attributed of its own. Vilifying IT is dumb; if we can use it responsibly and effectively, we should. Malaria is a global shame.
I'm actually surprised there hasn't been more work done on figuring out how to kill mosquitos, but nothing else, using DDT.
For example, if it was delivered by carbon-dioxide baited traps rather than indiscriminately sprayed, or used to coat mosquito nets in some kind of time-released binding rather than sprayed?
I don't know enough about the ecology of DDT to know if those kind of approaches are feasible, it's a little outside of my baliwick, but I do think that it was visciously effective stuff.
I live in a west nile virus area, and they're doing heavy mosquito control work here - mostly using some kind of hormone goo that screws up mosquiot larvae and nothing else, honest guvnor.
One of the problems with DDT is that it is extremely persistent in soil. It can last for up to 15 years, and degrades very slowly. It breaks down into two substances which are similar in toxicity.
It's also pretty indiscriminate in what it affects, i.e., there is a big toxic impact on "non-target species." Mosquitos often breed in aquatic environments, and DDT is extremely toxic to aquatic invertebrates.
I think Vinay has something when he asks why more has not been done to develop alternatives to DDT that would be equally effective on the target species while avoiding the known, devastating impacts. "Following the money" could yield some of the answer.
I'm almost just guessing here, but the potential profits that would result from de-regulation of DDT are probably huge--it is, as Howard notes, already developed and researched, so there would be very little R&D cost to the companies that would like to sell it, as opposed to developing different, equally effective, less biologically indiscriminate and devatating options. Delivery methods for DDT are also well-established and would require little in the way of infrastructure investment (again, just informed guessing).
Malaria is a shame and a crime. DDT is effective in preventing the spread of malaria. It does not follow from that, that DDT is the only effective means of curtailing malaria.
Article on chemically-treated mosquito nets, from the April 12 issue of The Hindu:
Pierre Guillet of the WHO, said that long-lasting insecticide-treated bed nets were the most cost-effective tools to fight mosquitoes. Trials in Senegal proved beyond doubt that the nets dramatically reduce deaths caused by malaria.
Some highly detailed chemical and toxicological information on DDT:
Mosquitoes don't like chrysanthemums.
Guess what the active ingredient in mosquito coils is? Pyrethrin - extracted from the chrysanthemum plant, Dendranthemum (Chrysanthemum) cinerariaefolium.
How about making sure no open non-moving water sources are left open to the air. Along with the use of Bacillus thuringiensis dunks, like those available in over here in the US.
Actually, I was suggesting ways of *delivering* DDT specifically to mosquitos, rather than finding alternatives to it. But that'd be great too.