Movie: Using DDT to Fight Malaria

[Renew Deal]

Dr. D. Rutledge Taylor is serious about rehabilitating the reputation of the pesticide DDT so that it can be used more widely in the developing world to battle malaria.

But in “3 Billion and Counting,” a documentary he has made on the subject, he undercuts his cause by adopting what seems like a disingenuous naïveté early in the film: he and his producer, Helene Udy, try to give the impression that they had never even heard of malaria until the day before yesterday. By the time they switch to no-nonsense advocacy, you’re unclear as to their credibility.

Presumably that approach was taken to make an unpleasant subject more viewer-friendly, but it wasn’t necessary; Dr. Taylor is brash and telegenic enough to keep things interesting. As for the argument, it’s not exactly new: advocates have been speaking out in support of increased DDT use for a decade, contending that its negative effects were exaggerated or misrepresented when it was banned by the United States in 1972 and that in any case they are outweighed by the millions of deaths caused by malaria.

Dr. Taylor goes further than this, hinting at a conspiracy involving drugmakers and others to keep DDT off the market and bluntly pointing fingers at Rachel Carson (“Silent Spring”); William D. Ruckelshaus, who as administrator of the Environmental Protection Agency issued the 1972 ban; and others. The guy’s not much of a filmmaker, but he certainly gets your attention.
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http://movies.nytimes.com/2010/09/17/movies/17three.html

[rawtribe]

1. DDT and Birds

http://www.stanford.edu/group/stanfordbirds/text/essays/DDT_and_Birds.html

The potentially lethal impact of DDT on birds was first noted in the late 1950s when spraying to control the beetles that carry Dutch elm disease led to a slaughter of robins in Michigan and elsewhere. Researchers discovered that earthworms were accumulating the persistent pesticide and that the robins eating them were being poisoned. Other birds fell victim, too. Gradually, thanks in no small part to Carson's book, gigantic "broadcast spray" programs were brought under control.

But DDT, its breakdown products, and the other chlorinated hydrocarbon pesticides (and nonpesticide chlorinated hydrocarbons such as PCBs) posed a more insidious threat to birds. Because these poisons are persistent they tend to concentrate as they move through the feeding sequences in communities that ecologists call "food chains." For example, in most marine communities, the living weight (biomass) of fish-eating birds is less than that of the fishes they eat. However, because chlorinated hydrocarbons accumulate in fatty tissues, when a ton of contaminated fishes is turned into 200 pounds of seabirds, most of the DDT from the numerous fishes ends up in a relatively few birds. As a result, the birds have a higher level of contamination per pound than the fishes. If Peregrine Falcons feed on the seabirds, the concentration becomes higher still. With several concentrating steps in the food chain below the level of fishes (for instance, tiny aquatic plants crustacea small fishes), very slight environmental contamination can be turned into a heavy pesticide load in birds at the top of the food chain. In one Long Island estuary, concentrations of less than a tenth of a part per million (PPM) of DDT in aquatic plants and plankton resulted in concentrations of 3-25 PPM in gulls, terns, cormorants, mergansers, herons, and ospreys.

"Bioconcentration" of pesticides in birds high on food chains occurs not only because there is usually reduced biomass at each step in those chains, but also because predatory birds tend to live a long time. They may take in only a little DDT per day, but they keep most of what they get, and they live many days.

The insidious aspect of this phenomenon is that large concentrations of chlorinated hydrocarbons do not usually kill the bird outright. Rather, DDT and its relatives alter the bird's calcium metabolism in a way that results in thin eggshells. Instead of eggs, heavily DDT-infested Brown Pelicans and Bald Eagles tend to find omelets in their nests, since the eggshells are unable to support the weight of the incubating bird.

[mike_c]

2. the worst problem with DDT was ALWAYS misuse and over-application....

The compounds which replaced DDT and similar chlorinated hydrocarbons were (and are) far more toxic to vertebrates than DDT. The main problems with DDT were overuse, persistence in the environment, overuse, bioaccumulation, overuse, and overuse. Did I mention overuse?

People seem to think that if a little pesticide works well, a whole freakin' lot should work a whole lot better. That's not the case with dose dependent pesticides like DDT. Lethal insecticidal doses are quite small-- beyond that, applying extra is simply polluting. Look at the maps of global DDT concentrations from the early 1970s-- the stuff was dumped everywhere by the ton and spread rapidly to nearly every habitat on Earth.

DDT can be used for malarial vector control in ways that prevent it's bioaccumlation and exploit its persistence. Sprayed on the inside walls of homes and structures at very low doses it has virtually no vertebrate toxicity and cannot bioaccumulate up any food chains. It disrupts the malarial transmission cycle by killing female mosquitoes who rest on the walls after taking a blood meal from sleeping residents during the night. If restricted to the tropics, it is persistent and long-lasting indoors where it's sheltered from UV exposure but breaks down rapidly once exposed to sunlight (it needs to be kept out of the soil where it is protected from UV degradation).

[Warpy]

3. I think there's a use for DDT, but much more sparingly than in the past

The reason it was stopped is because it's such a persistent poison and doesn't break down over time. It entered the food chain and had devastating effects on the bird population.

However, applications where it can be used and then recovered, as in dusting places with bedbug infestations and then vacuuming it up later using vacuum systems with HEPA filters to retrieve it, should be one approved use.

As for controlling malaria, this is a better idea than large scale DDT spraying like they did in the south up until the early 70s: http://www.oxfamamericaunwrapped.com/Mosquito-nets-gift.html for treated nets and https://www.kintera.org/site/c.qsKYL6PGLnF/b.5764899/k.70BF/Support_Malaria_No_More/apps/ka/sd/donor.asp?c=qsKYL6PGLnF&b=5764899&en=qlJWKaMSKbJRK5PLIhK6LnO6LrJVJ6PTJoK3JhMVKlJ7JsK for untreated nets.