Tim Lambert (deltoidblog AT gmail.com) is a computer scientist at the University of New South Wales.
Members of the "we hate Rachel Carson" club have been touting a new study on indoor residual spraying as showing that DDT remains effective against malaria even when the mosquitoes are resistant. For examples, see Angela Logomasini and Ron Bailey. The study found that DDT-resistant mosquitoes were still repelled from huts sprayed with DDT so that occupants would be protected from 73% of mosquitoes. But it also found that there was 92% protection with dieldrin, which mosquitoes were not resistant to. In other words, an insecticide that killed the mosquitoes worked better, as you might expect.
So while the study suggests that DDT might be more effective than tests on how effectively it kills mosquitoes suggests, it does not seem a good idea to continue to use it where the mosquitoes are resistant -- a switch to a more effective insecticide would seem wise. The experience in Sri Lanka where DDT resistance led to a malaria epidemic despite DDT spraying also points to the wisdom of switching.
One additional point -- the study found that DDT acted as a spatial repellent, with mosquitoes repelled without coming into contact with the DDT sprayed on the walls. Presumably this was because there were particles of DDT in the air in the hut. Since this would rely on DDT continually escaping from the walls, it is not clear how long this effect would last for. I would have liked to have seen them test for this one and three months after spraying.
Bug girl has some more thoughts on the study, as does John Quiggin.
Comments
And don't forget the Wall Street Journal promoting that study, as well. They might as well have printed the press release :(
Posted by: bug_girl | August 18, 2007 8:44 PM
Bug girl, that is quite scary, for a newspaper to regurgitate unquestionably like that. So, am I allowed to assume that the "MSM" is right-wing from now on?
Once again - anything to stop holy capitalists and the holy western consumers from changing their behaviour just because some evil, regressive and quite possibly effete left-wingers whine and bring up science, right?
Posted by: xel | August 18, 2007 9:52 PM
Well, given that last night I was invited along for a "guys' night out", I'm not sure the "effete" applies to me.
(And I'm conflicted about that, actually) :(
There was a long discussion about the issues of communicating science to the media at the Loom.
And, er...what is MSM?
Posted by: bug_girl | August 19, 2007 11:18 AM
As might surprise nobody, it turns out that a poison which repels mosquitoes is less effective than one which does not. "Historical review of malarial control in southern African with emphasis on the use of indoor residual house-spraying", Musawenkosi L. H. Mabaso, Brian Sharp, Christian Lengeler, 2004, Tropical Medicine & International Health 9 (8), 846-856. doi:10.1111/j.1365-3156.2004.01263.x http://www.blackwell-synergy.com/links/doi/10.1111/j.1365-3156.2004.01263.x/full/?cookieSet=1, needs a login
"For these reasons, when comparisons have been made, better malaria control has generally been achieved with pyrethroids than with DDT." "Control of Malaria Vectors in Africa and Asia" C.F.Curtis http://ipmworld.umn.edu/chapters/curtiscf.htm
Posted by: z | August 19, 2007 11:37 AM
"And, er...what is MSM?" Main-stream media, is what it means. Right-wingers had to abbreviate the term so they can claim it is left-wing biased as many times as possible in a small amount of time.
"(And I'm conflicted about that, actually) :(" I do not think that is anything to be sad about :). No one should expect people to choose between some sort of easy parameters for categorization.
Posted by: xel | August 19, 2007 11:49 AM
exactly, Z. The paper is a total non-event research wise, but has been made important by a lobbying group. Gah!
Of course, Beck thinks that IPM isn't real, or if it is, I'm lying about it, so...well, nuff said.
Posted by: bug_girl | August 19, 2007 12:23 PM
DDT has a low but not zero vapor pressure, couple of tenth ppb, which is going to be there as long as there is any on the walls. The effective amount in the air may be higher due to pooling effects. There could also be entrainment in aerosols from cooking/bathing, sneezing, etc.
Posted by: Eli Rabett | August 20, 2007 10:24 PM
A bit off topic. Lambert, when are you going to compile all of your DDT stuff (and GW, Lott, and the rest) into a book? With respect to DDT/Carson, no one else comes close to the content you have here.
Just a thought.
Posted by: cce | August 21, 2007 6:16 AM
"As might surprise nobody, it turns out that a poison which repels mosquitoes is less effective than one which does not. "
That's true of right-wing pundits as well.
They would be much more effective if they were not so repulsive to normal people.
Posted by: JB | August 28, 2007 6:38 AM
Ronald Bailey has learned the lesson about repellents. So he prefaces his criticism of DDT with an acceptance of the science on eggshell thinning. Otherwise, normal people would rightly ask "who is this anti-science nut?"
"Banning DDT saved thousands of raptors over the past 30 years, but outright bans and misguided fears about the pesticide cost the lives of millions of [sic] people who died of insect-borne diseases like malaria. The 500 million people who come down with malaria every year might well wonder what authoritarian made that decision."
Posted by: JB | August 28, 2007 6:52 AM