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  • From: tvoivozhd <tvoivozd AT infionline.net>
  • To: homestead AT lists.ibiblio.org
  • Subject: Re: [Homestead] Rethinking DDT--or should we?
  • Date: Sat, 08 Jan 2005 16:56:12 -0500

Lynda wrote:

The fact is that IPM works. IPM creates jobs. Of course, there aren't big
bucks in IPM for the big $$ companies. Here's the other side of the
argument over DDT:

DDT A PANACEA FOR WEST NILE?

THANK GOODNESS HEALTH AUTHORITIES HAVE MORE SENSE

Jim Bull

Detroit News columnist Thomas Bray laments that DDT is not being considered
for use in the fight to control the spread of West Nile virus (Still in
Denial about West Nile, 5-18-03). Bray asserts that DDT would be the most
effective weapon to use to combat West Nile. He quotes an EPA hearing
examiner as saying that DDT is safe, not carcinogenic, not mutagenic, nor
teratogenic to humans. He goes on to report that the same examiner stated
that DDT does not harm wildlife if used properly. On that basis he concludes
that the ban on use of DDT is unwarranted and has doomed people, especially
children, to die from malaria.

Although DDT may not alter the genetic structure of an organism, it
certainly has plenty of toxic effects. The US EPA "Persistent
Bioaccumulative and Toxic Chemical Program" reports that DDT is a probable
human carcinogen, damages the liver, can cause liver cancer, temporarily
damages the nervous system, reduces reproductive success, and damages the
reproductive system. In Israel, breast cancer rates decreased dramatically
after DDT was banned from use on dairy farms. One reason DDT effects the
reproductive success of organisms is that it is an endocrine disruptor which
mimics estrogen. This can result in lower fertility in human males. In some
species of fish it can even change their gender. It certainly can disrupt
courtship and may make mating impossible in many species.

Because of DDT's affinity for fat, it is readily excreted in cow and human
milk, which is why the ban in Israel had such a dramatic effect. Since DDT
resists being metabolized, it is stored in the fatty tissue of animals and
accumulates over time. This effect is compounded in predators that eat lots
of prey species with DDT present in their bodies. While DDT can outright
kill some fish that have eaten too many insects laden with it, other fish
live to pass on their accumulation to predators, including humans. Although
it was banned in 1972, over thirty years later there are still fish
consumption advisories for DDT in the Great Lakes and many other watersheds.

In predatory birds, DDT did its damage in another way--it prevented
sufficient production of calcium carbonate in the eggshell making process.
The result was eggshells so thin that they broke when the adult female
attempted to incubate them, thus many fewer young were hatched. The Bald
Eagle, the Peregrine Falcon and many other birds were on the brink of
extinction until DDT was banned. Banning DDT saved our national symbol.

And not just large birds were affected. Many insect and worm-eating birds
succumbed to the effects of DDT's bioaccumulation. As a child growing up in
the 1960s, I remember seeing American Robins convulsing in severe DDT
tremors before they died. We sent more than one carcass to ornithologist
Walter P. Nickell (and one time DAS president) at the Cranbrook Institute of
Science so he could forward them to Michigan State University for analysis.
It was not a pretty sight to see. Nickell and George Wallace at M.S.U.
supplied this kind of data to Rachel Carson as she researched her book,
Silent Spring.

A few other traits of DDT should cause concern. It takes fifteen years or
more to break down in the environment (which is why we still have fish
advisories warning about DDT) and it can be absorbed by some plants, which
means that a vegetarian diet will not save you from its toxic effects.

Maybe a certain amount of DDT can be consumed without killing the organism,
but this does not mean the substance has "no deleterious effects on wildlife
if used properly." There is no way to use DDT that will prevent
bioaccumulation, persistence in the environment or absorption by plants.
Delayed toxic effects are still toxic nonetheless.

Would DDT have prevented the spread of malaria and would it be the best tool
to use to combat West Nile? Probably not. There is one other fact about DDT
and most other pesticides that needs to be told: insects develop resistance
to pesticides. The few insects that do not succumb to the pesticide survive
to reproduce and spread their genetic resistance. In 1997, the National
Research Council reported 4,000 examples of resistance to pesticides in 500
species of insects. In many cases the resistant insect population grows to
levels that surpass what they were when spaying began. Before DDT was
banned, this resistance was already becoming evident.

What should we do? Precisely what most health organizations and communities
are doing, using Integrated Pest Management (IPM). In IPM the ecology of the
insect is studied, and a variety of measures are taken to control the
infestation based on that information. A chemical or biological pesticide is
used only as a last resort, and then only if it can be shown to be effective
and that the benefits outweigh the risks.

While we are justifiably concerned about West Nile, its human victims and
the sporadic mortality of crows and other birds, it is not a serious health
threat for most people. Birds are the primary hosts, not humans. Less than 1
in 150 people bitten by infected mosquitoes get any symptoms of the disease,
and most of those do not develop the brain infection known as encephalitis.
No more than 10% of those who develop encephalitis die and most of those
cases have been elderly people whose other health problems make them more
susceptible. Flu, asthma and respiratory diseases each kill more people per
day than the total number killed by West Nile in the two worst months of the
"epidemic." West Nile is scary because it is new to us. We need to have a
healthy respect for it, but not the panic fomented by sensational media
reports. A sense of perspective is important when dealing with any serious
problem.

Eliminating habitat for larval mosquitoes in back yards, including old
tires, pet water bowls, and other containers with still water will make it
impossible for mosquitoes to complete their metamorphosis to biting adults.
Using mosquito repellents, wearing long sleeve shirts and long pants, and
reducing activities at dawn or dusk when mosquitoes are most active have
been shown to significantly reduce mosquito bites.. Spraying pesticides, on
the other hand, reduces the adult mosquito population only temporarily, as
populations recover quickly and pesticide resistance emerges. Studies have
shown that spraying distracts the public, lulls them into a sense of safety
and deters them from implementing the very factors that could prevent
mosquito contact in the first place. And, what Bray did not mention is that
DDT and other pesticides do not differentiate between good insects and
pests. Monarch butterflies and the economically important honeybee could be
affected as well. If pesticides are to be used in some cases, after other
IPM methods have been tried, the larvicidal bacteria that come in pellet
form are the best choice. Even that biological control method may have some
risks, despite claims that it is safe and is specific to only mosquitoes.
Nobody knows for sure that this bacterium will not infect beneficial insects
or other organisms. But it is far safer than chemical pesticides. And of the
chemical pesticides, DDT would be one of the worst to consider. Thank
goodness it is no longer an option in this country.

There is also a problem with Bray's assertion that the ban on DDT is to
blame for the continued high rates of malaria worldwide--most of the
developing world still uses DDT, and much of it is imported from U.S.
manufacturers. IPM is not only safer, it is the most effective approach to
combating insect or any other pests, animal or plant. Maybe if the countries
that continue to rely so heavily on DDT tried IPM, the numbers of malaria
victims would finally start to decrease.

----- Original Message -----
From: Gene GeRue <genegerue AT ruralize.com>
To: <homestead AT lists.ibiblio.org>
Sent: Saturday, January 08, 2005 8:49 AM
Subject: [Homestead] Rethinking DDT--or should we?



This is a sobering article. Along with others we have recently read, it
points out that malaria kills many times more people than the recent
tsunami did. But--somebody give me a reality check, please--I find myself
wondering if such human catastrophes are not simply Nature protecting
herself, a way that Gaia is creating a balance from the increasing
destructiveness of its dominant species. I feel pretty certain that human
overpopulation is the biggest threat to our planetary home. Yet, not one

of

us could look a sick child in the face and not want to help in any way
possible. But looking at the big picture, consider the outcome if all

lives

were saved. Am I losing my humanity?



yvoivozhd:
http://www.millennium-debate.org/ind23may023.htm (GM mosquitos to replace malaria-carrying mosquitos---and to resistance to pesticides either)

Bti (Bucillus thuringiensis israelensis) which is a bacteria applied to cobs of corn that are thrown into standing water also used to kill mosquito larva.

[ Back to EurekAlert! ] Public release date: 16-Jul-2004
[ Print Article | E-mail Article | Close Window ]

Contact: Michael Bernstein
m_bernstein AT acs.org
202-872-6042
American Chemical Society
Cinnamon oil kills mosquitoes
NOTE FOR REPORTERS: The statement in our original news release (distributed 7-15) that cinnamon oil can "kill mosquito larvae more effectively than DEET" is misleading since we neglected to point out that DEET is most commonly used in insect repellants, not as a larvicide. We apologize for not making this clear. Please disregard the previous version of this news release and use the following version.

Cinnamon oil shows promise as a great-smelling, environmentally friendly pesticide, with the ability to kill mosquito larvae, according to a new study published in the July 14 issue of the Journal of Agricultural and Food Chemistry, a peer-reviewed journal of the American Chemical Society, the world’s largest scientific society.

The researchers also expect that cinnamon oil could be a good mosquito repellant, though they have not yet tested it against adult mosquitoes.

Besides being a summer nuisance, mosquitoes pose some major public health problems, carrying such deadly agents as malaria, yellow fever and West Nile virus. While conventional pesticide application is often effective in controlling mosquito larvae before they hatch, repeated use of these agents has raised serious environmental and health concerns.

"These problems have highlighted the need for new strategies for mosquito larval control," says Peter Shang-Tzen Chang, a professor in the School of Forestry and Resource Conservation at National Taiwan University and lead author of the paper. Scientists are increasingly turning to more benign natural chemicals to ward off mosquitoes and other pests.

Chang and his coworkers tested eleven compounds in cinnamon leaf oil for their ability to kill emerging larvae of the yellow fever mosquito, Aedes aegypti. "Four compounds — cinnamaldehyde, cinnamyl acetate, eugenol and anethole — exhibited the strongest activity against A. aegypti in 24 hours of testing," Chang says.

Larvicidal activity is judged with a measurement called LC50. "The LC50 value is the concentration that kills 50 percent of mosquito larvae in 24 hours," Chang explains. Lower LC50 translates into higher activity, because it takes a lower concentration to kill larvae in the same amount of time. All four compounds had LC50 values of less than 50 parts per million (ppm), with cinnamaldehyde showing the strongest activity at an LC50 of 29 ppm.

Other common essential oils, such as catnip, have shown similar promise in fighting off mosquitoes, but this is the first time researchers have demonstrated cinnamon’s potential as a safe and effective pesticide, according to Chang.

Cinnamaldehyde is the main constituent in cinnamon leaf oil and is used worldwide as a food additive and flavoring agent. A formulation using the compound could be sprayed just like a pesticide, but without the potential for adverse health effects — plus the added bonus of a pleasant smell.

Bark oil from the Cinnamomum cassia tree is the most common source of cinnamaldehyde, but the tree used in this study — indigenous cinnamon, or Cinnamomum osmophloeum — has been of interest to researchers because the constituents of its leaf oil are similar to those of C. cassia bark oil. The leaves of C. osmophloeum, which grows in Taiwan’s natural hardwood forests, could be a more economical and sustainable source of cinnamon oil than isolating it from bark, Chang says.

Though the team only tested the oil against the yellow fever mosquito, cinnamon oil should prove similarly lethal to the larvae of other mosquito species, the researchers say. In further studies they plan to test cinnamon oil against other types of mosquitoes as well as different commercial pesticides.

"We think that cinnamon oil might also affect adult mosquitoes by acting as a repellant," Chang says. The researchers haven’t yet tested this theory, but they plan to find out in the near future.

The Council of Agriculture of the Executive Yuan, a government agency in Taiwan, provided support for this research.

— Jason Gorss

###

The online version of the research paper cited above was initially published June 10 on the journal's Web site. Journalists can arrange access to this site by sending an e-mail to newsroom AT acs.org or calling the contact person for this release.
[ Back to EurekAlert! ] [ Print Article | E-mail Article | Close Window ]

http://rds.yahoo.com/S=2766679/K=kill+malaria+mosquitos/v=2/SID=w/l=WS1/R=33/IPC=us/SHE=0/H=0/SIG=125gmv6f3/EXP=1105301071/*-http%3A//www.worldchanging.com/archives/001405.html (vaccine against malaria by 2010?)


iological Controls
Introduction of natural predators:
Mosquito-eating fish: Gambusia
gambusiaGambusia affinis is a natural predator on mosquito larvae. These fish can be stocked in ponds or ditches, if the water is deep enough. The nice thing about natural predators is that the mosquito larvae do not evolve chemical resistance. However, the Gambusia fish might out compete native fish in the area if its population is not kept in control. In the picture below, a truck stocks a body of water with fish.

Gambusia truck

Bacterial Insecticides
btiAnother option is to use bacteria to kill the larvae. Bacillus thuringiensis israelensis (B.t.i.) kills mosquito larvae, but does not harm fish, humans, or other insects except the blackfly. The larvae ingest the bacteria as they filter food with their mouth brushes and die. One limitation of B.t.i is that it has no effect on the egg and pupal stage, or on larvae that are ready to pupate and have stopped feeding.




Chemical Controls
Larvicides
Petroleum or special mineral oils can be sprayed on the surface of water where mosquitos develop. This only works well on standing water where the oil can produce a nice even film. The oil prevents the pupae and larvae from getting access to air, and as a result, they suffocate.

Adulticides
Adulticides are not usually necessary when a good larvae control program is in place. Early in the war on malaria in the 50's and 60's DDT was used to kill adult mosquitos, but in some places the vector has evolved resistance, and DDT is toxic to animals. Malathion and Deltamethrin are available instead, although they are more expensive. Biological controls should be used when possible, so that there is no risk of chemical resistance. Repellents like DEET and Permethrin can reduce the risk of transmission. For the debate on DDT and malaria see DDT and Insecticide Resistance.

Other forms of control
Mechanical forms of control include the aforementioned destruction of mosquito habitats (use the drop down menu for more info), wearing protective clothing, and putting up screen barriers. There are some interesting products on the market for vector control. One is the LarvaSonic, an acoustic larvacide. This device transmits a frequency into the water at the same resonance as mosquito larvae air bladders. The internal tissue inside the mosquito larva ruptures and it dies instantly.

http://www.fightingmalaria.org/news.php?ID=169&month=October+2003 (DDT has almost no advantage over other insecticide sprays---re-use of this banned chemical is is for propaganda value---its fearful damage to birds and amphibians is well-documented, and only too well known)

http://www.worldchanging.com/archives/000590.html (follow the money---who would benefit by re-introducing DDT instead of more environmentally-benign chemicals and simple, effective bed mosquito-netting.

Note there is not a word from any of the bring-back-DDT looneys about the billions of mosquitos in eavestroughs, tree-branches, creekside puddles, drainage ditches. The same looneys carefully avoid mention of the fact that, lacking spray-helicopters, homeowners aren't going to do a damned thing about such huge sources of the present and future generations of mosquitos eager to bite them anywhere outside, and to re-invade their house at the earliest opportunity---any time a door or window is opened.

Like the pyethrins, DDT has some residual effect to repel or kill mosquitos, but it sure as hell is not a magic bullet as the looneys imply. No one knows this better than I do---nor is anyone more familiar with the buzzing sound of mosquitos testing my DDT-sprayed bed mosquito-net. All I can say is that they are fewer in number after a room is hermetically-sealed for the night---all to return anew the next daY.

The reason I survived India and Burma was three-fold---eating Atabrine pills like popcorn, spraying my bed mosquito-net before I turned in, and spraying the interior of the thatched hut. Omit any one of these if the Death March is your favorite tune.

One of my favorite people, Major Rebori, came to the Air Commandos as an instructor in Burma, from Orde Wingate's
outfit. Due to the exigencies of jungle combat, he could not take these precautions when with Wingate. He was bedridden with the shivers every day, and died of Malaria a few months later, still in his early 30's.






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