tributyltin: Pesticide Linked to Obestity, Diabetes: via RXR-like nuclear receptors

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Link to whole-text science article follows the news item, as does a

related story about bees and pesticides.

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Another Pesticide Linked to Diabetes

Scientists: Obesity-Chemical Exposure Link is Both " Plausible and

Provocative "

By Dan Shapley

http://www.thedailygreen.com/environmental-news/latest/pesticides-diabetes-47120\

105

A common pesticide used to kill pests on food crops, boats, wood and

textiles could be causing diabetes, according to new research by

Japanese scientists published in /Bioscience/.

The pesticide in question, tributyltin, had already been known to cause

chemical burns and other skin irritation, dizziness, difficulty

breathing and flu-like symptoms to workers exposed to contaminated dust.

It had already been known that tributyltin suppresses the immune system,

as well as reproductive problems and increased rates of infant mortality

and deformities in lab rats. Lab studies have also shown that

tributyltin can disrupt the endocrine system of mammals, upsetting

hormone levels in the pituitary, gonad and thyroid glands, and causing

disruptions to reproductive, immune and nervous systems and the liver.

That's to say nothing of its effect on marine organisms, which are also

well documented. It is highly toxic to mollusks, causes female snails to

develop male characteristics, and it builds up in the food chain,

affecting predators that consume prey exposed to the chemical.

Now, new research implicates it in the obesity epidemic.

According to the American Institute of Biological Sciences

<http://www.eurekalert.org/pub_releases/2008-12/aiob-ppm112508.php>:

" The harmful effects of the chemical on the liver and the nervous

and immune systems in mammals are well known, but its powerful

effects on the cellular components known as retinoid X receptors

(RXRs) in a range of species are a recent discovery. When activated,

RXRs can migrate into the nuclei of cells and switch on genes that

cause the growth of fat storage cells and regulate whole body

metabolism; compounds that affect a related receptor often

associated with RXRs are now used to treat diabetes. RXRs are

normally activated by signaling molecules found throughout the body.

" The BioScience article, by Taisen Iguchi and Yoshinao Katsu, of the

Graduate University for Advanced Studies in Japan, describes how

RXRs and related receptors are also strongly activated by

tributyltin and similar chemicals. Tributyltin impairs reproduction

in water fleas through its effects on a receptor similar to the RXR.

In addition, tributyltin causes the growth of excess fatty tissue in

newborn mice exposed to it in utero. The effects of tributytin on

RXR-like nuclear receptors might therefore be widespread throughout

the animal kingdom.

" The rise in obesity in humans over the past 40 years parallels the

increased use of industrial chemicals over the same period. Iguchi

and Katsu maintain that it is " plausible and provocative " to

associate the obesity epidemic to chemical triggers present in the

modern environment. Several other ubiquitous pollutants with strong

biological effects, including environmental estrogens such as

bisphenol A and nonylphenol, have been shown to stimulate the growth

of fat storage cells in mice. The role that tributyltin and similar

persistent pollutants may play in the obesity epidemic is now under

scrutiny. "

Earlier this year, a National Institute of Health study fund that a

different pesticide, trichlorfon, commonly used on golf courses, was

associated with an 85% increase in risk of diabetes for even infrequent

users, and a 250% increase in risk for workers who had applied it more

than 10 times. The same pesticide has been used to kill cockroaches,

crickets, bedbugs, fleas, flies and ticks, but its main current use is

on turf, such as at golf courses.

It was the most extreme connection researchers found between pesticide

applicators and diabetes, but not the only one. Use of any of the

pesticides studied for more than 100 days in a lifetime increased

diabetes risk 17%. The other pesticides studied were aldrin, chlordane,

heptachlor, dichlorvos, alachlor and cynazine, all of which are

chlorinated pesticides.

Diabetes affects nearly 21 million Americans, and rates of disease have

been increasing dramatically in recent years, particularly among children.

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For the remainder of the month, the full text of the article will be

available for free download through the copy of this Press Release

available at:

http://www.aibs.org/bioscience-press-releases/081201_persistent_pollutant_may_pr\

omote_obesity.html

or via

http://www.aibs.org/bioscience-press-releases/resources/Iguchi.pdf

..

Europe hopes havens will give bees a break

Plan Bee encourages governments to set aside safe places for bees to buzz.

By Momigliano | Correspondent of The Christian Science Monitor

December 2, 2008 edition

http://www.csmonitor.com/2008/1202/p04s01-wogn.html