Snippets From Science

• Snippets from the Health & Science section of The Week (August 6, 2010):

Item 1: Women who wear high heels on a regular basis often experience pain when walking without the heels. Ultrasound and MRI scans indicate that in such women the Achilles tendon has shortened and thickened. This leads to a stiffening of the tendon. Simple exercises, such as standing on tiptoes and raising and lowering the heel 20 times a day, may help.

Item 2: Residual antidepressants, such as Prozac, are excreted in human waste. Treatment plants don’t remove these chemicals, and they often end up in open waterways. Biologists at the U. of Portsmouth in England report that shrimp in some estuaries metabolize the drug and begin to behave as if they had lost their fear. They leave darker, more secluded waters and venture out into more open water where they are exposed to predators.

Item 3: Scientists have developed an inexpensive pre-sex vaginal gel that when used at least 80 percent of the time by African women can cut the number of HIV infections by half. Two-thirds of the 33 million people in the world with HIV live in Africa, and the search continues for inexpensive ways to protect men and women from AIDs.

• There is much controversy about the toxicity of bisphenol A (BPA), a chemical that is omnipresent in our lives (it is used to enhance the plasticity of polycarbonate baby bottles, water bottles, plastic microwavable containers, the lining of food and soda cans, epoxy resins, and white dental sealants).

The Food and Drug Administration (FDA), the Environmental Protection Agency (EPA), and the American Chemical Council (ACC) believe the chemical is safe at a concentration of 50 micrograms/kilogram of body weight/day, but no one really knows whether it is toxic to humans. However, studies by the Center for Disease Control report that 95 percent of Americans tested have detectable levels of BPA in their bodies, at or above levels known to cause adverse effects in lab animals. In one experiment, pregnant rodents were exposed to levels of BPA 2,000 times lower than the EPA’s “safe dose” level. The result: sexual abnormalities in their offspring. Other studies suggest that BPA exposure may affect the development of human fetuses, infants, and young children. In 2008, Health Care of Canada declared BPA to be a toxic chemical. Do we believe the findings of most scientists, government agencies, or the ACC? It’s no surprise that the ACC goes out of its way to convince legislators that BPA is safe. This group has 300 or more lobbyists in Washington and spends around $40 million a year arguing, among other things, “…the evidence that BPA has an effect on humans has not been proven.” (Sources include: Scientific American, Sept., 2008; Milwaukee Journal Sentinel, Feb. 14, 2010; Politico, April 20, 2010; naturenews, April 21, 2010, many other sources. For the views of ACC, visit http://www.americanchemistry.com.)

• Wisconsin’s largest dragonfly, the Common Green Darner (Anax junius), showed up in great numbers this summer. It’s been a good summer for dragonflies in general, since they like an early spring, warm, sunny days, and abundant rainfall. If you watched the recent pro golf tournament at Whistling Straits on TV, you saw Green Darners zoom across the field of view. Dragonflies in feeding swarms have been putting on quite a show, gobbling up small insects and performing complex aerial maneuvers. They hover and dart back and forth on whirring wings, grabbing prey from below after a blink-of-the-eye barrel roll or tight loop, then they zoom on to the next prey. Most dragonflies dine on the wing and gorge themselves on mosquitoes, flies, gnats, and even smaller dragonflies. Without dragonflies, there would be even more mosquitoes to dine on us.