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From Old Moms to Plastic Water Bottles

Posted by | June 13, 2009

Science is full of unexpected discoveries, some coming at decidedly awkward times. Just as there can be a breakthrough in negotiating the end to a war that comes to everyone’s surprise on a major holiday, or intense spurts in which a writer completes a book in a week, there are times a scientist may feel awash in troubles but then see the world afresh as the facts fall into place in a new way.

An element of chance enters science, just as it does everyday life. But, as Louis Pasteur noted, chance favors the mind that’s prepared to understand the world from a new angle.

Here’s the story of a prepared mind and the discovery that may have major implications for our plastic water bottles and other food packaging.

Prof. Patricia Hunt is a genetics expert who  investigates how and why older moms are more likely to give birth to babies with a number of birth defects. Many of us women don’t know it, but the tiny eggs in our ovaries are actually as old as we are – we don’t make them afresh as life goes along. And the older those egg cells are, the more likely they are to have certain problems. To be blunt, older moms run a greater risk of having babies with certain birth defects.

Scientists do study human moms, but we can also learn a good bit from seeing how and why the eggs inside a “mouse mom” change over time. When scientists study animals, we generally have one set of mice with problems and another group called the “control.” The idea is to treat both groups in exactly the same way (same food, same bedding material, same little exercise wheels, same tiny televisions). Any differences between the groups should comes about due to the one crucial difference that’s being studied, say the presence of a particular gene or the age of the egg cell.

Normally, the control group shows boring results. It’s the regular stuff of mouse life. But some years ago, Hunt found she had a puzzle on her hands. Quite suddenly, the mice in even the control group in her lab were having a lot of miscarriages. Hunt and her team had to retrace their steps and look for anything that would explain the change.

In the end, Hunt discovered that the mice’s plastic water bottles had been cleaned at one point with a harsh detergent. That detergent apparently meant that some chemicals in the plastic – chemicals that are like the hormone estrogen  – were moving from the bottles into the water. That small change created the big differences in the mouse mom’s reproductive life.

The possible implications in Hunt’s discovery for people are substantial. We use hard plastics every day. They come in different kinds, but some of them can add the estrogen-like chemical “bisphenol-A” into the liquid or food they contain. It’s still not crystal clear that bisphenol-A itself is really the culprit at issue in the matter – there’s complex chemistry at issue – and more will be heard from on that front in the news.

Still, millions of Americans have decided they want to limit their exposure to the chemicals that come out of hard plastics. Stainless steel water bottles, or those made of plastics advertised as “free of bisphenol-A” are one option, and you can see lots of them at the store. (My 40-year old glass thermos purchased for 50 cents at the next-door-neighbor’s yard sale works nicely for me, but that solution will be over the day I drop the Thermos.)

Thanks to Professor Hunt’s work and her prepared mind, we’ve learned a lot about plastics in recent years, including some surprising discoveries that came along to unexpected ways. The fruits of science are not always what we can predict, but they make a valuable harvest – and they can change even basics in our kitchens and lunch boxes.

Pasteur was right in emphasizing we must prepare our minds – and those in the next generation – so that they can continue to make the discoveries that will propel our progress in the 21st century.