EarthTalk: Arctic Ice | Endocrine Disrupters
Dear EarthTalk: Why is the Arctic such a crucial area to focus on in efforts to stem global warming? — Joseph Constabile, Dedham, MA
The image of a polar bear standing on a shrinking iceberg has become one of the most iconic symbols of global warming, yet few of us realize just how important the Arctic’s ice is, wherever we may live on Earth. Researchers consider the Arctic to be an “indicator region” for the rest of the planet, given that even small differences in temperature there can have profound ecosystem impacts and can give us a better idea of the types of problems we can all expect down the road.
Of course, the effects of global warming have been under scrutiny in the Arctic for decades already. Since 1979, the extent of the Arctic’s permanent ice cap has shrunk by upwards of 20 percent. Even worse, the remaining ice has thinned by as much as two-thirds in some parts of the Arctic. Recent models suggest this ice loss will only accelerate in the next several years due to a global warming feedback loop called the “albedo effect,” whereby less ice means less reflection of the sun’s radiation back into space and thus more warming at the Earth’s surface. And not only is the ice shrinking, parts of the ice cap are also rupturing: The Ward Hunt Ice Shelf, the largest block of ice in the Arctic and intact for some 3,000 years, finally cracked in 2000, and within two years split all the way through.
These changes up north are already starting to have ripple effects elsewhere. For starters, the entire Arctic ecosystem is being forced to shift with the changing climate. Animals like polar bears, whales and seals are changing migration patterns, in turn impacting native people who depend on them for sustenance. Meanwhile, other organisms are overpopulating, given all the new habitat opening up. Rising temperatures have allowed the spruce bark beetle to add an extra reproduction cycle each year. As a result the pesky little beetles decimated 3.4 million acres of Alaska’s forests over just 10 years.
And then there’s the issue of sea level rise. Thanks in large part to melting Arctic glaciers, sea level is expected to rise some three feet on average around the world in the next century, flooding over 22,000 square miles in the United States alone. This pressing issue threatens island nations especially. Countries like the Maldives, precariously perched just six feet above sea level, are as concerned as anyone about melting glaciers in the Arctic. And warming in the Arctic also affects weather patterns vital for food production all over the world. Cold water from the melting ice could also potentially halt the Gulf Stream, which brings warm weather to Europe. This would result in a steep drop in temperature for much of northwestern Europe and would affect weather patterns far beyond.
While it may seem futile for us to try to stop Arctic ice melting, we do in fact have the power. We can all work to reduce our carbon footprints by flying and driving less, turning down (or off) the heat or air conditioning, speaking up to our elected officials, and even divesting from companies that support the continued development of fossil fuels.
Dear EarthTalk: What are endocrine disrupters, how do they make their way into my body and what can I do to avoid them? — Jo McGovern, Albany, NY
The endocrine system controls the various functions of cells, tissues and organs in our bodies through the secretion of hormones. The major glands that regulate the flow of these hormones include the pituitary, thyroid, parathyroid, and adrenal glands, as well as the pancreas and reproductive glands (ovaries in women, testicles in men). A properly functioning system ensures optimum mood, growth, development, metabolism, sexual function and reproduction.
Endocrine disruptors are chemicals that mimic or block the action of natural hormones. According to the Environmental Working Group (EWG), there is no end to the tricks that endocrine disruptors can play on our bodies. These chemicals can increase the production of certain hormones, decrease the production of others, turn one hormone into another, compete with essential nutrients and more.
Some 80 million pounds of atrazine, an herbicide named on EWG’s Dirty Dozen List of Endocrine Disruptors, are applied in the U.S. each year. A 2010 University of California (UC) Berkeley study found that atrazine-exposed male amphibians were feminized as a result. Ten percent of those exposed developed into females that copulated with unexposed males and produced viable eggs. “Given the overwhelming evidence of unacceptable risk, I’m quite frankly surprised that atrazine is even still in use,” said Dr. Tyrone Hayes, professor of Integrative Biology at UC Berkeley and the study’s lead author.
Monsanto’s Roundup, a trade name for glyphosate and the most widely used herbicide in the U.S. with 250 million pounds sprayed each year, was also recently found to have hormone disrupting capabilities. Studies released in 2015 determined that Roundup decreased levels of progesterone and corticosterone, a steroid hormone produced in the adrenal glands. An earlier study determined that even at lower, “non-toxic” exposure levels, Roundup reduced testosterone levels. Recently it was announced that the U.S. Environmental Protection Agency (EPA) will analyze the impacts of atrazine and glyphosate on 1,500 endangered plants and animals under the terms of a settlement reached with the Center for Biological Diversity (CBD). “This settlement is the first step to reining in the widespread use of dangerous pesticides that are harming both wildlife and people,” said Brett Hartl, CBD’s endangered species policy director.
Buying organic produce and drinking filtered water can reduce your exposure to hormone-disrupting herbicides and pesticides. Another good reason to install a water filter is to remove perchlorate, a chemical that is also named on EWG’s Dirty Dozen list. A 2010 study found that, in pharmacologic doses, perchlorate inhibits iodine uptake, an element needed for the production of thyroid hormones. The findings were alarming as adequate iodine intake is essential for normal neurodevelopment in infancy and childhood. While further research is needed to determine the impacts of perchlorate in the environment, the American Thyroid Association recommends that women who are planning a pregnancy or who are pregnant ingest 150 mg of iodine daily to ensure adequate iodine nutrition and to overcome the potential adverse effects of perchlorate exposure.
While it may be frightening to think about all the potential exposures to endocrine disruptors around us today, purchasing environmentally-conscious, natural-based products for you, your family and your home; eating organic, fresh, unpackaged foods and drinking filtered water from a glass container are simple ways to help keep your hormones and endocrine system in balance.
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