For Some Chemicals, Less Is More

For decades many scientists have believed that "the dose makes the poison" -- a chemical may be harmless in small amounts but devastating in higher amounts. But this latest research demonstrates that endocrine-disrupting chemicals act differently than other substances.
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When scientists suspect a chemical may cause cancer or other illnesses, one way they do testing is to expose lab animals to high doses of the substance and then see what happens. When anything tested this way shows harmful effects, industry goes on the offensive, arguing that only massively unlikely doses to people could cause harm (they don't mention that they lobbied for using this high-dose testing method, since it's cheaper than other methods). For example, in 2011, when animal testing prompted California to propose listing a chemical in caramel coloring (a main ingredient in cola) as a substance known to cause cancer, Coke claimed that a person would have to drink more than 18,000 cans of soda to be impacted.

In fact, independent scientists noted that a single can of soda contained almost four times as much of the chemical as the proposed safety standard.

Now, another troubling development in product safety is showing that we have not been protective enough about potentially harmful chemicals in products for our children and families. About a year ago, I wrote about chemicals that can mimic and alter the body's hormones, and about the "Toxic Shell Game" whereby companies that are forced to replace harmful chemicals often do so with other similar chemicals that may also harm our health.

For example, the hormone-altering chemical bisphenol A (BPA) has been a recent target of regulators, so some companies switched to a lesser-known and unregulated chemical cousin called bisphenol S (BPS). Now new research released Thursday shows that BPS can also alter our natural hormones, even at extremely low doses.

Natural hormones are produced by our endocrine system and serve to regulate our development, metabolism, and reproduction. But chemicals found in hundreds of products -- including compounds used in many plastics (including many items marketed to children), food containers, cosmetics and other common products -- can act like hormones and disrupt endocrine functioning, causing harm to our and/or our children's sexual development, as well as other health problems.

Last March, a comprehensive review of 800 studies by 12 leading scientists concluded that these endocrine-disrupting chemicals can cause health problems and disabilities even when people are exposed to tiny doses -- doses much smaller than would be used in traditional lab testing.

For decades many scientists have believed that "the dose makes the poison" -- a chemical may be harmless in small amounts but devastating in higher amounts. But this latest research demonstrates that endocrine-disrupting chemicals act differently than other substances, since they can be more harmful at lower doses.

This seems impossible, but think about it like a lock and a set of keys that all fit the lock. If you force many keys into the lock, it won't unlock -- more likely, it will jam and stop working altogether. But use just a single key, and that's enough to turn the lock.

That's how some hormone-altering chemicals appear to have the power to wreak havoc in our bodies at very small doses. Like many keys, large doses may be incapable of having much of an impact, because they overwhelm the receptors in our bodies where hormones do their work. Smaller doses, like just one key, can fit into these receptors -- and that's when hormone-altering chemicals cause health problems.

After health advocates worked for decades to end lead poisoning threats, medical experts came to the conclusion that there is no safe level of lead exposure, especially for children. Now, the lead author of the recent study has stated that there are "no safe doses for these hormone-altering chemicals." The study's authors expressed concern that government "safety" levels for such chemicals have been improperly established since the substances have never been tested for low-level effects.

Last year's study was just one of the more recent and compelling affirmations of the impact of low-dose effects. The book Our Stolen Future brought the concept to wide public attention in 1996, and its authors continue their groundbreaking scientific and journalistic work today. More than 10 years ago, an EPA expert panel acknowledged that animal studies demonstrated that low-dose effects were a problem not addressed by current testing and regulations.

In response to the latest study on BPS, Environmental Health News reports, "The American Chemistry Council, which represents chemical manufacturers, did not respond to requests for comment." Last year, the industry denied the findings from the independent review of more than 800 studies, saying that the review was not valid for assessing human health threats and that the low-dose effects found in hundreds of studies over more than a decade "have not been proven."

In other words, industry says we should continue to expose our children and families to their potentially harmful chemicals while people get sicker and sicker, instead of simply designing safer products in the first place. In contrast, in response to public concern for children's health, a team of scientists just released a tool intended to promote products designed to avoid endocrine-disrupting effects.

Industry's lobbying against common-sense health protections is especially disturbing given CEH's recent discovery of the cancer-causing and hormone-altering flame-retardant chemical chlorinated Tris in foam diaper-changing pads, foam nap mats, and other baby and children's foam products sold at Walmart, Target and other national retailers. What's especially outrageous is that Tris was banned from children's pajamas more than 30 years ago -- yet our testing shows that it is still widely used in many other products for infants and children.

As I stated in my previous post, it's simply wrong to use our children as guinea pigs in the chemical industry's experiments. That's why we are working to change the rules of the game, so companies are required to demonstrate safety before products end up in our homes, schools, and workplaces. That's how we are going to end the toxic shell game, and promote markets for products that are designed to be safe for workers, the environment, and our children and families.

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