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Saturday, March 12, 2016

Better Living through Chemistry: Phthalates from Cradle to Grave

From the Archives

By Todd Helmus
March 10, 2016

Editor's Note: The European Union, adhering to a "precautionary principle" which allows it to ban chemicals that pose a plausible, rather than irrefutable threat of harm, in 2005 prohibited phthalate content in children's toys and other products that kids might introduce into their mouths. In other words, anything that would fit. Only late in 2009 did the U.S. take any regulatory action, barring these ubiquitous plasticizers from products, including baby-bottle nipples and pacifers, specifically intended to be inserted into children's mouths. Manufacturers are taking steps themselves to limit or eliminate phthalate content in kids' stuff, presumably for fear of lawsuits downstream. We also subscribe to a precautionary principle when it comes to children's health.

 Have you ever heard of phthalates? They’re almost everywhere, in almost everything. Including you.

These chemical compounds, technically, di-esters of phthalic acid, are widely used as plasticizers--substances added to plastics to increase their flexibility, transparency, durability and longevity. Their principal use is to soften polyvinyl chloride, although they crop up in an absolutely staggering number of consumer products, including food containers and wrappers, flooring and other building materials, ink and paint, electronic equipment, medical devices, perfumes (they bind scented oils), soaps, lotions, cosmetics and other personal care products--even sex toys.

In 2004, manufacturers reported producing about 800 million (!) pounds of phthalates per year, or about 10 – 60% of typical plastics by weight. There's a relatively simple, unscientific test for phthalate content in otherwise unscented items: the more strongly they have that "new shower curtain" smell, the higher the levels. Next time, better sniff that rubber ducky before you buy it!

Here’s why: Dr. Renshan Ge of the Population Council and his colleagues from Fudan University and Second Military Medical University in Shanghai found a clear correlation between prenatal phthalate exposure and low birth weight in infants, a leading predictor of death in children under 5 years of age, and of the development of cardiovascular and metabolic disease later in life. Their paper was published in the Journal of Pediatrics.

According to Dr. Ge:

"Our results showed that phthalate exposure was ubiquitous in these newborns, and that prenatal phthalate exposure might be an environmental risk factor for low birth weight in infants."

Ironically, a concurrent New York study conducted by the Mount Sinai School of Medicine found that children with higher phthalate levels were much more likely later to become obese.

And another reason: according to a University of Rochester Medical Center study published in the International Journal of Andrology:

"... prenatal exposure to phthalates, as measured by the concentration in their mothers’ urine, led to less stereotypically masculine play by pre-school boys."

Said lead author Shanna H. Swan, Ph.D., professor of obstetrics and gynecology, director of the URMC Center for Reproductive Epidemiology and an expert on phthalates, “Because testosterone produces the masculine brain, we are concerned that fetal exposure to anti-androgens (testosterone suppressors) such as phthalates -- which are pervasive in the environment -- has the potential to alter masculine brain development.”

Then, this: Korean scientists also measured urine phthalate concentrations and evaluated symptoms of attention-deficit/hyperactivity disorder (ADHD), using teacher-reported symptoms and computerized tests that measured attention and impulsivity. Their study, published in the journal Biological Psychiatry, found a significant positive association between phthalate exposure and ADHD, meaning that the higher the concentration of phthalate metabolites in the urine, the worse the ADHD symptoms and/or test scores.

Senior author Yun-Chul Hong, M.D., Ph.D. explained that, "These data represent the first documented association between phthalate exposure and ADHD symptoms in school-aged children."

John Krystal, M.D., the editor of Biological Psychiatry, also commented:

"This emerging link between phthalates and symptoms of ADHD raises the concern that accidental environmental exposure to phthalates may be contributing to behavioral and cognitive problems in children. This calls for more definitive research."

Finally: again from the University of Rochester Medical Center: exposure to phthalates, already connected to reproductive problems, has now, for the first time, been linked to abdominal obesity and insulin resistance in adult males. Said study lead author Richard Stahlhut, M.D., M.P.H., a preventive medicine resident at the university:

“This research adds to the growing suspicion that low-dose exposures to phthalates and other common chemicals may be reducing the levels of testosterone in men or impeding its function, thereby contributing to rising obesity rates and an epidemic of related disorders, such as Type 2 diabetes.”

The paper was published the journal Environmental Health Perspectives.

"Substantial declines in testosterone levels and sperm quality have been observed in the United States and other countries over the last several decades. That urgently requires explanation," Stahlhut remarked. Animal studies have shown consistently that phthalates depress testosterone levels.

Recent human studies have found that phthalates are associated with poor semen quality (sperm count and motility) in men and subtle changes in the reproductive organs in boy babies.

Stahlhut said this connection between phthalates and testosterone helped to establish a basis for the study. His group hypothesized that phthalates might have a direct link to obesity, since low testosterone appears to cause increased belly fat and pre-diabetes in men.

Naturally, nearly all of this is disputed by the American Chemistry Council, whose handsome Phthalates Information Center website features a panoramic picture of a pristine mountain lake.

One of its Orwellian home page headlines? “Did You Know? Science Protects Our Health.”

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