Our toxic society

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Another in the series discussing the chemicals that live in our bodies, byproducts of our industrial culture. Our President's friend, Exxon-Mobil, is the largest producer of phthalates, by the way, so I'll expect the bully pulpit to resound with calls to ignore this 'scare story'.

WSJ.com - From an Ingredient In Cosmetics, Toys, A Safety Concern
In the 12th week of a human pregnancy, the momentous event of gender formation begins, as X and Y chromosomes trigger biochemical reactions that shape male or female organs. Estrogens carry the process forward in girls, while in boys, male hormones called androgens do.

Now scientists have indications the process may be influenced from beyond the womb, raising a fresh debate over industrial chemicals and safety. In rodent experiments, common chemicals called phthalates, used in a wide variety of products from toys to cosmetics to pills, can block the action of fetal androgens. The result is what scientists call demasculinized effects in male offspring, ranging from undescended testes at birth to low sperm counts and benign testicular tumors later in life. “Phthalate syndrome,” researchers call it.

Whether phthalates -- pronounced “thallets” -- might affect sexual development in humans, too, is now a matter of hot dispute. Doses in the rodent experiments were hundreds of times as high as the minute levels to which people are exposed. However, last year, federal scientists found gene alterations in the fetuses of pregnant rats that had been exposed to extremely low levels of phthalates, levels no higher than the trace amounts detected in some humans.

Then this year, two direct links to humans were made. First, a small study found that baby boys whose mothers had the greatest phthalate exposures while pregnant were much more likely than other baby boys to have certain demasculinized traits. And another small study found that 3-month-old boys exposed to higher levels of phthalates through breast milk produced less testosterone than baby boys exposed to lower levels of the chemicals.

Scientists are raising questions about phthalates at a time when male reproductive disorders, including testicular cancer, appear to be on the rise in many countries. Seeking an explanation, European endocrinologists have identified what some see as a human counterpart to rodents' phthalate syndrome, one they call “testicular dysgenesis syndrome.” Some think it may be due in part to exposure to phthalates and other chemicals that interfere with male sex hormones.

We know abnormal development of the fetal testes underlies many of the reproductive disorders we're seeing in men,” says Richard Sharpe of the University of Edinburgh in Scotland, a researcher on male reproduction. “We do not know what's causing this, but we do know high doses of phthalates induce parallel disorders in rats.”

Of course, the industry claims that there is nothing to worry about:

Users and producers of phthalates say they are perfectly safe at the very low levels to which humans are exposed. Phthalates are among the most widely studied chemicals and have proved safe for more than 50 years, says Marian Stanley of the American Chemistry Council, a trade association.

Great, I feel better now. Wouldn't want to get science involved. Bill Moyers PBS program discussed these guys (also here, with a link to ScoreCard.org which allows you to search by zipcode to determine which chemicals are in your neighborhood).

A few more excerpts after the jump.


The phthalate debate is part of the larger societal issue of what, if anything, to do about minute, once-undetectable chemical traces that some evidence now suggests might hold health hazards.

With much still unknown about phthalates, scientists and regulators at the Environmental Protection Agency are moving cautiously. “All this work on the effects of phthalates on the male reproductive system is just five years old,” says the EPA's leading phthalate researcher, L. Earl Gray. “There appears to be clear disruption of the androgen pathway, but how? What are phthalates doing?”

To Rochelle Tyl, a toxicologist who works for corporations and trade groups studying chemicals' effects on animals, the broader question is: “If we know something bad is happening, or we think we do, do we wait for the data or do we act now to protect people?” Based on her own studies of rodents, Dr. Tyl says it is still unclear whether low levels of phthalates damage baby boys.

Some countries have acted. In 2003, Japan banned certain types of phthalates in food-handling equipment after traces turned up in school lunches and other foods. The European Union has recently banned some phthalates in cosmetics and toys. In January, the European Parliament's public health committee called for banning nearly all phthalates in household goods and medical devices. In July, the full parliament asked the EU's regulatory body, European Commission, to review a full range of products “made from plasticised material which may expose people to risks, especially those used in medical devices.”

..Still, because researchers don't know the function of the genes that were altered in the rat study, EPA experts say it's too early to base regulatory decisions on such gene changes. “We're a long way, in my opinion, from considering changes in gene expression as 'adverse' for risk assessment,” says the environmental agency's Dr. Gray.

Exxon Mobil Corp. and BASF dominate the $7.3 billion phthalates market. An Exxon Mobil spokeswoman says risk assessments by government agencies in Europe and the U.S. confirm “the safety of phthalates in their current applications.”

Phthalates are cheaper than most other chemicals that can soften plastics. But a BASF press release says European manufacturers have been replacing phthalates with plasticizers designed for “sensitive applications such as toys, medical devices and food contact.”

Makers of pills sometimes coat them with phthalates to make them easier to swallow or control how they dissolve. A case study published last year in the journal Environmental Health Perspectives said a man who took a drug for ulcerative colitis, Asacol, for three months was exposed to several hundred times as much dibutyl phthalate as the average American. The drug's maker, Procter & Gamble, says it coats the pill with the phthalate so it will stay intact until it reaches inflamed colon areas. P&G says a daily dose of the drug has less than 1% of the 0.1 milligram of dibutyl phthalate per kilogram of body weight that the EPA regards as a safe daily dose.

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This page contains a single entry by Seth A. published on October 4, 2005 10:07 AM.

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