Chemical May Inhibit Male Sex Development

A manmade ingredient of many plastics, cosmetics and other consumer products may be interfering with prenatal male sexual development, new research suggests.

A study of 85 infant boys found a correlation between increased exposure to some forms of the chemical phthalate and smaller penis size and incomplete testicular descent.

It is the first time phthalate has been shown to influence the sexual development of human males.

"This is clearly something that needs to be examined in a larger sample," said Shanna Swan, a professor at the University of Rochester School of Medicine and Dentistry who headed the study.

A paper describing the research will appear in a future issue of Environmental Health Perspectives, a journal of the National Institute for Environmental Health Sciences. Swan discussed the findings in an interview Thursday.

Previous experiments in rats indicate that the chemical interferes with testosterone during gestation, producing a condition known as "phthalate syndrome." Rats with the syndrome suffer from genital birth defects, infertility and testicular cancer.

The human study raises concerns because the infants did not experience levels even close to the high doses used in rat experiments. The boys' exposures, measured by analyzing their mothers' urine during pregnancy, were no higher than those found among the general population.

The last few decades have seen a rise in the types of birth defects that would be expected from prenatal testosterone interference, including hypospadia, a defect in which the urethra does not extend to the tip of the penis, and undescended testicles. Testicular cancer has increased as well, although it is a different type than rats experience in phthalate syndrome.

"The results are both groundbreaking and potentially troubling," said Russ Hauser, a professor at the Harvard School of Public Health who was not involved in the research. "A majority of the U.S. population is exposed to phthalates at the level measured in Shanna's study."

The study does not necessarily indicate that the boys were harmed by their exposure to phthalate, however, and none of them exhibited overt birth defects. The researchers found a correlation between exposure to some forms of phthalate and a measurement called the anogenital index — the distance between the genitals and the anus.

Though that measurement has no physiological significance by itself, it is connected to penis size at birth and is "a very good indicator of internal malformations," said Paul Foster, a senior fellow at the National Institute of Environmental Health Sciences. Newborn rats and other lab animals with phthalate syndrome have unusually short anogenital distances.

A growing body of research suggests that some chemicals used in consumer products may cause public health problems by interfering with sex hormones. A study in the current issue of the journal Endocrinology exposed newborn mice to bisphenol-A, a chemical found in plastics and dental sealants, at doses comparable to those found in the human environment. At puberty the mice were more likely to develop cancer-related mammary duct abnormalities.

"In humans this would cause breast cancer," said Tufts University cell biologist Anna Soto, the study's lead author.

Excerpt:

Phthalates in Cosmetics - Buyer Beware or Just Another Scare?

You step out of the shower, dry off and apply satiny-smooth lotion all over your body. Are you hydrating your skin or damaging your fertility? And what about that French manicure you have scheduled for Saturday? Will it make your hands look gorgeous at Saturday night’s affair or render your husband infertile? Also, your eau de toilette, will it make you smell like Spring all day long or merely increase your unborn child’s risk of birth defects?

Clearly these questions do not occur to the average consumer, as we stroll down the personal care aisle in our local drug store or go about our grooming rituals, but there is a growing group of advocates who say that these are the very questions we should be asking ourselves.

However, other groups urge caution stating that we should not throw the baby out with the bath … or toilette water …as the case may be.

Certain “controversial” chemicals known as “phthalates” (pronounced THAL-aytes) are used in hair products, deodorants, body lotions, fragrances and nail polishes. Small amounts of a phthalates known as di-butyl phthalate (DBP) make nail polish chip resistant and when perfumes are dissolved in di-ethyl phthalate (DEP) or di-methyl phthalate (DMP), their scent lingers longer. In hair sprays, phthalates avoid stiffness by allowing the spray to form a flexible film on the hair.

Some health advocates argue that use of these chemicals among women of child-bearing age is leading to birth defects and declining sperm counts across the globe, while others argue that phthalates have been used for years and there is no evidence that they cause any harm in humans. The truth probably lies somewhere in the middle.

Phthalates in Cosmetics 101

Phthalates are a group of chemicals used in hundreds of products. Some examples include toys, vinyl flooring and wall covering, detergents, lubricating oils, food packaging, pharmaceuticals, blood bags and tubing and personal care products such as perfume, nail polish, hair sprays, body lotions, soaps and shampoos.

A recent review by the independent Cosmetic Ingredient Review (CIR) Panel found no evidence that the use of phthalates in cosmetics pose any health risk to users. The decision incensed certain healthcare advocate groups who say phthalates should be banned from use in women´s cosmetics. The Environmental Working Group of Washington, DC recently called on women of reproductive age to shun cosmetics containing dibutyl phthalates (DBP) at a press conference.

According to Not Too Pretty, an advertising campaign sponsored by Coming Clean, the Environmental Working Group and Health Care Without Harm, cosmetic and personal care companies say that the level of phthalates in their products is "safe," and this might be true if people were exposed to only one phthalate from one source at a time.

However, they state, exposures add up and since many phthalates have similar effects, we may be affected by the total exposure to this group of chemicals. In other words, what appears to be a "tolerable" level of exposure to a single phthalate could contribute to an unsafe overall exposure.

There’s activity across the globe when it comes to phthalates and cosmetics. Earlier this year, the European Parliament prohibited the use of the phthalates DEHP and DBP in cosmetics. A European study found that four out of five products tested in Britain and Sweden contained at least one phthalate and more than half contained multiple phthalates.

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