updated 12/22/2011 12:17:50 PM ET 2011-12-22T17:17:50

A large number of common drugs and supplements contain chemicals called phthalates, which are often found in plastics, found a new study. These chemicals have been linked to a variety of hormonal and reproductive problems in both rats and people.

Scientists can't yet say how levels of phthalates in pills might translate into health risks. But for now, pregnant women and children might want to be cautious, said scientists behind the work, especially those who take regular doses of medicine for chronic conditions.

It may be impossible to completely avoid phthalates in medicines, though, because not all phthalate-containing drugs mention inactive ingredients on their packaging. And researchers don't want people to stop taking the pills they need.

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Instead, the new work points to the need for both further research and possible action by regulating agencies.

"Since medications are an important component of health care, I would not ask the consumer to make these decisions," said Russ Hauser, a reproductive physiologist at the Harvard School of Public Health and one of the authors of the new study. "This decision about whether phthalates should be used in medications should be made at the federal level by the F.D.A."

Phthalates describe a class of chemicals that have a wide range of industrial uses. As ingredients in plastics, they provide flexibility and resilience. In coatings on capsules and pills, they can help regulate the release of drugs over time or the delivery of active ingredients to specific areas in the digestive tract where it is most useful for them to be absorbed.

In previous research, scientists have detected high levels of phthalate breakdown products in the urine of patients taking coated medicines for a variety of conditions, including cystic fibrosis and chronic inflammation of the digestive tract.

To get a sense of how widespread these chemicals are in a broader set of pharmaceutical products, the researchers started with about 450 drugs that are listed as not safe to crush or chew because of their special coatings. Next, they scanned newsletters for information about new drugs, said Kathy Kelley, a co-author and research pharmacist at Boston Unviersity's Slone Epidemiology Center.

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To cast an even wider net, they did Internet searches. They trolled the aisles of pharmacies looking for phthalates on ingredient lists. And they contacted manufacturers in cases where that information was not readily available.

Because the FDA does not require companies to disclose the use of phthalates if the chemicals are used in recipes for drug delivery systems that are trade secrets, the researchers also looked through patents for mentions of the chemicals.

In total, the search included between 500 and 1,000 supplements and drugs, both prescription and over-the-counter. Of those, the team reported in Environmental Health Perspectives, more than 100 contained two forms of phthalates that have been shown to have deleterious health effects in studies on animals and human infants.

Called dibutyl phthalate (DBP) and diethyl phthalate (DEP), these chemicals affect the reproductive tracts of developing males, leading to hormonal, fertility and reproductive problems, said Shanna Swan, a reproductive epidemiologist at the Mount Sinai School of Medicine in New York. Among other studies, she has found that preschool boys who had been exposed to the highest levels of DBP in the womb were least likely to choose typically male toys.

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In the new study, which only included a fraction of the many thousands of drugs on the market, phthalates showed up in all kinds of products, including blood pressure medications, laxatives, anti-inflammatories, antibiotics, muscle relaxers, dietary supplements and lots of acid-reducers. The chemicals were most common in drugs that had either timed-release or targeted-release properties.

It's too early to know what the health risks are, but pregnant women are the biggest source of concern, Swan said, especially if they take coated medicines for long-term issues. A drug called Asacol, which is prescribed for ulcerative colitis, is known to have particularly high levels of phthalates, for example, and phthalate-free alternatives for that medicine are available.

"I would recommend that pregnant women who take regular medication for a chronic condition try and avoid phthalate-containing medications," Swan said. "These only add to the phthalate burden they are receiving from other sources, such as food, personal care products, and household products."

For anyone who wants to avoid phthalates, Kelly suggested, read labels for inactive ingredients. You can also keep an eye out for delivery systems that are most likely to use phthalates, such as "delayed-release," "controlled-release," "time-release," "targeted-release," and "enteric coatings." Without a direct reference to phthalates, though, it can be impossible to know whether the chemicals are present or how much might be there.

© 2012 Discovery Channel


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