Airborne Cancerous Agents Can Reach Fetus

DNA Damage Could Affect Fetal Development in 1st Trimester

From the WebMD Archives

March 29, 2004 -- In the first trimester, a fetus can be exposed to airborne carcinogens (cancer-causing substances), including cigarette smoke, new studies show. This early exposure during a vulnerable period of fetal development could cause DNA damage that may increase cancer risk, researchers say.

They presented their findings today at the American Association of Cancer Research annual meeting in Orlando.

Earlier studies have shown about 50% of carcinogens the mother is exposed to pass through the placenta to the fetus. But how much reaches the baby during the first trimester -- a critical period in fetal development, when the fetus is more vulnerable to DNA damage that could cause serious problems?

Smoking Puts Fetus in Danger

In this newest study, researchers studied amniotic fluid taken from 500 women -- some who smoked a little, some who smoked more than two packs a day, some who were exposed to secondhand smoke daily.

The amniotic fluid contains a fetus' urine, therefore representing whatever compounds the fetus has been exposed to, explained lead researcher Steven Myers, MD, with the University of Louisville in Kentucky, in a news teleconference.

A known tobacco carcinogen -- polynuclear aromatic hydrocarbon (PAH) -- has been found in amniotic fluid, as has benzo(a)pyrenes, another cancer-causing agent.

However, this is the first time researchers have identified PAH in the fetus in this early stage of fetal development, said Myers.

In their amniotic fluid tests, they found PAH levels ranging from 1.5 micrograms per liter (in nonsmokers) to about 12 micrograms per liter (in women who smoked two packs or more daily).

"What we're finding is that as a mother smokes more, more is passed to the amniotic fluid, to the fetus," said Myers. In fact, two-pack-a-day smokers passed 10 times the cancer-causing compounds to their developing fetuses.

"That's a very large amount of carcinogenic agents," said Myers. "It means that large numbers of potentially harmful compounds are being passed to the baby."

His research group will continue following these fetuses until they are delivered. "We hopefully are going to be able to follow them as infants to see if they have more respiratory problems, learning problems, growth problems," said Myers.

They also are looking at the mothers' diets, since many eat charbroiled meat, which contains carcinogenic compounds. "And because many of the women live in rural areas where industrial air pollution is a problem, it is conceivable that some toxins are coming from that," all of which could affect fetal development.

SOURCE: American Association of Cancer Research 95th Annual Meeting, Orlando, March 27-31, 2004.

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