Fetuses Found Affected by Secondhand Smoke : Tobacco: Doctors say newborns of nonsmokers have toxic effects in hair. Study opens new research paths.
In research that provides the first biochemical proof that secondhand cigarette smoke affects unborn children, doctors in Toronto have shown that tobacco’s toxic elements accumulate in the fetuses of pregnant women who do not smoke but who live or work closely with smokers.
The study confirms long-held suspicions that being in the womb does not protect fetuses from exposure to secondhand smoke.
Moreover, experts say the new methods used by the researchers will help scientists answer crucial questions about whether passive smoke increases a baby’s risk of low birth weight, prematurity, slow neurological development and sudden infant death syndrome, all of which have been linked to smoking during pregnancy.
By measuring levels of nicotine and cotinine--a long-lasting byproduct of nicotine--in the hair of newborns, the study found that levels of cotinine were twice as high in infants of so-called passive smokers than in those born to nonsmokers.
One baby was exposed to so much secondhand smoke that the researchers found it was as if the mother had smoked five cigarettes a day.
“The message (to pregnant women) is: “It’s not enough for you not to smoke,” said Dr. Gideon Koren, the study’s lead author. “You should try to convince your husband, common-law or fellow worker not to smoke, or insist that they not smoke, because their smoke gets into the baby.”
The research was published today in the Journal of the American Medical Assn. in an issue devoted exclusively to the health effects of tobacco, and was presented Tuesday in New York during a daylong AMA briefing. The AMA has taken strong political stands against smoking, and the coordinated media push drew the anger of the Tobacco Institute, a trade industry group.
In other news, the journal reported:
* The decline in smoking rates in the United States during the past 25 years appears to have stalled, even though nationwide efforts to control tobacco are being hailed as a public health success story. A study conducted by the U.S. Centers for Disease Control found that in 1991, an estimated 25.7% of the U.S. population smoked--slightly higher than the previous year’s estimate of 25.5%.
* Sales of single cigarettes are booming. Researchers at Cal State San Bernardino found that half of all California convenience stores surveyed sold single cigarettes--often to minors in minority neighborhoods--even though it is against the law to sell cigarettes to children under 18, and illegal to sell them if they are not properly packaged, with warning labels. The researchers say such sales encourage young people to smoke.
* Cigarette advertising has resulted in a major increase in smoking by adolescent girls. A 44-year study showed that from the end of World War II through 1967, smoking rates in adolescent girls climbed slowly and steadily. But the rates shot up in the late 1960s, after aggressive advertising campaigns targeting young women, such as the early Virginia Slims campaign.
The advertising study, conducted at the UC San Diego Cancer Center, is an extension of research showing that the Joe Camel cartoon character used to advertise Camel cigarettes was widely recognized by children. Its lead author, cancer epidemiologist John P. Pierce, urged federal regulators to curb certain images in cigarette ads.
“There was no public health action against tobacco marketing after evidence that Joe Camel impacted young people because the tobacco industry demanded evidence linking advertising to . . . smoking in minors,” Pierce said. “This study provides such evidence.”
However, Brennan Dawson, a spokeswoman for the Tobacco Institute, attributed the surge to the women’s liberation movement. “Advertising follows social change,” she said. “It doesn’t lead it.”
As for the research on secondhand smoke in fetuses, Dawson said the study provides no evidence that there are long-term dangers for infants exposed to secondhand smoke. But other studies suggest that there are such dangers and experts say that, employing the methods used by the Toronto researchers, it will not be long before scientists can answer those questions more definitively.
The researchers at Toronto’s Hospital for Sick Children took their measurements by snipping five or six strands of hair from infants one to three days after birth. Other studies have measured nicotine and cotinine in blood and urine.
But most mothers do not smoke in the hours right before giving birth, and by the time their babies are born the tobacco byproducts have been expunged from their bodies. The use of hair allows researchers to date the infant’s exposure to smoke and to determine more precisely the extent of that exposure.
“Before, there were such poor measures of exposure that you couldn’t easily divide children by degree,” said Dr. Jonathan E. Fielding, a UCLA professor of public health and pediatrics. “Now, we will be able to say, look, if a kid had a high level of cotinine at birth, does that correlates with a higher likelihood of slower development? I think that is very, very important.”
Ninety-four pregnant women participated in the study--36 women who smoked between one and 40 cigarettes a day, 35 nonsmokers, and 23 so-called “passive smokers,” who either lived or worked with someone who smokes frequently.
The researchers looked closely at measures of cotinine, because cotinine remains in the body much longer than nicotine and because it is a good indicator of the presence of carbon monoxide--one of the most toxic byproducts of tobacco.
For infants of smokers, levels of cotinine were about 10 times higher than infants of nonsmokers. Babies born to passive smokers showed one-fourth to one-fifth as much cotinine as the smokers. Because nicotine occurs naturally in some foods, including tomatoes, eggplant and potatoes, even nonsmokers and their infants showed a certain amount of it.
