Second-Hand Smoke Traces Detected in Babies' Urine
By Michael Smith, MedPage Today Staff Writer
Reviewed by Zalman S. Agus, MD; Emeritus Professor at the University of
Pennsylvania School of Medicine.
May 12, 2006
MINNEAPOLIS, May 12 Nearly half the infants in a small study exposed to
second-hand smoke from their parents' cigarettes showed signs of a potent
carcinogen in their urine, according to investigators here.
"The take home message is, 'Don't smoke around your kids,'" said Stephen
Hecht, Ph.D., of the University of Minnesota.
Dr. Hecht said the study, published in the May issue of Cancer Epidemiology,
Biomarkers & Prevention, is the first to show that many infants living with
at least one smoking parent have been exposed to the tobacco-specific
carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, or NNK.
NNK is known to cause cancer in rats and is believed to play a significant
role as a cause of lung cancer in smokers and in nonsmokers exposed to
second-hand smoke.
Dr. Hecht and colleagues enrolled 144 mothers with babies ages three months
to a year. Pairs were eligible if the mother was older than 18, not
currently breast feeding, was herself a daily or occasional smoker, and if
the infant recently had been exposed to tobacco smoke either in the home or
in a car.
The researchers tested mainly for metabolites of NNK (compounds dubbed total
NNAL) but also for nicotine, cotinine, and their respective glucuronides.
"NNAL is an accepted biomarker for uptake" of NNK, Dr. Hecht said. "You
don't find NNAL in urine except in people who are exposed to tobacco smoke,
whether they are adults, children, or infants."
All told, the study showed that:
Total NNAL was detectable in 67 of the 144 infants (46.5%), and the mean
level of total NNAL in the 144 infants was 0.083 picomoles per milliliter.
134 infants (93.1%), had detectable cotinine and 141 (97.9%), had detectable
nicotine.
The mean levels of total cotinine and total nicotine were 0.133 and 0.069
nanomoles per milliliter, respectively.
"The presence of NNAL in the urine of these infants can be explained only by
their exposure to the tobacco-specific carcinogen NNK," the researchers
concluded. The most likely vector was second-hand smoke, although some could
also be absorbed from surfaces, such as rugs and furniture.
In fact, Dr. Hecht said, "the level of NNAL detected in the urine of these
infants was higher than in most other field studies of environmental tobacco
smoke in children and adults."
As might be expected, the more direct exposure the infant had to tobacco,
the more likely he or she was to have NNK metabolites in the urine, the
researchers found.
Among the 77 infants with no detectable total NNAL, the children were
exposed to smoke from an average of 27 cigarettes a week, while among those
with detectable NNAL, the average was 76. The difference was statistically
significant at P<0.0001.
But that shouldn't be a consolation to light-smoking parents, Dr. Hecht
said: "With more sensitive analytical equipment, the NNAL from urine of
babies in lower-frequency cigarette smoking households would most likely be
detectable."
The authors noted that a broad range of potentially effective interventions
to decrease exposure exists. These include:
Efforts to encourage women to quit before or during pregnancy and to avoid
postpartum relapse.
Encouraging smoking cessation among household members.
Establishing no-smoking policies for the home and car.
They pointed out that "evidence that nicotine is present in dust and
surfaces of houses in which smoking takes places indicates that the complete
elimination of smoking in homes is preferable to an emphasis on not smoking
in the presence of children."
They added that "regulatory and economic policies (e.g., increasing the
excise tax on cigarettes) are important approaches to decreasing the overall
prevalence of smoking and therefore decreasing environmental tobacco smoke
exposure of children."
Leanne Wynne
Midwife in charge of "Women's Business"
Mildura Aboriginal Health Service Mob 0418 371862
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