Sizing up the hazards of cocaine use.

Sizing up the hazards of cocaine use

A Canadian team has detected cocaine metabolites in hair samples taken from adult cocaine users and from newborn infants exposed to cocaine in the womb. The finding, they say, may help efforts to gauge the effects of maternal cocaine use on a developing fetus by enabling scientists to spot exposed infants and to identify pregnant women who have used cocaine during pregnancy.

Studies of cocaine's reproductive risks have been hindered by the lack of a surefire method for identifying cocaine users. Previous research has shown that current methods of detecting drug use are unreliable. Urine tests, for example, miss about 50 percent of cocaine users, and many people deny illegal drug use when interviewed.

Researchers led by Karen Graham and Gideon Koren of the University of Toronto studied hair samples taken from 16 adults who admitted using cocaine but who had negative urine tests for benzoylecgonine, a cocain metabolite. In all 16 hair samples, the team found benzoylecgonine in amounts that mirrored the frequency of drug use. For example, in samples from occasional cocaine users, the average concentration of benzoylecgonine was 62' nanograms of the metabolite per gram of hair analyzed. In samples from people who reported heavy cocaine use, the team found 8,775 nanograms of benzoylecgonine per gram of hair. Hair samples from the 21 controls, who said they had never used cocaine and who had negative urine tests, showed no evidence of benzoylecgonine. The researchers report their findings in the Dec. 15 JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION.

Hair clipped from the scalps of seven newborns whose mothers admitted using cocaine during pregnancy contained an average of 5,430 nanograms of benzoylecgonine per gram of hair tested. That finding may help clinicians diagnose and treat infants who have been exposed to cocaine during gestation. These infants can have cocaine-related medical problems but are difficult to diagnose, Koren says. The research suggests doctors must perform hair analysis within the baby's first two months, he says, because infants quickly lose their downly fetal hair, sprouting new hair that may shown no trace of cocaine or its metabolites.

In an accompanying editorial, David N. Bailey of the University of California, San Diego, cautions that the practice of analyzing hair for cocaine may never becomes standard practice in most U.S. hospitals. The method used by the Canadian team is too costly, complicated and time-consuming to become a routine method of drug screening in most clinical laboratories, Bailey says.

In related study published in the Dec. 16 LANCET, Koren concludes that researchers who find no link between maternal cocaine use and fetal health problems have trouble getting their data out to the scientific community.

Koren and his colleagues studied all abstracts on cocain use during pregnancy that were submitted to the Albuquerque, N.M.-based Society for Pediatric Research between 1980 and 1989. Of the nine abstracts reporting no adverse effects, peer reviewers accepted only one (11 percent) for presentation at the society's annual scientific meeting. Of the 49 abstracts describing reproductive risks from cocaine use, reviewers accepted 28 (57 percent).

Whe Koren's group compared the rejected abstracts from both categories, they found that researchers conducting the negative studies (those finding no link between health problems and maternal cocaine use) were more likely to verify cocaine use and to include a large control group.

"This strengthens the suggestion that most negative studies were not rejected because of scientific flaws, but rather because of bias against their message," the authors contend.