The results of an industry-sponsored study, released this week, on the possible toxic effects of smoking clove cigarettes show that clove cigarette smoke is no more harmful to laboratory rats than smoke from conventional cigarettes.
Scientists not connected with the study, however, caution that a single study on rats does not provide conclusive evidence that the pungent-smelling imported cigarettes from Indonesia do not cause lung damage in humans.
The independent study, which was conducted by the Department of Inhalation Toxicology at the Huntingdon Research Centre in Huntingdon, England, is the first inhalation study made available to the public on clove cigarettes (or kreteks) , which have come under attack in the past year for causing serious health problems and allegedly leading to the death of one Orange County teen-ager.
The British inhalation study was funded by P. T. Djarum and House of Sampoerna, both of Indonesia, although an industry spokesman said the laboratory wasn't told who was backing the study. The two firms are the largest manufacturers of clove cigarettes--which contain 60% tobacco and 40% ground cloves.
"I think the study shows that clove cigarettes have been vindicated as far as being guilty of what the critics have said they are guilty of: that these things are much worse for you than non-clove cigarettes," said G. A. Avram, executive director of the Specialty Tobacco Council, an organization representing the major manufacturers and importers of clove cigarettes in the United States.
Avram, who released the results of the 119-page study at a news conference in Washington, said the study "clearly establishes that clove cigarettes do not cause acute respiratory distress or anesthetize the lungs on the test animals." (Eugenol--the major component of cloves--is used as a mild dental anesthetic; critics of clove cigarette say the eugenol in the cigarettes numbs smokers' throats.)
The results of the British inhalation study differ sharply from those of an as-yet-unpublished study conducted last year by the American Health Foundation, which shows that eugenol can cause extensive lung damage and may be lethal to laboratory animals when administered directly into the lung via the trachea (in contrast to inhalation studies, in which laboratory animals breathe smoke).
Another study by the American Health Foundation, however, supports the findings of the British study: In that, an inhalation study, there were no acute toxic effects among hamsters exposed
to clove cigarette smoke, according to Edmond LaVoie, associate division chief of environmental carcinogens at the nonprofit, independent research foundation in Valhalla, N.Y.
LaVoie added, however, that "one cannot discount the data obtained in the intratracheal experiments because there are limitations in using small rodents in inhalation experiments." The American Health Foundation studies on clove cigarettes will be published soon in Archives of Toxicology, a scientific journal.
In view of the findings in the British inhalation study, however, Avram maintains that "the burden of proof has shifted and it's now up to them (clove cigarette critics) to prove there is a problem with clove cigarettes instead of clove cigarettes being put on the defensive."
Robert Phalen, director of the air pollution health effects laboratory at the College of Medicine at UC Irvine and author of "Inhalation Studies," a professional reference book, observed that the inhalation study "is important, but I'd say a single study is not definitive for something that has widespread use."
Phalen added that "there's a segment of the population--somewhere around 5%--that have very sensitive lungs. These people can over-respond to a variety of chemicals when inhaling. The rat is not a good model for those people."
Moreover, Phalen said, "You can never, in a small single animal study, say that something is safe. Let's say clove cigarettes hypothetically caused one smoker in a thousand to die. You could never detect that in a study of human beings unless you had tens of thousands of people and you couldn't detect that level of risk in a study using less than several thousand animals."
"The conduct of a single study is suggestive but in no case convincing evidence one way or the other unless the study is so designed as to be essentially foolproof and these studies are so complicated that they rarely can be made foolproof," said Dr. Tee L. Guidotti, professor of occupational medicine at the University of Alberta Faculty of Medicine in Edmonton, Canada, who has done research on clove cigarette toxicity.