If the nicotine doesn't get you, the pesticides just might. That's the upshot of a study by researchers at the Colorado School of Mines in Golden, who say they have found previously undetected pesticides in tobacco smoke.

Using electron monochromator-mass spectrometry, the scientists found three pesticides suspected of being toxic to the human endocrine system as well as carcinogenic in a wide sampling of experimental and commercial cigarette smoke samples.

The three nitro-containing pesticides, including flumetralin, commonly used in tobacco farming, survive the combustion process.

Flumetralin, a suspected endocrine disrupter already banned for use on tobacco in Europe, belongs to a class of chemicals that may be active at miniscule levels, the researchers say.

Endocrine disrupters can produce adverse effects on early development, reproduction and other hormonal processes.

When the three unidentified compounds turned up in the smoke, the researchers utilized a unique selective and sensitive instrument to analyze the chemical "fingerprints" of the substances and identify the new compounds as dinitroaniline pesticides.

They found the three pesticides in both the mainstream and sidestream smoke, with the sidestream showing the higher levels for all three compounds. Although the pesticides are reduced in quantity, they survived the combustion at an estimated level of 10 percent of the original residue on the tobacco.

The research has just been published online in the American Chemical Society journal, Analytical Chemistry, in an article by John Dane, Crystal Havey and Kent Voorhees.

Pendimethalin and trifluralin are the other two pesticides identified in this study.

Pendimethalin has been identified as an endocrine disrupter that specifically affects the thyroid. Trifluralin is also an endocrine disruptor that affects the reproductive and metabolic systems. Both compounds are suspected human carcinogens.

None of the three pesticides has been previously reported in either the mainstream or sidestream smoke from current U.S. tobacco.

"No information exists for long-term low-level inhalation exposures to these compounds," said Voorhees, "and no data exists to establish the possible synergistic effect of these pesticides with each other, or with the other 4,700-plus compounds that have been identified in tobacco smoke."