Assessment of chlorinated pesticide residues in cigarette tobacco based on supercritical fluid extraction and GC-ECD.

Abstract

It has been established that the organochlorinated compounds (OCC) DDT and DDE are xenoestrogens which influence both normal and neoplastic estrogen-responsive tissues. Therefore, it has been hypothesized that OCC contribute to the risk for breast cancer. Although the food chain has been recognized as a major source of human exposure to these compounds, tobacco and tobacco smoke were also considered as sources of exposure to OCC. This study was aimed at quantifying OCC in tobacco and cigarette smoke and at documenting changes in the concentrations of these pesticides in tobacco products since 1970 when OCC were banned for use on tobacco. To determine the levels of OCC residues on tobacco, we developed a new method based on superficial fluid extraction, followed by clean-up on an alumina column, and analysis by gas chromatography with electron capture detection. The detection limit for an individual OCC is 1 ng/g tobacco, the relative SD is < 10% for each analyte and the new method compares well with the standardized method that involves conventional organic solvent extraction. The major OCC determined in the tobaccos and in cigarette smoke of US commercial brands that were manufactured in the proceeding three decades were p.p'-isomers of DDD (1540-20 220 ng/g tobacco), DDT (720-13 390 ng) and DDE (58-730 ng). Since 1970, the concentrations of individual OCC in tobacco have gradually decreased by > 98%. The transfer rate from tobacco into mainstream smoke amounts to 22% for DDD, 19% for DDT and 27% for DDE. Today, the concentrations of the OCC in US tobacco are below the maximum permissible limits set by the Environmental Protection Agency. While until 1970 the OCC in tobacco and tobacco smoke contributed significantly to the bioaccumulation of the pesticides in smokers, at this time tobacco and cigarette smoke are a minor source of human exposure.