A technique for monitoring carcinogenic pollutants in environmental tobacco smoke that is a thousand times more sensitive than previous techniques has been developed by chemists in LBL's Energy and Environment Division (E&E).
Combining the use of two dual computer-programmable fluorescence detectors with high performance liquid chromatography and a unique new sample preparation method, the LBL scientists have been able to screen for a wide range of polycyclic aromatic hydrocarbons and their equally hazardous alkyl derivatives in environmental tobacco smoke. This marks the first time that so inclusive an indoor air test of these carcinogens has been reported.
The technique is being reported by Kariyawasam Mahanama at the American Chemical Society's 1992 Fall Meeting in Washington, D.C. Mahanama is one of three chemists who collaborated on the development of the detection technique and sample preparation method. The others are Lara Gundel and Joan Daisey.
A recent draft report from the Environmental Protection Agency concludes that exposure to environmental tobacco smoke (ETS), which includes the smoke from a burning cigarette as well as "second-hand" or exhaled smoke, causes some 3,000 U.S. lung-cancer deaths and thousands of new cases of childhood asthma each year. ETS is also linked to pneumonia, bronchitis, and other health problems.
Some organizations have challenged these findings on the basis that the chromatography-based methods most frequently used to determine the origins of carcinogens were primarily developed for outdoor air and lack both the sensitivity and the selectivity needed for indoor air studies. The problem is particularly acute for analyzing ETS.
Explains Joan Daisey, the leader of E&E's Indoor Environment Program, "Most detection methods require large samples. This is not a problem for monitoring outdoor air. When monitoring indoor air, however, you can't collect large samples without cleaning the air and altering the concentrations of what you are measuring."
Another problem is that previous techniques were designed to detect polycyclic aromatic hydrocarbons (PAHs) but not alkyl PAHs. Although alkyl PAHs are not much of a problem outdoors, they are present at relatively high levels in ETS.
The LBL technique can work with less than a milligram of sample and enables researchers to identify and estimate the concentrations of both parent and alkyl PAHs with precision and accuracy.
Says Mahanama, "The most significant advantage of our detection method is the ability to quantitate chromatographically inseparable or hardly separable compounds using selective fluorescence detection."
The new detection method also enables the LBL researchers to significantly shorten sampling times and reduce the amount of hazardous solvent waste material generated for analysis when it is used in conjunction with the new technique for preparing samples.
ETS contains other chemicals that interfere with or complicate the detection of carcinogens. These chemicals must be removed from ETS samples prior to analysis. The LBL scientists have also developed an effective sample cleanup method involving the use of a silica sorbent as a trap for interferences.
Says Gundel, "The method is suitable for indoor air sorbent bed and filter samples of ETS. It can also be used to determine semi-volatile and particulate-phase PAH in ambient air."
Gundel, Mahanama, and Daisey have achieved another major advance in ETS analysis with the development of a technique for separating vapor and particle (gas and solid) phase PAH. If both phases are present in a sample, complications result that can throw carcinogen measurements off by at least 15 percent.
The LBL scientists have corrected this problem by directing their samples through an annular denuder, a glass cylinder coated on its inner surface with a polymeric sorbent. When the ETS sample passes through the denuder, molecules of PAH gas stick to the inner coating while PAH molecules in solid particles continue on. The sample then passes through a filter to collect the solid particles. In this manner, concentrations of PAHs in each phase can be measured separately.
All of these studies were funded in part by a grant from the National Heart, Lung and Blood Institute of the U.S. Department of Health and Human Services.