Cigarette smoke cadmium breakthrough from traditional filters: implications for exposure

Abstract

Cadmium, a carcinogenic metal, is highly toxic to renal, skeletal, nervous, respiratory and cardiovascular systems. Accurate and precise quantification of mainstream smoke cadmium levels in cigarette smoke is important because of exposure concerns. The two most common trapping techniques for collecting mainstream tobacco smoke particulate for analysis are glass fiber filters and electrostatic precipitators. We observed that a significant portion of total cadmium passed through standard glass fiber filters that are used to trap particulate matter. We therefore developed platinum traps to collect the cadmium that passed through the filters and tested a variety of cigarettes with different physical parameters for quantities of cadmium that passed though the filters. We found <1% cadmium passed through electrostatic precipitators. In contrast, cadmium that passed through 92 mm glass fiber filters on a rotary smoking machine was significantly higher, ranging from 3.5 to 22.9% of total smoke cadmium deliveries. Cadmium passed through 44 mm filters typically used on linear smoking machines to an even greater degree, ranging from 13.6 to 30.4% of the total smoke cadmium deliveries. Differences in the cadmium that passed through from the glass fiber filters and electrostatic precipitator could be explained in part if cadmium resides in the smaller mainstream smoke aerosol particle sizes. Differences in particle size distribution could have toxicological implications and could help explain the pulmonary and cardiovascular cadmium uptake in smokers.

Fig. 1

A Pt trap used for quantitative determination of Cd breakthrough is shown placed in tandem with a glass fiber filter pad attachment on a rotary smoking machine.

Fig. 2

Analyses of Cd trapped on individual Pt trap segments shows that trapping was quantitative with three Pt gauze segments per trap. Data is from mean of 10 individual segment analyses of cadmium from a commercial cigarette that freely passed through a 44mm glass fiber filter used with a linear smoking machine.

Fig. 3

ETV-ICP-MS confers very high signal intensity on a few nanograms of ¹¹¹Cd even without a reactive gas that would have further enhanced sensitivity.

Fig. 4

Plot of percent cadmium breakthrough from 44 mm filters versus cigarette tobacco filler mass normalized to filter length.