Quantification of SHS exposure reduction is a major research focus in the fields of tobacco control, clinical medicine, epidemiology and public health policy. This research is needed to evaluate the effectiveness of approaches being employed to reduce exposure and especially critical when the intervention is targeted to highly vulnerable populations such as asthmatic children. It is widely acknowledged that a direct measurement of SHS is preferable to reports and impressions of exposure. Available metrics of direct exposure have for years been limited to airborne nicotine and its metabolite cotinine. Nicotine is highly specific to SHS and can be measured accurately to very low levels using an existing passive sampler. Cotinine, readily measured in urine or saliva, has also been used extensively. Measurement of other SHS constituents, including particulate matter and other gases has been too expensive, cumbersome and intrusive to be implemented in intervention or epidemiology studies.
Research by LBNL and others has shown that the indoor behavior of nicotine is much different than that of other SHS constituents. Nicotine quickly sticks to indoor materials, impeding its movement from room-to-room throughout a residence and causing a build-up of nicotine contamination in places where habitual smoking occurs. Re-emission of nicotine materials affects daily concentration patterns and provides a source for nicotine in the air for months to years even after smoking has ceased completely. As a result, nicotine exposure may not be quantitatively indicative of exposure to other SHS components such as particles or toxic gases that don’t stick to materials. Use of nicotine as the sole indicator of exposure thus may lead to misclassification or inaccurate evaluation of intervention effectiveness.
In response to this urgent research need, LBNL has developed a compact, inexpensive and easy-to-deploy SHS sampler that allows integrated measurement of nicotine, 3-ethenylpyridine (3-EP, another gas is specific to SHS and sorbs much less than nicotine), and SHS particulate matter over periods of a few days to a week. The sampler has the additional capability to resolve data to three daily periods – e.g. overnight, daytime, and evening – to allow study of emissions and exposures correlated with typical activity schedules. The sampler was developed under TRDRP Grant 11RT-0202 and targeted for use in a large smoking intervention study currently underway through the Palo Alto Medical Research Institute and Kaiser Foundation Research Institute.
The initial TRDRP grant funded development, preliminary validation of each component measurement technique, and construction of a prototype. The device has successfully detected levels of SHS particles and gases (nicotine and 3-EP) that are consistent with those resulting from smoking of 1 or 2 cigarettes over a 1-week period. During the proposed extension of the project, laboratory and field validation of the samplers will be completed so that they can be available for large-scale epidemiological studies of SHS exposure.
Laboratory validation of the TRDRP-funded SHS sampler will be conducted with air that contains SHS, wood smoke, diesel exhaust and cooking fumes, all at realistic indoor concentrations, to establish sensitivity, stability and selectivity for each SHS constituent.
The field validation plan includes:
a) Monitoring SHS simultaneously with the TRDRP sampler and conventional active sampling methods in a convenience sample of up to 20 residences with active smokers,
b) Comparing SHS concentration data from the new SHS sampler and conventional active sampling methods, as well as actual limits of detection, specificity and stability in the field;
c) Developing guidance on the use of TRDRP-sampler data for SHS exposure assessment that discriminates between exposure resulting from long-term nicotine re-emission and exposure resulting from new or recent smoking;
d) Comparing operational and analytical costs; and
e) Assessing its potential contribution to large-scale exposure assessment studies. |