Research still uncovering new dangers from cigarette smoke

It seems strange that, after all these years, research is still being carried out into the danger of cigarettes but as a team at Lawrence Berkeley National Laboratory has proved this week, there’s still plenty to uncover.

It is well known that cigarette smoke contains many contaminants, including toxic metals but the Berkeley Lab team wanted to find out exactly which of those metals exist in secondhand or thirdhand smoke.

Thirdhand smoke refers to the toxic residues that linger on indoor air, surfaces and settled dust long after cigarettes have been consumed. 

Because many of the metals found in tobacco smoke can also originate from industrial processes or occur naturally, it is not an easy question to answer.

Hugo Destaillats, the principal investigator of the study, and a senior scientist in the Indoor Environment Group of Berkeley Lab’s Energy Technologies Area explained: ‘It is important to quantify the trace metals from secondhand and thirdhand smoke because some trace metals are present in other indoor and outdoor pollution sources. For well over a decade, our group has studied toxic organic contaminants emitted during smoking. We are now also interested in completing the picture of smoke’s persistent legacy by assessing how trace metals may contribute to tobacco’s health burden.’

The team, from the Indoor Environment Group, smoldering six cigarettes in a room-size environmental chamber at the Lab and collected samples of aerosol particles over the following 43 hours

They used Teflon-coated filters to capture freshly emitted aerosol samples immediately after smoldering (secondhand smoke). Then took additional samples over longer periods of time (thirdhand smoke).

Using… ‘an advanced triple quadrupole inductively coupled plasma mass spectrometry (QQQ ICP-MS) system’ they detected high levels of 28 trace metals in both secondhand and thirdhand smoke, including were several toxic metals such as cadmium, arsenic, chromium, beryllium, and manganese.

The researchers used those results from to predict the concentration of trace metal contaminants in a smoker’s home under different air exchange rates. In almost all of the modeled scenarios, they found that the predicted indoor air concentration for cadmium, arsenic, and chromium exceeded California’s cancer risk guideline. The amount of cadmium that remained airborne was significantly higher than those of other metal traces.

The researchers believe this is a first step in understanding how tobacco smoke contributes to our overall exposure to trace metals in the indoor environment.

Xiaochen Tang, a researcher in the Energy Analysis and Environmental Impacts Division of Berkeley Lab’s Energy Technologies Area, and first author of the study said: ‘In smoking environments, these trace metals are found in indoor air and also on surfaces and in dust particles, and people can be exposed to them through pathways such as dermal uptake and ingestion.

‘We focused our analysis on the inhalation of airborne metal contaminants, so our results represent only part of the total exposure burden. Given the persistence of trace metals in the environment, it would be important to better understand the efficacy of ventilation, cleaning, and vacuuming as removal mechanisms for these contaminants.’