Release of carbon granules from cigarettes with charcoal filters

To inspect cigarettes with a triple granular filter for charcoal granules on the cut filter surface and, if present, to determine whether the charcoal granules on the filter are released during smoking.

400 Lark cigarettes in 20 packs were examined individually by each of three investigators for the presence of charcoal granules on the cut surface of the cellulose acetate filter. Without removing the cigarettes from the pack, the filters were examined with a stereo zoom microscope for charcoal granules. The percentage of cigarettes that had charcoal granules was defined, and charcoal granules on each filter were counted. Randomly selected cigarettes were then smoked by consenting adult smokers to assess whether the charcoal granules were released during smoking. Lark cigarettes were smoked with a conventional cigarette holder that had been configured to contain an in-line membrane. After smoking, the membrane was analysed microscopically for charcoal granules and other components of the filter that had been released during smoking.

Charcoal granules were observed in 79.8% (319/400) of the cigarettes examined. The number of granules per cigarette was 3.3 (SD 3.7). Gaps between the tipping papers--the wrapping papers that surround the filter--were often seen (70%; 242 (71); n = 400 cigarettes). Further, the charcoal cavity was about 60% empty. For all smokers (n = 8/8), charcoal granules were released during smoking. The number of charcoal granules captured on the membranes was 22.5 (16.2) per cigarette.

Charcoal granules are incorporated into cigarette filters to aid in removing toxins in cigarette smoke. In studies of Lark, a popular American cigarette with a charcoal filter, charcoal granules were observed on the filter surface, and were released from the filter when the cigarettes were smoked. During smoking, the toxin-containing charcoal granules are inhaled or ingested. The specific adverse health effects of inhaling or ingesting carbon granules have not been addressed; nevertheless, the smoker, as an educated consumer, should be informed of the possible health risks.