AN INTERNATIONAL LITERATURE SURVEY OF IARC GROUP-I CARCINOGENS REPORTED IN MAINSTREAM CIGARETTE-SMOKE

The International Agency for Research on Cancer (IARC) currently lists 44 individual chemical agents, 12 groups or mixtures of chemicals and 13 exposure circumstances as ''Group 1 human carcinogens''. A compreh ensive search of the published literature revealed that nine of the 44 chemical agents classified as ''Group I carcinogens'' by IARC have be en reported to occur in mainstream cigarette smoke. The other 35 have never been reported to occur in cigarette smoke. The nine agents repor ted are benzene, cadmium, arsenic, nickel, chromium, 2-naphthyl-amine, vinyl chloride, 4-aminobiphenyl and beryllium. The reported yields of each of these nine agents in mainstream smoke varies widely. The rang e of yields reported for a given compound is influenced by the type of cigarette tested and when the analysis was conducted. In micrograms/c igarette, the ranges that have been reported for each of the nine comp ounds are: benzene (0.05-104), cadmium (0-6.67), arsenic (0-1.4), nick el (0-0.51), chromium (0.0002-0.5), 2-naphthylamine (0.0002-0.022), vi nyl chloride (0.0013-0.0158), 4-aminobiphenyl (0.00019-0.005) and bery llium (0-0.0005). Although some of the variation in ,reported yields m ay be due to differences in analytical methodology, several correlatio ns between the yield of a particular chemical in mainstream smoke and certain cigarette characteristics were observed. For example, charcoal filtration was associated with reduced vinyl chloride, and the concen tration of sodium nitrate in the tobacco was positively correlated wit h the mainstream yield of both 2-naphthylamine and 4-aminobiphenyl. Be nzene yield in mainstream cigarette smoke was correlated with the amou nt of tobacco burned and with the 'tar' level. Agronomic factors such as production practices and soil characteristics, and environmental co nditions such as rainfall, reportedly influence the accumulation of me tals, for example, cadmium, beryllium, chromium, nickel and arsenic, i n the leaf. The use of fertilizers low in nitrate and heavy metals wou ld be expected to substantially reduce the yields of most of the ''IAR C Group 1 carcinogens'' reported to occur in mainstream cigarette smok e. Additionally, modifications in cigarette design, for instance, the use of enhanced charcoal filters or heated instead of burned tobacco, would also be expected to reduce the yields of several of these agents . (C) 1997 Elsevier Science Ltd. All rights reserved.