Phenolic alcohol components of lignin

The benzpyrene content of the total tar as well as the active fractions is far too low to account alone for the positive results [in laboratory animal]. So far, no carcinogens have been identified in large enough quantity in tobacco tar or its fractions to account for the observed activity. 

These Wynder-Wright 1957 results led to an intensive but unsuccessful eighteen-month search for a supercarcino-genic PAH. The absence of such a PAH was subsequently confirmed by the USDA group at Athens, Georgia, by their identification of over 500 PAHs in the PAH fraction from cigarette MSS, an identification procedure that completely accounted for the fraction in the cigarette smoke studied (3732, 3736, 3756-3759). 

In 1959, unable to explain the bioassay (mouse skin-painting) results with CSC on the basis of either its B[a]P content (less than 2% explainable) or its total PAH content (less than 3% explainable), Wynder and Hoffmann (4307) at the 1959 American Association for Cancer Research (AACR) meeting added the concept of promotion by low molecular weight phenols to the concept of tumor initiation by PAHs in an attempt (unsuccessful) to explain the bioassay results. They reiterated their view the following year at the 1960 AACR conference (4309) The phenol fraction could be established as an important promoting portion of the tobacco smoke condensate.  

A similar comment that the amount of tumorigenic PAHs found in CSC could not by themselves account for the total biological activity observed was included in a more detailed publication (4307) of their AACR presentation. They also stated (4308) that the higher PAHs played an important role in the carcinogenicity of CSC but when the various known concentrations of the carcinogenic PAHs as estimated in CSC were summed, it was obvious that they could not account for the established carcinogenicity of the CSC nor of its isolated PAH fraction. 

Severalcarcinogenichigheraromaticpolycyclichydrocarbons [are] present in tobacco smoke condensate. They include benzo[a]pyrene. .., benzo[e]pyrene. .., chrysene. .., benz[a] anthracene. .., dibenz[a,/i]anthracene. .., and dibenzo[a,i] pyrene. .. From the amount in which these materials have been found in tobacco smoke condensate it was evident that these, by themselves, could not account for the total biological activity observed. 

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