Recent findings of Patterson et al. (14) that maleic hydrazide (MH), when pyrolyzed in a nitrogen atmosphere yields benzo (a) pyrene (BaP), could lead to the implication that MH residues in tobacco could also yield BaP in tobacco smoke. Neat MH when pyrolyzed would give high enough concentrations of C₂ and C₄ units for them to polymerize to give BaP, but in MH-treated tobacco smokes the concentration of these C₂ and C₄ units are so low that the formation of BaP from the polymerization of these units is mathematically impossible. The only possible route for the formation of BaP from MH in MH-treated tobacco smoke is by the incorporation of MH C₂ and C₄ units in the tobacco smoke “carbon pool.” But the possibility is exceedingly small. Evidence and data so far available on maleic hydrazide are not sufficient to suggest that MH in tobacco is a health hazard to the smoker. Systematic study on the pyrolysis of pesticides in tobacco smoke is a powerful tool not only in the understanding of the fate of pesticides and other compounds present in minute quantities in tobacco, but also reveals events taking place during the smoking of tobacco.

(Full article published with kind permission from "Tobacco International")