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There has been speculation that the addition of menthol to cigarettes may affect the manner in which cigarettes are smoked, potentially influencing smokers' exposures to smoke constituents that have been associated with smoking-related diseases. One hundred twelve male and female smokers participated in a parallel-arm study to determine whether the ad libitum smoking of menthol cigarettes results in differences in smoke constituent exposure biomarkers in blood and urine relative to those smoking nonmenthol cigarettes having similar machine-measured (Federal Trade Commission) yields of f9 to 10 mg ''tar.'' The study subjects were provided cigarettes of their preferred menthol or nonmenthol types prior to two 24-hour study intervals spaced one week apart. Carboxyhemoglobin levels were measured in blood samples drawn at midafternoon following the two 24-hour urine collection periods. Six urinary nicotine metabolites (nicotine, cotinine, trans-3 ¶-hydroxycotinine and respective glucuronides) were determined as measures of nicotine intake, and urinary 4-(N -nitrosomethylamino)-1-(3-pyridyl)-1-butanol (NNAL) and its glucuronide were determined to assess exposure to the tobacco-specific nitrosamine 4-(N-nitrosomethylamino)-1-(3-pyridinyl)-1-butanone. Subjects' median blood carboxyhemoglobin values did not differ significantly between the cigarette types. Neither total urinary NNAL nor urinary nicotine equivalents exhibited statistically significant differences between the menthol and nonmenthol cigarette smokers. The present findings indicate that moderately heavy smokers of menthol and nonmenthol cigarettes of similar machinegenerated smoke yield exhibit essentially identical levels of biomarkers of smoke constituent exposure. These results are consistent with the substantial majority of epidemiology studies to date that suggest the risks attending the smoking of menthol and nonmenthol cigarettes are similar. (Cancer Epidemiol Biomarkers Prev 2009;18(2):622 -9)

Crystalline nickel sulfide (alpha NiS) and cobalt sulfide (CoS2) particles can cause greater cell transformation and cellular toxicity than the respective amorphous metal sulfide particles. Cultured mammalian cells phagocytose the crystalline metal sulfide particles more readily than the amorphous ones. In the case of the nickel sulfides, the crystalline metal sulfide particles had negatively charged surfaces (Zeta potential: -27.012 mV) in contrast to the amorphous particles, which were positively charge (Zeta potential: +9.174 mV). X-ray photoelectron spectroscopy analysis of amorphous and crystalline NiS particles revealed that the outermost surface (1-4 nm) of the two particles had striking differences in Ni/S ratios and in their sulfur oxidation states. Rendering particles' surfaces more negative by reduction with lithium aluminum hydride enhanced their phagocytosis, and in the case of amorphous NiS chemical reduction resulted in an incidence of morphological transformation of Syrian hamster embryo cells comparable to that observed with untreated crystalline alpha NiS.

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