Unlike CdCl2 or CdS, Cd(CH3)2 is a volatile compound (bp 105.5 °C), which readily reacts with water to yield cadmium hydroxide but does not oxidize spontaneously in air. In fact, there is a gradation in stability among the Group 12 methyl derivatives, with Cd(CH3)2 ranking in an intermediate position between dimethylmercury, quite stable and dimethylzinc, AZD6244 very reactive toward oxygen and water [122]. Indicative of its stability, Cd(CH3)2 toxicity could be assessed, including through animal inhalation

studies, and a maximum 8-h work-place exposure has been set at 1 μg/m3[123]. While CH3 is the most abundant alkyl radical generated in the high temperature zone, homologue radicals with higher carbon content are also present that could react in the same way. In fact many other radicals present

in smoke could be expected to react with Cd(0) but very little information is available on such reactions. Thus, the following discussion is focused on Cd(CH3)2, since its reactivity is well documented and it is epitomical when discussing the consequences of the transitory formation of a volatile and reactive cadmium derivative. It should however be understood that Cd(CH3)2 may not be the main cadmium volatile intermediate that is actually formed in smoke. Cd(CH3)2 could certainly move to the filter during a puff, and exit the cigarette with mainstream smoke. Because of its reactivity, Cd(CH3)2 will deposit onto the unburnt tobacco downstream with C59 wnt order a high efficiency; yet, elements captured on the unburnt tobacco Adenosine during a puff can be mobilized in subsequent puffs, so that this capture

is not incompatible with the observed cadmium transfer to mainstream smoke (only 5–10%). The consequence of this high capture is a yield per puff that increases with puff number, which has indeed been observed [78]. Moreover, in such a case it is expected that a higher smoke flow rate through the tobacco rod would decrease the retention of gas-phase cadmium since it is diffusion-controlled. This was also observed. Compared to the ISO yields, cadmium yield was found to be more increased under HCI than nicotine was, whereas lead yield remains to a constant ratio to nicotine (Table 6 and Table 8). Specifically, a high and flow rate-sensitive capture of cadmium by the tobacco filler was evidenced by studies where the deposited cadmium was separately assessed in the unburnt tobacco and in the filter plug after machine-smoking the cigarettes using both ISO conditions and undefined “heavy” puffing conditions [82]. The fact that elements captured on the unburnt tobacco during a puff can be mobilized by subsequent heating also increases the possibility of transfer to sidestream smoke. Hot gases can diffuse out of a smoldering cigarette as sidestream emission, the temperature of this gas stream is about 350 °C [116]. Cadmium can diffuse out as CdCl2, which would be gaseous.