Cigarettes, thiocyanate

Cyanide in the body is biotransformed to thiocyanate quickly. People may also be exposed to thiocyanate from dietary, industrial, and medical sources. The plasma concentration of thiocyanate has also been used as an index of long-term exposure to cigarette smoke (Liu and Yun 1993). Some authors have determined thiocyanate in body fluids as a measure of cyanide exposure, while others measure cyanide concentrations in body fluids as a measure of cyanide exposure. 

Methods for Determining Biomarkers of Exposure and Effect. Besides environmental exposure, exposure to cyanide can also occur from consumption of cyanide-containing food, metabolism of certain drugs, and smoking cigarettes. Since so many factors can influence cyanide exposure, the exact correlation between cyanide concentrations in the body and its level in the environment has not been made. Therefore, measuring cyanide and/or thiocyanate levels in blood and urine cannot be used as a biomarker for exposure to low cyanide concentrations. Analytical methods of required sensitivity and reliability to detect cyanide and thiocyanate in blood, plasma, and urine of both unexposed and exposed persons are available (see Table 6-1 and Table 6-3). Further studies determining biomarkers for exposure to low cyanide concentrations would be useful. 

Cyanide and thiocyanate are normal constituents of blood (77). Sources of cyanide include some foods, for example, cyanogenic glycosides in bitter almonds, fruit seeds, and a number of plants, cigarette smoke, and smoke from fires. The blood concentration of cyanide in healthy subjects was... 

Kage et al. (75) applied their GC/ECD/GC/MS method to the analysis of blood levels in two casualties who died from cyanide poisoning. Blood levels of cyanide and thiocyanate in a subject who died following ingestion of sodium cyanide were 0.52 and 0.10 umol/ml respectively (= 13 and 5.6 xg/ml). Levels determined in a fatal victim of smoke inhalation were 0.28 and 0.13umol respectively (= 7.3 and 7.5 xg/ml). Fatal levels of cyanide are estimated as 0.05-0.1 umol/ml (= 1.3-2.6 xg/ml). The lower levels of thiocyanate in comparison to cyanide in the blood were attributed to the sudden death they were twice the mean levels ( 0.06 pmol/ml) found in cigarette smokers. 2-Aminothiazoline-4-carboxylic acid was detected in the urine of moderate cigarette smokers at concentrations between <0.3-1.1 xM (76). 

Serum concentrations of thiocyanate are two to three times higher in smokers than in nonsmokers. In populations not exposed to excessive amounts of thiocyanate from diet or industrial environmental pollution, thiocyanate concentrations in serum can be used to identify and quantify tobacco smoking (Scherer, 2006 Butts etal., 1974). Because of the variability in cyanide generation from smoking a cigarette, the correlation between serum (or urine) concentration of thiocyanate and the number of cigarettes smoked per day is rather low (Foss and Lund-Larsen, 1986). 

In addition to our published analyses of size measures and those provided in Table 2, we conducted a series of additional analyses involving different alcohol exposure variables, substitution of serum thiocyanate data for the cigarettes per day measure, transformations of several measures, and the use of missing data techniques to avoid reductions in sample size. This deliberate analytical dredging of the data yielded results consistent with the findings provided in Table 2. These analyses increased our confidence in the analytical plan and in the robustness of the findings regarding these outcome measures. 

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