The analysis of protein-bound thiocyanate in plasma of smokers and non-smokers as a marker of cyanide exposure

Abstract

When cyanide is introduced into the body, it quickly transforms through a variety of chemical reactions, normally involving sulfur donors, to form more stable chemical species. Depending on the nature of the sulfur donor, cyanide may be transformed into free thiocyanate, the major metabolite of cyanide transformation, 2-amino-2-thiazoline-4-carboxylic acid or protein-bound thiocyanate (PB-SCN) adducts. Because protein adducts are generally stable in biological systems, it has been suggested that PB-SCN may have distinct advantages as a marker of cyanide exposure. In this study, plasma was analyzed from 25 smokers (chronic low-level cyanide exposure group) and 25 non-smokers for PB-SCN. The amount of PB-SCN found in the plasma of smokers, 1.35 µM, was significantly elevated (p < 0.0001) when compared to non-smokers, 0.66 µM. Differences in sub-groups of smokers and non-smokers were also evaluated. The results of this study indicate the effectiveness of analyzing PB-SCN in determining instances of chronic cyanide exposure with possible extension to confirmation of acute cyanide exposure.

Figure 1.

The concentration of PB-SCN found in the plasma samples of smokers compared to non-smokers. The individual data points represent the concentration of PB-SCN in each sample. The solid line represents mean concentration of each group.

Figure 2.

Individual concentrations of PB-SCN found in the plasma of male smokers (MS), male non-smokers (MNS), female smokers (FS) and female non-smokers (FNS). The solid line represents mean concentrations of the group.

Figure 3.

Individual concentrations of protein-bound thiocyanate found in the plasma samples of male and female smoking sub-groups separated based on the number of cigarettes consumed daily. The solid line represents the mean concentrations of each sub-group.