Monitoring of exposure to acrylonitrile by determination of N-(2-cyanoethyl)valine at the N-terminal position of haemoglobin

Abstract

A selected ion monitoring gas chromatography-mass spectrometry (GC-MS) procedure was developed to determine the interaction product formed by acrylonitrile (ACN) with the N-terminal amino group in haemoglobin. The product, N-(2-cyanoethyl)valine (CEV), was analysed following its release from the protein by a modified Edman degradation procedure. Quantitation was achieved using N-(2-cyanoethyl)-[2H8]Val-Leu-Ser as internal standard. The limit of detection of the assay was 1 pmol CEV/g globin. A close to linear dose-response relationship was found for adduct formation in rats treated with ACN by gavage. On the basis of a linear extrapolation, a dose of 1 mg/kg body wt yielded 248 pmol CEV/g globin. Two groups of workers who were exposed to ACN contained 1984 +/- SD 2066 (n = 9) and 2276 +/- SD 1338 (n = 7) pmol CEV/g globin respectively. These values were highly significantly greater (P < 0.01 following a one-way analysis of variance with a logarithmic transformation of the data) than those in a group of control workers in the same factory (31.1 +/- SD 18.5 pmol CEV/g globin, n = 11). The concentrations of N-terminal CEV in globin samples from 13 smoking and 10 non-smoking mothers and from their newborns were determined. Adduct levels in the smokers averaged 217 +/- 85.1 pmol CEV/g globin, significantly higher than the levels in non-smokers, which were undetectable. Individual values in the mothers were very highly correlated with the levels in their babies (which averaged 99.5 +/- 53.8 pmol CEV/g globin), which demonstrates that transplacental transfer of ACN occurs. Significant correlations were also found between the number of cigarettes smoked per day by the mother and the CEV levels in both the mothers' and newborns' globin. There was, however, no correlation between the CEV levels and those of the ethylene oxide adduct N-(2-hydroxyethyl)valine in samples from either the mothers or babies.

A correlation study applied to biomarkers of internal and effective dose for acrylonitrile and 4-aminobiphenyl in smokers

“…Nevertheless, the adduct ratio between smokers and non-smokers remains consistent across all those studies (3- to 5-fold increase in smokers compared to non-smokers). The mean CEVal value in our study (133 pmol/g Hb) was similar to another study showing mean levels of 112 pmol/g Hb for 264 smokers and 6.5 pmol/g Hb for 100 non-smokers (Scherer et al, 2007) and half of what was reported in an earlier assessment (217 pmol/g Hb) in pregnant smoking mothers (Tavares et al, 1996). However, this study was conducted in a relatively small group of 13 heavy smoker females and the ISO Tar yield of the product was not specified.…”

“…For instance, only a moderate linear correlation was found between 4-ABP-Hb and plasma cotinine (ng/ml; L R 2 33%; Maclure et al, 1990), which is very similar to the value we obtained when performing a linear correlation between 4-ABP-Hb and 4-ABP (expressed in ng/L; L R 2 30%) or 4-ABP-Hb with TNEQ (µg/mL; R 2 24%). A moderate correlation ( L R 2 40%) was reported for acrylonitrile haemoglobin adducts and CPD in the Tavares et al’s (1996) study. In our study, a similar comparison gave only a 19% correlation, but our smoker group was much larger.…”

Synthesis and characterization of peptide adducts for use in monitoring human exposure to acrylonitrile and ethylene oxide

“…Full details of this analytical procedure will be reported elsewhere [12]. As an example of the approach, Figure 5 depicts the GC-MS selected ion recording traces for three N-(2-cyanoethyl)valine determinations.…”

“…The procedure for the Edman degradation of this protein is described in detail elsewhere [12] and, in summary, involves:…”

Smoking While Pregnant

“…5 Analytical studies have found elevated levels of tobacco-specific mutagens or cotinine in amniotic fluid, fetal urine, or fetal blood from smoking mothers compared with nonsmoking mothers, 5-9 providing direct evidence of the presence of such compounds in utero. Protein adducts of tobacco-specific compounds have been identified in cord blood, [10][11][12] indicating that such compounds interact covalently with fetal macromolecules, with potentially mutagenic consequences.…”