1,3-Butadiene (BD) is a common environmental and industrial chemical widely used in
plastic and rubber manufacturing and also present in cigarette
smoke and
automobile exhaust. BD is classified as a known human
carcinogen based on evidence of carcinogenicity in laboratory animals treated with BD by inhalation and epidemiological studies revealing an increased risk of
leukemia and lymphohematopoietic
cancers in workers occupationally exposed to BD. Upon exposure via inhalation, BD is bioactivated to several toxic
epoxides including
3,4-epoxy-1-butene (EB),
3,4-epoxy-1,2-butanediol (EBD), and
1,2,3,4-diepoxybutane (DEB); these are conjugated with
glutathione and excreted
as 2-(N-acetyl-L-cystein-S-yl)-1-hydroxybut-3-ene/1-(N-acetyl-L-cystein-S-yl)-2-hydroxybut-3-ene (MHBMA), 4-(N-acetyl-L-cystein-S-yl)-1,2-dihydroxybutane (DHBMA), and 1,4-bis-(N-acetyl-L-cystein-S-yl)butane-2,3-diol (bis-
BDMA). Exposure to DEB generates monoalkylated
DNA adducts,
DNA-
DNA crosslinks, and
DNA-
protein crosslinks, which can cause base substitutions, genomic rearrangements, and large genomic deletions. In this study, we developed a quantitative nanoLC/NSI+-HRMS methodology for 1,4-bis-(gua-7-yl)-2,3-butanediol (bis-N7G-BD) adducts in urine (LOD: 0.1 fmol/mL urine, LOQ: 1.0 fmol/mL urine). This novel method was used to quantify bis-N7G-BD in urine of mice treated with 590 ± 150 ppm BD for 2 weeks (6 h/day, 5 days/week). Bis-N7G-BD was detected in urine of male and female BD-exposed mice (574.6 ± 206.0 and 571.1 ± 163.4 pg/mg of
creatinine, respectively). In addition, major urinary metabolites of BD, bis-
BDMA, MHBMA and DHBMA, were measured in the same samples. Urinary bis-N7G-BD adduct levels correlated with DEB-derived metabolite bis-
BDMA (r = 0.80, Pearson correlation), but not with the EB-derived
DNA adducts (EB-GII) or EB-derived metabolites MHBMA and DHBMA (r = 0.24, r = 0.14, r = 0.18, respectively, Pearson correlations). Urinary bis-N7G-BD could be employed as a novel non-invasive
biomarker of exposure to BD and bioactivation to its most mutagenic metabolite, DEB. This method will be useful for future studies of
1,3-butadiene exposure and metabolism.