Arsenic exposure is considered a major environmental threat to human health. It is already known that high-level arsenic exposure has adverse effects on human health. Since the pregnant women are known to be more susceptible to some chemical exposures than ordinary people, the understanding regarding the health effects of low-level arsenic exposure on pregnant women is critical and remains unclear. The aim of this study is to investigate the urinary metabolic changes of pregnant women exposed to low-dose arsenic, and to identify biomarkers from metabolomics analysis. Urine samples of 246 pregnant women were collected in the first trimester of pregnancy and were divided into three groups based on the tertile distribution of urinary arsenic concentrations which were determined using inductively coupled plasma mass spectrometry (ICP-MS). Changes in the metabolite profile were measured using ultra-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry (UPLC/Q-TOF MS). Arsenic- related metabolic biomarkers were investigated by comparing the samples of the first and third tertiles of arsenic exposure classifications using a partial least-squares discriminant model (PLS-DA). Nine urine potential biomarkers were putatively identified, including LysoPC (14:0), glutathione, 18-carboxy-dinor-LTE4, 20-COOH-LTE4, cystathionine ketimin, 1-(beta-d-ribofuranosyl)-1,4-dihydronicotinamide, thiocysteine, p-cresol glucuronide and vanillactic acid. The obtained results showed that environmental arsenic exposure, even at low levels, could cause metabolite alterations in pregnant women which might be associated with adverse health outcomes. This is the first report on metabolic changes in pregnant women for arsenic exposure. The findings may be valuable for the arsenic risk assessment for pregnant women.
