Monitoring the Level of Urinary Metabolites of Toluene and Xylene in Pregnant Women in Isfahan and Khansar and their Relationship with Demographic Factors and Air Quality Index

Aim: In this study, the levels of urinary metabolites of toluene and xylene isomers in pregnant women in Isfahan and Khansar cities and their associations with air quality index (AQI) and demographic factors were investigated. Materials and Methods: Depending on the population, 55 pregnant women from Isfahan and 15 pregnant women from Khansar, a total of 70 people were enrolled in the study and 140 urine samples were collected during their 1^st and 3^rd trimesters of pregnancy (autumn and spring). Urinary metabolites of hippuric acid (HA), ortho-, meta-, and para-methyl HA (o-m-p-MHA) were extracted by dispersive liquid-liquid microextraction method, derivatized and analyzed using gas chromatography/mass spectrometer. The results were statistically correlated with AQI level and demographic factors using appropriate statistical methods. Results: Mean urinary concentrations of HA, o-m-p-MHA in the 1^st trimester of pregnancy were 371.2, 1.14, 2.48, and 1.97 mg/g cr, and those in the 3^rd trimester were 582.1, 3.54, 6.93, and 2.43 mg/g cr, respectively. In the 1^st trimester, the mean urinary level of ortho-MHA was significantly associated with the outdoor exposure time on workdays and fragrances use (P < 0.05). In the 3^rd trimester, the mean concentration of HA was significantly correlated to age and outdoor exposure time on workdays (P < 0.05). Conclusion: The mean urinary concentrations of HA and MHA isomers in the 1^st trimester of pregnancy in Isfahan were more than those in Khansar. Because the level of air pollution in Isfahan was higher than Khansar and that in autumn was higher than spring. In the 3^rd trimester of pregnancy, the mean levels of MHA isomers in Isfahan were more than those in Khansar. Only the amount of p-MHA was significantly associated with AQI in the 1^st trimester of pregnancy. Thus, women who lived in high-traffic urban areas with high AQI were more exposed to toluene and xylene compounds.