Biomonitoring of DAPs levels in urine and amniotic fluid of pregnant women in Seville (Spain): evaluation of prenatal exposure

Among all population groups, pregnant women are one of the most vulnerable due to increasing concern about prenatal exposure to environmental pollutants, including pesticides such as organophosphates (OPs). In this regard, dialkyl phosphates (DAPs) are nonspecific metabolites excreted in urine and widely used to assess OP exposure. Thus, this study aimed to assess the risk of indirect OP exposure by determining six DAPs (dimethyl phosphate (DMP), O,O-dimethyl thiophosphate (DMTP), O,O-dimethyl dithiophosphate (DMDTP), diethyl phosphate (DEP), O,O-diethyl thiophosphate (DETP), and O,O-diethyl dithiophosphate (DEDTP)) in urine and amniotic fluid (AF) from a 74-pregnant-women cohort in Seville (Southern Spain). Sample preparation was based on electromembrane extraction (EME), a microextraction technique using an electric potential to selectively extract analytes across a supported liquid membrane (SLM). The analysis was performed using ion-pair ultra-high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (UHPLC-ESI-MS/MS). Results showed that DAPs can cross the placental barrier, as most AF samples showed between 80 and 99 % positive levels, depending on the compound, however, the studies in this regard are very scarce. Nonetheless, these levels were slight, and both mean and maximum concentrations detected in AF were lower than urine levels in every case. Moreover, the percentage of positive samples in urine was lower (44-92 %). Thus, this research highlights the importance of studying the presence of these metabolites, both in urine and in AF, and the physiological outcomes that their presence may cause both in the mothers and infants.