# Maternal-Foetal Effects of Exposure to Bisphenol A: Outcomes and Long-Term Consequences
## 4 Characterisation of Bisphenol A (BPA)  
BPA production and use have been steadily rising annually, and as this EDC is utilised in an increasing number of materials, the number of contamination pathways is also growing. This includes contamination from the use and wear of the containers as well as pollution from their disposal in aquatic, marine, air and soil ecosystems [17]. In terms of its chemical composition, BPA is designated by IUPAC as 4_A_\({}^{\prime}\)-isopropyldienediphenol, with the chemical formula C\({}_{15}\)H\({}_{16}\)O\({}_{2}\), with excellent physical and chemical properties, giving plastics good mechanical properties [5,18,19]. Because of its chemical structure, BPA interacts as an agonist or antagonist through a receptor-dependent signalling pathway. This EDC's mode of action involves primarily binding to oestrogen-activated receptors (ER), \(\alpha\) and \(\beta\) (ER\(\alpha\) and ER\(\beta\)), and other receptors [8,20]. BPA is absorbed through the digestive tract and, to a lesser extent, through direct contact with the skin. Once ingested, it is metabolised by the intestinal microbiota and the liver via the uridine 5\({}^{\prime}\)dyspho-glucoronosyltransferase system, resulting in BPA mono glycuronide (BPA-G) and BPA sulphate (BPA-S), with BPA-G being the main metabolite of BPA in humans [21]. This compound acts through activation of the oestrogen receptor (ER), with a stronger affinity for the beta oestrogen receptor (ER$) than for the alpha oestrogen receptor (ER$). BPA-G did not show ER-mediated estrogenic activity, whereas it showed pro-inflammatory effects through competitive inhibition of peroxisome proliferatorator-activated receptors (PPAR-\(\gamma\)) [21]. Despite having a short half-life of approximately 6 h, constant exposure to BPA leads to its regular presence in the body. Lastly, it is excreted in conjugated form by the kidney, and measuring its urinary excretion is a good way of assessing the presence of this compound in the body since it is mostly excreted within 24 h (Figure 2) [22]. However, it is important to note that foetuses and newborns are unable to conjugate BPA and are, therefore, highly sensitive and exposed to this endocrine disruptor [23]. As a result, it is not easily eliminated from the body and remains accumulated in the various tissues/organs of the newborn. Although it has not yet been studied in detail, it is expected that due to prolonged exposure to BPA, its capacity for endocrine disruption and promotion of oxidative stress and inflammation, the development of the foetus may be considerably affected. The most common way in which humans are exposed to BPA is orally, through the consumption of contaminated food and drink from containers used and reused for preservation and preparation, and through skin contact or inhalation [24]. BPA is a non-persistent chemical, which is why it is found in greater concentration in urine samples, although it is found in accumulation in the various organs, fluids and tissues of the human body and is likely to have harmful long-term consequences [25; 26]. Several studies have shown that, with an emphasis on the body of a pregnant woman or a recent mother, the small portion that is not excreted as maternal urine (31.9 ug/L) can be found in smaller quantities in biological fluids such as human colostrum (3.41 ng/mL), breast milk (0.61 to 0.7 ug/L), amniotic liquid (median = 0.26 ng/mL), placental tissue (median = 12.7 ng/g), umbilical cord blood (0.2 to 9.2 ng/mL) and maternal blood (0.3 to 18.9 ng/mL) [3; 27]. Figure 2: Sources, routes of exposure, maternal biological samples of BPA exposure and consequent metabolism. The figure was created on PowerPoint version 2204 using pictures from BioRender. Numerous studies have already demonstrated the effects of BPA on a variety of human and animal physiological systems due to its ubiquitous use and endocrine-disrupting properties, particularly estrogenic and anti-androgenic [28].