An insight into bisphenol A, food exposure and its adverse effects on health: A review

Abstract

Bisphenol A (BPA) is a synthetic chemical widely employed to synthesize epoxy resins, polymer materials, and polycarbonate plastics. BPA is abundant in the environment, i.e., in food containers, water bottles, thermal papers, toys, medical devices, etc., and is incorporated into soil/water through leaching. Being a potent endocrine disrupter, and has the potential to alter several body mechanisms. Studies confirmed its anti-androgen action and estrogen-like effects, which impart many negative health impacts, especially on the immune system, neuroendocrine process, and reproductive mechanism. Moreover, it can also induce mutagenesis and carcinogenesis, as per recent scientific research. This review focuses on BPA's presence and concentrations in different environments, food sources and the basic mechanisms of BPA-induced toxicity and health disruptions. It is a unique review of its type because it focuses on the association of cancer, hormonal disruption, immunosuppression, and infertility with BPA. These issues are widespread today, and BPA significantly contributes to their incidence because of its wide usage in daily life utensils and other accessories. The review also discusses researched-based measures to cope with the toxic chemical.

Keywords: BPA toxicity; bisphenol A; endocrine disruptor; epoxy resins; polycarbonate plastics; synthetic chemical.

FIGURE 1

Humans exposure to BPA via different sources and exposed roots. Dietary sources (food containers/packaging, baby bottles, water bottles, lunch boxes, water tanks, and microwave utensils) and non-dietary sources (electronic equipment, paints, thermal paper, flame retardants, medical and dental materials, sports equipment, printing inks, and DVDs) contaminate landfill, soil, air, water, and food that directly or indirectly affect the human through different exposure routes.

FIGURE 2

Bisphenol A as an endocrine disruptor. Estrogens negatively affect the release of follicle-stimulating hormone (FSH) and luteinizing hormones (LH). BPA can inhibit the estrogen binding to its receptors at the pituitary level, resulting in high levels of FSH and LH hormones in circulation. This can lead to reproductive system issues such as polycystic ovarian syndrome. BPA acts as anti-androgen by binding with androgen and glucocorticoid receptors and affecting their action. BPA can disturb the action of the thyroid hormone by inhibiting TR-mediated transcription of T₃-response genes.

FIGURE 3

Effect of BPA on the reproductive system. (A) When exposed to BPA, females can develop fertility-related issues as it is very similar to estrogen structure and function. It binds to estrogen receptors and causes irreversible alteration to the hypothalamic-pituitary-ovarian axis. BPA will provoke estrogen and thus increase the chances of PCOs, delay puberty, miscarriages, endometriosis, premature births, and most of the time, BPA can cause infertility. (B) Exposure of males to bisphenol interferes with the reproductive system. BPA causes atrophy in the testis, apoptosis in Leydig cells and germ cells, and reduction in testosterone biosynthesis, which will either cause the reduction in spermatozoa reduction or inhibition of GnRH neurons. It causes sperm quality and quantity alterations, retardation of testicular development, infertility, and reduction in sperm motility.

FIGURE 4

Carcinogenic activity of BPA; BPA interacts with the estrogen receptors and interferes with DNA methylation and gene expression after entering the nucleus. Thus altered gene expression leads to hypercell proliferation, which may lead to cancer.

FIGURE 5

Effect of the BPA immune system BPA can promote autoimmunity via T-helpers 1, 2, and 17. Aryl hydrocarbon receptors (AhR) are involved in regulating immune responses, followed by the production of T-helper 17 a critical factor in T-cells in various autoimmune diseases.