There are numerous anthropogenic chemicals in the environment and to date more than 137 million chemicals have been registered. Humans are exposed to up to 200 chemicals a day, but some are used without any specific safety studies. Many people increasingly depend on chemicals as they give us many benefits and convenience to our everyday living. In this article, I will argue for the continued usage of Bisphenol A (BPA), which is one of the widely used chemicals for plastic raw materials and coatings, but constantly controversial in its safety over the world.
This article approaches the bisphenol A (BPA) exposure problem from a scientific point of view and analyzes the chemical structure and properties of BPA, and whether and how it might affect human health, why it is controversial. Especially, this article will also analyze whether BPA is indeed a harmless environmental hormone and safe for human consumption.
Keywords: bisphenol A, exposure, health risk
Is Bisphenol A a Harmless Environmental Hormone?
Bisphenol A (a systematic name for 2,2-Bis(4-hydroxyphenyl)-propane, abbreviated as BPA hereafter) was first discovered by the Russian chemist Alexander P.
Dianin in 1892 and is an aromatic compound consisting of two phenols with an alcohol group attached to the benzene ring. It is synthesized by reacting two phenols with one acetone. Currently, it is widely used as the raw material for manufacturing plastics such as polycarbonate (PC) and epoxy resin. Especially, since polycarbonate can be made transparent, it is used for a variety of products such as food containers, receipts, CD materials, and baby bottles.
Epoxy resin is used to coat dental resins or beverage cans. There are so many bisphenol A containing products that provide convenience in our lives and the consumption of BPA is steadily increasing in many countries (Almeida, et.al, 2018). Therefore, there are also many routes and possibilities for direct or indirect contact with the human bodies of various ages. Such exposures to BPA have raised concern over its safety; e.g. it has been claimed that BPA could cause many diseases for adults and adversely affects child growth. A number of studies suggested that a long-term consumption of BPA can lead to cancer and can be detrimental to childrens brain development. Other studies have also reported that BPA can cause neurological development problems even in very small amounts (Moon et al., 2012). But despite such worries and studies, the Food and Drug Administration (FDA) has rather confirmed that the exposure of moderate amounts of BPA is not harmful (Wright, 2018). Over the past decade, many researchers have studied and obtained data on BPA, but there is no clear answer to the many important questions about the impact of BPA (Rubin, 2011), and the debate over BPA safety issue is still ongoing. This paper will closely examine the two major potential problems caused by BPA: (1) endocrine disturbance, (2) neurodevelopmental disorder, and argue for the refrained use of BPA.
Bisphenol A has a similar structure to estradiol and diethylstilbestrol (DES), which play an important role in the reproductive and sexual functions female estrogens. Because of its similarity, BPA acts as a xenoestrogen that has an estrogen-like function (Figure 1). Since BPA has a low melting point of 158 degrees Celsius, it can be easily dissolved and absorbed into the body (Flint et al., 2012). When this chemical enters the body, the hormone moves to the receptor of significant hormones such as brain, thyroid, and pituitary gland, sending false signals and interfering with smooth hormone action. According to Kharrazian (2014), BPA has a strong effect on the cells of pituitary lactate, mimics estrogen to bind estrogen receptors, thereby stimulating the prolactin secretion, which increases the immune stimuli of prolactin. In summary, BPA acts like estrogen and causes disturbance in the endocrine system (Moon et al., 2012). An experiment conducted in 1930s have shown that endocrine abnormalities occurred even when ovarian-free rats were injected with a very low concentrations of BPA (Rochester, 2012). It works in the same way for humans exposed to BPA through foods, products, and air and it has been reported to increase the risk of many disorders such as abnormal feminization, gynecomastia, and breast cancer (Rochester, 2012).
Figure 1: Structures of Bisphenol A, Diethylstilbestrol, and Estradiol (Kharrazian, 2014)
Bisphenol A: Neurobehavioral Developmental Disorder
Bisphenol A has been also shown to exhibit potentially harmful neurological effects, particularly in relation to the promotion of brain development and neurodegenerative diseases (Ellahi and Rashid, 2017). Especially, the concentration of BPA was high in young age groups. According to Ellahi and Rashid (2017), fetuses and children are particularly vulnerable to exposure to environmental pollution than adults because they have behavioral characteristics such as sucking toys and playing on the floor, and their abilities to detoxify the toxic substances are less developed. Also, baby bottles are one of the products that mainly contain BPA. For these reasons, many parents are concerned that their babies will be damaged in the nervous system and looking for BPA-free products. The study had concluded that BPA is associated with several health outcomes such as childhood asthma, wheezing, ADHD anxiety, and depression (Moms Exposure to BPA, 2016). However, a study by Spaneir (2012) found the following:
Higher prenatal BPA exposure was associated with increased odds of wheeze in the child at 6 months of age, but this association was diminished by 3 years of age. BPA exposure was associated with wheeze at 16 weeks but not 26 weeks of gestation or at birth, signifying a possible critical window of exposure early in gestation.
Nevertheless, it seems that the evidences of negative effect of BPA to young children seem overwhelming.
There are many opinions about the safety of BPA globally. As argued above, there are strong indications BPA causes, among others, endocrine damage and neuropathy. However, a recent study by the US Food and Drug Administration (FDA) and European Food Safety Authority (EFSA) on this issue has shown that BPA generally does not significantly affect the human body (Almeida et al.,2018). Such an argument is commonly based on the tolerable daily intake (TDI) data, a safety standard aimed at consumer protection. TDI refers to the maximum amount of substance that an individual can be exposed to in their daily lives, and the current TDI of BPA is 4 ?g / kg of bw /day. It was concluded that the human exposure to BPA was much lower than TDI, and BPA would be released rapidly without accumulating in the body (No Consumer Health Risk, 2015). Even though these specialized organizations have claimed that BPA is safe, there are still a number of studies showing that BPA is consistently causing side effects. In fact, Canada has banned the use of BPA in baby bottles from 2012, France in 2010, Europe Union (EU) in 2011, and United States in 2012 as the risk of BPA have become newly revealed.
Overall, by analyzing scientific data on BPA and carefully examining the divided opinions, I take the position that the use of BPA should be refrained. In addition to the polycarbonate (PC) and epoxy resin products, there are many other BPA products around us and there is a strong possibility that the TDI figure given by the FDA is under-estimated (IHS Markit, 2016). According to Rubin (2011), 92.6% of the 2500 people who participated in the National Health and Nutrition Examination Survey (NHANES) study were found were detected with BPA in their urine samples. Even if the average BPA exposure is much below the TDI and BPA is released quickly out of the body, a single exposure to or a long term accumulation of high concentration of BPA will ultimately result in chemically undesirable consequences and cause serious diseases including those two described in this paper. Therefore, it is not only necessary to develop alternatives, but also to require consumer efforts to avoid using BPA (Figure 2). Some preventive measures were suggested by Ellahi and Rashi (2017) as shown below.
Use tableware made of glass, ceramic, or polyethylene (PE).
Avoid eating food or beverage that are packaged in metal cans.
Dispose of any plastic appliances whose ingredients cannot be identified.
Figure 2: List of Preventive Measures for the Use of BPA