How Harmful is BPA for Human Health? – Effects of Bisphenol A Plastics

By Neha Yeul

April 22, 2023
close up of plastic waste items

What if I told you that you consume about 5 grams of plastic each week? that’s equivalent to the weight of an ID card, guess what it’s true.

So you’re basically eating an ID card each week.

Tiny particles of plastic enter our food chain through the food we eat, the water we drink, and the air we breathe, plastic is everywhere.

Microplastics” is a new class of pollutants rapidly rising in our environment.   

Although plastic is pretty helpful in many ways, it can, unfortunately, leach into our foods and then be absorbed into our bodies. 

Plastic can have several bad effects on our health, including birth defects and effects on the reproductive, neurological, and gastrointestinal systems.

A 2015 study found that BPA impairs neurological development 1.

Dr. Bruce Blumberg, a molecular biologist, says we are surrounded by chemicals, particularly, Bisphenol-A (BPA).

When we cook food in plastic, in a microwave oven, these ester bonds break and leak into the food 2.

BPA has made its way into products all around us, in bottles, cartons, milk packets, cash register receipts, canned bottles, and whatnot.

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What Exactly is Bisphenol-A?

Bisphenol-A (BPA) is a synthetic compound that is widely used in the production of clear and flexible polycarbonate plastics and epoxy resins, it has a Chemical formula: C15H16O2

BPA was first synthesized in 1891 by Russian Chemist Aleksandr Dianin.

However, it was not until the 1930s that its adverse implications as a synthetic mimic of estrogen or oestrogen (female sex hormone) were discovered.

In the 1950s, BPA began to be used in the production of polycarbonate plastic and epoxy resins.

BPA has chemical structures bound together by ester bonds, these ester bonds are sensitive to heat.

It is commonly found in food and beverage containers, such as water bottles, food storage containers, and the lining of canned foods.

BPA is also used in the production of some medical devices, dental sealants, and thermal paper (such as receipts).

Sources of Bisphenol-A (BPA) Plastics

Bisphenol-A plastics are simply to be found everywhere, they have made their way into almost every daily-use product, it is present in:

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  • Plastic bottles
  • Milk containers 
  • Plastic toys 
  • Baby bottles
  • Plastic food containers
  • Microwave-friendly dishes
  • Bowls and pots
  • Eyeglass lenses and frames
  • Canned foods and beverages
  • Dental sealants and fillings
  • Cash receipts 
  • Instantly printable tickets
  • Ink used to print newspapers
  • Electronic devices and appliances
  • Phthalates – a class of chemicals found in fragrance.

Effects of BPA on the Human Reproductive System

BPA-based products offer various health effects, including those on our reproductive system, metabolic processes, growth, and development.

Several studies and experiments on rats have evinced that BPA is bad for the nervous, digestive, and reproductive systems.

Bisphenol-A (BPA) Could Cause Birth Defects

close up of a pregnant woman's womb

It’s often quoted that a mother’s womb is the safest place in the world, where a fetus develops for nine months and gets oxygen and food from the mother.

Typically, chemicals that can cross the placenta of the unborn child in the mother’s womb may cause birth defects. 

The placental tissues make up a semipermeable membrane that limits what and how much can be passed from the mother to the baby.

Some factors that determine whether a chemical may pass through the placenta from the mother to the fetus include: 

  • Molecular weight
  • Lipid (fat or fat-like) solubility
  • Polarity (molecular charge)
  • Protein binding and 
  • Receptor mediation

If a drug can cross the placenta in the early stages of pregnancy at a concentration high enough to result in abnormal fetus development, it is called teratogenic.

Recently, scientists found microplastics in human placentas for the first time, the microplastics were transported to the placenta via the bloodstream due to the consumption and use of plastics in daily life.

Bisphenol-A and phthalates are microplastics known to be teratogenic because they can cross the placental barrier to reach the growing fetus, and that is worrisome.

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In 2018, the American Academy of Pediatrics told families to stop using plastic food containers entirely.

Risks of Precocious, Delayed Puberty & PCOD due to BPA

close up of a sanitary pad

Precocious puberty is a condition in which puberty hits as early as 7 to 9 years old in girls and 9 to 11 years old in boys.

Girls experience enlargement of their breasts and an increase in reproductive hormones like estrogen and progesterone, which leads to an early irregular menstrual cycle.

Boys experience the early appearance of a beard and mustache owing to increased testosterone levels.

What are the Reproductive Hormones?

Reproductive hormones are chemicals in the body that are involved in puberty, fertility, and sexuality. Estrogen and progesterone are female reproductive hormones produced in the ovaries. Testosterone is the male reproductive hormone produced in the testes.

It is not a normal experience for most of them, as physicians recommend hormone shots frequently to balance the imbalance of hormones.

These patients also suffer from disturbed mental health, as they feel embarrassed by the fact that their bodies are developing before those of their friends, and may get social ignorance or weird looks from their own friends.

A study analyzed the pubertal timings of 179 girls and 159 boys in California and found that girls developed pubic hair, breast development, and early menarche (menstrual cycle), which was linked to exposure to monoethyl phthalate [MEP], mono-n-butyl phthalate, and mono-isobutyl phthalate3.

In the case of boys, it resulted in early genital development like odd beard growth at young ages.

Another study among children between the ages of 8 and 14 evinced that several high-molecular-weight phthalates and Bisphenol-A caused delayed puberty in girls and earlier puberty in boys4.

When girls reach puberty too early, they often gain weight, which is hard to treat even when they are older.  

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Delayed puberty is the absence of breast development in girls and the absence of testicular size development in boys after the ages of 13 and 14, respectively.

Among women, polycystic ovarian syndrome or PCOD is a frequent illness, in which the women experience irregularities in the menstrual cycle, continuous bleeding for more than 20 days in a month, or an absence of menstruation for months.

PCOD has also been associated with exposure to plastics in several studies5.

BPA Implies Risks of Prostate Cancer & Infertility in Men

The term “cancer” refers to abnormal cell growth, which is typically the result of gene mutations.

Bisphenol-A, phthalates, DDT, and PCBs are endocrine-disrupting chemicals that disrupt our body’s normal functioning, as the required hormones are not released at the required time.

What are Endocrine-Disrupting Chemicals?

Endocrine-disrupting chemicals mimic, block, or interfere with hormones in the body’s endocrine system. They compete with the hormone molecules for the binding sites and thus affect the synthesis, secretion, or transport of hormones in our body.

Researchers often term phthalates and BPA as estrogen-mimicking and testosterone-lowering chemicals.

A study was conducted to find out the mechanism of prostate cancer development through the effects of endocrine-disrupting chemicals including BPA. 

Testosterone is a steroid hormone that plays a crucial role in the development of masculine characteristics in the body.

Whereas estrogen is a steroid hormone responsible for regulating the female reproductive system.

However, both hormones, testosterone, and estrogen, are found in men and women, albeit in different amounts, an imbalance in the ratios of testosterone and estrogen leads to diseases.

The biosynthesis of testosterone requires 5-alpha-Reductase isozymes (5α-R types 1, 2, and 3), and the biosynthesis of estrogen requires an aromatase enzyme.

Scientists injected experimental rats with BPA and found that it inhibited the enzyme 5-alpha reductase, which stopped testosterone production in their bodies.

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The study also found that Bisphenol-A plastics increased the activity of the aromatase enzyme (an enzyme that converts testosterone into estrogen).

Rats that were given BPA had a higher ratio of estrogen to testosterone in their blood, which is linked to prostate cancer6.

We have very tight windows of when, say, our brain and liver are made. When an endocrine-disrupting chemical gets in the way during these windows, it can change the ways these processes happen, the change is often irreversible7.

Kristi Pullen Fedinick, an NRDC staff scientist

Another study compared the men who worked at a chemical plant that manufactures BPA to the men who worked at a tap water factory.

The results show that the men who worked in contact with BPA had significantly lower serum testosterone levels, especially free testosterone levels (testosterone molecules that are not bound to any other molecule and freely move throughout the body through blood vessels) when compared to other men in the tap water factory. This shows the effect of BPA on fertility in men.

Obesity is Linked with BPA and Phthalate use

close up of belly of an obese person

Several studies have linked BPA and phthalate use to obesity.

Weight gain is also another issue faced by girls who experience precocious puberty, which is often untreatable even in the later years of life.

Industrial pollutants are contributing to America’s obesity epidemic. Dr. Blumberg calls those chemicals “obesogens.”

Despite what we’ve heard, diet and exercise alone are insufficient to explain the obesity epidemic.

Dr. Bruce Blumberg, UC Irvine

In Japan, Heindel and his team of researchers experimented on lab-based cells.

Usually, lab-based cells are human cells that are seeded in Petri plates and provided with body temperature to simulate the human body.

They multiply to become fibroblasts, which make up the body’s connective tissue.

Fibroblasts are pluripotent cells with the capacity to grow into any type of cell based on the requirements of the body and these pre-fibroblasts can become adipocytes–fat cells. 

The Japanese team found that Bisphenol-A and some other industrial compounds stimulate these pre-fibroblasts to become fat cells and fat tissues can store the BPA in them.

BPA also stimulated the proliferation of existing fat cells, “The fact that an environmental chemical has the potential to stimulate the growth of ‘preadipocytes’ has enormous implications,” Heindel wrote.

Heindel’s findings were on the cells in Petri dishes (in vitro), however, Newbold tried this experiment on mice (in vivo).

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She exposed newborn mice to low doses of hormone-mimicking compounds (equivalent to what people are exposed to in the environment).

The mice gained 20% more weight and had 36% more body fat than mice who were not exposed after six months8.

Dr. Blumberg quotes, “One of the messages of the obesogens research is that prenatal exposure can reprogram the metabolism so that you are predisposed to becoming fat.”

BPA Plastics Are Linked to Heart Diseases

As discussed earlier, men and women have a particular ratio of testosterone and estrogen in their blood.

However, an imbalance in the testosterone-to-estrogen ratio may contribute to heart diseases, several studies have been performed to find the effects.

A study compared the ratio of testosterone to estrogen in 55 men with coronary heart disease and 60 controls and they found that patients with coronary heart disease had an imbalance of testosterone to estrogen ratio in their serum.

The study shows that the testosterone and estrogen ratio plays an important role in heart disease development. 

In yet another study of postmenopausal women with coronary heart disease, an imbalance in the ratio of estrogen to testosterone in the blood evinced the risk factors for heart disease9.

BPA Causes Insulin Resistance – Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) is a condition with persistently high blood glucose levels caused by insulin resistance and eventual pancreatic β-cell dysfunction.

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We now know that Bisphenol-A is an endocrine disruptor chemical it also impairs glucose homeostasis and pancreatic β-cell function by affecting gene expression and mitochondrial morphology.

Due to BPA, the body develops insulin resistance which also results in long-term adverse metabolic effects after fetal and perinatal exposure. 

You may have met or known about small kids having diabetes mellitus; exposure to endocrine disruptors like BPA may be one of the causes of their disease10.

Is the Use of BPA-free Plastic the Solution?

Is switching to non-BPA or BPA-free plastic the solution to this problem? Yes but not really.

BPA-free plastic is made up of BPF and BPS, which may imply the same effects as those of BPA, instead, stainless steel, ceramic, and glass utensils are better options.

Non-stick pans can contain phthalate-containing plastics like PVC.

Utensils made of bamboo can also be used, which is a sustainable and eco-friendly alternative to plastic that is also naturally anti-bacterial. 

How to Identify Bisphenol-A (BPA) Plastics?

The plastic identification code number – usually stamped on the bottom of the container – is the most reliable way to determine whether an item is BPA-free.

There are seven categories, with numbers 1-6 being BPA-free, this means that only those with the number 7 will have the chemical.

The table below will help you identify the type of plastic you use11:

NumberCode letter(s)Name of plastic or resinExamples of use
1PETE / PETPolyethylene terephthalateSoft drinks bottles
2HDPEHigh-density polyethyleneSome reusable plastic food storage containers
3V / PVCVinyl or polyvinyl chlorideDebit and credit cards
4LDPELow-density polyethylenePlastic shopping bags
5PPPolypropyleneSome reusable plastic food storage containers
6PSPolystyreneFoam drinking cups
7OTHEROther substances (including Bisphenol-A)Any item not made of the above materials

Scientists are developing plastic from natural sources, for example, an interesting project led by Neha Jain, Zerocircle, in Pune, India, is making plastic with the help of seaweeds.

Have a look at Can Indian Seaweed Replace Plastic? 

Not to worry—once we keep ourselves away from plastic exposure, the one that is within our body will go away.

I say this because these components are primarily stored in the fat cells, and fatty cells eventually die and renew themselves.

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We can make a big difference in protecting our health and the environment by making small changes. 

The more we stay away from plastics, a new pile of microplastics will not build up, and the older ones will perish.

How can we Minimize Our Plastic Exposure?

Here are some ways to avoid endocrine-disrupting chemicals like BPA or avoid exposure to plastic.

  • Dust your belongings often as dust contains a large portion of microplastics that settle on furniture and cover sheets, along with soot particles, pollen grains, and soil.
  • Consume organic and fresh food, some pesticides have BPA as their main ingredient so it’s always better to eat organic and freshly cooked food and avoid packaged and processed food stored in plastic. 
  • Drinking filtered water, It’s recommended to use NSF-certified water filters, which reduce bad chemicals after they are installed and cared for, and use glass, stainless steel bottles, or bamboo bottles for storing and drinking water. 
  • Wash your hands thoroughly in short intervals and before eating food is very important and use fragrance-free soaps because they contain BPA or phthalates.
  • Avoid canned foods, the epoxy lining that prevents corrosion in cans is made up of BPA, if the cans contain acidic foods like tomato sauce or soda, you will eat some plastic, even if it is just a small amount.
  • Restrict using plastics and switch to alternatives on an individual level.

References

  1. Maede Ejaredar, Elias C Nyanza, et al., ‘Phthalate exposure and childrens neurodevelopment: A systematic review’, Environmental Research, 2015, https://doi.org/10.1016/j.envres.2015.06.014[]
  2. Frederick S. vom Saal, Claude Hughes, ‘An Extensive New Literature Concerning Low-Dose Effects of Bisphenol-A Shows the Need for a New Risk Assessment’, Environmental health perspectives, 01 August 2005, https://doi.org/10.1289/ehp.7713[]
  3. Kim G Harley, Kimberley P Berger, et al., ‘Association of phthalates, parabens, and phenols found in personal care products with pubertal timing in girls and boys.’, Oxford Academic, 4 December 2018, https://doi.org/10.1093/humrep/dey337[]
  4. Kimberly Berger, et al., ‘Association of Prenatal Urinary Concentrations of Phthalates and Bisphenol-A and Pubertal Timing in Boys and GirlsEnvironmental Health perspectives, 11 September 2008, https://ehp.niehs.nih.gov/toc/ehp/2018/126/9[]
  5. Eleni Kandaraki, et al. ‘Endocrine Disruptors and Polycystic Ovary Syndrome (PCOS): Elevated Serum Levels of Bisphenol-A in Women with PCOS’, The Journal of Clinical Endocrinology & Metabolism, 01 March 2011, https://doi.org/10.1210/jc.2010-1658[]
  6. Castro, B., Sánchez, P., et al., ‘Bisphenol-A exposure during adulthood alters expression of aromatase and 5α-reductase isozymes in rat prostate.’, PloS one, 6 February 2013, https://doi.org/10.1371/journal.pone.0055905[]
  7. Alexandra Zissu, ‘9 Ways to Avoid Hormone-Disrupting Chemicals’, Natural Resources Defence Council, 18 January 2016, https://www.nrdc.org/stories/9-ways-avoid-hormone-disrupting-chemicals’[]
  8. Sharon Begley, ’Why Chemicals Called Obesogens May Make You Fat.’, Newsweek, 09 October 2009, https://www.newsweek.com/why-chemicals-called-obesogens-may-make-you-fat-79445[]
  9. Wen Dai, Yan Li et al, ‘Estradiol/Testosterone imbalance: impact on coronary heart disease risk factors in postmenopausal women.’, Cardiology, June 2012, https://doi.org/10.1159/000337274[]
  10. Farrugia F, Aquilina A, Vassallo J, Pace NP, ‘Bisphenol-A and Type 2 Diabetes Mellitus: A Review of Epidemiologic, Functional, and Early Life Factors’, Int J Environ Res Public Health, 15 January 2021, https://pubmed.ncbi.nlm.nih.gov/33467592[]
  11. Plasticboxshop, ‘BPA Plastic: Hazard or Hysteria?’, https://www.plasticboxshop.co.uk/bpa-plastic-a-true-health-hazard-or-just-hysteria[]
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