Each year thousands of man-made chemicals are added into our environment with little knowledge as to the potential long-term side effects on health.
One of the chemicals that has received increasing attention in the last five years is Bisphenol A (BPA).
Should you be concerned?
Sources of BPA
Over six billion pounds of Bisphenol A are produced each year and it is estimated that 100 tons of it is released into the atmosphere, mostly through industrial waste water [ref name="source1"]Vandenberg LN, Maffini MV, Sonnenschein C, Rubin BS, Soto AM. 2009 Endocr Rev 30: 75-95[/ref] [ref name="source2"] Balabanič D, Rupnik M, Klemenčič AK. Reprod Fertil Dev. 2011;23(3):403-16[/ref]
Public concern, however, has been over its widespread use in “hard” polycarbonate plastics (including many baby bottles, pacifiers, & sippy cups) and epoxy resins found in the linings of canned food, canned beverages, dental sealants and even flame retardants used in electronics. [ref name="source3"]Newbold RR. Hormones (Athens). 2010 Jul-Sep;9(3):206-17[/ref]
Health Concerns Regarding BPA
BPA is known to exert weak estrogen activity in animal and human studies. In fact, BPA has been shown to be mainly responsible for estrogenic activity leaching from our landfills into the surrounding ecosystem. [ref name="source4"]Coors A, Jones PD, Giesy JP, Ratte HT. Environ Sci Technol.2003;37(15):3430–4[/ref]
Similar concerns exist with weak estrogen-like compounds in soy and popular supplements. [ref name="source5"]Patisaul HB, Jefferson W.Front Neuroendocrinol. 2010 Oct;31(4):400-19. Epub 2010 Mar 27[/ref] Some clinicians suggest that food chemicals with low estrogenic activity (such as flax and soy) may actually exert some health benefits, while man-made estrogen-like chemicals may be more likely causing harm.
What we know is that up to 95% of individuals tested have levels of BPA in their urine [ref name="source6"]Calafat AM, Kuklenyik Z, Reidy JA, Caudill SP, Ekong J, Needham LL. Environ Health Perspect. 2005 113: 391-395[/ref] BPA has also been found in breastmilk, amniotic fluid, neonatal blood, placenta, and cord blood. [ref name="source7"]Vandenberg LN, Hauser R, Marcus M, Olea N, Welshons WV. Reprod Toxicol. 2007 24: 139-177[/ref]and almost all organic and non-organic canned foods, soups, juice, tuna, and green beans contain some BPA.
Bisphenol A is widely categorized as an “endocrine disruptor“. Endocrine disruptors are man-made chemicals that have potential to cause reproductive abnormalities, and some like BPA have been shown to behave like estrogen in the body.
The Environmental Protection Agency (EPA) defines an endocrine disruptor as:
An exogenous agent that interferes with the production, release, transport, metabolism, binding, action, or elimination of natural hormones in the body responsible for the maintenance of homeostasis and the regulation of developmental processes [ref name="source8"]Kavlock RJ, Daston GP, DeRosa C, et al. Environ Health Perspect. 1996 104: Suppl 4: 715-740[/ref].
Simply put, these chemicals disrupt hormone function by mimicking or even blocking the normal activity of hormones.
Epigenetics (“above the gene”) is the science behind how dietary and chemical signals from our environment help regulate how our genes are expressed for better or for worse.
Those changes in gene expression can then be passed to our offspring without any involvement of genetic mutations.
Currently tens of thousands of man-made chemicals are released in to our environment with little to no understanding of their potential impact on human and ecosystem health. Our understanding of how toxins interact with our physiology to produce health effects is growing rapidly. The field of toxicology will be especially affected by advances in our understanding of epigenetics. [ref name="source9"]LeBoran, MJ, et al. Mutat Res. 2010 Oct;705(2):83-95. Epub 2010 Apr 23[/ref].
What is exciting about the research is that we are discovering clues as to how our genetic risk to certain diseases can be increased or decreased through toxin exposure, as well as diet and lifestyle choices.
Endocrine disruptors such as bisphenol A have actually been shown to alter gene expression and cause epigenetic changes in those exposed. [ref name="source10"]Wolstenholme JT, Rissman EF, Connelly JJ. Horm Behav. 2011 Mar;59(3):296-305[/ref] [ref name="source11"]Pozharny Y, Lambertini L, Clunie G, Ferrara L, Lee MJ. Mt Sinai J Med. 2010 Mar;77(2):225-35 [emphasis mine][/ref].
In April 2011, a Nature Reviews. Endocrinology article offered this statement:
“Exposure to endocrine disrupting chemicals (EDCs) is associated with dysfunctions of metabolism, energy balance, thyroid function and reproduction, and an increased risk of endocrine cancers. These multifactorial disorders can be ‘programmed’ through molecular epigenetic changes induced by exposure to EDCs early in life, the expression of which may not manifest until adulthood. ” [ref name="source12"]Walker DM, Gore AC. Nat Rev Endocrinol. 2011 Apr;7(4):197-207. [emphasis mine][/ref]
Despite widespread excitement in the emerging field of epigenetics, most BPA research has still largely been based on animal models. Despite growing public concern, new guidelines regarding chemicals such as BPA have been slow to develop.
Safety reports on BPA suggest that BPA has a half-life of two hours, with all metabolites being recovered in the urine [backref name="source29" /].
I still wonder whether exposures are large and/or frequent enough to overcome the bodies ability to flush it out, and what effect the substance (even at low doses) may have long-lasting effects despite short-term exposures – especially when it comes to genetic expression.
Estimated exposure to BPA tends to be below levels proven to be safe, but in rat models, even low-dose exposure has been correlated with health effects [ref name="source33"]Prins GS, Tang WY, Belmonte J, Ho SM. Basic Clin Pharmacol Toxicol. 2008 Feb;102(2):134-8[emphasis mine][/ref].
BPA may actually exert different effects at both very low and very high dosages [backref name="source3" /].
Despite the controversial nature of BPA research, what have these studies shown?
Possible Health Effects of BPA
Fertility, Reproductive Health & Pregnancy Outcomes:
Because of its estrogenic behavior, there has been concern of BPA’s impact on fertility, reproductive health, and pregnancy outcomes.
A 2009 article published in the journal reviewed evidency of BPA’s direct influence on the placenta. The article noted that BPA exposure may be associated with adverse pregnancy outcomes such as:
- intrauterine growth restriction
- premature births
- & pregnancy loss[ref name="source13"]Benachour N, Aris A. Toxicol Appl Pharmacol. 2009;241(3):322–8[/ref] and indirect association with recurrent miscarriages.[ref name="source14"]Sugiura-Ogasawara M, Ozaki Y, Sonta S, Makino T, Suzumori K. Hum Reprod. 2005;20(8):2325–9[/ref]
A popular 2008 Canadian documentary called “The Disappearing Male” noted the concern over man-made “endocrine disruptors” and their effect on male fertility. The film noted that male sperm counts have declined 50% in the last fifty years, and that exposures during key moments of development can be crucial in determining sex and reproductive health.
There is also evidence that a mother’s exposure to BPA while pregnant can affect the fertility of male children [ref name="source15"]Salian S, Doshi T, Vanage G. Reprod Toxicol. 2011 Apr;31(3):359-62. Epub 2010 Oct 20[/ref] and exposure may also be associated with early puberty in females. [ref name="source16"]Roy JR, Chakraborty S, Chakraborty TR. Med Sci Monit. 2009 Jun;15(6):RA137-45[/ref] Long-term risk of excess estrogen exposure for females may include breast, endometrial, ovarian, and colon cancers. In males, BPA is suggested to lower testosterone levels by its effects on testis and the pituitary [ref name="source33"]Toxicol Lett. 2010 Apr 15;194(1-2):16-25[/ref].
According to the Cleveland Clinic, uterine fibroids occur in 25-80% of women. Although causes are not completely identified, alternative providers tend to blame “estrogen dominance” for their presence.
Signs and symptoms of uterine fibroids may include:
- Disordered menstrual bleeding & severe menstrual cramps
- A feeling of fullness in the lower abdomen
- Problems with urination (frequent/infrequent)
- Pain during intercourse
- Low back pain
- Chronic vaginal discharge
Human studies have shown associations of BPA and similar chemicals with low sperm formation, low testosterone, genital malformation, and higher incidence of breast cancer. [ref name="source17"]Klingmüller D, Alléra A. Dtsch Med Wochenschr. 2011 May;136(18):967-72[/ref]
Additionally, BPA may be associated with cryptorchidism (undescended testicles), hypospadias (defect in opening of the urethra) in males, and miscarriages, impaired fertility, and a disrupted menstrual cycle in females. [ref name="source18"]Balabanič D, Rupnik M, Klemenčič AK. Reprod Fertil Dev. 2011;23(3):403-16[/ref]
Pregnancy and Infancy:
Certain groups such as pregnant mothers and young children may be more vulnerable to the effects of BPA. [ref name="source19"]Groff T. Curr Opin Pediatr. 2010 Aug;22(4):524-9[/ref]. (As noted earlier, BPA has been found in breastmilk, amniotic fluid, neonatal blood, placenta, and cord blood. [backref name="source7" /])
Toxic levels in infants and children tend to be higher in concentration due to their small body size & they are considered high risk because of the rapid development of their immune and nervous systems.
Time Magazine noted in May 2011 that BPA exposure in Pregnancy may be connected to Childhood asthma.
There is also serious concern of genetic changes being induced by toxic exposures to a developing fetus or infant, and that those changes may be less reversible than the effect of toxic exposure in adults [backref name="source3" /]
Brain and Nervous System:
Because most brain and nervous system development occurs during the first few months and years of life, young children may be more vulnerable to BPA exposure. Beyond reproductive abnormalities, concern over the potential neurological effects of bisphenol A and exposure during pregnancy and the first few years of life has sparked fierce political debate over the neurological implications of BPA exposure.
Studies in rats and non-human primates have shown evidence of an association of BPA with a 70-100% loss of nerve synapses in the hippocampus (area of brain involved in memory) and the spine by blocking normal estrogen and androgen (i.e. testosterone) activity.
Cognitive decline, depression, and schizophrenia are conditions associated with a similar loss of nerve synapses [ref name="source20"]Hajszan T, Leranth C. Front Neuroendocrinol. 2010 Oct;31(4):519-30[/ref].
International publicity and debate over bisphenol A has been re-fueled largely because of recent insights into how BPA may negatively affect the brain and nervous system.
Diabetes and Obesity:
There is a positive association of BPA and similar endocrine-disrupting chemicals with obesity in both human and animal studies. [backref name="source3" /] Some believe that pre-natal and post-natal exposure to BPA may play a role in weight gain [ref name="source22"]Rubin, AS, Soto, AM. Mol Cell Endocrinol. 2009 May 25;304(1-2):55-62[/ref]. BPA may also increase the amount of inflammatory chemicals released from existing fat tissue [ref name="source21"]Ben-Jonathan N, Hugo ER, Brandebourg TD. Mol Cell Endocrinol. 2009 May 25;304(1-2):49-54[/ref].
Bisphenol A has shown to alter control of blood sugar in both rats and humans and may promote the development of type 2 diabetes [ref name="source23"]Alonso-Magdalena P, Ropero AB, Soriano S, Quesada I, Nadal A. Hormones (Athens). 2010 Apr-Jun;9(2):118-26[/ref].
Chronic exposure to low levels of estrogenic chemicals like BPA over time increased the rates of prostate cancer in rats [ref name="source24"]Prins GS, Tang WY, Belmonte J, Ho SM. Basic Clin Pharmacol Toxicol. 2008 Feb;102(2):134-8[/ref].
Alterations in testosterone and estrogen levels have been linked to elevated prostate specific antigen (PSA) and the potential to promote prostate cancer development [ref name="source25"]Ellem SJ, Risbridger GP. J Steroid Biochem Mol Biol. 2010 Feb 28;118(4-5):246-51[/ref] [ref name="source26"]Schatzl G, et al. Prostate. 2001 Apr;47(1):52-8[/ref]; [ref name="source27"]Sofikerim M, Eskicorapci S, Oruç O, Ozen H. Urol Int. 2007;79(1):13-8[/ref].
Some evidence suggests an antagonistic effect of BPA on Thyroid hormone function [ref name="source28"]Zoeller RT, Bansal R, Parris C. Endocrinology. 2005 Feb;146(2):607-12. Epub 2004 Oct 21[/ref]. Additionally, epigenetics may also play a role between endocrine disruptors and thyroid function [backref name="source12" /].
The European Food Safety Authority released an opinion on BPA in 2008 that because of differences in the metabolism of rodents and humans, rats are likely at greater risk than humans. In 2010, upon push to review their opinion based on an international push to ban BPA from baby bottles, the EFSA reconfirmed their 2008 opinion stating that there was flaws in the research designs that had been used as rationale for a ban.
A 2011 review published in Critical Reviews in Toxicology, noted the “deadlocked controversy” over BPA. The review supported that the tolerable daily intake of BPA remain set at 0.05 mg/kg per day (50 ug/kg/day). The authors remarked that no adverse health effects have been consistently observed at doses ≤5 mg BPA/kg/day [ref name="source29"]Hengstler, LG, et al. Crit Rev Toxicol. 2011 Apr;41(4):263-91[/ref].
It’s important to note that the study was partly funded by a BPA-interest group
A separate review article published in Reproductive Toxicology in 2007 stated:
We are confident that adult exposure to BPA affects the male reproductive tract, and that long lasting, organizational effects in response to developmental exposure to BPA occur in the brain, the male reproductive system, and metabolic processes. We consider it likely, but requiring further confirmation, that adult exposure to BPA affects the brain, the female reproductive system, and the immune system, and that developmental effects occur in the female reproductive system [ref name="source30"]Richter, CA, et al. Reprod Toxicol. 2007; 24(2): 199–224[/ref].
More recently, a June 2011 issue of the journal Human Reproduction Update, the authors claimed that there is enough evidence present to take “precautionary actions” regarding women’s reproductive health and endocrine disruptors such as bisphenol A [ref name="source31"]Caserta, D, et al. Hum Reprod Update. 2011 May-Jun;17(3):418-33. Epub 2011 Jan 24[/ref].
Additionally, a Harvard study published in April 2011 in Current Opinion in Pediatrics suggested “Even in the absence of epidemiological studies, concern over adverse effects of BPA is warranted given the unique vulnerability of the developing fetus and child. Healthcare providers are encouraged to practice primary prevention and counsel patients to reduce BPA exposures,”[ref name="source32"]Braun JM, Hauser R. Curr Opin Pediatr. 2011 Apr;23(2):233-9[/ref].
BPA is just one of many sources of endocrine disruption that are becoming ubiquitous in our envioronment….a small stress here, and a small stress there, and the hypothetical possibility of combination effects have some alternative health professionals concerned.
Despite research claims that BPA is safe at the current guidelines, there is debate over the potential bias of industry-sponsored research.
Other reviews have painted a different story, and consumer pressures against BPA have been building over the last decade.
Uniquely, BPA exposure has been shown a “U-shaped” response-curve, meaning an effect is only seen at low and high doses, making it impossible to make conclusions on the effect of low exposure based on high-exposure studies [backref name="source3" /], and may also complicate “tolerable intake” guidelines.
As public concern clearly affects both policy and research dollars, it is important to voice any of your concerns as the industry is surely spending money to voice its opinions as well.
The good news is that because of consumer pressure, at least $30 million has recently been set aside to fund ten, two-year studies on the safety of BPA.
Epigenetic influences may take longer than two years to develop. Whether the results of these two-year studies will add to the confusion regarding the safety of BPA is still to be determined, but it’s a good sign that policymakers are listening.
Tips on Avoiding BPA Exposure:
Taking “precautionary actions” can be more simple than you can think:
- Purchase products stored in glass containers
- Eat foods and herbs that support detoxification such as broccoli, cauliflower, brussel sprouts and turmeric.
- Purchase BPA-free baby bottles, pacifiers and infant feeding cups.
- Avoid the use of #7 labeled plastics.
- Do not microwave or heat food in plastic containers.
- Ensure proper ventilation for rooms & offices containing computers and electronics.
- Do not store food in scratched or damaged plastic containers, or other containers with plastic lining.
- Consider asking a health professional about special urine testing especially if there is history of reproductive difficulties, uterine fibroids, breast cancer, menstrual abnormalities, or history of infertility.
Share and find tips with other readers:
How do you reduce personal exposure to man-made toxins? (LinkedIn Discussion Group)