BPA mimics sex hormones.
A dose of 0.23 parts per trillion (ppt) can have worse effect than higher doses.
Effects happen within minutes.
Human fetuses are being exposed to BPA in that range.
At trace levels BPA
- Acts as an endocrine disruptor — it mimics (displaces) or interrupts production of hormones
- Alters development and function of the brain, thyroid gland, pancreas and prostate gland
- Damages eggs and chromosomes
- Changes sperm
- Alters the structure of genitals
- Increases growth of breast cancer and prostate cancer cells
- Induces early onset of puberty
- Contributes to obesity
- Promotes hyperactivity
- Alters cognition
- Affects glutathione (detoxification) metabolic pathways
- Other effects
The breakdown products of BPA also disrupt hormones.
This study found one of BPA's breakdown products has estrogenic activity 250x stronger than BPA itself.
Exposure to 20 ppb BPA produces aneuploidy.
Aneuploidy is a cause of miscarriages, Down syndrome, and mental retardation.
The top photo shows normal chromosome alignment during cell division (meiosis).
Chromosomes are lined up at the center of the cell — this is called the meiotic spindle.
The bottom photo shows a cell exposed to BPA — chromosomes are scattered throughout the cell.
When this cell divides, each new cell will have the wrong number of chromosomes.
A grandchild can be affected by grandmother's exposure to BPA.
Human eggs (ova) begin developing while a female is still
in the womb.
These immature ova are known as primary oocytes.
BPA crosses the placenta into the developing fetus.
Then it can scramble chromosomes in the primary oocytes as they develop.
If these primary oocytes survive to become mature ova their chromosomes will remain disordered.
Embryos conceived from these disordered ova have increased risk of spontaneous abortion.
Surviving embryos will become children with disorders.
These immature ova are known as primary oocytes.
BPA crosses the placenta into the developing fetus.
Then it can scramble chromosomes in the primary oocytes as they develop.
If these primary oocytes survive to become mature ova their chromosomes will remain disordered.
Embryos conceived from these disordered ova have increased risk of spontaneous abortion.
Surviving embryos will become children with disorders.
Thus, when a woman (1st generation) is exposed to BPA, her daughter (2nd generation) can give birth to a child (3rd generation) with chromosomal abnormalities.
The amount of BPA necessary to trigger this is so small it can be passed from one body to the next for generations...
BPA can influence obesity by altering gene function during fetal development (see here, here, and here).
It starts by causing low birth weight.
Then comes abnormal weight gain that persists throughout life.
Exposure to BPA during development reduces DNA methylation.
This changes epigenetic behavior.
In turn this causes genetically identical mammals to develop differently.
Mice used in this study normally grow up lean and brown-haired.
But ones exposed to BPA in the womb grew up fat and blond.
BPA affects female reproductive capacity.
Prenatal exposure can cause uterine damage
to developing females while still in the womb.
Women with a history of miscarriages have shown BPA burdens 3x higher than other women.
Women with polycystic ovarian syndrome (PCOS) have shown higher levels of BPA than other women.
A relationship between BPA and endometrial hyperplasia has been found.
Women with higher BPA had a more benign form of the condition.
Women with lower BPA had the worst form.
This situation — where lower doses cause greater harm — is called hormesis.
Women with a history of miscarriages have shown BPA burdens 3x higher than other women.
Women with polycystic ovarian syndrome (PCOS) have shown higher levels of BPA than other women.
A relationship between BPA and endometrial hyperplasia has been found.
Women with higher BPA had a more benign form of the condition.
Women with lower BPA had the worst form.
This situation — where lower doses cause greater harm — is called hormesis.
Exposure to 2.5 ppt BPA daily while in the womb leads to a 4x higher rate of pre-cancerous breast lesions during puberty.
Hence, a woman (1st generation) exposed to BPA can produce a daughter (2nd generation) with higher risk of breast cancer.
Many studies show BPA's ability to cause breast cancer.
BPA can interfere with prostate cancer treatment.
Prostate cancer tumors depend on testosterone to proliferate.
Drugs are used to reduce testosterone.
When the tumor is exposed to BPA it no longer requires testosterone to divide and grow.
In 1998 the EPA set BPA's oral reference dose (RfD) at 0.05 mg/kg/day = 50 ppb.
That was believed to provide a 1000x safety margin.
But the calculation was based on observations starting at high doses.
BPA exhibits hormesis.
Tiny doses can have different, greater effects than large doses.
Many studies confirm disruptive effects from extremely low exposure to BPA.
BPA is used extensively in plastics, epoxies, and resins.
The world market for BPA is projected to exceed 6.3 million metric tons annually by 2015.
Common applications include
Automobiles and replacement parts
Baby bottles
Beverage containers
Bottle tops
"Bullet-proof" materials
CDs and DVDs
Cosmetics
Dental sealants, composites, and tooth coatings
Electronic equipment
Flame retardants
Food can linings and other food containers
Medical devices (e.g. blood oxygenators, incubators, dialysis machines)
Microwave ovenware and food containers
Milk and juice containers
Mobile phones
Plastic eating utensils
Plastic windows
Plastic wrap
Polyvinyl chloride (PVC) products
Recyclable plastics #7 (although not all)
Refrigerator shelving
Resins
Sports helmets
Sunglasses
Thermal paper (cash register receipts)
Toys
Water bottles (including Lexan® and Nalgene®)
Water supply pipes
Baby bottles
Beverage containers
Bottle tops
"Bullet-proof" materials
CDs and DVDs
Cosmetics
Dental sealants, composites, and tooth coatings
Electronic equipment
Flame retardants
Food can linings and other food containers
Medical devices (e.g. blood oxygenators, incubators, dialysis machines)
Microwave ovenware and food containers
Milk and juice containers
Mobile phones
Plastic eating utensils
Plastic windows
Plastic wrap
Polyvinyl chloride (PVC) products
Recyclable plastics #7 (although not all)
Refrigerator shelving
Resins
Sports helmets
Sunglasses
Thermal paper (cash register receipts)
Toys
Water bottles (including Lexan® and Nalgene®)
Water supply pipes
BPA is made by Dow Chemical, Bayer, General Electric Plastics, Sunoco Chemicals and Hexion Specialty Chemicals.
Eating packaged food can result in BPA levels similar to natural hormone levels.
A pregnant women risks her baby's health by eating a single serving of food from a BPA-lined can.
Look here for an analysis of BPA levels found in canned foods.
BPA migrates out of polycarbonate water bottles.
An infant drinking 1 quart (946 ml) of fluid from a polycarbonate baby bottle can easily ingest 30 µg BPA daily.
For a 10 lb (4.5 kg) baby that equates to 7 ppb — a level known to cause harm.
Leaching increases exponentially when polycarbonate baby bottles are heated.
Boiling water increases the rate of migration 55x.
BPA continues to leach from baby bottles even after repeated washings, and even if the bottles are not heated.
Glass or PES bottles are a better alternatives.
Consider Green to Grow and BornFree.
Breast milk is best — BPA is present in canned baby formula.
Bisphenol-a was invented in 1891 and investigated for use as a synthetic hormone in the 1930's.
A review of 152 studies looking for harm from low-dose exposure to BPA found adverse affects in 129.
Only 33 found none, including all 12 industry-funded studies.
The quantity and quality of human sperm has decreased over the last 60 years.
The incidence of male genital tract defects and cancers has increased during that same time.
Wildlife are experiencing similar developmental, reproductive and endocrine impairment.
All of this coincides with the creation and distribution of enormous quantities of hormonally-active synthetic chemicals like BPA and phthalates.
BPA is showing up consistently in human body burden studies, including placental and fetal tissue.
Urine analysis indicates 95 percent of people have been exposed to BPA.
BPA is not the only widespread endocrine disruptor.
Nonylphenol ethoxylate (NPE) is a chemical added to domestic and industrial detergents to boost their cleaning ability.
In the U.S roughly 240 million pounds were produced in 2004 — and an estimated 77 million pounds ended up in U.S. waterways.
Nonylphenol compounds are also used in the manufacture of paper, textiles, paints, lube oils, tires and other products.
Ethinylestradiol is a chemical used in contraceptive pills.
Traces can linger in the woman's body for months or years.
Exposure to this chemical while in the womb can lead to prostate cancer when the male reaches adulthood.
Diethylstilbestrol (DES) is an infamous example.
During the 1940's to 1970's DES was given to pregnant women who were prone to miscarriages.
Many "DES babies" suffered considerable harm to their reproductive systems.
Girls exposed in the womb endured high rates of diseases such as fibroid tumors and endometriosis — leading causes of infertility and hysterectomies.
We now know that DES did its damage during fetal development by activating hormones at a time when they would normally be silent.
As with "newer" endocrine disruptors, the effects of DES appear to pass into at least the third generation.
DES was eventually abandoned.
Today's endocrine disruptors cause harm at far lower exposures than the amounts of DES used.
Many other chemicals have been identified as endocrine disruptors and still more are suspected.
Searching for xenoestrogen, phytoestrogen, mycoestrogen, or pharmacological estrogen will illustrate this.
Plus there are more hormones than just estrogen that get disrupted.
What happens during random, repeated exposures to multiple endocrine disruptors — at the same time other body burden chemicals are present?
That real-world scenario is complex...
More about BPA at
‣ Environmental Working Group —
incudes tips on how to reduce exposure
‣ Safer States
‣ Environmental Health News consensus statement summary
‣ The perspective of a scientist — who happens to be a mother, too
‣ Safer States
‣ Environmental Health News consensus statement summary
‣ The perspective of a scientist — who happens to be a mother, too