Many believe that human populations are at risk from the effects of BPA. Over 200 lab animal studies strongly suggest that BPA exposure creates risks of dangerous developmental, neural and reproductive health effects in infants and children.
The plastic industry continues to claim that there are no credible scientific studies that demonstrate that the BPA that leaches from its products is harmful. They say this despite hundreds of widely reported and published studies that confirm the risks.
Below are examples of more recent studies and how they show a solid link between the ingestion of BPA with the growing health problems of the human population.
BPA has been linked to increased cancer cell growth. A number of studies have shown that exposure to the chemical while in the womb results in breast cancer during adulthood. One such study, conducted in 2006 by T.J. Murray and colleagues from the Department of Anatomy and Cellular Biology at Tufts University School of Medicine, found that prenatal exposure to low doses of BPA increased the risk of developing breast cancer during adult life.
This hypothesis was paralleled in a more recent study funded by the National Institute of Environmental Health Sciences. During the study, conducted by Dr. Ana Soto and colleagues, pregnant female mice were given doses of BPA that fell within the range of expected human exposure. They found that “female mice exposed to BPA in utero from days eight to eighteen of fetal development experience alterations in mammary gland development.”
Numerous studies have also linked low doses of BPA with prostate disease and cancer. One such study showed that when receiving very low doses of BPA in its fetus stage, a developing mouse had increased prostate size due to hyperplasia.
Another study made a startling conclusion regarding BPA and prostate cancer cells. During this experiment, BPA was shown to stimulate human prostrate cancer cells and therefore interfere with standard adult hormone treatment. The study’s authors, using a series of cell culture experiments, added levels of BPA that have been proven present in over 93 percent of people in the United States. This increased a process in prostate cancer cells that renders them less responsive to the standard hormone treatment.
Chromosome Sorting Errors
In 1998, Dr. Patricia Hunt and her colleagues made an accidental but dramatic discovery. During her original research, which did not involve the testing of BPA, Dr. Hunt was shocked to find chromosome errors in the mice she was studying. These mice were being kept in plastic cages and being fed water out of plastic bottles when the research team noticed the chromosomal errors. Dr. Hunt was able to trace the effect to the Polycarbonate cages and water bottles.
Through more extensive research she discovered that BPA can cause chromosomes to sort incorrectly, even at very low doses. The incorrect sorting and lining up of these chromosomes can in turn result in deceases like Down’s syndrome, Turner Syndrome and Klinefelter Syndrome. The findings confirmed that extremely low doses of BPA exposure are linked to an error in cell division called aneuploidy, which may be the culprit in causing up to 20% of all birth defects.
Dr. Hunt made another shocking discovery. Her research found that BPA can lead to chromosomal abnormalities that are able to affect future generations. This means that a pregnant mother ingesting BPA can be directly affecting her future grandchild’s health.
After replacing all the caging materials to non polycarbonate ones, all cell division returned to normal. The results of Dr. Hunt’s research were published in 2003.
Impaired Brain Development
Bisphenol A is known to mimic the action of the hormone estrogen. Some studies have found that in parts of the brain, BPA can have the effect of restricting estrogenic activity. The natural estrogen in a human body usually regulates viability and increases the growth of connections between neurons. There is grave concern that the inhibitory effects of BPA can lead to altered brain development.
Mounting evidence from recent years show that this BPA altered brain development, lead to a number of different potential problems, including hyperactivity and increased aggression, changes in response to painful and fear provoking stimuli, impaired learning and memory as well as other problems.
A 2003 study, which administered BPA to pregnant mice, found that exposure to BPA in the male fetus led to increased aggressive reactions and behaviors.
A Japanese study, published in 2004, found that five-day-old male rats exposed to low doses of BPA exhibited significant hyperactivity at four to five weeks of age.
Another study published in 2004 found that male offspring of rats exposed to BPA significantly failed to avoid being electrically shocked by contacting the same apparatus compared with the control offspring. This revealed that exposure to BPA could have an effect on the developing brain, causing seriously impaired memory
Obesity and Diabetes
BPA has been associated with changes in pancreas and thyroid function, as well as the increased secretion of insulin, which can lead to Type II Diabetes, obesity and hypertension.
In 2002, a Japanese team of researchers at the Ehime College of Health Science discovered that BPA can increase the conversion of embryonic cells into fat cells. Cells treated with BPA also increased their fat content by 150 percent over 11 days. This experiment documented that BPA could trigger and promote the two main processes in developing obesity.
A recent study conducted by Dr. Paloma Alonso Magdalena and her research team unveiled the link between environmental estrogens, such as BPA, and insulin resistance. Their research found that the chronic exposure (at levels currently found in humans) to BPA caused insulin resistance in adult mice. Insulin resistance is a precursor to Type II Diabetes, hypertension and cardiovascular disease in humans.
Reproductive development and sperm defects
BPA has been linked to both sperm defects in males and impaired female reproductive development.
Dr. Motoharu Sakaue and his colleagues in Japan independently discovered that BPA reduces the number of sperm in rats, even when given doses after puberty. After feeding small doses to rats, they noted a generalized decline in the ability of treated rats to produce sperm. These scientists concluded that BPA retarded the development of sperm cells that normally takes place as the male rat’s reproductive system matures. They further concluded that the effects occurred in a dose range “relevant to the daily level of exposure in man.”
A few years earlier, Dr, Frederick vom Saal and his colleagues also linked exposure to BPA with reduced sperm production. They discovered, in their 1998 study, that males born to rats exposed to BPA produced 20% less sperm after they matured that normal males.
In a study published in 2002, researchers discovered that exposure to estrogenic compounds, such as BPA, during critical periods of fetal development could result in adverse effects on the development of reproductive organs which do not become apparent until later in life. During the study, pregnant rats given low doses of BPA gave birth to female rats with vaginal deformations. The researchers concluded that these deformations were triggered by a disruption of the estrogen signal required for normal development.