What is BPA (bisphenol A)? Is BPA harmful?
Bisphenol A, often known as BPA is a chemical found in hard plastics and the coatings of food and drinks cans which can behave in a similar way to estrogen and other hormones in the human body. BPA is used to make many products, including water bottles, baby bottles, dental fillings and sealants, dental devices, medical devices, eyeglass lenses, DVDs and CDs, household electronic and sports equipment. BPA can also be found in epoxy resins which is used as coatings inside food and drinks cans.
Bisphenol A is an endocrine disruptor – a substance which interferes with the production, secretion, transport, action, function and elimination of natural hormones. BPA can imitate our body’s own hormones in a way that could be hazardous for health. Babies and young children are said to be especially sensitive to the effects of BPA.
Although public authorities set BPA safety levels, many experts believe these levels should be reviewed after a number of recent studies were published. The Endocrine Society, USA, in 2009 expressed concern in a public statement over current human exposure to BPA.
A CDC (Centers for Disease Control and Prevention) study found 95% of adult human urine samples and 93% of samples in children had bisphenol A.
What are the possible health effects of bisphenol A (BPA) on humans?
- Reproductive disorders – scientists from Brigham and Women’s Hospital showed that BPA exposure can affect egg maturation in humans.
- Male impotence – Dr De-Kun Li, a reproductive and perinatal epidemiologist at Kaiser Permanente’s Division of Research in Oakland, California, reported in the journal Human Reproduction that BPA exposure may raise the risk of erectile dysfunction. Sexual desire and problems with ejaculation were also linked to BPA exposure among men.
- Heart disease (females) – BPA can cause heart disease in women, scientists at the University of Cincinnati found.
- Heart disease in adults – another US study linked BPA exposure to diabetes and heart disease in adults.
- Sex hormones in men – an August 2010 study linked BPA exposure to changes in sex hormones in men.
- Type 2 diabetes – A UK study linked higher levels of urinary BPA to type 2 diabetes, cardiovascular disease and liver-enzyme abnormalities.
- Brain function, memory, learning – US researchers linked BPA exposure to loss of connections between brain cells in primates, potential problems with memory and learning, as well as depression.
- Women’s eggs – Californian researchers found that exposure to bisphenol A may affect the quality of a woman’s eggs retrieved for in vitro fertilization (IVF).
- Chemotherapy – University of Cincinnati scientists found that BPA exposure may reduce chemotherapy treatment efficacy.
- Breast cancer – A Yale School of Medicine study found a possible increase in breast cancer risk among females exposed to BPA and DES (Diethylstilbestrol) in the womb.
- Asthma – A US study suggested a link between increasing asthma rates and a particular threshold of BPA.
A Bisphenol exposure sources
Experts say the main source of human BPA exposure is from bisphenol A leached from the plastic lining of canned foods. BPA found in polycarbonate plastics, especially when cleaned with harsh detergents, high-temperature liquids, or those containing acidic liquids are also sources.
Scientists from Health Canada reported low but measurable levels of BPA in canned sodas (soft drinks). BPA is an ingredient in the internal coating of food and drink cans, used to prevent direct contact with the metal.
Thermal paper and carbonless paper also have varying levels of BPA which can get onto your hands and fingers. Examples of thermal paper commonly used are movie theater tickets, labels and airline tickets. Experts say the problem is not absorption through the skin, much more likely transference from hands/fingers into the mouth (ingestion).
One study found that BPA levels can rise by two-thirds if people drink from polycarbonate bottles.
A breastfed baby will have much lower levels of BPA compared to a bottle-fed baby.
How to avoid A Bisphenol exposure
According to various consumer groups, those wishing to reduce BPA exposure should not eat/drink canned foods and drinks unless the labeling says it is BPA free.
Scientist from the Silent Spring Institute, USA and Breast Cancer Fund, USA report that after just three days on a fresh food diet, BPA and DEHP levels in children and adults fell considerably.
You should not microwave foods in plastic containers. Plastic containers should not be washed in the dishwasher. You should avoid cleaning plastic containers with harsh detergents.
Fetus, infants and young children
Very young and unborn humans are more susceptible to BPA exposure and its effects than adults. This is probably because they cannot eliminate xenobiotics so well. A xenobiotic is a substance found in an organism which is not generally produced or expected to be present in it.
Most urine studies have found higher BPA concentrations in children than adults.
Bottle-fed babies are the most exposed.
BPA and the environment
According to studies, BPA can undermine the reproduction and development of aquatic life, especially fishes. There is also compelling evidence that aquatic invertebrates, reptiles and amphibians are also affected.
Ocean-borne plastic trash can contaminate the environment.
BPA is a major soil pollutant which can interfere with nitrogen fixation at the roots of several types of plants.
A report by the Royal Society, UK, found that BPA has been shown to undermine the reproduction of all animal groups studied. It was also found to induce genetic abnormalities in amphibians and crustaceans.
A Canadian study reported that rivers with BPA contamination had a much higher female-than-male proportion of some types of fishes.