The Worldwide Obesity Epidemic: Links to Bisphenol A
By The Editors
In a previous post, we discussed globesity – the escalating global epidemic of overweight and obesity – and said that controlling globesity requires a variety of approaches, including the understanding of the association between obesity and exposure to environmental pollutants.
There are many widespread environmental pollutants that may be contributing to the development of obesity. One of these pollutants is bisphenol A (BPA). In 2012, a study published in the Journal of the American Medical Association indicated that urine BPA is associated with obesity in children and adolescents. Now, results from a study published in the scientific journal PLOS One show that high levels of exposure to BPA might contribute to obesity in girls 9 – 12 years old. The former study involved a U.S. population, while the latter study involved a Chinese population. Therefore, worldwide exposure to BPA in the human population may be contributing to the worldwide obesity epidemic.
What is BPA? According to the US Food and Drug administration (FDA), BPA is an industrial chemical used to make a hard, clear plastic known as polycarbonate, which has been used in many consumer products, including reusable water bottles. BPA is also found in epoxy resins, which act as a protective lining on the inside of metal-based food and beverage cans.
How does BPA get into the body? The National Institute of Environmental Health Sciences tells us that the primary source of exposure to BPA for most people is through the diet. While air, dust, and water are other possible sources of exposure, BPA in food and beverages accounts for the majority of daily human exposure. Bisphenol A can leach into food from the protective internal epoxy resin coatings of canned foods and from consumer products such as polycarbonate tableware, food storage containers, water bottles, and baby bottles. The degree to which BPA leaches from polycarbonate bottles into liquid may depend more on the temperature of the liquid or bottle, than the age of the container. BPA can also be found in breast milk.
In the U.S., BPA has been detected in more than 92% of urine samples, including samples from children. In addition, BPA has been detected in populations from many other countries. The study published in PLOS One was conducted in Shanghai as part of a larger national study of puberty and adolescent health. “This study provides evidence from a human population that confirms the findings from animal studies — that high BPA exposure levels could increase the risk of overweight or obesity,” said Dr. De-Kun Li, principal investigator of the study and a senior research scientist at the Division of Research, Kaiser Permanente Northern California.
Dr. Li and colleagues studied 1,326 male and female children in grades 4 to 12 at three Shanghai schools (one elementary, one middle and one high school). In addition to urine samples collected with BPA-free materials, they obtained information on other risk factors for childhood obesity, such as dietary patterns, physical activity, mental health and family history.
The researchers found that a high urine BPA level was associated with overweight among female students aged 9 –12 years old (likely in pubertal developmental stages), but not in male students. These results are consistent with results from experimental animal studies, where exposure to high BPA level led to weight gain in females, but not in males.
In conclusion, the study suggests that BPA could be a potential environmental obesogen, a chemical compound able to disrupt the normal development and balance of lipid metabolism, which can lead to obesity,
At this point, because the results obtained by Dr. Li and colleagues are consistent with those from studies performed in animal models and other studies performed in humans, it is reasonable to conclude that there is a genuine underlying association between exposure to BPA and obesity.
This article caught my attention, because most Americans associate obesity with “fast-food” or a poor diet, along with a lack of exercise. This author brings up a point, that there can be other underlying factors causing the obesity epidemic in the United States. I looked into BPA further and found numerous side effects it can further cause. (http://www.ncbi.nlm.nih.gov/pubmed/22249005) The results are quite alarming. This article states that BPA are chemicals in worldwide production, with production capacity estimated at 10-billion pounds per year in 2011 for use in manufacturing polycarbonate plastic. Also, at this time there is limited human data relating obesity with environmental chemicals, but there has been an increase in experimental animal research relating environmental chemical exposure to obesity, insulin, and glucose dysregulation, and type 2 diabetes. Findings from these studies have led to an increased awareness that exercise and diet likely do not explain the rate of increase in obesity that has been documented over the last two decades. While the contribution of environmental chemicals to the obesity epidemic remains a largely unexamined issue, the dramatic increase in the incidence of obesity has occurred in parallel with a dramatic increase in the use of plastic . Ultimately, due to all of these facts, something needs to be done to prevent these chemicals from being used and/or placed in every day plastic household items.
It is so sad to learn from this post that we are exposed to BPA via food and drinks. No matter if adults or children, Americans or Chinese, as long as we’re aware of the source of BPA exposure and BPA obesogenic activity, we can limit further exposure to it. However, there is one more and very critical route of exposure to BPA that is difficult to control: from pregnant women to their fetus. In 2011, Nishikawa et al. demonstrated the placental transfer of BPA from pregnant rats to the fetus. And a Chinese group published a paper in the journal Endocrinology showing that perinatal exposure of rats to BPA resulted in increased body weight in the offspring, even if on a normal diet. These findings raise my concern that if prenatal exposure to BPA changes or modify genes that relate to obesity during fetal development, the baby might have a greater risk to suffer obesity in his/her lifetime. To make it clear, if BPA could turn on obesity related genes, or make these genes much easier to be stimulated or induced by environmental factors in the fetus, the babies might be born overweight or have a high chance to be overweight when they grow up.
This article caught my attention, because I did some side research and discovered that 64% of women in the United States of America are obese. (http://win.niddk.nih.gov/statistics/)
I always had the misconception that one’s diet and exercise control the factor of obesity. After reading this article, I have realized that there are more factors that can cause obesity such as BPA. The obesity epidemic needs to stop because it is very unhealthy for our society and the fact that obesity is affecting children is very sad. In a case where an individual eats a proper diet and exercises, but is still obese, then it is appropriate to question the environment. An interesting fact is that BPA is present in water bottles which is quite alarming for our society in this day and age because on average 9 out of 10 people drink from a water bottle on a daily basis. I believe our society needs to find ways to keep away from BPA, and one way I have read about is that there are types of water bottles that do not contain BPA.
Elaborating on obesity being unhealthy, It has a great impact on the immune system due to the occurrence and severity of specific types of infectious illnesses are higher in obese people as compared to normal people together with the occurrence of poor antibody responses to antigens in overweight subjects. When your food is high in sugar and/or fat, or simply just eating too many calories can make you more susceptible to infection. Due to the fact that this will increase the blood sugar or give the chance of getting oxidative damage. Oxidative damage is pretty much overly making reactive oxygen species in it’s comparison to the body’s ability to detoxify cells and this will cause the damage leading to infection.