How Environmental Toxins Affect Our Genetic Behavior
The majority of disease can not be explained by genes alone, including diseases that we commonly think of as being genetic in nature, such as breast cancer. While our DNA is the building block that determines our physiology, biology, and the diseases we get, what many of us do not know is that our environment has the largest influence on the way in which our DNA behaves. A new ground breaking study led by Michael Skinner, PhD at Washington State University, shows how environmental chemicals affect gene activity, resulting in drastically higher disease rates which increase in our offspring for many generations.
In his lecture “Ghosts in Your Genome?” at Mount Sinai yesterday, Skinner explained that we already know the environment has a massive impact on disease frequency because of the difference in regional disease rates ie. there are lower rates of heart disease for people living in Japan versus the US which is not due to the genetic coding of the Japanese, since a Japanese person that moves to the US will assimilate into the same environment and acquire the same risk factors for heart disease. There are also data that show that genetic mutations are associated with disease in low frequencies. This is not new news.
The recent study by Dr. Skinner and his team shows new data that exposure to the synthetic chemicals BPA, pthlalates, DEET, permethrin, dioxins and jet fuel during a certain critical developmental stage in pregnancy results in disease in offspring. The effects mostly involve endocrine disruption, resulting in a host of reproductive diseases, infertility, premature menopause, and premature death of sperm-forming cells. What was both surprising and alarming was that the incidence of disease increased for the future generations that never even encountered the triggering pollutant.
In the study, the highest rate of disease occurred in the third generation out (the child of the exposed pregnant female’s fetus once it matured and gave birth). 100% of females in the third generation developed polycystic ovarian disease, 90% of the females experienced premature puberty, and 90% had premature ovarian failure, among other diseases. According to Skinner, rather than altering genes, the tested pollutants altered chemical switches that regulate genes, known as “epigenetic” switches that can lock a gene on or off.
What Does This Mean For Us?
While the majority of us haven’t been exposed to Agent Orange or jet fuel repeatedly, all the chemicals tested in the study “promoted epigenetic transgenerational changes.” Skinner says that now he suspects most pollutants have the potential to do this, as opposed to one or two harmful substances. We are most exposed to phthalates in our food and personal care products, BPA in plastics, and pesticides and fungicides in our produce. While one might conclude that our children and grandchildren are doomed based on our exposure to phthalates and BPA alone, there are some steps we can take to reduce our exposure.
Choose Organic Produce
The data in Skinner’s study presents a strong scientific argument for the importance of eating organic whenever possible. Studies have shown that families that eat mostly organic were able to reduce the pesticides in their urine by 90%. The good news is, the standards for what constitutes as “organic” have recently become more strict (pesticide use is close to zero) and larger production volumes of organic produce have brought the price down significantly in the past five years (just today I noticed on Fresh Direct the price of organic cilantro was the same price as conventional)! It is especially important to buy organic produce that is typically higher in pesticides when grown conventionally, which includes apples, bell peppers, blueberry, celery, cherries, grapes, kale, nectarines, peaches, potatoes, lettuce, spinach and strawberries (generally when the skin is thin and porous and often consumed). Check out the EWG’s Guide To Pesticides In Produce.
Eat a Hormone-Free Diet
Hormones in animal products cause endocrine disruption in humans. Meat in the US contains 6 hormones (which is permitted in the US but not in other areas of the world that have higher standards such as the EU) and meat also contains phthlalates. During the Q&A session yesterday, Shanna H. Swan, PhD explained that it is also generally wise to limit meat for cardiovascular health, and when doing so we must ensure adequate protein intake. We like beans, lentils, tempeh, and quinoa as vegan protein sources.
Read Ingredients On Personal Care Products
Avoid products containing phthalates and parabens. While research on parabens has shown only weak estrogenic activity and remains largely inconclusive, phthalates are proven endocrine disruptors that alter genital development and sex hormones, which mold sex differences in the brain (and thus behavior). Dr. Swan’s 2009 study of prenatal phthalate exposure among preschool children showed that when the concentrations of two common phthalates in mothers’ prenatal urine are elevated their sons are less likely to play with male-typical toys and games, such as trucks and play fighting. Phthalates are also thought to increase the development of breast cancer. Most Americans tested by the Centers for Disease Control and Prevention have metabolites of multiple phthalates in their urine.
Children’s exposure to phthalates is greater than that of adults. A 2008 study showed that “reported use of infant lotion, infant powder, and infant shampoo were associated with increased infant urine concentrations of [phthalate metabolites], and this association is strongest in younger infants. These findings suggest that dermal exposures may contribute significantly to phthalate intake and “young infants are more vulnerable to the potential adverse effects of phthalates given their increased dosage per unit body surface area, metabolic capabilities, and developing endocrine and reproductive systems.” Women may be at higher risk for potential adverse health effects of phthalates due to their greater use of cosmetic products. Diethyl phthalate and dibutyl phthalate are especially common in cosmetics and personal care products.
Avoid BPA, Bottled Water, and Heated Plastic
BPA is an endocrine disruptor and may present neurological difficulties after prenatal exposure. A 2011 study that investigated the number of chemicals pregnant women are exposed to in the U.S. found BPA in 96% of women. BPA is still contained in some plastics in the US, although it was declared to be a toxic substance in Canada in 2010 and it is banned in baby bottles in both Canada and the EU.
Choose safer plastics, those labelled 1, 2, 4, and 5. Avoid plastics labeled 3, 6, and 7. It is also advisable to avoid bottled water all together, since many studies have found phthalates such as DEHP in bottled water and soda, even in category “1″ plastic bottles, which are thought to have phthalates introduced during plastics recycling. Bruce D. Gelb, MD, Professor of Human Genetics at Mount Sinai School of Medicine says do not ever heat tupperware, saran wrap, or anything plastic in the microwave – use glass instead. Avoid plastic-lined paper coffee cups, soup cups, and other disposable food containers. Bring your own stainless steel, glass, or ceramic thermos or mug!
Gelb also says that tap water is safer than bottled water. Old buildings may pose threats of lead and other toxins being leached into tap water through the pipes. One (free) approach is to run the tap every morning for a few minutes to flush out the water that sat in the leaching pipes overnight. Another approach is to install a water filtration system. If fluoride (an endocrine disruptor) is added to your local tap water, consider installing a reverse osmosis or activated alumina water filter.
This discovery of epigenetic biomarkers and how they react to synthetic chemicals in our environment is a huge advancement for preventative medicine that could make it possible to identify our disease biomarkers at a young age. Skinner says “we might actually have a means in the future to use epigenetic biomarkers to asses what you – or your ancestors – were exposed to earlier in life.” Dr. Skinner’s research has been highlighted in BBC and PBS documentaries and was selected in the top 100 discoveries by Discover magazine in 2005 and 2007.
Image Sources: Chemical Sensitivity Network; EWG
Data Sources: ScienceNews: Pollutants long gone, but disease carries on by Janet Raloff; Gizmodo: You Might Be Infertile Because Your Grandparents Were Mucking Around in Harmful Chemicals by Kristen Philipkoski; Environmental Health Perspectives: Polyethylene Terephthalate May Yield Endocrine Disruptors by Leonard Sax, Montgomery Center for Research in Child and Adolescent Development, Exton, Pennsylvania, USA; Science Daily: Phthalate Exposure Linked to Less-Masculine Play by Boys Nov. 16, 2009; International Journal of Andrology: Prenatal phthalate exposure and reduced masculine play in boys Nov 16. 2009; Environmental Health Perspectives: Decrease in Anogenital Distance among Male Infants with Prenatal Phthalate Exposure; Cancer.org; Lopez-Carillo, L., Hernandez-Ramirez, R.U., Calafat, A.M., Torres-Sanchez, L., Galvan-Portillo, M., Needham, L.L., Ruiz-Ramos, R., & Cebrian, M.E.(2010). Exposure to phthalates and breast cancer risk in Northern Mexico. Environmental Health Perspectives, 114 (4), 539-544. Pediatrics.org: Baby Care Products: Possible Sources of Infant Phthalate Exposure; Science Daily: 99% of Pregnant Women in US Test Positive for Multiple Chemicals Including Banned Ones, Study Suggests, January 14, 2011; How to Remove Fluoride from Drinking Water; Oestrogenic activity of parabens in MCF7 human breast cancer cells, J Steroid Biochem Mol Biol. 2002 Jan;80(1):49-60.
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