By Dr. Larry Chiaramonte
In 1968, Virginia Slims cigarettes were launched with the tag line “You’ve come a long way, baby” to appeal to a burgeoning new feminism. Now we find that cigarette habits begun that year among teenage girls may be linked to a higher propensity to asthma among their grandchildren.
Research by Virender K. Rehan, MD, found that pregnant rats given nicotine begat asthmatic pups that begat their own asthmatic pups, even without nicotine exposure in the third generation. The problem extends to rug rats as well as lab rats. Dr. Rehan and another researcher, John S. Torday, PhD, also cited the Children’s Health Study from Southern California, which reported “that grandmaternal smoking during pregnancy increases the risk of asthma in grandchildren regardless of whether the mother smoked or not…They say this multi-generational transmission could explain why 98% of inherited human diseases are unaccounted for by the prevailing view of genetic trait transmission, known as Mendelian genetics.” This comports with findings by Dr. Kari Nadeau that exposure to black carbon not only induces asthma but induces subtle changes in gene expression—epigenetics—that can also be passed down to children and probably grandchildren.
The study is not the only bad news this week under the heading “asthma and the way we live now.” An article published in the Journal of Allergy and Clinical Immunology by researchers at Columbia University—including Matt Perzanowski whose work on black carbon has been discussed here–found a substantial correlation between children’s exposure to the chemical bisphenol A (BPA) and an elevated risk for asthma.
Most of us worry about genetically modified food and chemical additives. In this case, the issue is not what’s in the food, it’s what the food is in; as reported in the Boston Globe, BPA, which is found in hard plastics and the linings of cans, “interferes with the body’s production of certain hormones, has already been linked to increased obesity risks in kids and a heightened likelihood of heart disease, diabetes, and kidney disease later in life.” The new research measured BPA levels in urine and compared those with rates of asthma. The study found a 40 percent increased risk of asthma in inner city children with the highest BPA levels at 3, 5, and 7 years old.
I don’t have any prescriptions for what ails us here. I’m not temperamentally inclined to call for massive new regulations to instantly reverse the legacy of industrial innovation that has landed us in this mess. Our bodies have been assaulted by the new environment, inside and out. Many chemicals interact with the rapidly dividing cells from the first moments of life, making subtle alterations in the way organs and systems develop that have nothing to do with the traits encoded in the DNA. Asthma is one outcome but clearly there are others. I wish we were half as innovative getting out of trouble as we are getting into it.
Image from Virginia Wesleyan College; http://facultystaff.vwc.edu/
Thanks for this wonderful post touching on the newly emerging field of epigenetics! It explains so much about how forces in our environment (nurture) affect how our DNA (nature) gets expressed to make us susceptible to things like asthma and allergies. I don’t know the field terribly well, but do you have any idea how many generations these epigenetic changes may last? I suppose it could be tricky to assess in people, but are there any clues from animal studies? Thanks again for a fantastic post!
Dear Jessica,
Thanks for your response. The field of epigenetics is very new and we follow it very avidly because it provides a plausible framework for so much medical activity of relatively recent vintage. In addition to Kari Nadeau’s piece, we have featured Anne Ellis and Michelle North, “Do Allergies Develop in the Womb?” parts one and two. As to the health of generations to come, I think it’s too soon even with lab rats to ascertain how many generations such changes can last, let alone humans. Unfortunately, with people we face the problem that whatever is inducing these changes is still in our environment and new substances are being introduced all the time, so there’s no way to predict. On a hopeful note, there’s this from Dr. Susan Prescott in our review of her book The Allergy Epidemic:
“In theory, the very fact that modern diseases have increased means they must be modifiable. The same factors that are promoting the disease could also be actively harnessed to reduce the risk of disease.”