Epigenetics story neglects need to reduce current exposures.
A well-written article in Time Magazine overviews the burgeoning field of epigenetics and how manipulating epigenetic changes holds promise for curing diseases, but the article neglects to explain that limiting current environmental exposures could prevent the harmful epigenetic changes that cause disease in the first place.
Epigenetics involves the study of chemical changes that occur to DNA and the proteins that organize it. These changes do not alter the DNA sequence so the genetic code remains the same. The changes do affect gene expression – whether genes are turned on or off. Altering gene expression can have huge repercussions on normal cell function and, in turn, the health of organisms, regardless of whether the organisms are bacteria, plants or humans.
Author John Cloud discusses in his article how environmental factors such as poor nutrition and smoking can cause epigenetic changes that can not only affect a person's health but the health of their future children. Some of these environmental factors involve a personal choice: smoking harms the smoker, which is a fact that even tobacco companies acquiesce. But, the idea that smoking may predispose your children to obesity and other related health concerns might give some smokers pause.
A broader point – which is implied but not directly stated in the article – is that some of the things that cause harmful epigenetic changes can be purposely avoided. Preventing harmful epigenetic changes is an idea that holds even more promise for the future than using drugs and medicines to modify those changes once they occur.
Contaminants are another type of environmental factor. Contaminants such as lead, PCBs and particulate air pollution are some of the many toxicants known to cause epigenetic changes. For example, the lead burden in pregnant women can cause epigenetic changes in their newborn children, according to a study that evaluated DNA in blood from the umbilical cord (Pilsner 2009*).
More research is needed to sort out the exact consequences of epigenetic changes caused by lead and other environmental contaminants. However, the substances are already known to be harmful in other ways. Indeed, waiting for further epigenetic studies to precisely define the ways these substances cause harm is not needed in order to decide to take steps to lessen exposure.
It is not always easy to avoid environmental contaminants. For various reasons, people might not have a choice about where they live. Those in inner city neighborhoods may not be able to avoid the substandard housing that is contaminated with lead paint and dust. Other exposures are even more out of our control and occur regionally because of the air we breathe and the food and drink we consume. These exposures are not easily changed on a person-by-person basis.
When avoidance is impossible, a concerted effort is needed to invest in the remediation of contaminated areas (such as lead-contaminated housing) and to more aggressively reduce the production and spread of current contaminants (such as air pollution). Short-term investments done now to improve the current state of environmental health can have a large, long-term payoff, namely the reduction of future harm caused by epigenetic changes in the present and future generations.
The article would have been strengthened and readers would have gained perspective had the author also discussed limiting exposures to prevent epigenetic changes.
*Pilsner, RJ, H Hu, A Ettinger, BN Sánchez, RO Wright, D Cantowine, et al. 2009. Influence of prenatal lead exposure on genomic methylation of cord blood DNA. Environmental Health Perspectives. doi: 10.1289/ehp.0800497.
