More work needed to understand what chemical tags on DNA, proteins mean
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Nearly everything people do, eat or come into contact with can change them in little ways — sometimes with big consequences. Exposure to some chemicals can damage DNA, leading to cancer and other problems. Other molecular changes—chemical tags added to DNA or to proteins called histones — may affect health without injuring DNA.
There are more than 100 varieties of these chemical tags, collectively known as epigenetic marks. While they may help humans and other organisms respond to their environments, the tags can also alter development and body functions in unhelpful, even harmful, ways. Yet people who make decisions about safe levels of exposure to chemicals, heavy metals and other environmental factors generally aren’t including epigenetic alterations in their deliberations.