Arsenic changes DNA activity which may lead to cancer.
Mo, J, Y Xia, Z Ning, TJ Wade and JL Mumford. 2008. Elevated human telomerase reverse transcriptase in blood cells associated with chronic arsenic exposure in Inner Mongolia, China. Environmental Health Perspectives doi:10.1289/ehp.11532.
Exposure to arsenic is thought to cause cancer but how... is still unknown. New research from China suggest that it may be due to arsenic's effect on genes that keep DNA stable.
In the study, researchers examined 324 people in a Chinese population drinking arsenic-contaminated water. Using molecular research tools, they showed that arsenic changes the activity levels of certain genes that control the stability of DNA.
Normal cells show very little or no activity of this gene, which produces an enzyme called telomerase. Hence their telomerase levels are low. Tumor cells, though, generate high levels of the enzyme, so measuring its activity is used to diagnose human cancers.
In the study, arsenic exposure was analyzed chemically in the water and from toenail samples. Participants' blood was analyzed for changes in telomerase activity. The research team found that people with more exposure to arsenic had higher levels of telomerase. This new finding that telomerase activity is increased complements this prior work and implicates arsenic as a tumor promotor.