Long-term but low-level exposure to cadmium, a metallic element commonly used in batteries and electrical products, may lead to cancer, a study published on Sunday suggests.
Most cancer-causing substances work by directly damaging the DNA of a cell, inflicting changes in the genetic code that causes the cell to proliferate uncontrollably.
Cadmium is a known carcinogenic but the authors say, it seems to work dangerously subtly by targeting a mechanism called mismatch repair, which roots out and fixes mutations that can spontaneously occur in cells after they divide.
If the repair system is inhibited, that allows genetic flaws to be passed on in the cell and its descendants, thus boosting the risk that they will become cancerous.
Inherited glitches in mismatch repair have long been fingered as potential causes for cancer, but the big unknown is whether this mechanism can also be affected by substances in the environment.
Dmitry Gordenin at the US National Institute of Environmental Health Sciences tested several agents to see if they affected mismatch repair in yeast, a closely studied lab subject.
Prolonged exposure to low, non-lethal doses of cadmium increased the level of DNA damage in yeast cells by up to 2,000 times, Gordenin's team reports in Nature Genetics, a specialist monthly journal published by Nature.
"The strong mutagenic action of cadmium was observed at concentrations comparable to those found in the environment and at levels that can accumulate in the human body," they write.
"Further studies are needed to identify conditions and cell types in which cadmium could inhibit human (mismatch repair)," they say. "Even moderate inhibition of (it) has implications for human health."