Infant toenails can accurately predict arsenic exposure before birth, according to a new study by the Dartmouth College.

Researchers said that the fetus begins to grow toenails during the first trimester - a reliable way to measure arsenic exposure during the entire gestation period. They also said that utero and early-life exposure to arsenic may have detrimental effects on children, even at the low to moderate levels.

Previous studies showed that prolonged arsenic exposure from water and food causes certain forms of cancer and skin lesions, and heightens the risk of heart disease and diabetes.

For the study, the researchers determined the infant's exposure to low arsenic in utero by evaluating infant toenails using plasma mass spectrometry. The study involved 170 mother-infant pairs from New Hampshire.

The researchers found that doubling of maternal postpartum toenail arsenic concentration lead to a 54 percent increase in infant toenail arsenic concentration when compared to 20 percent following the doubling of maternal urine arsenic concentration. Plus, the doubling of maternal toenail and urine arsenic concentrations was linked with a 68 percent increase in infant toenail arsenic concentration.

Researchers observed similar outcomes in a group of 130 mother-infant pairs from Rhode Island.

"In utero exposure to arsenic occurs through maternal drinking water and dietary sources, and infant toenails appear to be a reliable biomarker for estimating arsenic exposure during the critical window of gestation," said senior author Professor Margaret Karagas in a press release.

The finding is published in the Journal of Exposure Science & Environmental Epidemiology.