Miami: Young babies who are fed formula have far higher levels of arsenic in their bodies than breast-fed infants, according to research released on Monday.

Arsenic in the urine of six-week-old babies who were fed formula was 7.5 times higher than babies who were drinking breast milk, said the study in the February 23 edition of the journal Environmental Health Perspectives.

A total of 72 babies in the northeastern state of New Hampshire were included in the study. Breast milk from nine mothers was also tested and was found to contain very low concentrations of arsenic, the researchers said.

The study found that arsenic levels in tap water far exceeded the amount found in powdered formula, but said that both contributed to arsenic exposure.

“This study’s results highlight that breastfeeding can reduce arsenic exposure even at the relatively low levels of arsenic typically experienced in the United States,” said lead author Kathryn Cottingham of Dartmouth College.

“This is an important public health benefit of breastfeeding.”

Arsenic is found in bedrock and often contaminates well water.

It can be cancer-causing and had been linked to increased fetal mortality, decreased birth weight and problems with brain development.

The study authors urged people, particularly those in rural areas, to have their water wells tested for arsenic.