Health authorities have assured the public Victoria’s water supply is safe after US experts raised concerns about the impact of high levels of fluoride in drinking water on children’s IQs.

Melbourne Water adds less than 1 milligram of fluoride a litre to the water supply to help prevent tooth decay, a Melbourne Water spokesman said, and adding fluoride to drinking water was required by Victoria’s health laws.

A spokesman for Victoria’s Department of Health said fluoride was safe and effective.

”It prevents tooth decay and the very controlled way it is introduced into Victoria’s drinking water supply should give us no cause for concern,” he said.

A review by US chemical experts published in The Lancet Neurology on Saturday said studies, mainly from China, suggested high levels of fluoride in drinking water reduced the IQ of children.

Democratic Labour Party Senator John Madigan said people should have a choice about ingesting fluoride. The Department of Health water fluoridation information line is 1800 651 723.