The US government has communicated that it is seriously planning to restrict the amount of perchlorate, which is a chemical in rocket fuel, explosives and bleach, and also found in the drinking water consumed by millions of Americans.
Studies have shown a link between consuming perchlorate and thyroid problems in pregnant mothers and babies, the Environmental Protection Agency said in a statement.
"Scientific research indicates that perchlorate may disrupt the thyroid's ability to produce hormones that are critical to developing fetuses and infants," the EPA said.
"Monitoring data show more than four percent of public water systems have detected perchlorate and between five million and 17 million people may be served drinking water containing perchlorate."
The EPA said it decided to reverse the decision in 2008 by the George W. Bush administration not to regulate water for the chemical, after the agency received 39,000 public comments and reviewed research by health experts.
"Our decisions are based on extensive review of the best available science and the health needs of the American people," said EPA administrator Lisa Jackson.
The establishment of the first-ever national standard for perchlorate "will include receiving input from key stakeholders as well as submitting any formal rule to a public comment process," the EPA said.
Senator Barbara Boxer, who heads the Senate Committee on the Environment and Public Works, hailed the EPA decision.
"Perchlorate is a toxic chemical found in rocket fuel. It does not belong in our drinking water," Boxer, a Democrat from California, said at a hearing.
Boxer said that the Bush administration, by refusing to regulate perchlorate, had left "millions of Americans in dozens of states at risk."
The chemical can be either naturally occurring or man-made, and is used in making rocket fuel, fireworks, flares and explosives. It may also be present in bleach and in some fertilizers, the EPA said.
The EPA added that it is "moving towards establishing a drinking water standard to address a group of up to 16 toxic chemicals that may pose risks to human health."