U.S. health regulators denied a request to ban a chemical used in water bottles, soup cans and other food and drink packaging, saying there is not enough scientific evidence it may cause harm.

The U.S. Food and Drug Administration denied the petition from an environmental group to ban the chemical bisphenol A, or BPA, which has been used for decades to harden plastic or make the epoxy resin that lines tin cans.

But BPA can also leach into food and water from these protective coatings, and environmental and consumer groups argue it can interfere with hormones in humans and cause health problems.

U.S. regulators said studies showing harm have been inconclusive so far, although they continue to review the evidence. The FDA said it would provide an updated safety review of BPA later this year, based on further analysis and government studies.

"I cannot stress enough that this is not a final safety determination on BPA," said Douglas Karas, an FDA spokesman.

The FDA agreed to rule on whether to ban BPA use in food and beverage packaging as part of the settlement of a lawsuit with the Natural Resources Defense Council (NRDC).

The NRDC said studies show long-term exposure to BPA is harmful, especially in fetuses, babies and young children.

"BPA is a toxic chemical that has no place in our food supply. We believe FDA made the wrong call," said Dr. Sarah Janssen, senior scientist at NRDC.

"The FDA is out-of-step with scientific and medical research. This illustrates the need for a major overhaul of how the government protects us against dangerous chemicals."

Consumer concern has already led to discontinuation of BPA use in the production of baby bottles and sippy cups in the United States, the NRDC has said. A sippy cup, which has a lid and spout, allows children to drink without spilling.

In response to further scientific studies, Canada declared BPA a toxic substance in 2010. Both Canada and Europe have already banned it in the production of baby bottles, and France banned it in food packaging.

But use of the chemical remains widespread in food packaging in the United States. BPA is the key compound in epoxy resin linings in cans that keep food fresher longer and prevents it from interacting with metal and altering the taste.

Conflicting studies

Human exposure to the chemical has been found to be widespread, although it has not been definitively shown to cause harm to adults. Babies and young children do not metabolize and excrete the chemical as quickly as adults, which some believe may put them at greater risk.

The environmental groups point to studies that show the chemical can interfere with how the body absorbs the hormone estrogen, leading to behavioral problems in girls, a hormonal syndrome in women, and a variety of physiological effects in animals.

It has also been linked in some studies of rats and mice to cancer, obesity, diabetes and heart disease.

But whether BPA is actually to blame for these health problems is still a matter of debate.

In 2008, NRDC filed a petition with the FDA requesting a ban on BPA in food packaging, food containers and any material likely to come in contact with food.

When the FDA did not respond to the petition, NRDC sued in 2010 asking the court to require the agency to respond. The settlement of a case brought before the U.S. District Court for the Southern District of New York required the FDA to make a decision on BPA use by March 31.

The FDA has previously acknowledged it had concerns about the chemical's effects on the brain, behavior and prostate glands in fetuses, infants and young children.

However, in the statement on Friday, the FDA said recent studies have shown exposure to the chemical in infants is much less than previously estimated.

Trade groups for chemical and can manufacturers say they stand behind the chemical, and point to some studies from governmental health agencies that deem BPA safe and effective for food contact. They also note that its use has substantially reduced deaths from food poisoning.

"Instead of bowing to pressure from activist groups, the agency is relying on science to set public health policy," said Dr. John Rost, chairman of the North American Metal Packaging Alliance, a trade group for canned food and beverage makers.

"A ban without conclusive scientific evidence of risk would compromise the safety of canned foods and beverages enjoyed by millions of Americans everyday," he said in a statement.

Unlike the case with plastic used in baby bottles and sippy cups, there are few economically viable alternatives to the chemical in epoxy resins right now.

Some companies such as Campbell Soup said they have been researching alternatives to BPA, and are planning to phase it out.