The US Food and Drug Administration has concluded that levels of arsenic in rice are too low to cause short-term health effects.

The FDA tested 1,300 samples of rice and rice products after consumer reports in 2012 urged the government to limit arsenic in rice after tests of more than 60 popular products.

Foods such as Kellogg's Rice Krispies and other brands of infant cereal contained some level of inorganic arsenic, a known human carcinogen.

In the rice grains, the average levels of arsenic ranged from 2.6 to 7.2 micrograms per serving, with instant rice at the low end of the range and brown rice at the high end.

"One of the things we need to emphasise is that arsenic is a naturally occurring contaminant, and because it's in soil and water, it's going to get into food," said Senior Advisor for Toxicology Suzanne C. Fitzpatrick. "It's not something that we can just pull off the market.”

Arsenic is a chemical element distributed in the Earth's crust. Human activities such as fuel burning, mining and the use of arsenic compounds in pesticides have also added arsenic to the environment. But scientists say even if you stripped all human contributions, there would still be arsenic in food.

And rice is particularly vulnerable. "Rice is grown in water and takes in arsenic. You're going to see greater levels in rice than in other foods," said Ms Fitzpatrick.

The FDA's next step will be to use new tools that provide greater specificity to analyse the long-term effect of exposure to arsenic in rice.

Risk assessment teams will also consider if certain segments of the population are more vulnerable because of their lifestyle (such as ethnic groups that eat a lot of rice) or life stage (pregnant women and children).