According to the consumer update released Monday, the FDA said arsenic is part of the Earth's crust and is in very small amounts of water, air and soil.

As vegetables and plants grow, arsenic becomes absorbed into the food.

The FDA emphasizes that it cannot be removed completely.

The way rice grows leads to it absorbing more arsenic than other crops.

The FDA said the concern is inorganic versus organic forms of arsenic. The former is more toxic.

The terms refer to chemical elements: "If arsenic atoms bond with carbon, the compound is organic. If there’s no carbon present, it’s inorganic."

Arsenic, which is a carcinogen, has led to heightened concerns about its health effects on fetuses and growing infants.

Rice cereal became a concern when the FDA determined that infants consume three times more rice that adults because of it is often the base of a baby's diet.

Potential health effects of high levels of inorganic arsenic during pregnancy may lead to delays in infant learning development.

"Related to cancer, FDA estimated that exposure to inorganic arsenic in rice and rice products ... would account for far less than 1 percent of the nation’s lung and bladder cancer cases."

When a commenter questioned the presence of arsenic in the food in the first place on Facebook, the FDA said, "Arsenic occurs both naturally in the environment and as a result of human activity, including from erosion of arsenic-containing rocks ... contamination from mining ... and previous or current use of arsenic-containing pesticides."

The FDA said those caring for an infant or expecting one should do the following feed their baby iron-fortified foods beyond rice cereal fortified with iron, such as multigrain and oat cereal.

Toddlers should have a diet with a variety of grains, such as wheat and barley.

Pregnant women should also consume a variety of grains.

More information can be found at the FDA website.