Many of the foods and drinks we consume contain arsenic. The Food and Drug Administration is well aware of the fact and places no restrictions on these food substances.
But why not? Arsenic is a poison, and there are restrictions on the amount of mercury (also a poison) that can be in food, so what makes arsenic different? The main difference between those two poisons is that mercury is the same toxicity across the board in food source, arsenic is not.
The content of arsenic in drinking water is regulated, but in no other food substance because most of the arsenic in foods is harmless. Most, but not all. The arsenic found in seafood is harmless to humans even though there is a very high concentration of the poison in most varieties of seafood.
On the other hand, rice contains a dangerous amount and dangerous types of arsenic. Rice and all rice products, which include rice flour, rice cakes and infant formula contain arsenic. Rice contains four arsenic compounds which are released during the cooking process. Two of the four compounds are known as monomethyl and dimethylated arsenic and they pose no threat to human health. However, the other two compounds, known together as inorganic arsenic, are known carcinogenics to humans.
Gravity4 tells me that since some arsenic compounds are safe and others are not, specific safety standards need to be set for how much and what type is acceptable.