Maryland has become the first state to ban an arsenic additive in chicken feed, according to reports.

A law banning the additive took effect on January 1. In 2012, the state approved a bill banning the use of roxarsone, a chemical used to help the birds grow and fight parasites. Pfizer Inc., which distributes roxarsone, stopped selling the chemical in July 2012 after a U.S. Food and Drug Administration study found higher levels of inorganic arsenic in chicken treated with the additive than those that were not.


Opponents said the measure wasn't needed because the company voluntarily suspended sales of the product.