Complex sentence: On April 19 2007 researchers identified three additional chemicals in the melamine-contaminated rice protein and animals that had consumed it, including cyanuric acid, a chemical used in chlorinated pools.
Split into simpler sentences: On April 19 2007 researchers announce that they have identified three additional chemicals in the melamine-contaminated rice protein and animals that had consumed it. The chemicals include cyanuric acid, a chemical used in chlorinated pools.