Many pillows now carry CertiPUR-US certification. This seal exclusively applies to the synthetic foam in a pillow and shows that the foam is slightly less toxic and bad for the environment than conventional polyfoam. CertiPur foam is free from polybrominated diphenyl ether (PDBE) and some of the most hazardous chemical flame retardants, and the foam is tested for formaldehyde, mercury, lead, and other heavy metals, and regulated phthalates.  Still, even CertiPur foam is, well, synthetic. The petroleum-based product will still off-gas some VOCs, is made with fossil fuels, and is not biodegradable or remotely eco-friendly.