Some homes in the United States still teem with potentially dangerous chemicals that were banned years ago, researchers have found. And they’re coming from the most comfortable seat in the house. For example, the flame retardant PentaBDE, which belongs to a group of compounds called polybrominated diphenyl ethers (PBDEs) and was used to make sofas less flammable until being phased out by the U.S. and European Union in 2004, can persist in household dust for years, according to one recently published study that sampled California homes. Another recent study, published in Environmental Health Perspectives, showed that PentaBDE affects concentration and IQ in children whose mothers were exposed during pregnancy.