Story at-a-glance: PBDE is a dangerous flame-retardant chemical and has been detected in the highest levels in the world among pregnant women in Northern California. California's strict flammability laws, mandated in the 1970s, caused many manufacturers to add flame retardant chemicals to consumer products, which may explain the high exposure levels. Prenatal exposure to PBDEs may disrupt thyroid function and proper brain development. Tips for reducing your PBDE exposure around your home via PBDEs in Mattresses May Put Pregnant Women in Danger.