Polystyrene, polyisocyanurate, and polyurethane are insulation materials that increase energy efficiency and whose use in buildings, especially energy efficient buildings, is growing rapidly. At the same time, the flame retardants currently in use with these materials are often chemicals that are known to be toxic or have not been adequately evaluated for their impact on human health and the environment. For example, all polystyrene foam insulation used in buildings is treated with HBCD, a persistent, bioaccumulative, and toxic flame retardant. The impacts of exposure to flame retardant chemicals upon workers, building occupants, and the environment should be considered when selecting insulation materials. When informed of the problem of toxic flame retardants, the green buildings community can request alternative insulation materials, safer flame retardants, or other strategies to meet fire safety requirements without toxicity.