Toxicity of organophosphorus flame retardants

As the development and use of organophosphorus flame retardants have become more prevalent, concerns about potential toxicity are being raised. To date, most studies on potential toxicity have focused on simple phosphate esters and often include both alkyl and aryl esters or, in some cases, even halogenated phosphate esters (which should more properly be included among organohalogen flame retardants). The inclusion of several kinds of esters into a single study leads to muddled conclusions. Each class of phosphate esters should be subjected to toxicity assessment separately. Furthermore, the potential toxicity of the more effective (lower level of oxygenation at phosphorus: phosphonates, phosphinates, phosphine oxides) organophosphorus flame retardants has been little explored. The few results available suggest that these compounds exhibit no or minimal toxicity (lower than that of phosphates?). This represents an area that should be the focus of careful detailed studies to establish any potential toxicity.