An evaluation of the risks to human health and the environment posed by exposure to three flame retardants: tris(1-chloro-2-propyl) phosphate (TCPP), tris(1,3-dichloro-2-propyl) phosphate (TDCPP), and tris(2-chloroethyl) phosphate (TCEP). In view of their many similarities, TCPP and TDCPP are covered together. Data on all three flame retardants are limited and largely confined to studies of environmental levels and adverse effects detected in experimental animals and "in vitro" test systems. The monograph on TCPP and TDCPP describes manufacturing processes and summarizes current use. For both chemicals, studies show that residues are found infrequently and at low concentrations in food items. In view of the low volatility of both chemicals, the report concludes that human exposure from these sources will be very low and will not present an acute health hazard for the general population. Likewise, no adverse effects on the environment are anticipated from the use of either of these flame retardants. The second monograph evaluates TCEP. Experimental studies show low to moderate acute oral toxicity. In repeat dose experiments, TCEP caused adverse effects on the brain, liver and kidneys. The report concludes that TCEP is not an irritant to the eye or skin and is not teratogenic, although some adverse effects on the fertility of male rats and mice have been demonstrated. Data indicating low environmental exposures support the conclusion that TCEP poses a very low risk of adverse health effects for the general population.