Petroleum production is accompanied by the production of saline water, called 'produced water.' Produced water discharged into fresh water streams, estuarine, coastal and outer continental shelf waters can contain enhanced levels of radium isotopes. This document reports on the first phase of a study to estimate the risk to human health from radium isotopes in produced water. Data collected at produced water outfalls in Louisiana were reviewed to determine their usefulness for developing estimates of environmental radium concentrations resulting from produced water discharges. Major gaps and uncertainties in the available data were identified. The first phase involved five major steps: (1) Evaluate the usefulness of available outfall data for developing estimates of radium environmental concentrations; (2) Review the literature on the bioaccumulation of radium by aquatic organisms; (3) Review the literature on the effects of radiation on aquatic organisms; (4) Review the Information available concerning the human health risks associated with exposure to Ra-226 and Ra-228; and (5) Perform a worst-case, screening-level assessment of the health and environmental risks posed by Ra-226 and Ra-228 discharged in produced waters.