17 Conclusions Kwajalein lagoon contains levels of plutonium equivalent to global fallout concentrations. Concentrations of plutonium in tissues of mullet are predictable from relevant concentration factors and water concentrations. The concentration of plutonium measured in two species of reef fish collected during 1975 and 1976 are orders of magnitude lower than concentrations measured in similar or the same species collected during ' 1972 (Ne 73, Se 75). We conclude that the expected dose rates to man from ingested plutonium via the marine food pathway at Kwajalein is 0.005% of the EPA Recommended guideline of 3 mrad/yr to bone (Ep 77). The magnitude of the plutonium levels reported in fish collected from Kwajalein lagoon during 1972 (Ne 73) was excessively high and the concentrations are inconsistent with the present environmental data from the lagoon. Our data shows that concentration factors for plutonium in fish muscle and bone tissues appears to be independent of species, trophic levels and locations which leads us to believe that there is a great deal of validity in the concept of a concentration factor for estimating concentrations of plutonium in fish. DOE ARCHES