aie 407874 Reprinted from ENVIRONMENTAL Science & Technology Vol. 5, July 1971, Pages 634-635 Copyright 1971 by the American Chemical Society and reprinted by permission of the copyright owner Mercury in Selected Fish Protein Concentrates Thomas M. Beasley! Laboratory of Radiation Ecology, College of Fisheries, University of Washington, Seattle, Wash. 98105 m@ Levels of mercury in fish protein concentrates (FPC) have been measured. Concentrates prepared from surface feeding fishes taken from different locales contained 0.3 to 0.9 ppm mercury. These concentrations appear consistent with the knownenrichmentfactors which occur in the chain: water- fish—concentrate. ish protein concentrates (FP) are currently under study as a possible source of protein for the dict of the world’s populations. These products are made by processing whole marine organisms which yield a palatable supplement having a protein content of about 80°% (Ayres, 1966). Previous measurements of radionuclides in rpc have shown that the enrichment of radioactivity through the chain: water— organism-concentrate was significant (Beasle yet al., 1969). Such enrichment processes must also occur in the case of trace elements. Thus, if not removed in processing, undesirable amounts of certain trace elements might be present in final FpC products. In particular, mercury concentrations in these products are of interest, since both natural and industrial input of this clement to the environment is currently a topic of national concern (Abelson, 1970). Therefore, the analysis of a Jimited number of Free products was undertaken to determine whether or not, in the case of mercury, the enrichment processes discussed above were significant. The tee products were obtained from the National Center for Fish Protein Concentrate, College Park, Md. Mercury was determinedin the concentrates by dissolving 10-2 samples with concentrated HNO, and HCIO, acids in a Bethee apparatus as suggested by Gorsuch (1959). High specific activity * Present address: Environmental Sciences Branch. Division of Biology and Medicine, Atomic | nergs Conmunission, Washington. 1D.C. 20544, 634 Environmental Science & Technolory MOE ARCH! 3He (>0.1 Ci/g) was used to determine mercury recovery through dissolution, solvent extraction (Handley and Dean, 1960), and final colorimetric determination using the dithizonate complex of mercury (AoaAc, 1965). Several concentrates were analyzed twice; once as received and a second time after addition of a known amount of mercury. This was done to confirm the validity of yield determinations using ?°*Heg. In all cases, total mercury concentrations agreed well with the sum of the mercury in the concentrate and the mercury which was added. Duplicate analyses were performed for each concentrate. The results in Table I indicate significant concentrations of mercury in these products. The value for alewife taken from Lake Michigan may reflect the input of unusual amounts of mercury to these waters from industrial sources (Abelson, 1970). The concentrates prepared from fishes taken from the open oceans are surprisingly similar in their Hg concentrations. It is interesting to note, however, that Robertson (1970) recently reported fairly uniform concentrations of mercury (~0.1 ug He/liter) in surface water samples taken from the Atlantic and Pacific oceans and Mediterranean sea, Assuming this uniform concentration of mercury in surface waters and an accumulation factor of 103 for He in fishes (Johnels and Westermark, 1969), wet weight concentrations of mercury in surface feeding fishes should approximate 0.1 ppm He. Since a further concentration factor of approximately 5 occurs in the preparation of fish protein concentrates (Brown, 1970), Hg concentrations near 0.5 ppm in these products might be expected. Considering the approximate, rather than the exact, nature of the parameters used in this calculation, the agreecment beiween the observed concentrations of Fable T and those expected is quite good. This suggests that mercury ts Nol removedin the process used to produce these products. The mercury concentrations measured here exceed the as practical residue limit” for marine products of 0.02 10 0.05 ppm established by committees of the Food and Agricultural Organization of the United National (wHo, 1967} and several exceed the “action level” of 0.5 ppm recommended by the LS. Food and Drug Administration. However, Berglund and