The determination of lead in seafoods

Includes bibliographical references.During the summer months of 1972, a study was undertaken to ascertain the lead concentration of the following canned and fresh seafood products: crab, herring, clams, tuna, salmon, and shrimp. Wet ashing was employed as the technique of extraction, with atomic absorption spectrophotometry being used as the method of analysis. In addition the study attempted to (1) compare lead levels of organisms from different trophic levels, (2) compare the lead concentration of the various canned products with their fresh food counterparts and (3) compare lead levels of different brands of the same canned food. The mean lead concentrations of the six canned food species were as follows (in ug Pb/g dry weight): clam; 3.85, crab; 3.07, shrimp; 3.02, salmon; 1.72 tuna; 1.64, and herring; 1.40. The following were the mean lead values of the six fresh food species (in ug Pb/g dry weight): crab; 4.07, clams; 3.06, shrimp; 2.06, herring, 1.69, tuna; 1.26, and salmon; 1.02. Nested analysis of variance revealed significant differences in mean lead concentrations between the six species of canned food, but not between the brands of a given species. It was determined that a significant difference also existed between the six fresh food species, but no significant difference was detected between a canned food species and its fresh food counterpart. It was found that trophic level in the food chain could not be used as an indicator of an organism's relative lead concentration. A relationship was found to exist, however, between lead concentration and class of organism, with fresh and canned shellfish displaying significantly higher lead concentrations than both the fresh and canned fish. Possible factors which could influence this relationship, such as differences in habitat, physiological differences, and shell deposition, are discussed. The problems of lead contamination due to the canning process, and the establishing of federal, standards for the lead content of foods are also discussed.M.S. (Master of Science