Toxic Heavy Metals in Vegetables and Forage Grasses in Missouri’s Lead Belt

Abstract

Abstract Missouri supplies approximately 75% of the U.S. production of lead. Lead poisoning of horses in the vicinity of one smelter alarmed local residents about the possible hazards of consuming their fruits and vegetables. County Extension Directors selected cooperators in 7 counties in the lead mining and smelting area and 3 “control” counties in N.C. Missouri to grow lettuce, radishes, and greenbeans for toxic metal analysis. Seed and cultural instructions were furnished all cooperators. All samples were washed in distilled water. Atomic absorption analyses detected the following maximum levels of Pb in μg/g dry weight: lettuce leaf 1324, radish root 518, and greenbean pods 136. Cd levels in μg/g dry weight were as follows: lettuce leaf 34.5, radish root 13.7, and greenbean pods 8.5. Vegetables from control counties contained markedly lower levels of Pb and Cd. Only one smelter is located in the new mining area and considerable Pb ore (essentially powdered PbS) is transported by rail or truck to smelters in older mining areas of S.E. Missouri. Forage grasses (Festuca arundinacea and Tridens flavus) were collected along ore truck and control routes. Maximum levels of Pb (4350 μg/g dry weight, unwashed) and Cd (4.32 μg/g) were detected in samples along highway rights-of-way of ore truck routes. Considerably lower levels were detected along control routes.