The purpose of this study was to determine if there was an elevated health risk due to ingestion of radionuclides (radium-226 and lead-210) or toxic metals (cadmium, lead, and mercury) in fish from lakes on previously mined lands in the central Florida phosphate region. The study lakes comprised four unreclaimed lakes, two reclaimed lakes, three natural lakes (control lakes), and one man-made reservoir. Largemouth bass (Micropterus salmoides), bluegill (Lepomis macrochirus), shellcracker (Lepomis microlophus), speckled perch (Pomoxis nigromaculatus), catfish (Ictalurus sp.), and tilapia (Tilapia sp.), were sampled.
Cadmium was observed sporadically and at low levels, and appears to be an insignificant contaminant for this area. Mean lead levels were generally an order of magnitude below the U. S. Fish and Wildlife 1984-1985 study observation of 0.110 Fg/g. Only 20% of all samples exhibited measurable levels, and almost half of those were confined to two lakes with no difference between natural or impacted lakes. Mercury was found to be widely distributed above 0.005 Fg/g. At 84% positive results, all lakes were affected by mercury to some degree. Natural lakes exhibited a higher trend for mercury than impacted lakes. Radionuclide data did not exhibit significant differences between natural or impacted lakes.
Dart Morales et al., Grove Scientific & Engineering Company. July 2002.