Blood Metal Concentrations of Manganese, Lead, and Cadmium in Relation to Serum Ferritin Levels in Ohio Residents

The objectives of this study were to assess ferritin-specific profiles of blood metal concentrations such as manganese, lead, and cadmium and to evaluate whether ferritin may affect the behavior of the blood metals in relation to menstruation, menopause, or sex in Ohio residents. Recruited participants included residents from Marietta, East Liverpool, and Mt. Vernon, OH, USA, who were aged 30–75 years and lived at least 10 years in their respective town. The levels of the neurotoxic metals such as manganese, cadmium, and lead were assayed in whole blood. Serum was analyzed for ferritin level [as a biomarker of iron (Fe) status]. An association between blood metal concentrations and independent variables (age, serum ferritin, manganese exposure status, and sex) by multiple regression analysis was assessed, controlling for various covariates such as BMI, educational level, smoking, and alcohol drinking status. Overall, the geometric means of blood manganese, cadmium, and lead levels of all participants ( n = 276) were 9.307 μg/L, 0.393 μg/L, and 1.276 μg/dL, respectively. Log serum ferritin concentrations were inversely associated with log blood manganese concentration ( β = −0.061 log ferritin and β = 0.146 categorical ferritin) and log blood cadmium concentrations ( β = −0.090 log ferritin and β = 0.256 categorical ferritin). Log serum ferritin concentrations were not associated with log blood lead concentrations. Variables of age, sex, and exposure status were not associated with log manganese concentrations; however, log blood cadmium concentrations were higher in older population, women, and smokers. Log blood lead concentrations were higher in older population, men, and postmenopausal women. Our study showed that iron deficiency is associated with increased levels of blood manganese and cadmium, but not blood lead, in Ohio residents. These metals showed different toxicokinetics in relation to age, sex, and menopausal status despite similar relationships between ferritin and metal concentrations.