The Impact of Fertilizers on the Uptake of Manganese in Cherry Belle Radish Plants: Implications for Human Health

Miracle-Gro Singles, Miracle-Gro Shake and Feed, and Vigoro fertilizers are associated with net loss/enhancement of Mn, up to an order of magnitude when referenced to controls in soil, radish vegetables, and radish leaves; Mn enhancements are a factor of 4 to 65 below the daily required intake for humans (2-5.5 mg/day). Manganese levels were measured by atomic absorption spectrometry (AAS). Control soil, radish vegetables, and radish leaves contained 65 μg/g to 146 μg/g (median = 108), 65 μg/g to 357 μg/g (median = 281), and 185 μg/g to 401 μg/g (median = 323) of Mn, correspondingly. Manganese uptake was ten times greater in radish leaves compared to radish vegetables and enhanced by a factor of 3 in soils. Edible radish leaves/vegetables contain 65 times less than human Mn daily requirements. This equates eating 140 lb/day of radish vegetables/leaves. The fertilizers have a minor impact on Mn accumulation in radish leaves/vegetables. The USDA Nutrient Database for radish (0.69 μg/g of Mn) contradicts this notion as one would need to consume ~ 7 to 18 lb/day of radish to satisfy their daily intake. This study complements investigations showing that fertilizers induce minimal uptake of heavy metals in food; simultaneously, the net loss of Mn amounts observed in some samples of radish leaves and vegetables is analogous to the dilution effect of minerals/nutrients in edibles. Although a deficiency/excess of Mn in one's diet may lead to adverse health effects, background inhalation exposure in general public, occupational, and emergency response settings has a greater influence on one's propensity toward developing adverse health effects related to Mn inhalation exposure.