Home gardeners who repeatedly use certain "organic" fertilizers made from sewage sludge may be eating more contaminated produce than supermarket shoppers. As a result, their kidneys and hearts may be damaged.
The reason: Use of such fertilizers often results in unsafe cadmium levels in produce, says Al Page, PhD, soil scientist at the University of California, Riverside, and director of the Kearney Foundation of Soil Science.
The World Health Organization and the Food and Drug Administration say that in ambient conditions, cadmium from all sources (liquid, food, atmosphere) should be limited to 70 μg/day. Years of excessive intake can lead to slow, subacute renal tubular damage. Page notes that cadmium is retained by soil as well as the body, so potential problems increase exponentially with time.
Acid soils of southeast, northeast, and some midwest states are naturally high in cadmium. Additives in commercial agriculture increase soil pH; this in turn