Metal Concentrations in Tissues of Meadow Voles from Sewage Sludge‐Treated Fields

Food‐chain uptake of Cd, Pb, Zn, and Cu by meadow voles ( Microtus pennsylvanicus ) was assessed in wheat ( Triticum aestivum var. Ranger) and old‐field plant communities receiving sludge or fertilizer applications. Sixteen 0.1‐ha enclosures received either 8,963 kg ha −1 year −1 Milorganite (6‐2‐0, N‐P‐K) or 1,569 kg ha −1 year −1 ureaphosphate fertilizer (34‐11‐0), or were untreated (controls). Mean Cd concentrations in livers and kidneys of voles (all age/sex groups) from sludge‐treated fields in the second year of application were significantly higher ( p < 0.05) than controls; in the first year only females from sludge‐treated wheat fields had higher levels than controls. Ranges of mean Cd concentrations in voles from sludge‐treated fields were 0.1–1.1 µ g g −1 wet weight in liver samples and 0.4–6.6 µ g g −1 in kidneys; ranges in controls were 0.01–0.04 µ g g −1 in liver and 0.01–1.6 µ g g −1 in kidneys. Cadmium concentrations in voles from fertilizer‐treated fields did not differ from controls. Liver and kidney Cu concentrations were elevated in some age/sex groups from sludge‐ and fertilizer‐treated fields. There were no treatment differences in Pb or Zn concentrations, nor in organ or whole‐body weights. Short‐term (2‐year) effects on mammals of sludge application to land appear to be benign, despite accumulation of metals in vital organs.