Evaluation of heavy metal concentration in drinking water, feed, and milk of dairy cows in Kombolcha metropolitan town, Ethiopia

Abstract

Cadmium (Cd), chromium (Cr), and lead (Pb) are significant industrial pollutants that contaminate soil, water, plants, and food, posing severe health hazards. Chromium, in particular, is associated with respiratory, kidney, and reproductive issues. In Kombolcha, untreated industrial wastewater increasingly threatens agricultural productivity and water quality. This study examined heavy metal contamination in dairy cows' feed, drinking water, and milk. A cross-sectional survey and laboratory tests using a flame atomic absorption spectrophotometer analyzed 40 samples from water sources, feed, and milk. Water samples showed mean Pb levels of 0.0205 ± 0.004 mg/L and Cd at 0.0112 ± 0.0029 mg/L, with Cr below detection. In elephant grass, Cd was 1.47 ± 0.0016 mg/kg; Cr 1.87 ± 0.115 mg/kg; and Pb 11.4 ± 0.0031 mg/kg. While Cr and Pb in hay and brewery grain were within safe limits, levels in elephant grass and some milk samples exceeded international safety standards. The findings highlight the vital need to improve wastewater treatment and strengthen health protections.