Heavy Metal Accumulation And Spatial Variation In Domestic Chicken Tissues Across Industrial, Urban, And Rural Areas Of Nowshera, Khyber Pakhtunkhwa, Pakistan

Abstract

Heavy metal contamination of food products is an important environmental and public health concern because persistent metals can accumulate in edible tissues and enter the human food chain. This study evaluated the concentrations of cadmium (Cd), lead (Pb), and nickel (Ni) in the thigh muscle, liver, and gizzard of locally raised domestic chickens collected from rural, urban, and industrial habitats in Pabbi, Nowshera, and Jehangira, District Nowshera, Khyber Pakhtunkhwa, Pakistan. Nine locally raised domestic chickens were sampled, with one chicken collected from each habitat (rural, urban, and industrial) within each of the three selected tehsils. In addition, one commercially reared broiler chicken was included as a reference sample. Approximately 1 g of each tissue (thigh muscle, liver, and gizzard) was collected, subjected to acid digestion, and diluted to a final volume of 50 mL before analysis. The concentrations of cadmium (Cd), lead (Pb), and nickel (Ni) were determined using atomic absorption spectrophotometry. Because the three tissue samples were obtained from the same individual chickens and the number of independent chickens was limited, non-parametric statistical tests were used to assess differences among tissues and habitats. The Friedman test showed a significant difference in Cd concentration among tissues (χ² = 7.26, p = 0.027), whereas differences in Pb (p = 0.169) and Ni (p = 0.459) were not significant. Habitat-related differences were significant for Cd in the gizzard (H = 6.87, p = 0.032) and Ni in the liver (H = 6.44, p = 0.039). Several individual tissue samples contained metal concentrations exceeding the reference limits reported in the study, including Pb (7.50 mg/kg) in muscle and Cd (4.70 mg/kg) in liver. In the broiler reference chicken, Cd was detected in the liver and gizzard, whereas Pb and Ni were below the reported detection limit. Overall, the findings demonstrate spatial and tissue-specific variation in heavy metal accumulation in locally raised domestic chickens and highlight the potential food-safety implications of environmental metal exposure in the study area. Larger studies with increased sample sizes and assessment of environmental exposure pathways are recommended to better characterize contamination levels and associated health risks.