Contaminación de agua, pasto, leche y queso por plomo y mercurio en la microcuenca Llallimayo de Melgar-Puno

River pollution by heavy metals of mining origin is an emerging problem in the Andes of Peru, with effects on animal health, human health, and environmental health. The objective of this study was to evaluate the contamination of water, pasture, milk, and cheese by lead and mercury in the Llallimayo-Melgar-Puno micro-watershed, located in the area of ​​influence of the Arasi S.A.C. gold mine. The samples were obtained in the micro-watershed by random sampling. The lead and mercury content in the samples was determined by atomic absorption spectrophotometry. The results indicate that lead levels were higher than the maximum permissible limits in water (53.5 ± 19.8 mg/L), milk (50.6 ± 18.3 mg/L), and cheese (45.9 ± 13.0 mg/kg), but not in grass (30.3 ± 14.1 mg/kg DM) in accordance with DS No. 004-2017-MINAM-Peru. Mercury levels were also higher than the maximum permissible limits in water (7.25 ± 1.41 mg/L), but lower than the maximum permissible limits in pasture (5.17 ± 1.26 mg/kg DM), milk (5.17 ± 2.33 mg/kg), and cheese (6.94 ± 4.25 mg/kg). Consequently, water, milk and cheese in the Llallimayo-Melgar-Puno micro-watershed are contaminated with high levels of lead with obvious implications for animal health, human health, and environmental health, while mercury is found at high levels in water, but not in pasture, milk or cheese.