Introduction: Currently in Colombia, agricultural and mining activities are a source of contamination by heavy metals. The municipality of Montelíbano, Córdoba is characterized by the exploitation of nickel, since one of the deposits of this metal is located. Agricultural activities are carried out, Arsenic can be involved. In Colombia, there is little evidence regarding the exposure of these heavy metals and the interactions between these substances. Objective: To determine the exposure to arsenic and nickel, the levels in environmental matrices and the association with some related factors, Montelíbano, Córdoba. 2021. Materials and methods: Descriptive cross-sectional study with non-probabilistic sampling of 100 individuals. 63 occupationally exposed and 36 environmentally exposed. Biological (hair) and environmental (water and fish) samples to measure nickel and arsenic levels. Results: 95.24% of the occupationally exposed people were men, 63.89% of the environmentally exposed people were men. 63% had a trade, 90.48% worked in mining and 9.52% were farmers. The majority of the population did not reside in industrial zones. The median age of the occupationally exposed persons was 54 years, the median of the environmentally exposed persons was 59.50 years. 41.27% of occupationally exposed people ate food while working and did so daily. 77.78% of the occupationally exposed wear gloves and 68.25% wear a respirator. 80.95% of the occupationally exposed used leather boots. Most of the population consumed tap and filter water. The most consumed fish was the Bocachico 1 to 2 times a week. Nickel and arsenic concentrations in hair are above the reference value (both populations). Statistical analyzes and correlations between metal levels in hair, sociodemographic and occupational variables are presented. The presence of arsenic and the use of personal protection elements influence nickel concentrations in hair. A slight but significant correlation is found between the levels of nickel and arsenic. Conclusion: In the study area there is environmental and occupational exposure to mixtures of heavy metals, directly to Nickel and indirectly to Arsenic. It is recommended to carry out studies that allow solving the evidenced limitations and delve into the biomonitoring of mixtures of metals and chemical substances, and thus obtain information, and an overview regarding this problem not only in this municipality in particular, but in the country.
