Objectives: Industrially contaminated sites (ICS) represent an important public health issue in European countries. The Silesian Voivodeship, the region located in the southern part of Poland, the historical center of industry, has many sites that meet ICS criteria. Most of them are landfills containing lead, cadmium and zinc. Material and Methods: The aim of the study has been to evaluate determinants of lead and cadmium blood levels for preschool children living in the vicinity of selected environmental hazards in Piekary Śląskie, the city located in the region of Silesia. Data about exposure was obtained from the parental questionnaire and was verified by levels of biomarkers in children’s blood. Finally, 678 preschool children were studied. Results: Obtained results have confirmed that the statistically significant higher level of lead in blood has been revealed in the case of younger children whose fathers have a higher level of education and whose mothers smoke cigarettes at home, as well as for those living in the vicinity of any environmental hazard. In the case of cadmium, a higher level of the biomarker has been reported for older children who rather do not live close to any environmental hazard. We have recognized 30% of children with blood lead level (PbB) exceeding 2 μg/dl and 0.8% of children with blood cadmium level (CdB) exceeding the reference value (0.5 μg/l). Conclusions: Own observation has confirmed that preschool children living in Piekary Śląskie are still exposed to heavy metals existing in environment. The source of the higher level in blood is not only the hazardous vicinity in the place of residence but also well-known factors associated with the age of children, parental life style and educational background. The parental questionnaire could be useful to identify potential determinants of exposure to lead and cadmium, however exposure must be verified by measurement of a proper biomarker. Int J Occup Med Environ Health 2018;31(3):351–359