Solanum tuberosum L. contain bioactive compounds such as glycoalkaloids and nitrates, which in high concentrations can be harmful to human health. It was demonstrated that the content of harmful substances in both groups of analysed compounds depended to a large extent on the variety, environmental and agrotechnical factors. The highest content of glycoalkaloids was found in the Eurostar variety with light yellow flesh, and the lowest average content of these compounds was recorded in the Salad Blue variety with purple flesh. In the case of nitrates, the lowest average content was also found in the Eurostar variety, and the highest in the Rote Emmalie variety with red flesh. Analysis of the results from individual years of research showed that the highest accumulation of both TGA and nitrates occurred in 2021, while the lowest values were recorded in 2023. During the three years of the field experiment, air temperature and total precipitation were recorded. Based on the collected data, the Sielianinow hydrothermal index (K) was calculated. In 2021 and 2022, the values of this index were classified as optimal, while in 2023 the conditions were described as very dry. The results obtained indicate that the concentration of most undesirable substances was within the applicable food safety standards, although some varieties showed elevated levels of glycoalkaloids and nitrates, which justifies the need for further monitoring of their content.