Authors' contribution Wkład autorów: A. Study design/planning zaplanowanie badań B. Data collection/entry zebranie danych C. Data analysis/statistics dane-analiza i statystyki D. Data interpretation interpretacja danych E. Preparation of manuscript przygotowanie artykułu F. Literature analysis/search wyszukiwanie i analiza literatury G. Funds collection zebranie funduszy Summary One of the main fat-soluble vitamins is vitamin D, whose primary function is the regulation of calcium-phosphate metabolism and mineralization of bone tissue. Vitamin D occurs in two forms: vitamin D2 (ergocalciferol)-found in plants and fungi (mainly yeasts) and vitamin D3 (cholecalciferol)-produced in animals. Hypovitaminosis of vitamin D leads to metabolic bone diseases in children and adults and can also affect the incidence of many chronic diseases such as: multiple sclerosis, diabetes, rheumatoid arthritis, bronchial asthma, cancer, atherosclerosis, coronary artery disease and heart failure. The aim of the current study was to assess the content of vitamin D in dietary supplements available in pharmacies and supermarkets in the EU. The evaluation involved analysing the ratio of vitamin D content in supplements in relation to the typical demand of the organism. This study assessed 15 popular over-the-counter dietary supplements in the form of tablets, capsules, lozenges and lollipops for children as well as in the form of effervescent tablets. On the basis of the labels on the packaging, the vitamin D content of the supplements was assessed in relation to the dietary demands of the body. Self-administration of over-the-counter multivitamin supplements is not an optimal way to increase vitamin D levels. It is recommended, therefore, that individuals requiring vitamin D supplementation seek specialist medical advice to optimal treatment strategies.

Abstract. The article presents the results of research on primary recycling properties of ceramic aggregates conducted following the procedures outlined in WT-1 2014 Aggregates − Technical Requirements. The material for the tests was obtained from a company producing sanitary ceramic products. Damaged ceramic products, coming from the factory waste heaps, were transported to the laboratory and crushed. This enabled producing aggregate that was later subjected to tests carried out on the aggregates commonly used in the production of mineral-asphalt mixes applied in making road surfaces. The factors that were examined include the following: the flow rate of fine aggregates (angularity of fine aggregate), fine particles content -methylene blue test, light-weight impurities content, frost resistance, bulk density of grains as well as water absorption determined by pycnometric method. The test results showed that the properties of the recycled aggregates are similar to those included in traditional aggregates used for the production of mineral-asphalt mixes. On the basis of the conducted analyses, the waste ceramic aggregate was recommended for use.

Authors' contribution Wkład autorów: A. Study design/planning zaplanowanie badań B. Data collection/entry zebranie danych C. Data analysis/statistics dane-analiza i statystyki D. Data interpretation interpretacja danych E. Preparation of manuscript przygotowanie artykułu F. Literature analysis/search wyszukiwanie i analiza literatury G. Funds collection zebranie funduszy Summary Background. The use of groundwater from private wells in households is increasing significantly. However, this water is usually untreated, making it a carrier of diseases. Chemical composition plays a key role in assessing groundwater quality. Due to rapid urbanization and industrialization of the environment, pollutants (especially toxic elements) are constantly being released into the aquatic environment and pose a threat to human and animal health. There is a large variety of microorganisms in aquifers. The use of groundwater from aquifers as sources of drinking water without water treatment or disinfection is a public health problem. Material and methods. The material for the study consisted of water samples taken from used and unused domestic wells in villages located in Lubelskie Province, Biała Podlaska County, Janów Podlaski municipality, Poland. ICP-OES was used to determine the composition of elements. The total number of mesophilic and psychrophilic bacteria was determined for 5 wells using the pour-plate method according to the Polish Standard PN-EN ISO 6222:2004. Results. The water from the wells is unfit for consumption due to high microbiological contamination. A study would have to be carried out on the content of specific pathogenic microorganisms. In most of the samples analyzed, the heavy metal content of the water is below admissible limits. Conclusions. Water resources of the highest quality should be increasingly protected and retained as drinking water reserves. This is extremely important in view of the progressing climate change and the slow process of groundwater renewal.