[Environmental tobacco smoke--assessment of formaldehyde concentration in urine samples of exposed medicine students].

Environmental Tobacco Smoke (ETS) is ranked as one of the factors of confirmed carcinogenicity to human. It consists of the mixture of smoke exhaled by the smoker as well as the sidestream smoke and contains many times higher concentrations of some toxic substances in comparison to the amount of toxic compounds inhaled by a smoker. From many years the issue of passive smoking has been the subject of many research and still not all of its aspects of affecting human health have been explored. Apart from the tobacco varieties, also diverse additives added during the process of tobacco manufacturing, including particularly carbohydrates, influence the composition of the environmental tobacco smoke. During smoking they can undergo many complex transformations, as a result of which toxic components of the environmental tobacco smoke are formed, carbonyl compounds in particular, like aldehydes. They are marked by a significant chemical reactivity which enables them to modify amino groups of proteins leading to the changes in their structure, biological functions and often antigenicity. Therefore their influence to the human body is the cause of numerous adverse health effects caused by the increase in free radical processes which can constitute to the source of these compounds. Well known representative of this group of xenobiotics is formaldehyde as a compound that reflects well the environmental exposure to carbonyl compounds. The considerable source of this compound is tobacco smoke. Therefore analysis of formaldehyde in body fluids is a valuable biomonitoring tool of exposure to it. The aim of this study was the evaluation of formaldehyde concentration in urine samples of medicine students exposed to ETS. The study material consisted of 149 urine samples of students from School of Medicine with the Division of Dentistry in Zabrze, Medical University of Silesia. The concentration of formaldehyde in urine samples was determined by a spectrophotometric method using the Purpald reagent. To verify the collected questionnaire data regarding exposure to constituents of tobacco smoke, the immuno-enzymatic method was used to determine main nicotine metabolites in tested urine samples. This enabled dividing the investigated students' group into active smokers, passively exposed to tobacco smoke and not exposed. Analysis of obtained results showed that mean concentration of formaldehyde in urine of active smokers (68.45 ± 58.67 µmol/l) and passive smokers (79.23 ± 53.64 µmol/l) were significantly higher in comparison to not exposed students (42.99 ± 30.29 µmol/l). Mean concentrations of formaldehyde in urine samples of active and passive smokers are comparable. The results of our study allow to conclude that passive exposure to tobacco smoke is an equivalent source of exposure to active smoking regarding formaldehyde adverse influence to human. Applied method enables to quick evaluation of formaldehyde concentration in biological samples.