The content of benzo(a)pyrene (BaP) in 62 small lakes was studied. It was found that the pollution with BaP was not high, although there was a wide variation in its concentrations. The mean value of BaP fluctuated from 0.11 to 9.30 ng L™'. The situation and economic use of the lakes played a certain part in the BaP content in their water. The study of seasonal variations of BaP in the small lakes did not establish distinct differences between the seasons. Only the urban and suburban lakes showed about an order of magnitude higher concentration of BaP in water in winter than in other seasons. The hydrobiological type (trophicity) of a lake did not influence the content of BaP in the lake water. The concentration of BaP in fish tissues depended on its amount in the lake water and on the fat content of the fish tissue.Key words: lakes, water pollution, polycyclic aromatic hydrocarbons, benzo(a)pyrene, fish tissue.Estonian small lakes have been thoroughly studied for many years. The results of a long-term study of a large group of scientists were concentrated in the book by Ott & Kdiv (1999). Changes in the trophic state of the lakes that had taken place during the study are described in the book. However, there is only one comment about the anthropogenic pollution of these lakes with carcinogenic substances. Various polycyclic aromatic hydrocarbons (PAHs) form a large group of environmental pollutants. Among them there are substances that are classified as probable and possible carcinogens (WH0..., 1987;Menzie et al., 1992). One of the most thoroughly investigated PAHs is benzo(a)pyrene (BaP) as a probable carcinogen and because of its wide-spread distribution in the environment and high activity and stability.The contamination of various Estonian water bodies with PAHs has been

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In Estonia the daily load of nitrates on the human organism-depends on the nitrate content in drinking water rather than in vegetables. A strong positive correlation between the nitrate concentration in the drinking water and amounts of nitrates in urine and saliva was found.The rural inhabitants get more nitrates from the drinking water than the city dwellers. As the amount of nitrates in the drinking water is big the nitrate excretion in urine does not reflect how much nitrate is ingested with food. Thus a high nitrate concentration in drinking water does not permit to use the measurement of nitrate excreted in urine for the estimation of the role of nitrate ingested with food.