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Risk Assessment of Obninsk water sources containing different-valent chromium

Congress: 2008
Author(s): Olga Momot, Boris Synzynys
Ecology Department, Obninsk State Technical University for Nuclear Power Engineering, Studgorodok, 1, Obninsk, Kaluga region, 249040, Russian Federation, tel.: +74843937212, fax: +74843970822, momot@iate.obninsk.ru
AbstractIntroduction UN Global monitoring program considers chromium as one of most hazardous environmental pollutants. Complex survey of water sources in Obninsk and its vicinity has been carried out in the period from 2000 to 2005. The recent actual situation has shown that the presence and dynamics of Cr content are of great interest. Total chromium content amounted to 0,008-0,012 mg/l. The choice of chromium as a priority pollutant is not random. Chromium is of great importance for our organisms: interaction with insulin in carbohydrate metabolic processes, pacticipation in the structure and function of nucleic acids. Chromium is referred to toxic microelements and can initiate mutagenic and carcinogenic effects, Cr (VI) compounds being more mutagenic as compared to Cr (III). Objective Health risk assessment at the use of water containing different-valent chromium. Methods The U.S. EPA methodology is used to establish individual health risk of this metal ingressed with groundwater for Obninsk population. Results Exposition was calculated from data on chromium content in freshwater, according to which Cr(III) and Cr(VI) content is 27 and 44% of the total chromium content, respectively, the rest part is organically bonded chromium. Taking into account all said above and standard exposition factors, the daily mean doses are calculated for the case of peroral chromium income with drinking water depending on chromium form (Crtotal, Cr(III), Cr(VI). Health risk of carcinogenic and noncarcinogenic effects when drinking water with Cr is calculated on the following data: RfD (Crtotal) = 0,005 mg/ (kg-day); RfD (Cr (III)) = 1,5 mg/(kg-day); RfD (Cr (VI)) = 0,003 mg/(kg-day); SF (Cr (III)) = 0,42[mg/(kg- day)]-1. Calculation results of the individual life risk depending on the effect type are presented in the Table. Table. Public health risk stipulated by chromium contained in water Source CR HQCr (III) HQCr(VI) HICr(III)+Cr(VI) HQCr Total Pipe water 1,75.10-5 4,02.10-5 0,014 0,014 0,44 As seen from the Table, the individual life risk of carcinogenic effects for water sources exceeded the acceptable risk 10-6, recommended in WHO publications and some foreign documents. Conclusion Situation with the risk of noncarcinogenic effects requires a special analysis. Hazard index (HI Cr(III) + Cr(VI)) obtained by adding the hazard indices (HI) for Cr(III) and Cr(VI) is not equal to the hazard index (HQCr Total ) determined from the total chromium content. This approach does not take into account the expected difference in fine mechanisms of the specific impact of three- and six-valent chromium. Therefore calculation of noncarcinogenic risk based on the total chromium content in pipe water is more preferable as compared to additive risk assessment. As a whole, the probability of noncarcinogenic effects of hazardous sources causes no concern as hazard coefficients are much below 1, i.e. a value which determines the acceptable risk of noncarcinogenic effects.
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