XA0201238 Rn, Tia, and U in drinking water in

P. Szerbin, G. Koteles

"Frederic Joliot-Curie" National Research Institute for Radiobiology and Radiohygiene, , Hungary

Abstract. Among radionuclides ingested by drinking water the most important ones are radon, radium and uranium, causing radiation exposure of the lungs, bones, and gastro-intestinal organs, mainly kidneys. For this reason, as a part of the National Environmental Health Program to determine the main risk factors of the Hungarian population from environmental substances, 222Rn, 226Ra, and U concentrations were measured in domestic water supplies. Water samples were taken from all of the 19 Hungarian counties. Three cities were chosen from each county by the criteria of number of the population. Samples were taken from the communal drinking water supplies. Radon was determined by short lived daughter products using scintillation technique after water degassing into Lucas cells. Radium and uranium were determined after chemical separation, by Lucas scintillation method and by liquid scintillation technique. The obtained results were compared to the available literature data. Radioactivity levels were assessed for conformity with the Hungarian standards, WHO guidelines, and used for dose calculations. It was concluded that the radioactivity of the drinking water in Hungary is in the order of magnitude of the worldwide average. The measured radioactivity levels never exceeded the limits of the valid Hungarian standards for annual intake limits and were adequate to WHO guidelines. It was found that public doses from radon, radium, and uranium ingestion by drinking water were 12.7, 8.8, and 7.3 p,Sv y"1, respectively. Summarizing the results of the survey it was concluded that comparing these doses to the public dose from other natural sources of radiation are negligibly small.

1. INTRODUCTION

It is well known that radioactivity of drinking water is much lower than that of the thermal and mineral underground waters (except some regions of specific geological environment) [1, 2]. However, in spite of the strongly rising contribution of mineral water in the human consumption, share of the traditional tap water is still dominant. From radionuclides in the drinking water the most important ones are: (i) 222Rn as source of exposure for epithelial cells of the gastro-intestinal tract, and as nuclide causing whole body exposure after dissolution in blood and tissue fluids. Besides, there are some data that during exhalation radon exposure of lungs cannot be neglected. (ii) 226Ra that accumulated in the mineral fraction of bone tissue, (iii) U isotopes that mostly act as toxic metals, destroying kidney tissue. In spite of some preliminary measurements, no comprehensive study of the drinking water radioactivity in Hungary has been done up till now. Despite of the fact that the presented study is not really a representative one, it seems to be a good step forward in this field of research.

2. METHODS

Water samples were taken from the public water supplies of the three largest by the number of population cities of all of the 19 Hungarian counties. Radon was separated on site by the Pylon Water Degassing Unit WG 1001 and measured by Pylon AB-5 radiation monitor 3.5 hours after radon separation.

158 Table 1. Natural radioactivity of drinking water of cities in 19 Hungarian counties

County City 222Rn 226Ra U (Bql1) (mBq l"1) (mBq r1)

Bács-Kiskun 2,43 51 6 Kecskemét 4,52 27

Hajdú-Bihar iajdúszoboszló 1,0 15 5 íajdúböszörmény 1,64 22 13 Debrecen 1,37 16

159 Table 1. (cont.) Törökszentmiklós 1,46 37 16 Komárom- Komárom 2,46 70 112 Tata 1,12 67 109 Esztergom 1,02 21 109 Nógrád Balassagyarmat 1,05 48 44 Szécsény 6,67 45 600 Salgótarján 0,31 32 11 Pest Budapest 8,99 15 44 Vác 4,78 43 82 Szentendre 1,32 8 126 Százhalombatta 5,06 22 36 Dömsöd 29,90 116 41 Cegléd 6,14 17 66 Somogy Nagykanizsa 5,24 22 50 Kaposvár 1,3 33 183 Balatonboglár 0,97 16 80 Siófok 0,42 70 213 Szabolcs-Szatmár-Bereg Nyíregyháza 0,26 17 22 tüsvárda 2,15 27 15 Mátészalka 3,73 81 17 Tolna Szekszárd 1,9 15 2 Bonyhád 11,19 53 172 Dunaföldvár 3,81 26 40 Vas Sárvár 4,75 38 15 Szombathely 4,2 44 112 ECörmend 16,87 88 24 Veszprém Ajka 0,54 63 192 Veszprém 9,33 21 95 Tapolca 2,35 80 148 Zala Zalaegerszeg 1,97 60 6 Keszthely 3,04 56 137 L,enti 8,83 34 14

160 Table 2. Mean radon, radium and uranium concentration in drinking water

County 222Rn 226Ra U

mean+S.D. mean±S.D. mean±S.D. (Bql1) (niBq I1) (mBq rl)

Bács-Kiskun 3,36±0,93 38±9 103±217

Baranya 14,10+12,34 64+78 100+48

Békés 4,95+2,63 34±15 5+5

Borsod-Abaúj-Zemplén 2,85±2,58 30±38 48±31

Csongrád l,69±0,71 13±5 3+1

Fejér 3,29±1,61 117+107 104+11

Győr-Moson—Sopron 5,16+1,44 24±19 145+223

Hajdú-Bihar 1,34+0,32 18+4 7±6 |

Heves 4,29+3,27 44±23 48±49

Jász-Nagykun—Szolnok 0,89±0,81 34±4 475+649

Komárom—Esztergom l,53±0,8 53±27 110±2

Nógrád 2,68±3,48 42±9 118±331

Pest 9,37±10,36 37+41 66±34

Somogy 1,98±2,2 35±24 132179

Szabolcs-Szatmár 2,05±l,74 42±34 18±4

Tolna 5,63±4,91 31±20 71 ±89

Vas 8,61+7,16 57+27 50±54

veszprém 4,07±4,64 55±30 145+.49 I

Zala 4,61±3,69 50±14 52±73 í

Mean 4,34+ 3,29 43±22 100±107

2.

The LLD for radon measurements was 2 mBq I'1. For radium and uranium measurements water samples were pre-concentrated by distillation. Radium was chemically separated and measured by activity of daughter radon after reaching equilibrium by Lucas scintillation technique by NP-420 P radon meter. The LLD of the radium determination was about 8 mBq I'1. Uranium was chemically separated by direct extraction from water into the organic phase of the liquid scintillation solution and measured by LSC spectrometer. The LLD for uranium measurements was around 1 mBq I*1.

161 Table 3. Rn and Ra in waters by literature data and previous measurements

County Eff. dose from 222Rn- Eff. dose from 226Ra- Eff. dose from U- ingestion ingestion ingestion +S.D. ±S.D. ±S.D.

Bács-Kiskun 9,8±2,7 7,7±l,09 7,5+15,8

Baranya 41,2+36,0 13,1±15,9 7,3±3,5

Békés 14,4+7,6 6,9+3,2 0,4±0,4

Borsod-Abaúj-Zemplén 8,3+7,54 6,1±7,7 3,5±2,2

Csongrád 4,9+2,1 2,7±0,9 0,2+0,1

Fejér 9,6±4,7 23,8±21,9 7,6±0,8

Győr-Moson—Sopron 15,1±4,2 5,0+3,9 10,6±16,3

Hajdú-Bihar 3,9±0,9 3,6+0,8 0,5±0,4

Heves 12,5+9,5 9,0±4,8 3,5+3,6

Jász-Nagykun-Szolnok 2,6±2,4 6,9±0,9 34,7±47,4

Komárom—Esztergom 4,5+2,3 10,8+5,6 8,0+0,1

Nógrád 7,8+10,2 8,5±1,7 15,9±24,2

Pest 27,3±30,2 7,5±8,3 4,8±2,5

Somogy 5,8±6,4 7,2±4,9 9,6+5,7

Szabolcs-Szatmár 6,0+5,1 8,5+7,0 1,3+0,3

Tolna 16,5+14,3 6,4+4,0 5,2+6,5

Vas 25,0±20,9 11,6±5,6 3,7±3,9

Veszprém 11,9+13,6 11,2+6,2 10,6+3,5

Zala 13,5±10,9 10,2±2,9 3,8±5,4

Mean 12,7± 9,6 8,8± 4,5 7,3± 7,8

3. 3. RESULTS AND DISCUSSION

Results of the measurements are given in the Table 1 and Table 2. The radon levels are two orders of magnitude higher than activity concentrations of radium. This is in good accordance with the available literature data for drinking, mineral, thermal and other underground waters (see Table 3.)- The uranium concentration of the investigated samples varied widely between LLD and 934 mBq I"1. It is somewhat higher that the uranium content of Hungarian surface waters (80-120 mBq I"1). The reason ofthat phenomenon could be the dissolution of the uranium from minerals during water migration or can be explained by deposition of uranium salts in the water tubing with subsequent dissolution caused by changes of water chemistry. In Hungary there is still no legislated ALI value for 222Rn ingestion by the public. The ALI values for 226Ra and U are 7 x 103 Bq and 5 x 104 Bq respectively [20]. The annual

162 intakes of these radionuclides calculated by mean 43 mBq I"1 226Ra and 100 Bq I"1 U concentration and by 2 1 d"1 water consumption are 0.4% and 0.01% of the corresponding ALI values. According to the WHO guidelines [21] for drinking water quality the water is suitable for human consumption if reference concentrations corresponding to the reference levels of committed effective dose 0.1 mSv y" are lower than 1 Bq 1 for Ra and 4 Bq 1" for U. The calculated mean radionuclide concentrations in the investigated samples are much lower than reference concentrations (1-10%), consequently the waters meet the WHO water quality guideline requirements. There are no reliable available literature data that could prove the harmful health effects of the ingested radon. In spite of this in the accordance with the conservative Linear No Threshold theory of the stochastic effect of the low doses, there are some publications, where dose-conversion factors were calculated for ingested radon. According these data the dose-conversion for radon varies between 0.4-4 nSv Bq"1 for the whole body [22, 23, 24, 25, 26, 271. Effective dose values for the public from radionuclide intake were calculated using 1 OOO the highest 4 nSv Bq conversion factor for Rn, the results are given in the Table 3. Effective doses were calculated for radium and uranium ingestion using 2,8 x 10"7 Sv Bq"1, and 234U + 238U: 4.5 x 10"8 + 4.9 * 10"8 « 1 x 10"7 Sv Bq"1 dose conversion factors [28], the results are shown in the Table 3. It was found that radiation doses to the Hungarian public from water consumption are 12,7+9,6 uSv y"1 from radon, 8,8+4,5 uSv y"1 due to radium, and 7,3±7,8 uSv y"1 from uranium in the drinking water. Comparing to the 2.18 mSv y"1 effective dose of the Hungarian public from radon inhalation in dwellings [29], and to the 2.4 mSv y"1 value of the worldwide average of the public dose from natural sources of radiation [30], these doses are negligibly small. 4. 4. CONCLUSIONS Radioactivity of the drinking water in Hungary is in the order of magnitude of the worldwide average. The measured radioactivity levels never exceeded the limits of the valid Hungarian standards for annual intake limits and were adequate to WHO guidelines. Public doses from radon, radium, and uranium ingestion by drinking water are negligably small comparing to the public dose from other natural sources of radiation

ACKNOWLEDGEMENT

Work was supported by the National Environmental Health Program (NEKAP).

REFERENCES

[1] SZERBIN, P., Natural radioactivity of certain spas and caves in Hungary. Environment International, 22(l):389-398; 1996. [2] KASZTOVSZKY, ZS., KUCZI, R., SZERBIN, P., On the natural radioactivity of waters in Hungary, Central European Journal of Occupational and Environmental Medicine, 2(4):335-347; 1996. [3] SCHONHOFER, S., Determination of radon-222 and radium-226 in mineral water and drinking water - a survey in Austria, Analyst, 114:1345-1347; 1989. [4] PIRES DO RIO, M.A., GODOY, J.M., AMARAL, E.C.S., Ra-226, Ra-228 and Pb-210 concentrations in Brazilian mineral waters, Radiation Protection Dosimetry, 24, 1/4:159-161; 1988.

163 [5] JACOMNO, V.F., BELLINTANI, S.A., OLIVIERA, J., MAZZALLI, B.P., FIELDS, D.E., SAMP A, M.H., SILVA, B., Estimates of cancer mortality due to ingestion of mineral spring water from a highly natural radioactive region of Brazil. J.Environ.Radioact, 33(3):319-329. 1996. [6] SALONEN, L., Natural radionuclides in ground water in Finland, Radiation Protection Dosimetry, 24,1/4:163-166; 1988. [7] SOHRABI, M., ALIREZAZADEH, N., TAJIK AHMADI H., A survey of Rn-222 concentrations in domestic water supplies of Iran, Health Phys., 75(4):417-421; 1998. [8] OTWOMA, D., MUSTAPHA, A.O., Measurement of Rn-222 concentration in Kenyan groundwater, Health Phys., 74(l):91-95; 1998. [9] BLACKBURN, R., AL-MASRI, M.S., Determination of radon-222 and radium-226 in water samples by Cerenkov-counting, Analyst, 118:873-876; 1993. [10] SOTO, J., QUINDOS, L.S., DIAZ-CANEJA, N., GUTIERREZ, I., FERNANDEZ, P.L., Ra-226 and Rn-222 in natural waters in two typical locations in Spain, Radiation Protection Dosimetry, 24,1/4:9-111; 1988. [11] KOBAL, I., KRISTAN, J., ANCIK, M., JERANCIC, S., SKOFLJANEC, M., Radioactivity of thermal and mineral springs in Slovenis, Health Phys., 37:239-242; 1979. [12] KOBAL, I., VAUPOTIC, J., MTTIC, D., KRISTAN, J., ANCIK, M., JERANCIC, S., SKOFLJANEC, M., Natural radioactivity of fresh waters in Slovenia, Yugoslavia, Environmental International, 16:141-154; 1990. [13] CAMPISANO, CD., Geochemical and hydrologic control on radon-222 and radium- 226 in ground water, In: Proc.Conf. on Ground Water Geochemistry, 23-52; 1988. [14] HOLBERT, K.E., STEWART, B.D., ESHRAGHL P., Measurement of radioactivity in Arizona groundwater using improved analiytical techniques for samples with high dissolved solids. Health Phys., 68(2): 185-194; 1995. [15] CECH, I.M., PRICHARD, H.M., MAYERSON, A., LEMMA, M., PATTERN of distribution if radium-226 in drinking water of Texas, Water Resources Reseaech, 23,10:1987-1995; 1987. [16] PARSA, B., HORTON, T., Radon-222 in drinking water: NJDEP-EERF collaborative stady, Health Phys., 58,2:209-212; 1990. [17] WATSON, A.P., ETNIER, EX., MC-DOWELL-BOYER, L.M., Radium-226 in drinking water and terrestrial food chains: trasfer parameters and normal exposure and dose, Nuclear safety, 25,6:815-829; 1984. [18] SZERBIN, P., KOTELES, GY., STUR, D. Radon concentration in Rudas thermal bath, Budapest. Radiat. Protection Dosimetry, 56:319-322; 1994. [19] A GELLERT-HEGYI barlangterapia beinditasahoz sziikseges elSzetes sugaregeszsegugyi es klimatologiai meresek elvegzese es szakvelemeny kialakitasa. Zarqjelentes. OMFB Mec-93-0115; 1993. (in Hungarian) [20] IONIZALO SUGARZAS ELLENI VEDELEM - atlalanos eloirasok. MSZ-62/1-1989. Magyar Nepkoztarsasag Orszagos Szabvany, 1989. (in Hungarian) [21] WORLD HEALTH ORGANIZATION, Guidelines for Drinking Water Quality, Second Edition, Volume 1, Reccommendations, Geneva; 1993. [22] ANDERSSON, I.,6., NILSSON, I., Exposure following ingestion of water containing radon-222. IAEA Symposium on Assessment of Radioactivity in Man. Vienna; IAEA; 317-326; 1964. [23] VON DOBELN, W.L., LMDELL, B., SOME aspects of Rn-222 contamination following ingestion. Arkiv for Fysik 27:531-572; 1964. [24] CRAWFORD-BROWN, D. J., The biokinetics and dosimetry of radon-222 in the human body following ingestion of groundwater. Environ. Geochem. Health 11:10-17; 1989.

164 [25] BROWN, W.L., HESS, C.T., Measurement of biotransfer and time constant of radon from ingested water by human breath analysis. Health Phys. 56:857-868; 1989. [26] SHARMA, N., Study of radon contamination in the human body: a first compartmental approach. Univ. of Maine; Thesis; 1995. [27] CSIGE,L; HAKL, J., HUNYADI, I., VASARHELYI, A., Radon sugarterhelesek a matraderecskei szaraz CO2 furdoben. Sugarvedelmi Tovabbkepzo Tanfolyam, XII: 13- 15; 1997. (in Hungarian) [28] CRP 72, INTERNATIONAL COMMISSION ON RADIOLOGICAL PROTECTION, ,,Age dependent doses to members of the public from intake of radionuclides: Part 5 Compilation of ingestion and inhalation dose coefficients", Oxford: Pergamon Press; 1996. [29] NIKL, L, The radon concentrations and absorbed dose rate in Hungarian dwellings. RadiatProtDosim., 67:225-228; 1996. [30] Sources and effects of ionizing radiation. United Nations Scientific Committee on the Effects of Atomic Radiation; 1993 Report to the General Assembly, United Nations, New York; 1993.

165