Izloženost stanovništva 226Ra u pitkoj vodi

This paper presents a new method for calculating the effective dose of 226Ra regularly ingested with drinking water over a long period of time. The method is based on the assessment of cumulated 226Ra activity in the fraction retained in the whole body at time t (in days) after intake [so called m(t) value]. For modelling, simulation, and visualisation of the continuous intake of 226Ra by drinking water, we used the Simulink® program package integrated with the Matlab®. The dose assessment was performed for 226Ra activities of 5 mBq L-1, 50 mBq L-1, 1000 mBq L-1 and 5000 mBq L-1. The results suggest that 226Ra activities above 1000 mBq L-1 produce effective doses which are below the recommended maximum. However, the potential effect of 226Ra activities of this extent is still unknown in children.U ovome radu opisana je metoda izračunavanja 226Ra efektivne doze kao posljedice svakodnevnog pijenja vode. Procjena efektivne doze bazira se na procjeni kumulativne aktivnosti koja je izračunana s pomoću m(t) vrijednosti (udjela aktivnosti u vremenu t nakon unosa u organizam). Proces kontinuiranoga višegodišnjeg pijenja vode (20 000 dana) simuliran je u programu Simulink (programski paket Matlab). Rezultati se odnose na vode koncentracija 226Ra od 5 mBq L-1, 50 mBq L-1, 1000 mBq L-1 i 5000 mBq L-1. Rezultati ove metode uspoređeni su s rezultatima metode koju predlaže Svjetska zdravstvena organizacija. Pokazalo se da kontinuiranim unosom 226Ra u organizam odraslog čovjeka kontinuirano raste koncentracija 226Ra u organizmu. Također time raste i 226Ra efektivna doza koja nakon 20000 dana doseže od 0.002 mSv (5 mBq) do 2.1 mSv (5000 mBq). Međutim, odgovarajuće godišnje 226Ra efektivne doze čak i pri pijenju vode koncentracije 226Ra od 5000 mBq L-1 ne prelaze vrijednost od 0,1 mSv, kako to predlaže Svjetska zdravstvena organizacija. Važno je naglasiti da se opisana metoda bazirala na parametrima svojstvenim odraslom organizmu te da je za procjenu doze na dječji organizam potrebno izraditi poseban model

Procesi uklanjanja 226Ra u postrojenjima za pripremu pitke vode u Hrvatskoj

Today, bottled and tap drinking water mainly originates from underground waters which might contain considerable amounts of naturally occurring radionuclides. One of the most toxic radionuclide in drinking water is 226Ra. Following the metabolism of calcium, it could be deposited into the bone where, in sufficient amount, it could cause bone sarcoma. Although current drinking water preparation techniques are not specifically designed for 226Ra removal they can reduce certain amounts of 226Ra. This paper presents the efficacy of standard water preparation processes (granular activated carbon, green sand and fixed-leaf filtrations) currently used by Zagreb water supply and two Croatian water bottlers in removing 226Ra. Compared with other studies, the results of our study show low to moderate efficacy in lowering the 226Ra concentration in drinking water. Even so, 226Ra concentrations still comply with the recommendation of the Word Health Organisation (WHO) and with Croatian legislation.Danas se kao pitke vode uglavnom rabe podzemne vode koje prirodno mogu sadržavati povišene koncentracije radionuklida. Jedan od radionuklida koji se u podzemnim vodama može naći u vrlo visokoj koncentraciji jest visokotoksičan 226Ra. Njegov metabolički put u organizmu sličan je metaboličkomu putu kalcija, što znači da se može deponirati u kostima i time povećati rizik od nastanka raka kostiju. Iako standardne metode za pripremu pitke vode nisu specijalno oblikovane za uklanjanje radija, pokazalo se da se koncentracija 226Ra tijekom tih procesa smanjuje. U ovom radu željela se ispitati efikasnost izdvajanja 226Ra prilikom standardnih procesa pripreme vode (filtracija na aktivnom ugljenu, filtracija na zelenom pijesku, pločasti filtar) koji se primjenjuju u Zagrebačkom vodovodu i dvjema punionicama vode u Hrvatskoj. U usporedbi s podacima koje navode drugi autori, opisani procesi filtracije pokazuju slabiju efikasnost izdvajanja 226Ra. Međutim, pitka voda dobivena tim procesima sadržava 226Ra u koncentraciji koja zadovoljava hrvatske propise te preporuke Svjetske zdravstvene organizacije

226Ra u pitkoj vodi Hrvatske

Owing to its exceptional radiotoxicity 226Ra in drinking water may directly affect human health. Its presence was investigated in several categories of drinking water in Croatia: well water, tap water from several municipal water supply systems and bottled mineral water. The method of 226Ra determination was alpha-spectrometric measurement after radiochemical separation. The 226Ra content in all investigated categories of waters are below the legislative level permissible for human health.Zbog svoje izuzetne radiotoksičnosti, 226Ra u pitkoj vodi može izravno utjecati na ljudsko zdravlje. U radu je opisano istraživanje specifične aktivnosti 226Ra u pitkoj vodi Hrvatske, i to: u uzorcima bunarskih voda, uzorcima vodovodnih voda u nekoliko gradova Hrvatske i u mineralnim vodama. 226Ra je određen alfa-spektrometrijskim mjerenjem nakon radiokemijske separacije. Istraživanje je pokazalo da je količina 226Ra u svim ispitivanim kategorijama voda ispod razine koju zakonska regulative smatra tolerantnom po zdravlje čovjeka

Radioactivity in Biosphere and Occupational Exposure in Croatia

U radu su prikazani rezultati sustavnog istraživanja radioaktivnosti životne i radne sredine u Republici Hrvatskoj od početka šezdesetih godina. Istraživana je radioaktivnost zraka, oborina, tla, rijeka, mora i jezera, pitke vode te ljudske i stočne hrane, kao i vanjska izloženost za radnike profesionalno izložene ionizirajućem zračenju. Maksimalna radioaktivna kontaminacija fisijskim radionuklidima zabilježena je ranih šezdesetih godina, u vrijeme najintenzivnijih atmosferskih nuklearnih pokusa. Od tada radioaktivnost radioaktivnih oborina eksponencijalno opada. Nuklearna nesreća u Čornobilju dovela je u Republici Hrvatskoj do ponovnog povećanja radioaktivnosti 137Cs u okolišu, dok je povećanje radioaktivnosti 90Sr, zbog njegove manje hlapljivosti, bilo neznatno. No, nakon tog kratkotrajnog povećanja ponovno je došlo do eksponencijalnog pada radioaktivnosti, tako da je godine 1998. prosječna brzina apsorbirane doze u zraku iznosila 0,128±0,004 μGy/h. Prosječan pripadnik hrvatske populacije je stoga zbog izloženosti osnovnom zračenju na godišnjoj razini primio dozu od oko 1,12±0,04 mSv. Ukupna kolektivna doza uključuje i dozu uzrokovanu primjenom izvora ionizirajućih zračenja u medicini te je značajan naglasak stavljen na kontrolu kakvoće izvora zračenja (koja se sustavno provodi od 1985) kako bi se smanjila ukupna kolektivna doza koju primi hrvatsko pučanstvo.This paper presents results of long-term investigations of radioactivity in general and occupational environments in the Republic of Croatia. Investigations of environmental radioactivity and occupational exposure monitoring in Croatia have been systematic since the early sixties. Investigations included radioactivity of the air, fallout, soil, river, sea and lake water, tap water, human foodstuffs, and animal feed. External dosimetry monitoring is carried out for workers occupationally exposed to ionising radiation in medicine, and industry. Radioactive contamination with fission radionuclides is associated with deposition of fallout originating from atmospheric explosions of nuclear weapons as well as from regular operation of nuclear facilities. Among hundreds of different radionuclides contained in various types of fallout only a few significantly contribute to the dose, particularly 90Sr and 137Cs. The maximum radioactive contamination with fission radionuclides was recorded in the early sixties, at the time of most intensive atmospheric nuclear tests. The fallout radioactivity has been exponentially decreasing ever since. The nuclear accident at Chornobyl temporarily raised 137Cs radioactivity levels in Croatia, whereas the increase in 90Sr radioactivity was not significant due to its low volatility. After a short-term increase, radioactivity dropped back to the pre-Chornobyl levels. Apart from radioactivity of fission products, investigations involved natural radioactivity and technologically enhanced natural radioactivity. Particular attention has been paid to radon as the most relevant source of natural radiation for humans. In 1998, the average absorbed dose in the air was 0.128±0.004 μGy/h. Consequently, an average Croat received the annual dose of 1.12±0.04 mSv through exposure to background radiation. However, as the overall collective dose includes the dose received by medical and civil use of radiation sources, significant effort has been put on the quality control of radiation sources (systematically implemented since 1985) as an important step for reducing the overall collective dose of Croatian population

Ukupna profesionalna izloženost tijekom karakterizacije, kondicioniranja i osiguravanja zatvorenih radioaktivnih izvora: novi dozimetrijski koncept uporabom aktivnih elektronskih dozimetara

Radiation dosimetry in protection against ionising radiation involves research of all possible pathways through which natural or man-made radioactive materials can contaminate a habitat and actually harm its biota. It also takes into account natural and artifi cial (man-made) electromagnetic ionizing radiation (γ and x radiation). This article presents a dosimetric study assessing exposure to man-made ionising radiation of local environment and total occupational exposure of two professional workers involved in characterisation, conditioning, and securing of unused radioactive sealed sources. The purpose of the study was to validate a new active electronic dosimeter (AED) of type ALARA OD and to develop a new monitoring method by tracing the external occupational exposure over real time. This method is used to continuously measure and record external radiation doses and, which is a novelty, establish dose rates receiving pattern as a function of real time. Occupational whole body dosimetric results obtained with AED were compared with results obtained with passive dosimetry (fi lm badge and thermoluminiscence). Air, dust, and silicon sand samples were analysed by gamma-spectrometry to estimate internal exposure of the two workers to 222Rn due to inhalation or ingestion of dust and sand in indoor air. In order to establish total occupational exposure, control radon measurement was performed in the immediate environment and the external Hazard index (Hex) was calculated.Dozimetrijski koncept zaštite od ionizirajućeg zračenja podrazumijeva istraživanje svih mogućih putova kojima radioaktivni materijal nastao u prirodi ili kao posljedica ljudskog djelovanja može ući u okoliš i utjecati na biotu ili onečistiti habitat oštećujući biotu. Taj koncept također uzima u obzir prirodno i umjetno (stvoreno ljudskim djelovanjem) elektromagnetsko ionizirajuće zračenje (γ i X-zračenje). U ovom radu predstavljena je dozimetrijska istraživačka studija kojom se istražuje i procjenjuje ukupna profesionalna izloženost dvaju radnika te izloženost lokalnog habitata ionizirajućem zračenju. Studija je obuhvatila karakterizaciju, kondicioniranje i osiguravanje nekorištenih, uskladištenih zatvorenih radioaktivnih izvora u cilju potvrđivanja i validacije novog aktivnog elektronskog dozimetra (AED) tipa ALARA OD te razvoj nove metodologije praćenja vanjske profesionalne izloženosti u vremenu. Kontinuirano mjerenje i snimanje primljenih vanjskih doza te kao novitet, brzine doze kao funkcije vremena, daju novu i jedinstvenu snimku profesionalnih doza i uzoraka primanja brzine doze na danome radnome mjestu. Rezultati mjerenja profesionalne doze za cijelo tijelo dobiveni uporabom AED-ova uspoređeni su s dozimetrijskim rezultatima [Hp(10)] dobivenim uporabom pasivnih dozimetara (fi lmskih i termoluminiscentnih dozimetara). Provedene su gamaspektrometrijske analize zraka, prašine i silikatnog pijeska te su dobiveni podaci iskorišteni za procjenu moguće unutarnje izloženosti radnika 220Rn inhalacijom zraka ili ingestijom prašine i pijeska. Radi određivanja ukupne profesionalne izloženosti bilo kojeg radnika uključenog u ovaj projekt, provedena su kontrolna mjerenja radona i izračunan je Hazard index (Hex)

226Ra and 228Ra in Croatian Rivers

The presence of natural radionuclides in Croatian rivers emphasizes the need for its continuous monitoring. Therefore results of 226Ra and 228Ra determination in Croatian river waters are presented in this paper. 226Ra and 228Ra were chosen as a possible source of human exposure due to their high radio-toxicity. Fifty liters of river water samples were collected from the Danube, Drava, Sava, Krka and Neretva rivers twice a year from 2002 to 2006. It is showed that activity concentrations of 226Ra ranged from 6.54 mBq/L to 59.44 mBq/L and 228Ra activity concentrations ranged from 2.57 mBq/L to 20.76 mBq/L. The highest values of both 226Ra and 228Ra were measured in the river Drava, and the lowest values in the river Sava. Statistically significant differences were not observed between radium concentrations from two watersheds (the Black Sea and the Adriatic Sea watershed), nor between 226Ra/228Ra ratio in rivers individually. The number of collected samples is insufficient to make more statistically significant conclusions. However the data obtained in this study could be the baseline for evaluating possible future changes

Radioactive Waste Due to Electric Power and Mineral Fertiliser Production

Istraživanja prirodne radioaktivnosti uz poznate izvore zagađenja, bilo da se radi o prirodno povišenoj radioaktivnosti određenog područja ili o tehnološki povišenoj prirodnoj radioaktivnosti, provode se već nekoliko desetljeća u Jedinici za zaštitu od zračenja Instituta za medicinska istraživanja i medicinu rada u Zagrebu. Saznanja o tehnološki povišenoj prirodnoj radioaktivnosti omogućila su dosadašnja istraživanja radioaktivnosti u blizini termoelektrana na ugljen i tvornice mineralnih gnojiva. Svi ugljeni i fosfatne rude sadržavaju prirodnu radioaktivnost, članove uranova i torijeva prirodnoga radioaktivnog niza. Iskorištavanjem tih sirovina, ugljeni u termoelektrani i fosfatne rude u proizvodnji mineralnih gnojiva koncentriraju u sebi sadržanu radioaktivnost u čvrstom ostatku procesa kojemu su podvrgnute. Posljedično je koncentracija prirodnih radionuklida u otpadu nekoliko puta veća nego što su koncentracije prirodnih radionuklida inače prisutnih u okolišu, osobito u okolnome tlu. Sav se otpad iz proizvodnje odlaže na odlagališta, ondje se gomila i prisutni prirodni radionuklidi zbog dugog vremena poluraspada (npr. 226Ra: T1/2=1600 godina) ostaju trajna prijetnja okolišu. Rezultati znanstvenih spoznaja iskorišteni su prilikom sanacije odlagališta pepela i šljake, a poslužili su i u izradi kriterija pri odabiru uvoznih sirovina. Izmjerene koncentracije prirodnih radionuklida uvoznih energetskih ugljena, koji se danas rabe u termoelektrani na ugljen, pokazuju povoljniji omjer prirodnih radionuklida tako da je sav otpadni pepeo podoban za uporabu u graditeljstvu odnosno u cementnoj industriji.Radiation Protection Unit of the Institute for Medical Research and Occupational Health in Zagreb has been conducting systematic investigations of radioactive contamination of the Croatian environment by anthropogenic fission products as well as by naturally occurring radioactive material (NORM) since 1963. Several critical sites in Croatia were identified for NORM, that is, for slag and ash repositories from coalfired power plants and phosphogypsum repository from a mineral fertilizer production plant. As the coals and phosphate ores contain naturally occurring radionuclides, especially the members of the uranium and thorium radioactive chains, utilising these materials in various industries only enhances their natural radioactivity in residual waste. Consequently, the resulting activity concentrations of natural radionuclides in waste material could be several times higher than in the adjacent soil. These deposited materials pose permanent risk of radiation exposure due to the long physical half-life of natural radionuclides (e.g., T1/2= 1600 years for 226Ra). Results of scientific investigations related to natural radioactivity are used in the recovery of slag and ash repositories and landfills, as well as in establishing regulatory criteria targeting import of coal and phosphate ores. In consequence, recently measured activity concentrations of natural radioactivity in imported materials used nowadays in coal-fired power plants are significantly lower than in previously used raw materials. Therefore, slag and ash can be used as additive materials in cement productio