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Chewing gum and human hair as retrospective dosimeters
Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences.ORCID iD: 0000-0002-4055-8688
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Retrospective dosimeters are sometimes needed after radiological/nuclear (RN) exposures to determine the doses to individuals. Conventional dosimeters may not be at hand or may not be applicable calling for alternative materials.

The possible exposure situations can be divided into external and internal; the radiation field stems either from outside the body or from a source within. This thesis investigates the possibility to use chewing gum and hair as retrospective dosimeters. The chewing gum would be used after an unexpected radiation event of external type whereas human hair is examined after chronic intake of uranium. Chewing gum containing xylitol and sorbitol was analyzed using electron paramagnetic resonance (EPR) and the hair was analyzed by alphaspectrometry following radiochemistry and by synchrotron radiation microbeam x-ray fluorescence (SR μ-XRF).

Xylitol and chewing gum (in this particular case, V6) are in the present work found to be valuable dosimeters after unexpected radiation events. The xylitol signal linearity with dose in the interval 0-10 Gy was confirmed (r2=1.00). The doses to the coating of the chewing gums were determined 4-6 days after irradiation with an uncertainty of less than 0.2 Gy (1 SD). Spectral dependence with time after exposure was found, but was, however, minimal between 4-8 days.

Hair was evaluated and compared with urine as biodosimeter after ingestion and inhalation intake of uranium. Concentrations of 234U and 238U and their activity ratios were measured in the hair, urine and drinking water sampled from 24 drilled bedrock well water users in Östergötland, Sweden, as well as among 8 workers at a nuclear fuel fabrication factory, Westinghouse Electric Sweden. The results show that there is a stronger correlation between the uranium concentrations in the drinking water of the well water and the users’ hair (r2 = 0.50) than with their urine (r2 = 0.21). There is also a stronger correlation between the 234U/238U activity ratios of water and hair (r2 = 0.91) than between water and urine (r2 = 0.56). The individual absorbed fraction of uranium, the ƒ value, calculated as the ratio between the excreted amount of uranium in urine and hair per day and the daily drinking water intake of uranium stretched from 0.002 to 0.10 with a median of 0.023. The uranium concentrations of the fuel factory workers’ hair and urine were also obtained as well as that of personal air sampler (PAS) filters for the determination of inhaled uranium activity. A large day-to-day variation (7-70 Bq d-1) of the inhaled 234U activity was seen over a 6 week period. Over a 12 week period the 234U activity concentration in urine was similarly seen to vary from 2 to 50 mBq kg-1. Four hair samples from the same subject and period showed less variation (100-240 mBq g-1). The uranium inhalation to urine and hair factors finh,u and finh,h were found to be 0.0014 and 0.0002 respectively given by calculations based on the measured PAS, urine and hair data from two individuals. The SR μ-XRF measurements showed that uranium is present in an outer layer of the hair shaft, about 10-15 μm wide. The  measurements also revealed particles containing uranium being present on the surface of unwashed hair shafts. However, the washed hair shafts showed few, if any, particles.

This thesis concludes that chewing gum and hair can be used as retrospective dosimeters after external radiation and after intake of uranium respectively.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2014. , 58 p.
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1408
National Category
Radiology, Nuclear Medicine and Medical Imaging Medical Biotechnology
Identifiers
URN: urn:nbn:se:liu:diva-108892DOI: 10.3384/diss.diva-108892ISBN: 978-91-7519-305-2 (print)OAI: oai:DiVA.org:liu-108892DiVA: diva2:733714
Public defence
2014-08-29, Berzeliussalen, ingång 65 (HU) plan 9, Campus US, Linköpings universitet, Linköping, 13:00 (English)
Opponent
Supervisors
Available from: 2014-07-11 Created: 2014-07-11 Last updated: 2014-09-08Bibliographically approved
List of papers
1. Dose response of xylitol and sorbitol for EPR retrospective dosimetry with applications to chewing gum
Open this publication in new window or tab >>Dose response of xylitol and sorbitol for EPR retrospective dosimetry with applications to chewing gum
2013 (English)In: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 154, no 2, 133-141 p.Article in journal (Refereed) Published
Abstract [en]

The purpose of this investigation was to study the radiation-induced electron paramagnetic resonance signal in sweeteners xylitol and sorbitol for use in retrospective dosimetry. For both sweeteners and chewing gum, the signal changed at an interval of 1–84 d after irradiation with minimal changes after 4–8 d. A dependence on storage conditions was noticed and the exposure of the samples to light and humidity was therefore minimised. Both the xylitol and sorbitol signals showed linearity with dose in the measured dose interval, 0–20 Gy. The dose-response measurements for the chewing gum resulted in a decision threshold of 0.38 Gy and a detection limit of 0.78 Gy. A blind test illustrated the possibility of using chewing gums as a retrospective dosemeter with an uncertainty in the dose determination of 0.17 Gy (1 SD).

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-85528 (URN)10.1093/rpd/ncs174 (DOI)000316968200001 ()22908355 (PubMedID)
Available from: 2012-11-22 Created: 2012-11-22 Last updated: 2017-12-07
2. Measurements of 234U and 238U in Hair, Urine, and Drinking Water Among Drilled Bedrock Well Water Users for the Evaluation of Hair as a Biomonitor of Uranium Intake
Open this publication in new window or tab >>Measurements of 234U and 238U in Hair, Urine, and Drinking Water Among Drilled Bedrock Well Water Users for the Evaluation of Hair as a Biomonitor of Uranium Intake
2014 (English)In: Health Physics, ISSN 0017-9078, E-ISSN 1538-5159, Vol. 107, no 2, 143-149 p.Article in journal (Refereed) Published
Abstract [en]

Hair is evaluated and compared with urine as a biomonitor for human intake of uranium. Concentrations of U and U and the activity ratio between them are measured in the hair, urine, and drinking water of 24 drilled bedrock well water users in Östergötland, Sweden. The samples are measured with α-spectrometry after radiochemical preparation using liquid-liquid separation with tributylphosphate. The results show that there is a stronger correlation between the uranium concentrations in the drinking water of each subject and the hair of the subject (r = 0.50) than with the urine (r = 0.21). There is also a stronger correlation between the activity ratios of water and hair (r = 0.91) than between water and urine (r = 0.56). These results imply that hair may serve as a robust indicator of chronic uranium intake. One obvious advantage over sampling urine is that hair samples reflect a much longer excretion period: weeks compared to days. The absorbed fraction of uranium, the f value, is calculated as the ratio between the excreted amount of uranium in urine and hair per day and the daily drinking water intake of uranium. The f values stretch from 0.002 to 0.10 with a median of 0.023.

Place, publisher, year, edition, pages
Wolters Kluwer, 2014
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:liu:diva-108889 (URN)10.1097/HP.0000000000000075 (DOI)000338678800005 ()24978285 (PubMedID)
Available from: 2014-07-11 Created: 2014-07-11 Last updated: 2017-12-05Bibliographically approved
3. Using Hair as a Bioindicator for Inhalation of Uranium: A Study on Nuclear Fuel Fabrication Workers
Open this publication in new window or tab >>Using Hair as a Bioindicator for Inhalation of Uranium: A Study on Nuclear Fuel Fabrication Workers
2014 (English)Manuscript (preprint) (Other academic)
Abstract [en]

Scalp hair is evaluated and compared with urine as a potential biomonitor following inhalation intake of uranium. The samples were collected among eight workers at a nuclear fuel fabrication factory and the sample concentrations of 234U and 238U were analyzed by α-spectrometry after radiochemical preparation using a TBP-based liquidliquid separation method. Personal air samplers (PAS) filters were also analyzed for determination of inhaled uranium activity.

The results show that there is a large day-to-day variation (7-70 Bq d-1) of the inhaled 234U activity over a 6 week period. A large variation is also seen for the 234U activity concentration among 12 urine samples collected over a 12 week period; (2-50 mBq kg-1). Four hair samples from the same subject and period showed less variation (100-240 mBq g-1) as they reflect the average excretion over a longer period than the periodic urine samples.

The total inhalation intake and excretion in urine and hair was obtained for two study subjects over a 6 week period. The uranium inhalation to urine and hair factors finh,u and finh,h were 0.0014 and 0.0002 respectively, given by calculations based on the measured PAS, urine and hair data. It has been demonstrated that scalp hair could be a valuable complement to urine as biomonitor of uranium intake.

Keyword
Hair, uranium, alpha spectroscopy
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:liu:diva-108890 (URN)
Available from: 2014-07-11 Created: 2014-07-11 Last updated: 2014-07-11Bibliographically approved
4. On the Distribution of Uranium in Hair: Non-Destructive Analysis Using SR-μXRF
Open this publication in new window or tab >>On the Distribution of Uranium in Hair: Non-Destructive Analysis Using SR-μXRF
2015 (English)In: Spectrochimica Acta Part B - Atomic Spectroscopy, ISSN 0584-8547, E-ISSN 1873-3565, Vol. 108, 28-34 p.Article in journal (Refereed) Published
Abstract [en]

In the present study the distribution of uranium in single human hair shafts has been evaluated using two synchrotron radiation (SR) based micro X-ray fluorescence techniques; SR μ-XRF and confocal SR μ-XRF. The hair shafts originated from persons that have been exposed to elevated uranium concentrations. Two different groups have been studied, i) workers at a nuclear fuel fabrication factory, exposed mainly by inhalation and ii) owners of drilled bedrock wells exposed by ingestion of water. The measurements were carried out on the FLUO beamline at the synchrotron radiation facility ANKA, Karlsruhe. The experiment was optimized to detect U with a beam size of 6.8 μm × 3 μm beam focus allowing detection down to ppb levels of U in 10 s (SR μ-XRF setup) and 70 s (SR confocal μ-XRF setup) measurements. It was found that the uranium was present in a 10–15 μm peripheral layer of the hair shafts for both groups studied. Furthermore, potential external hair contamination was studied by scanning of unwashed hair shafts from the workers. Sites of very high uranium signal were identified as particles containing uranium. Such particles, were also seen in complementary analyses using variable pressure electron microscope coupled with energy dispersive X-ray analyzer (ESEM–EDX). However, the particles were not visible in washed hair shafts.

These findings can further increase the understanding of uranium excretion in hair and its potential use as a biomonitor.

Place, publisher, year, edition, pages
Elsevier, 2015
Keyword
μ-XRF; Hair; Confocal; Uranium; Internal dosimetry
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:liu:diva-108891 (URN)10.1016/j.sab.2015.04.001 (DOI)000355360400005 ()
Available from: 2014-07-11 Created: 2014-07-11 Last updated: 2017-12-05Bibliographically approved

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