Fetal organ dosimetry for the Techa River and Ozyorsk Offspring Cohorts, part 2: radionuclide S values for fetal self-dose and maternal cross-dose

Abstract

One of the many objectives of the European Union's SOLO (Epidemiological Studies of Exposed Southern Urals Populations) project is to quantify the radiation dose-response following chronic in utero exposures to ionizing radiation. The project is presently conducting a pooled analysis of two cohorts of individuals born to exposed mothers-the Techa River Offspring Cohort (TROC) and the Ozyorsk Offspring Cohort (OOC). The TROC includes the offspring of mothers with external exposures to contaminated riverbanks and internal ingestions of (89)Sr, (90)Sr/(90)Y, and (137)Cs/(137m)Ba, while the OOC includes the offspring of mothers with external exposures seen within the Mayak plutonium production facilities and internal inhalation of (239)Pu and possibly (131)I. In the present study, a newly created Urals-based series of fetal and maternal models is employed to assess S values for all seven radionuclides. Among all fetal ages, S values ranged in magnitude from 10(-14) to 10(-10) Gy per Bq-s for fetal source organs and from 10(-18) to 10(-14) Gy per Bq-s from maternal source organs, depending upon particle type, particle energy, and fetal age. For a given radionuclide and fetal age, S values for fetal source organs were approximately two orders of magnitude higher than for maternal source organs. Little variation in S values was observed among fetal source organs, while variations of over 100 % with respect to the mean were observed for maternal source organs near the fetus. S value variations from maternal cross-fire were highly dependent on fetal position and separation distance from the maternal source organ. These radionuclide S values have been coupled with biokinetic models for use in cohort dose assessment within the SOLO project.

In utero exposure to radiation and haematological malignancies: pooled analysis of Southern Urals cohorts

“…Accumulated fetal doses of strontium-89, strontium-90, and cesium-137 were assumed to be the sources of internal in utero exposure. Fetal biokinetic and dosimetric models for strontium adapted for the Techa River population were used for the calculation (Maynard et al , 2015a, 2015b; Shagina et al , 2015a). The model published in the International Commission on Radiological Protection's Publication 88 was used to calculate the in utero doses from cesium (International Commission on Radiological Protection (ICRP), 2001).…”

“…Therefore, the offspring of female Mayak workers may have received high doses in utero (Vasilenko et al , 2007; Vostrotin et al , 2014). Second, because of discharge of nuclear waste into the surrounding environment in the 1950s (particularly into the nearby Techa River) and a major nuclear accident in 1957, when a chemical explosion of a storage tank released as much as 100 tons of high-level radioactive waste, the offspring of women living along the Techa River or areas affected by the fallout during this time period were also exposed to substantial doses in utero (Degteva et al , 2006, 2012; Maynard et al , 2015a, 2015b). The offspring of women exposed to each of these sources were identified and two cohorts established, with the oldest cohort members now in their early 60s.…”

ICRP dose coefficients: computational development and current status

“…9. These particular anatomical models were constructed for use in assessment of in-utero organ doses for the offspring of nuclear facility workers at the Russian Mayak plant, and people living along the nearby Techa River (Maynard et al., 2011, 2015a,b). They include explicit models of all fetal organ structures, including gestation-period-specific ossification centres of the fetal skeleton.…”

Strontium biokinetic model for the pregnant woman and fetus: application to Techa River studies

“…This model will be described in a separate paper, completing a series of the Sr biokinetic models developed with the use of extensive Southern Urals and Russian data on 90 Sr measurements in humans. In addition, new dosimetric models for the fetal skeleton were recently developed at the University of Florida to evaluate the doses due to 89,90 Sr, again taking account of Russian data to ensure applicability to the Techa River population (Maynard et al 2015a(Maynard et al , 2015b.…”