174 N. Blanchin et al.: Radioprotection 2026, 61( 2), 171 – 177
Fig. 2. Graphical representation of urinary measurements compared to predicted values with the ICRP 78 biokinetic model for ingestion( IMBA).
origin, no evidence from the radioprotection team’ s worksites investigation corroborated this hypothesis. Furthermore, the two significant positive urine test results from April 2015 and February 2016, followed by negative follow-up tests, cannot be explained by pre-April 2015 inhalation contamination.
Second scenario: chronic dietary origin, involving an unspecified compound with f 1 = 0.02, according to the“ ingestion” model from ICRP Publication 78( ICRP, 1997), the reference biokinetic model at the time( see Fig. 2)
It is observed that while the theoretical curve fits well with the urine measurement results, there is a discrepancy with the feces measurement results. The statistical test( chi-squared test) confirms the poor fit of the selected model with the data points. In practice, given the urinary values, the feces results should be ten times higher than those measured.
6
Important additional information leading to new interpretation hypotheses
In early 2018, a radiation protection officer from Mr CC’ s company, involved in the occupational investigation, provided new information about Mr. CC: he consumed several liters of cola daily( averaging 2L per day). Mr. CC confirmed this detail, which had not been disclosed during his initial interviews that focused primarily on his mineral water consumption.
We first focused on the chemical composition of this type of beverage. The label on a bottle of the implicated soda lists the following components: – Carbonated water. – Coloring agent: E150d( caramel color). – Acidifiers: phosphoric acid, sodium citrate. – Sugar or sweeteners: aspartame, acesulfame-K. – Natural flavors, including caffeine.
Additionally, a quick inquiry with the manufacturer revealed that the water used in production across different sites comes from the local distribution network. The uranium content is therefore presumed identical to the region’ s tap water. Nevertheless, a radiotoxicological analysis of a sample of the cola consumed by Mr CC was conducted by Cadarache medical analysis laboratory. The measured activity in this sample was 25 mBq / L, a value close to that of Volvic water, which is recognized as one of the least mineralized waters in France. By comparison, the most " radioactive " waters in France exhibit levels over 100 times higher than this cola sample( Mineral water and radioactivity Technical report, 2000). The hypothesis of elevated uranium content in the cola was thus ruled out.
However, chemistry colleagues at Cadarache urged us to investigate the cola hypothesis due to its chemical composition, particularly the presence of phosphoric acid, whichisknownforitsaffinity with uranium( see discussion below).
Mr CC was therefore asked to repeat radiotoxicological analyses after abstaining from cola for several days. The April 2018 test results showed a return to usual values for the general population(< 1.25 mBq / L). See Table 3.
Then Mr CC’ s urinary radiotoxicological analyses have always remained within the normal values for the general population(< 3 mBq / 24 h).
The radiotoxicological analyses of the feces samples have likewise remained unchanged, within the usual values observed in the general population and consistent with dietary intake.
The hypothesis of increased gastrointestinal absorption of uranium due to the chemical composition of cola was therefore proposed. By increasing the digestive absorption factor f 1 tenfold( from 0.02 to 0.2) in the ICRP Publication 78 biokinetic model, an excellent correlation( fit) was achieved between the theoretical curves and the urine and feces results from July 2016 to March 2018( see Fig. 3)
In this scenario, the estimated average intake is 40 mBq / day, which aligns with dietary intake primarily linked to Mr CC’ s consumption of cola( approximately 25 mBq / L).
The committed effective dose is estimated at 12.5 mSv over the studied period( approximately 2 yr).
Regarding the chemical toxicity of uranium on the kidneys, France’ s INRS indicates( INRS, 2024) a urinary excretion value of 250 mg / L( equivalent to 6.25 Bq / L) beyond which renal impairment can occur. The urinary activity levels measured in Mr. CC were well below this reference value.
Similarly, the World Health Organization( World Health Organization, 2022) recommends a guideline value of 30 mg / L for uranium concentration in drinking water, equivalent to 750 mBq / L. This value corresponds to an annual committed effective dose of 0.10 mSv, assuming a daily consumption of 2 liters of water.
The Table 4 summarizes recommended values from WHO, in the United States of America and in Canada.
The values found in the implicated cola-type beverage, based on analyses performed by the Cadarache laboratory, are also well below these levels. It should be noted, however, that these values can be exceeded in certain mineral waters
( Mineral water and radioactivity Technical report, 2000), whos e consumption should therefore be limited.