Estimation of dietary intake of 90Sr in Japan after the Fukushima Daiichi Nuclear Power Plant accident: market basket study, 2013-2018

Radionuclide contamination in foods has been a public concern in Japan after the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. To estimate time and regional trends of daily intake and annual committed effective dose of strontium-90 (⁹⁰Sr) after the accident, we analysed Market basket samples using a low background 2π gas-flow counter. Samples were collected from six regions, once a year from 2013 to 2018. There appeared to be little variation in estimated daily intake and annual committed effective dose of ⁹⁰Sr across the time periods and regions. The estimated maximum annual committed effective dose of ⁹⁰Sr was 0.00076 mSv/year, a value sufficiently lower than the intervention exemption level, 1 mSv/year, in foods in Japan. There was no noticeable difference between the range of estimated daily intake of ⁹⁰Sr in this study compared with daily intake measured before the FDNPP accident. These results suggested that no obvious increase in dietary intake of ⁹⁰Sr was observed after the FDNPP accident, and that the effects on commercial foods from ⁹⁰Sr due to the FDNPP accident were negligible.

Radionuclide concentrations in medicinal florae and committed effective dose through Ayurvedic medicines

Purpose: Ayurveda is one of the oldest systems of medicines in the world being practiced widely in the Indian subcontinent for more than 3000 years, and still remains as one of the important traditional health care systems. The Ayurvedic drugs are derived primarily from various parts of the plants, like root, leaf, flower, fruit or plant as a whole. Plants uptake minerals and other nutrients from the soil through their root system. Along with other minerals radionuclides present in the growing media also reach to the plant parts following the same pathway. Realizing the probable health hazards via the intake of Ayurvedic drugs, it is important to assess the concentration of natural radionuclides in commonly used medicinal plants.Materials and methods: NaI(Tl) scintillator-based gamma-ray spectrometry has been used to determine the activity concentrations of primordial radionuclides (²²⁶Ra, ²³²Th and ⁴⁰K) in the most commonly used medicinal plant parts as ingredients of Ayurvedic medicines in India.Results and discussion: The average specific activity (Bqkg^-1) of ²²⁶Ra, ²³²Th and ⁴⁰K was found to be 43 ± 18, 36 ± 15[Formula: see text] and 230 ± 46, respectively. The estimated annual committed effective doses due to the intake of common Ayurvedic medicines at prescribed dosage was found to be 39 ± 16 µSv y^-1,[Formula: see text] which is quite low as compared with the radiation dose limit of 1 mSvy^-1 from all natural sources, reported by the International Commission on Radiological Protection (ICRP-60).Conclusions: It is found categorically that intake of Ayurvedic medicines at normal dosage poses no radiological hazard to the individual. Present results are significant in the wake of myths that many hazardous materials including radioisotopes are present at higher levels. Obtained results also serve as a reference information for the distribution of radionuclides in medicinal plant species.