Dose estimation of radiation exposure from hormesis cosmetics

Cosmetics claiming hormesis effects are available through Internet. Although the hormesis effect is explained in each product of cosmetics, there is no explanation about the radiation source. The existence of the progeny nuclides of Th and U series (RI) was confirmed by the γ-ray spectroscopy using a HPGe detector. The highest radioactivity densities were 68 Bq/g of the Th-series included in the hormesis powder. Because the particle containing RI were of the size of 1-10 micrometer by observing and analyzing SEM-EDX, there is a risk of inhaling the powder to the deep into the lungs. Furthermore, as about 1% RI was dissolved in water, the uptake of the RI to the body would be possible. The highest value of the evaluation of uniform radiation exposure to some organs by the continuous usage for 10 years was 5.5 mSv/y of the hormesis powder inhalation to the lung. Furthermore, the calculated quantity of the radioactivity of progeny of 222Rn deposited in the body after continuous use of the hormesis cream every day for one year becomes 24 Bq. The possibility of accumulation of the radioactivity in the body from the hormesis cosmetics cannot be denied. The addition of the radioisotope to cosmetics is prohibited in some EU countries by the regulation. It's proposed in this paper that the legitimacy of the addition of the radioisotope should be seriously re-examined. (author)