How did Fukushima affect Japanese honey?
As scientists report in a new study from Japan, the 2011 Fukushima Daiichi nuclear power plant accident further increased awareness of food safety. In this study, the researchers analyzed the radioactivity of honey samples.
The research shows that honey collected in Japan contains both natural and artificial radionuclides. However, the levels detected in the honey were significantly below Japan’s standard limits for radioactive substances in food.
The authors of the study “Post-Fukushima Evaluation of Radioactivity and Lifetime Cancer Risk in Japanese Honey” are Satoshi Inose, Masanobu Shimizu, Takayuki Honda, and Yuya Koike. This study is currently available as a journal pre-proof, meaning it has been peer-reviewed and accepted, but may still undergo final edits.
“This study aimed to determine the distribution of natural and artificial radionuclides based on radioactivity analysis in honey collected from different regions of Japan. We also evaluated the lifetime cancer risk associated with daily honey consumption,” the authors explained in the study.
A total of 28 honey samples were collected from the prefectures of Hokkaido, Miyagi, Fukushima, Ibaraki, Tokyo, Yamanashi, Ishikawa, Kyoto, Nara, Mie, Hyogo, and Okinawa between 2021 and 2022. All honey samples were commercially available. As explained, the samples were left to stand for at least one month to establish radioactive equilibrium before the radioactivity analysis.
The radiation doses from eating honey are far below safety limits
“The artificial radionuclide 137Cs was deposited on the Earth’s surface as a result of global fallout from nuclear tests conducted in various parts of the world…” However, since honey collected before the 2011 Fukushima accident did not contain 137Cs, all the radioactivity detected in this study is attributed to the FDNPP accident. The study showed that 137Cs concentrations in honey from different prefectures varied, with the highest levels in Fukushima, yet all were below the safety standard. Differences are linked to plant and nectar types. As noted, “further studies are required to identify the nectar source and to establish the relationship between plant type and radioactive caesium concentration in honey.”
40K (potassium-40) was detected in all honey samples, while 232Th (thorium-232) and 226Ra (radium-226) were found only in some samples. Concentrations varied depending on the type of nectar and the region of collection. These differences are explained by the fact that different elements are transported from the soil to plants at different rates, and also depend on the type of nectar-producing plant and local environmental conditions. However, the number of samples in the study was small, so the results need to be confirmed with a larger sample size. In addition, the physicochemical properties and microbiological contamination of honey were also examined, and the relationship between these properties and the presence of natural radionuclides should be investigated.
The study used a relatively small sample size, and further research with a larger number of samples is needed
As the authors of the study concluded, the analysis of radioactivity was conducted on honey samples collected from different regions of Japan. 40K was detected in all samples, while 137Cs, 232Th, and 226Ra were present only in some samples. 137Cs was primarily detected in Fukushima Prefecture, and its concentration decreased with distance from the Fukushima Daiichi Nuclear Power Plant (FDNPP). The concentrations of artificial and natural radionuclides varied depending on the location and the nectar source.
The study used a relatively small sample size (28 honey samples), and further research with a larger number of samples is needed. Since bees collect nectar within an area of approximately 2–3 km, the composition of radionuclides in honey may reflect environmental conditions near the nectar collection sites. Future studies tracking the migration pathways through plants and bees, as well as radionuclide accumulation processes in the environment, could serve as valuable indicators of environmental status. The effective radiation dose from honey consumption is very low compared to recommended limits for the general public and the average annual global exposure. Additionally, the calculated lifetime cancer risk from honey consumption is within acceptable limits and meets all current food safety standards.
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