Concentrations of 137Cs and 40K in Mushrooms Consumed in Japan and Radiation Dose as a Result of Their Dietary Intake

Abstract

Mushrooms are known to accumulate radiocesium. To estimate the intake of radiocesium through the eating of mushrooms, about 30 samples belonging to 4 commonly consumed species (Lentinula edodes, Hypsizigus marmoreus, Grifola frondosa, and Tricholoma matsutake), were analyzed for (137)Cs and (40)K. The concentration ranges were 0.060-29 Bq kg(-1) (wet wt) for (137)Cs and 38-300 Bq kg(-1) (wet wt) for (40)K. The geometric mean concentration for (137)Cs was 0.56 Bq kg(-1) (wet wt), and the mean concentration for (40)K was 92 Bq kg(-1) (wet wt). The (137)Cs concentrations in L. edodes cultivated in mushroom beds (sawdust-rice bran media) were lower than those cultivated on bed logs (natural wood with bark). The annual intake of (137)Cs per person through mushrooms was calculated, by using the current analytical results and food consumption data in Japan, to be 3.1 Bq for (137)Cs, which is about 28% of the total dietary intake of this nuclide. The effective dose equivalent of (137)Cs through mushrooms was estimated to be 4.0 currency 10(-8) Sv, which is about the half the value obtained in our previous study. The decrease of the (137)Cs intake through mushrooms is probably related to changes in cultivation methods in recent years, from the use of bed logs to mushroom beds.

Radioactivity Levels in Some Mushroom Species and Consequent Doses

“…where D shows effective dose in Sv/year, Ac is activity in Bq/kg, F is a dose conversion factor (Sv/Bq) and Ai is average annual consumption of mushrooms (kg dm/kg fm) and R is average ratio between the dry mass (dm) and fresh mass (fm) of mush-rooms which has a mean value of 0.08 (kg dm/kg fm) 3 . The average mushroom consumption for adults is taken typical value of 4 kg fm 19 . The activity concentrations are averaged for five different edible mushrooms and annual effective doses are calculated.…”

Fukushima Daiichi reactor source term attribution using cesium isotope ratios from contaminated environmental samples

“…[26][27][28][29] Thus, in some cases it may be possible to apply a direct correction for pre-Fukushima radiocesium to the measured 135 Cs/ 137 Cs isotope ratios in brown rice and soil samples based upon reported pre-Fukushima 137 Cs concentrations in these matrices (NB: reliable application of such an approach for mushroom and soybean samples is inhibited by the lack of consistent 137 Cs concentration data in these matrices in the literature). [30][31][32] However, in the case of soils this approach assumes that samples to which this correction is applied represent undisturbed sample locations, as soil disturbances (e.g. erosion, soil tillage, etc.)…”

Contents of caesium-137 in forest ecosystem of the locality Újezd

“…Nejdéle kontaminace přetrvává v neobdělávaných půdách. Mezi nejvýznamnější zdroje vnitřní kontaminace obyvatelstva Cs-137 patří houby, lesní plody a maso lesní zvěře, která se jimi živí (Ban-nai et al, 2004;Fesenko et al, 2001).…”