Mercury in raw mushrooms and in stir-fried in deep oil mushroom meals

A critical review of the occurrence of scandium and yttrium in mushrooms

Scandium (Sc) and Yttrium (Y) along with the other rare earth elements (REE) are being increasingly extracted to meet the escalating demand for their use in modern high technology applications. Concern has been voiced that releases from this escalating usage may pollute environments, including the habitats of wild species of mushrooms, many of which are foraged and prized as foods. This review collates the scarce information on occurrence of these elements in wild mushrooms and also reviews soil substrate levels, including forested habitats. Sc and Y occurred at lower levels in mushrooms (<1.0-1000 µg kg-1 dw for Sc and<1.8-1500 µg kg-1 dw for Y) compared to the corresponding range for the sum of the lanthanides in the same species (16-8400 µg kg-1 dw). The reported species showed considerably more variation in Y contents than Sc which show a narrow median distribution range (20-40 µg kg-1 dw). Data allowing temporal examination was very limited but showed no increasing trend between the 1970s to 2019, nor were any geographical influences apparent. The study of the essentiality, toxicity or other effects of REE including Sc and Y at levels of current dietary intake are as yet undefined. High intake scenarios using the highest median concentrations of Sc and Y, resulted in daily intakes of 1.2 and 3.3 μg respectively from 300 g portions of mushroom meals. These could be considered as low unless future toxicological insights make these intake levels relevant.

In vitro gastrointestinal digestion and bioavailability of lithium from processed lithiated and nonlithiated white Agaricus bisporus mushrooms

AIM

In order to avoid side effects of lithium doses in some patients, some commonly cultivated mushroom species including A. bisporus have been successfully lithiated, with the potential to provide more acceptable sources of Li. This study assessed the in vitro release (potential bioaccessibility) and possible intake of Li using the action of artificial gastrointestinal juices on lithiated and nonlithiated (control) button mushrooms (Agaricus bisporus) that were subjected to certain modes of culinary processing.

METHODS

In the in vitro release study, mushrooms were processed using a number of routinely used domestic treatments including rehydrating dried mushrooms, blanching and blanching followed by pickling of fresh or frozen mushrooms. The in vitro digestion procedure used artificial gastrointestinal juices in a two-stage methodology that was adapted from 'The Bioaccessibility Research Group of Europe' method. The Li concentrations were determined using an inductively coupled argon plasma-dynamic reactive cell-mass spectrometer.

RESULTS

Lithium was found to be more bioaccessible from caps of lithiated mushrooms compared with nonlithiated. Releases from the caps and stipes of blanched or blanched and then pickled mushrooms through gastric digestion ranged from 32 ± 2 to 50 ± 1% relative to the dried product and was lower for gastrointestinal digestion, which ranged from 16 ± 1 to 20 ± 1%.

CONCLUSION

Losses of Li sustained through blanching or blanching followed by pickling of fresh mushrooms (41-87% wet weight) combined with limited accessibility during gastrointestinal release (16-55%) result in much lower bioavailability of the dose from lithiated products. A 300-g meal would provide <5% of the Li (6 mg) required for potential preventative treatments, such as reducing suicide rates and lowering dementia risk.

A method for the analysis of methylmercury and total Hg in fungal matrices

The aim of the study was to develop an efficient method for the determination of monomethyl-mercury (MeHg) and total mercury (THg) content in materials such as fungal sporocarps and sclerotia. Certified Reference Materials (CRMs) with the assigned values of MeHg and THg as well as the control materials (dried mushrooms) with known content of THg were evaluated for method validation. Recovery of MeHg from reference materials was at the following levels: from tuna fish at 87.0 ± 2.3% (THg at 101.9 ± 1.2%), from fish protein at 99.4 ± 1.3% (THg at 92.70 ± 0.41%), and from dogfish liver at 96.45 ± 0.73%. Recovery of THg from the fungal control material CS-M-5 was at 104.01 ± 0.60% (contribution of MeHg in THg content was at 6.2%), from CS-M-4 at 101.1 ± 2.0% (contribution at 3.2%), from CS-M-3 at 100.55 ± 0.67% (contribution at 0.6%), and from CS-M-2 at 101.5 ± 2.7% (contribution at 3.7%). The content of MeHg in randomly selected wild fungi and their morphological parts was in the range from 0.006 to 0.173 mg kg^-1 dry weight (dw). In the case of THg, the concentration values were in the range from 0.0108 to 10.27 mg kg^-1 dw. The MeHg content in the control materials with the assigned THg values was determined. Since the control materials play an important role in all elements of the quality assurance system of measurement results, they can be used to analyse MeHg as the first control material for fungi. KEY POINTS: • An extraction procedure for MeHg analysis in fungi was developed and optimized. • Recovery of MeHg from the certified reference non-fungal materials was > 87%. • Fungal control materials with assigned THg concentration can serve also for MeHg analysis.

Mercury in scarletina bolete mushroom (Neoboletus luridiformis): Intake, spatial distribution in the fruiting body, accumulation ability and health risk assessment

In the present work, we focused on two aspects of mercury (Hg) bioconcentration in the above-ground parts of Neoboletus luridiformis. In the first part, we monitored the bioconcentration potential of individual anatomical parts of a particular fruiting body and evaluated the obtained data by the spline interpolation method. In the second part, we focused on assessing the mercury content in 378 samples of N. luridiformis and associated samples of substrates from 38 localities with different levels of Hg content in Slovakia. From the obtained data of Hg content in samples of substrate and fungi, we evaluated ecological indicators (geoaccumulation index - Igeo, contamination factor - Cf a potential ecological risk - PER), bioconcentration indicators (bioconcentration factor - BCF; cap/stipe quotient - Qc/s) and health indicators (percentage of provisional tolerable weekly intake - %PTWI a target hazard quotient - THQ). Based on the Hg distribution results, the highest Hg content was found in the tubes & pores (3.86 mg/kg DW), followed by the flesh of cap (1.82 mg/kg DW). The lowest Hg content was in the stipe (1.23 mg/kg DW). The results of the BCF values indicate that the studied species can be included in the category of mercury accumulators. The results of the ecological indices representing the state of soil pollution pointed out that two localities (Malachov and Nižná Slaná) stood apart from all monitored localities and showed a state of an extremely disturbed environment. This fact was also reflected in the values of Hg content in the fruiting bodies of the studied mushroom species. In the case of the consumption of mushrooms from these localities, it can be stated that long-term and regular consumption could have a negative non-carcinogenic effect on the health of consumers. It was confirmed by the %PTWI (Malachov: 57.8%; Nižná Slaná: 53.2%) and THQ (Malachov: 1.11 Nižná Slaná: 1.02). The locality Čačín-Jelšovec is interesting from the bioconcentration characteristics point of view, where the level of environmental pollution was the lowest (Hg content in the soil was below the background value) compared to other localities, however, the THQ value was the highest (1.29).

Total mercury and methylmercury (MeHg) in braised and crude Boletus edulis carpophores during various developmental stages

We collected and processed Boletus edulis (King Bolete) carpophores grouped in four batches based on their developmental stage (button stage, young-white, large-white, and large-yellow). The study aimed, for the first time, to examine the B. edulis content and effect of braising and to estimate the intake of total mercury (THg) and methylmercury (MeHg) from a single meal based on whole (wet) weight (ww) and dry weight (dw). In braised carpophores, THg concentrations ranged from 0.2668 ± 0.0090 to 0.5434 ± 0.0071 mg kg-1 ww at different developmental stages, whereas crude products concentrations ranged from 0.1880 ± 0.0247 to 0.2929 ± 0.0030 mg kg-1 ww. The button stage crude carpophores were more highly contaminated with THg than at later stages of maturity, but MeHg levels were lower (p < 0.0001). On the other hand, braised button stage carpophores showed more MeHg than at later maturity stages. MeHg contributed at 1.9 ± 0.7% in THg in crude mushrooms and at 1.4 ± 0.3% in braised meals. The effect of braising was to increase the average THg and MeHg contents in fresh mushroom meals by 52 ± 31% and 53 ± 122% respectively, but a reduction of 40 ±14% and 40 ± 49% respectively was seen on a dw basis. The potential intakes of THg and MeHg from braised meals of B. edulis studied were small and considered safe.

137Caesium, 40K and total K in Boletus edulis at different maturity stages: Effect of braising and estimated radiation dose intake

We studied activity concentrations of artificial ¹³⁷Cs and natural ⁴⁰K and concentration of total potassium (K) in Boletus edulis at different maturity stages (button, young - white, large - white and large - yellow), and the effect of braising and human dietary intake. Mushrooms were collected from the northern region of Poland in 2019. The ¹³⁷Cs activity concentration was significantly higher in raw and braised button stage samples and decreased as the fruitbody matured, but conversely, ⁴⁰K was lower in the raw button stage than in older fruitbodies. ¹³⁷Cs activity concentrations in raw, button stage B. edulis were 36 ± 1 Bq kg^-1 ww (360 ± 1 Bq kg^-1 dw), increasing to 70 ± 2 Bq kg^-1 ww (290 ± 7 Bq kg^-1 dw) when braised. This activity was around fourteen-fold higher (p < 0.0001) than at higher maturity stages which showed 2.5 ± 0.7 Bq kg^-1 ww (25 ± 7 Bq kg^-1 dw) in raw and 4.9 ± 0.7 Bq kg^-1 ww (19 ± 4 Bq kg^-1 dw) in braised fruitbodies. In comparison to raw B. edulis, braising enriched the activity concentrations of ¹³⁷Cs at 110 ± 69% and ⁴⁰K at 80 ± 56% on a whole (wet) weight basis.

Ecological risk assessment at the food web scale: A case study of a mercury contaminated oilfield

Mercury, particularly methylmercury, can accumulate through food webs and generate high risks for species at higher trophic levels. Inorganic mercury can be methylated into the organic species methylmercury if suitable reducing conditions exist, for example, in hotspots like oilfields. We developed a conceptual model to conduct an ecological risk assessment based on the food web structure of the Shengli oilfield area, China. The model can identify species at risk and elucidate the sources of risks according to their diet. A risk rating criteria was developed based on the food web structure to categorize the different levels of risks for different species. As expected, the results indicate increasing risks for the biota higher in the food web hierarchy. Grasshoppers were mostly at no risk throughout the study area, whereas grubs at southwest were at minimal risks due to local high Hg concentration in the soil. Mantises, which are insect predators, were also at minimal risk. Herbivorous birds with similar feeding habits than grasshoppers were at no risk, but omnivorous and carnivorous birds were at moderate risk. The conceptual model is a useful tool to improve pollution remediation and establish risk control strategies based on ecological risks of the food web rather than just Hg concentrations in the environment.

Mercury in traditionally foraged species of fungi (macromycetes) from the karst area across Yunnan province in China

The objective of this study is to better quantify the occurrence, intake, and potential risk from Hg in fungi traditionally foraged in SW China. The concentrations and intakes of Hg were measured from 42 species including a "hard" flesh type polypore fungi and a" soft" flesh type edible species that are used in traditional herbal medicine, collected during the period 2011-2017. Three profiles of forest topsoil from the Zhenyuan site in 2015 and Changning and Dulong sites in 2016 were also investigated. The concentrations of Hg in composite samples of polypore fungi were usually below 0.1 mg kg-1 dry weight (dw) but higher levels, 0.11 ± 0.01 and 0.24 ± 0.00 mg kg-1 dw, were noted in Ganoderma applanatum and Amauroderma niger respectively, both from the Nujiang site near the town of Lanping in NW Yunnan. Hg concentrations in Boletaceae species were usually well above 1.0 mg kg-1 dw and as high as 10 mg kg-1 dw. The quality of the mushrooms in this study in view of contamination with Hg showed a complex picture. The "worst case" estimations showed probable intake of Hg from 0.006 μg kg-1 body mass (bm) ("hard" type flesh) to 0.25 μg kg-1 bm ("soft" flesh) on a daily basis for capsulated products, from 17 to 83 μg kg-1 bm ("soft" flesh) in a meal ("hard" type flesh mushrooms are not cooked while used in traditional herbal medicine after processing), and from 0.042 to 1.7 and 120 to 580 μg kg-1 bm on a weekly basis, respectively. KEY POINTS: • Polypore species were slightly contaminated with Hg. • Hg maximal content in the polypore was < 0.25 mg kg-1 dry weight. • Many species from Boletaceae family in Yunnan showed elevated Hg. • Locals who often eat Boletus may take Hg at a dose above the daily reference dose.

Interactions between Hg and soil microbes: microbial diversity and mechanisms, with an emphasis on fungal processes

Mercury (Hg) is a highly toxic metal with no known biological function, and it can be highly bioavailable in terrestrial ecosystems. Although fungi are important contributors to a number of soil processes including plant nutrient uptake and decomposition, little is known about the effect of Hg on fungi. Fungi accumulate the largest amount of Hg and are the organisms capable of the highest bioaccumulation of Hg. While referring to detailed mechanisms in bacteria, this mini-review emphasizes the progress made recently on this topic and represents the first step towards a better understanding of the mechanisms underlying Hg tolerance and accumulation in fungal species and hence on the role of fungi within the Hg cycle at Hg-contaminated sites. KEY POINTS: • The fungal communities are more resilient than bacterial communities to Hg exposure. • The exposure to Hg is a threat to microbial soil functions involved in both C and nutrient cycles. • Fungal (hyper)accumulation of Hg may be important for the Hg cycle in terrestrial environments. • Understanding Hg tolerance and accumulation by fungi may lead to new remediation biotechnologies.

Transgenic merA and merB expression reduces mercury contamination in vegetables and grains grown in mercury-contaminated soil

Arabidopsis, tobacco, tomato and rice with merA/merB expressed reduced mercury concentration of leaves, fruits or grains. These mercury-breathing plants produce agricultural products with acceptable levels of mercury from contaminated soil. Mercury contamination in plant food products can cause serious health risks to consumers. Transgenic approaches to enhance mercury phytoremediation have been accomplished with expression of bacterial merA and merB genes to convert toxic organic mercury to less toxic elemental mercury. However, little is known whether these genes can be used to produce safe foods from plants grown on mercury-contaminated land. We have used Arabidopsis and tobacco as model plants for leafy vegetables, and tomato and rice as representative fruit and grain crops to investigate whether merA and merB expression allows for production of safe foods from mercury-contaminated soils. Our results show that grown on heavily contaminated land with mercury, merA and merB expressing transgenic plants can produce vegetables, fruits and grains safe for human and animal consumption, while the wild-type plants cannot. The merA and merB transgenic plants can also efficiently remove mercury from soil. With increasing mercury contamination problems for the agricultural land worldwide, the use of the merA and merB genes can help produce safe food from mercury-polluted land and also remediate contaminated soils.

137Cs, 40K, and K in raw and stir-fried mushrooms from the Boletaceae family from the Midu region in Yunnan, Southwest China

The parallel batches of the same species and geographical origin mushrooms both raw and stir-fried were investigated to get an insight into the content and intake of ¹³⁷Cs, ⁴⁰K, and K from mushroom meals. The Boletaceae family species (Baorangia bicolor, Boletus bainiugan, Butyriboletus roseoflavus, Retiboletus griseus, Rugiboletus extremiorientalis, and Sutorius magnificus) were collected from the Midu County (Dali Bai Autonomous Prefecture) in 2018. The activity concentrations of ¹³⁷Cs in the caps of dried raw mushrooms were in the range 14 ± 1 Bq kg^-1 dry biomass (db) (R. griseus) to 34 ± 2 Bq kg^-1 db (R. extremiorientalis), and in stems from 16 ± 1 Bq kg^-1 db (B. bicolor and B. bainiugan) to 23 ± 1 Bq kg^-1 db (R. extremiorientalis). The mean activity concentration in the whole fruiting bodies in all six species was 18 ± 4 Bq kg^-1 db. The activity concentrations of ¹³⁷Cs were roughly the same in both dehydrated materials, stir-fried, and raw mushrooms, while the contents of ⁴⁰K and stable K were around 2- to 3-fold smaller in stir-fried than raw product. The raw and stir-fried mushrooms on a whole (wet) weight basis showed activity concentrations of ¹³⁷Cs in the range from 1.2 to 3.2 Bq kg^-1 ww (mean 1.9 ± 0.6 Bq kg^-1 ww) and 6.0 to 9.4 Bq kg^-1 ww (mean 7.0 ± 1.2 Bq kg^-1 ww), respectively. Evidently, when expressed on a whole (wet) weight basis, the cooked mushrooms showed on average around 3.5-fold greater activity concentration of ¹³⁷Cs when compared with raw mushrooms. The ¹³⁷Cs, ⁴⁰K, and total K enrichment in stir-frying (in a whole (wet) weight basis for the meal), confronted with the results for dehydrated raw and fried mushrooms, show the direct correlation with loss of mass (largely moisture) during the cooking procedure but not much of ¹³⁷Cs and ⁴⁰K. Edible wild mushrooms from Yunnan were little contaminated with radiocaesium. As assessed, the mean radioactivity dose from natural ⁴⁰K in around 9.3-fold exceeded the dose obtained for artificial ¹³⁷Cs from stir-fried mushroom meals, which both were very low doses.

Bolete mushroom Boletus bainiugan from Yunnan as a reflection of the geographical distribution of 210Po, 210Pb and uranium (234U, 235U, 238U) radionuclides, their intake rates and effective exposure doses

This pioneering study aimed to determine the activity concentrations of ²¹⁰Po, ²¹⁰Pb and uranium (²³⁴U, ²³⁵U, ²³⁸U) radionuclides in fruit bodies of wild bolete Boletus bainiugan Dentinger and to estimate its edible safety, which may give scientific evidence for the consumption of this species. The analyses were performed using alpha spectrometer after digestion, exchange resins separation and deposition. Measurement data were analysed and interpolation maps reflecting ²¹⁰Po, ²¹⁰Pb and uranium (²³⁴U, ²³⁵U, ²³⁸U) geographical distribution in Yunnan province (China) were presented. In addition, from the perspective of food safety, the possible related effective radiation dose to mushrooms consumers were estimated. The results indicated that ²¹⁰Po, ²¹⁰Pb and uranium (²³⁴U, ²³⁵U, ²³⁸U) radionuclides contents in B. bainiugan were significantly different with respect to geographical distribution, and their possible intake in a part of the region was considerably higher. A very interesting observation was done according to the values of ²³⁵U/²³⁸U activity ratio indicating the occurrence of uranium faction from the global fallout of nuclear weapon tests.

Contamination, bioconcentration and distribution of mercury in Tricholoma spp. mushrooms from southern and northern regions of Europe

The contamination, bio-concentration and distribution of mercury (Hg) in wild mushrooms of the genus Tricholoma such as T. equestre, T. portentosum, T. columbeta, and T. terreum were studied, and the possible dietary intake and risk for human consumers in Europe was estimated. Mushrooms, together with the associated forest topsoils were collected from 10 unpolluted and geographically distant areas, far from local or regional emission sources, in Poland (2 sites) and Croatia (8 sites). The Hg contents were in the range 0.10 ± 0.06 to 0.71 ± 0.34 mg kg^-1 dry matter in caps and 0.04 ± 0.02 to 0.38 ± 0.13 mg kg^-1 in stems. The corresponding topsoil concentrations varied over a relatively narrow range between sites, from 0.013 ± 0.003 to 0.028 ± 0.006 mg kg^-1 dry matter. Overall, the study results showed low levels of mercury both, in edible Tricholoma mushrooms and forest topsoils from background (unpolluted) forested areas in Croatia and Poland. The morphological distribution showed considerably greater concentrations of mercury in the caps relative to the stems with ratios ranging from 1.6 ± 0.6 to 3.9 ± 1.8. T. equestre showed good ability to bioconcentrate Hg, with bioconcentration factors (BCF) values in the range 18 ± 7 to 37 ± 18. The data suggests that Tricholoma mushrooms from unpolluted areas in southern and northern regions of Europe can be considered as a low risk food from the point of view of the tolerable Hg intake.

Uranium (234U, 238U) and thorium (230Th, 232Th) in mushrooms of genus Leccinum and Leccinellum and the potential effective ionizing radiation dose assessment for human

Evaluated has been bioconcentration potential by fungi and risk to human consumers from exposure to natural long-lived radioactive uranium (²³⁴U, ²³⁸U) and thorium (²³⁰Th, ²³²Th) sequestered in stems, caps and the whole fruiting bodies by mushrooms of the genus Leccinum and Leccinellum. Edible species in the study were collected from boreal forests in the northern regions of Poland and investigated: red-capped scaber (Leccinum aurantiacum), orange oak bolete (Leccinum aurantiacum var. quercinum), foxy bolete (Leccinum vulpinum), slate bolete (Leccinum aurantiacum var. duriusculum) and hazel bolete (Leccinellum pseudoscabrum). The study showed the species accumulated uranium (²³⁴U, ²³⁸U) and thorium (^230Th, ²³²Th) form soil to some degree but the calculated values of the bioconcentration factor were below 1. The evaluation showed that Leccinum and Leccinellum mushrooms can contribute to annual effective radiation dose maximally at about 0.9 μSv. Hence, consumption of these mushrooms might increase the annual effective ionizing radiation dose received by a human, while the exposure is considered low from the toxicological point of view even if eaten at elevated amounts.

Radiotoxic 210Po and 210Pb in uncooked and cooked Boletaceae mushrooms from Yunnan (China) including intake rates and effective exposure doses

The article presents results of a study on the radioactivity and exposure from a highly toxic alpha-radiation emitter polonium ²¹⁰Po, and beta emitter lead ²¹⁰Pb in several species of Boletaceae mushrooms and stir-fried mushroom meals from China. Edible mushrooms can efficiently concentrate some elements in flesh but little is known on highly toxic alpha- and beta emitters. In this study, the absolute values of radioactivity (Bq·kg^-1 dry weight) for ²¹⁰Po were in the range 2.0 ± 2.0 to 308 ± 9 in fresh species and 22.1 ± 1.2 to 142 ± 4 in a ready to eat meals, and for ²¹⁰Pb were 3.6 ± 0.5 to 51.8 ± 2.9 and 3.0 ± 0.14 to 9.6 ± 0.5, respectively. The studied batches of a corresponding species of mushrooms - raw and cooked - were not equivalent regarding the homogeneity of the composition. However the raw mushrooms (ingredient for any cooking), showed greater radioactivity in relation to stir-fried meals, and that can imply on a partial loss of nuclides. A daily portion of 100 g of stir-fried mushrooms could provide ²¹⁰Po and ²¹⁰Pb radiation in the range 0.2-2.1 μSv and 0.02-0.06 μSv, respectively. Assessed, the cumulative doses of exposure to ²¹⁰Po were 1.4-14 μSv in a week period and 75-722 μSv at annual timescale, and of ²¹⁰Pb amounted at 0.15-0.46 μSv and 8.3-24 μSv, respectively. The ²¹⁰Po can be possibly considered as a major source of ionizing radiation activity for persons with high mushroom meals consumption in SW Asia, while the number of available data is limited.

Artificial (137Cs) and natural (40K) radioactivity and total potassium in medicinal fungi from Yunnan in China

Evaluated has been radioactive contamination with ¹³⁷Cs in parallel to occurrence of ⁴⁰K and total K in 31 species of medicinal mushrooms from Yunnan, China. We chose species that were not previously studied. The activity concentrations of ¹³⁷Cs in the medicinal fungi in this study were low. The maximum values were 54 ± 4 Bq kg^-1 dry biomass (db) in caps and 48 ± 5 Bq kg^-1 db in stipes of saprotrophic fungus Gerronema xanthophyllum from the family of Tricholomataceae. Mushrooms with relatively higher activity concentrations of ⁴⁰K were among the non-polypore species but certain species from the genus Ganoderma such as G. applanatum, G. capense, G. philippii and G. sinense showed ⁴⁰K in the higher range of 900 ± 240 to 1400 ± 340 Bq kg^-1 db. The concentrations of total K in the fungal materials in this study were in the range from 2.9 ± 6.5 g kg^-1 db in Fomes rufolaccatus to 110 ± 6 g kg^-1 db in G. xanthophyllum. The species studied, which represented both some popular wood-decaying polypore fungi but also terrestrial forms from the herbal medicine of China, can be considered as little contaminated with ¹³⁷Cs and potentially good source of leachable K in extract and decoction or as a powdered form in capsules.

Arsenic and arsenic speciation in mushrooms from China: A review

Arsenic (As) is a natural environmental contaminant to which humans are usually exposed in water, air, soil, and food. China is a typical high-As region, and also a great contributor of the world production of cultivated edible mushrooms and a region abundant in wild growing edible mushrooms. Mushrooms can accumulate different amounts of As and different As compounds, so potential health risk of As intake may exist to people who use mushrooms with elevated As contents as food or medicine. A systematic literature search was carried out for studies on As and As compounds in mushrooms from China. We compiled existing data from published sources in English or Chinese and provide an updated review of the findings on As in mushrooms associated with environments and health risks. Future perspectives for studies on As in mushrooms have also been discussed.

Occurrence, distribution and estimated intake of mercury and selenium from sclerotia of the medicinal fungus Wolfiporia cocos from China

The contamination and distribution of mercury and selenium in the Chinese medicinal fungus Wolfiporia cocos was investigated. The sclerotial mercury concentrations ranged from 0.0043 to 0.027 mg kg¹ dry biomass (db) in the inner white part and 0.019-0.074 mg kg^-1 db in the shell (outer part), while selenium concentrations ranged from < 0.00048 to 0.0040 mg kg^-1 db (white) and 0.0034-0.038 mg kg^-1 db (shell). Positive correlations were found for mercury, as well as for mercury and selenium but they were not consistent for both morphological parts. Mercury concentrations exceeded selenium in 16 of 17 white part pools (molar quotient 0.53 to > 10) and in 11 of 17 shell pools (quotient 0.37 to 3.2). The estimated maximal exposure to mercury contained in sclerotial products based on 45 g per capita daily intake for a 60 kg individual over one week, was 0.000020 mg kg^-1 body mass (bm; white) and 0.000055 mg kg^-1 bm (shell) on a daily basis, and 0.00014 mg kg^-1 bm (white) and 0.00039 mg kg^-1 bm (shell) on a weekly basis. Relative to mercury, the corresponding intake rates of selenium were considered very low, i.e., they averaged on a daily basis at 0.00075 μg kg^-1 bm (white) and 0.0097 μg kg^-1 bm (shell) with maximum intake at 0.0030 μg kg^-1 bm (white) and 0.028 μg kg^-1 bm (shell).

137Cs and 40K in Cortinarius caperatus mushrooms (1996-2016) in Poland - Bioconcentration and estimated intake: 137Cs in Cortinarius spp. from the Northern Hemisphere from 1974 to 2016

Cortinarius caperatus grows in the northern regions of Europe, North America and Asia and is widely collected by mushroom foragers across Europe. This study shows that in the last three decades since the Chernobyl nuclear accident, C. caperatus collected across much of Northern Poland exhibited high activity concentrations of radiocaesium (¹³⁷Cs) - a long-lived radionuclide. The mushroom appears to efficiently bioconcentrate ¹³⁷Cs from contaminated soil substrata followed by sequestration into its morphological parts such as the cap and stipe which are used as food. The gradual leaching of ¹³⁷Cs into the lower strata of surface soils in exposed areas are likely to facilitate higher bioavailability to the mycelia of this species which penetrate to relatively greater depths and may account for the continuing high activity levels noticed in Polish samples (e.g. activity within caps in some locations was still at 11,000 Bq kg^-1 dw in 2008 relative to a peak of 18,000 in 2002). The associated dietary intake levels of ¹³⁷Cs have often exceeded the tolerance limits set by the European Union (370 and 600 Bq kg^-1 ww for children and adults respectively) during the years 1996-2010. Human dietary exposure to ¹³⁷Cs is influenced by the method of food preparation and may be mitigated by blanching followed by disposal of the water, rather than direct consumption after stir-frying or stewing. It may be prudent to provide precautionary advice and monitor activity levels, as this mushroom continues to be foraged by casual as well as experienced mushroom hunters.