M. J. Melgar

Mercury in edible mushrooms and underlying soil: Bioconcentration factors and toxicological risk

Wild growing mushrooms are a popular delicacy in many countries, but some species accumulate high levels of toxic heavy metals, e.g., mercury, both in unpolluted and mildly polluted areas. In this study, we examined the accumulation capacity of mercury in edible mushrooms in relation to certain factors and their possible toxicological implications. Total concentrations of mercury were determined by an anodic stripping voltammetric technique using a gold disc as the working electrode in 238 samples of the fruiting bodies of 28 wild growing edible mushrooms species and the underlying soil. The mushrooms were collected from different sites in the province of Lugo (NW Spain). The hymenophore (H) and the rest of the fruiting body (RFB) were analysed separately. The highest mean mercury concentrations (mg/kg dry weight) were found in Boletus pinophilus (6.9 in H and 4.5 in RFB), Agaricus macrosporus (5.1 in H and 3.7 in RFB), Lepista nuda (5.1 in H and 3.1 in RFB) and Boletus aereus (4.6 in H and 3.3 in RFB), while the lowest was found in Agrocybe cylindrica (0.34 in H and 0.26 in RFB) and Fistulina hepatica (0.30 in H and 0.22 in RFB). All mushroom species accumulated mercury (BCF>1) in relation to the underlying soils. There were no statistically significant differences between the mercury levels in the hymenophore and in the rest of the fruiting body. The total mercury concentrations were compared to data in the literature and to levels set by legislation. It was concluded that consumption of the majority of the studied mushrooms is not a toxicological risk as far as mercury content is concerned, although the species B.pinophilus, A.macrosporus, L.nuda and B.aereus should be consumed in low amounts.

Influence of some factors in toxicity and accumulation of cadmium from edible wild macrofungi in NW Spain

Cadmium content of 97 samples of some edible wild mushrooms, corresponding to 13 different species, was determined by graphite furnace atomic absorption spectrophotometry. Influence of some factors (species and ecology, morphological portion, and traffic pollution) and the importance of mushrooms as a dietary source of this heavy metal have been studied. Saprophite species showed higher levels than mycorrhizal ones (p < 0.001), with some exceptions such as Boletus and Amanita. The hymenophore was always the morphological portion which contained the highest cadmium levels (p < 0.001). Traffic pollution was not a significant factor for the cadmium accumulation in fungi. The samples of Agaricus macrosporus showed the highest mean levels (68.96 and 36.84 ppm dry matter (d. m.) for hymenophore and the rest of the fruit-body, respectively). The average cadmium content of the samples, with the exception of A. macrosporus, was 0.96 for hymenophore and 0.53 ppm d.m. for the rest of the fruit-body; and the range was between 0.18-4.32 and 0.10-1.91 ppm d.m. for hymenophore and the rest of the fruit-body. The concentration levels were compared to literature data and levels set by legislation, and the contribution of mushrooms to the weekly intake of cadmium per person was calculated. The possible health risk for the consumer is pointed out.

Assessment of Heavy Metal Contamination of Seawater and Marine Limpet, Patella vulgata L., from Northwest Spain

Abstract In the present work, both seawater and limpets (Patella vulgata L.) were collected from different sampling points in the Vigo estuary area (Galicia, NW Spain) and their heavy metal concentrations (Zn, Cd, Pb, Cu) were determined by means of a voltammetric technique. The results showed a direct relationship between the heavy metal levels in seawater and the content in biological samples, especially those obtained from limpet soft tissues, directly related to the increasing importance of anthropogenic environmental contamination. Heavy metal concentrations were usually higher in soft tissues than in shell, with a maximum difference corresponding to Cd and Zn (average of 93.6 and 86 folds, respectively). As expected, heavy metal content was higher in animal samples situated in inner part of the estuary zone, except for cadmium content in soft tissues, where a maximum of 5.62 ppm was quantified in limpet soft tissues collected next to the open sea area. Statistical analysis allowed the establishment of a clear relationship between Zn and Cd content in both shells and soft tissues from limpet, and especially between Zn and Cu in soft tissues (p<0.001).

Organophosphorus pesticide residues in raw milk and infant formulas from Spanish northwest

Residue levels of seven organophosphorus pesticides (OPPs), widely used as dairy cattle ectoparasiticides or in crops used for animal feed, were determined in raw milk and infant formulas. A total of 312 samples were collected (70 from infant formulas and 242 from raw milk) biweekly during a 24-month period. Pesticides were extracted by means of a solid phase system into acetone. An extract aliquot of acetone was injected into a gas chromatograph (GC) with a nitrogen-phosphorus detector. Recoveries of pesticides spiked in milk samples were 62.2 – 97.2 %. The frequency of total samples containing detectable levels of OPP residues was 6.73 % in total milk and 8.67 % in raw milk. The highest percentage incidence measured was for dichlorvos (5.78 %), followed by coumaphos (2.06 %), and parathion methyl (0.83 %). The range of positive results was calculated to be between 0.005 and 0.220 mg kg− 1. No residue was detected in the final product (infant formulas), so any risk to consumer health, especially to childrens health, would be limited.

Acaricide Residue Determination in Honey

The Varroa mite appeared in Spain in 1985, though it was detected in Galicia (NW Spain) in 1987 for the first time (Asorey 1987). The control of this mite was carried out by the use of different acaricides: amitraz (active component of Taktic) and coumaphos (active component of Perizin) were first used. After 1989, many beekeepers used fluvalinate, the active component of three formulations: Mavrik, Klartan and Apistan (Asorey 1989).

Radiocaesium activity concentrations in macrofungi from Galicia (NW Spain): Influence of environmental and genetic factors

Radiocaesium ((137)Cs) is an artificial radionuclide that can be captured from the soil through the mycelium of fungi. However, in Spain there are few data on its presence in edible mushrooms. (137)Cs activity concentrations were determined using 54 samples of wild and cultivated mushrooms and 18 samples of soil, all of them collected in Galicia (NW Spain) during 2010. Samples were analyzed by gamma spectroscopy with a High-Purity Germanium (HPGe) detector. The average activity concentration of (137)Cs in wild mushrooms was 249.2Bqkg(-1) dry weight (dw) and about 24.9Bqkg(-1) fresh weight (fw). Genetic factors (species) influenced the uptake of (137)Cs, highlighting Hydnum repandum as the greatest accumulator of all wild species (1016.4Bqkg(-1) dw), while cultivated species showed much lower levels (1.6Bqkg(-1) fw). Accumulation was also favored by fungal mycorrhizal ecology, whose mycelium was distributed in contaminated soil horizons. The mean levels detected in soils were 14Bqkg(-1) fw. Although some species behaved as bioexclusors of radiocaesium, the transfer factors (TF) suggest that mushrooms preferentially bioaccumulate (137)Cs. No sample reached the limit of 600Bqkg(-1) fw (about 6000Bqkg(-1) dw) indicated in the European legislation. In conclusion, the consumption of mushrooms harvested from the investigated areas poses no toxicological risk to human health due to radiocaesium.

Bioconcentration of chromium in edible mushrooms: influence of environmental and genetic factors.

Chromium concentrations were determined in 167 samples of wild edible mushrooms, collected from three different sites (urban, traffic and pastureland areas) in Lugo (NW Spain). The hymenophore (H) and the rest of the fruiting body (RFB) were analysed separately. The analyses were performed using inductively coupled plasma optical emission spectrometry (ICP-OES). The highest mean chromium levels (mg/kg dry weight) of 3.5 and 8.0, 4.5 and 6.2, and 6.2 and 4.3 were found in Lycoperdon utriforme, Coprinus comatus and Agaricus campestris in H and RFB, respectively. The highest concentrations of chromium were observed in terrestrial saprophytic species in relation to mycorrhizal species. With respect to the underlying substrates, chromium concentration was lowest in the pastureland area (24.6 mg/kg dw). All mushroom species were bioexclusors of chromium (BCF<1) with statistically significant differences (p<0.001). The consumption of mushrooms harvested from the areas investigated poses no toxicological risk to human health due to chromium.

Total contents of arsenic and associated health risks in edible mushrooms, mushroom supplements and growth substrates from Galicia (NW Spain).

The levels of arsenic (As) in the main commercial species of mushrooms present in Galicia, in their growth substrates, and mushroom supplements have been analysed by ICP-MS, with the intention of assessing potential health risks involved with their consumption. The mean concentrations of As in wild and cultivated mushrooms was 0.27mg/kg dw, in mushroom supplements 0.40mg/kg dw, in soils 5.10mg/kg dw, and in growth substrate 0.51mg/kg dw. No significant differences were observed between species, although the species Lactarius deliciosus possessed a slightly more elevated mean concentration (at 0.49mg/kg dw) than the other species investigated. In soils, statistically significant differences (p<0.05) were observed according to geographic origin. Levels in mushroom supplements, although low, were higher than in wild or cultivated mushrooms. Measured arsenic levels were within the normal range in samples analysed in unpolluted areas. Because of the low As concentrations found in fungi and mushroom supplements from Galicia, and considering the relatively small inclusion of these foods in peoples diet, it can be concluded that there is no toxicological risk of arsenic associated with the consumption of the species of mushrooms analysed or at the dosages indicated for mushroom supplements.

Assessment of drinking water contamination at springs along the road to Santiago (NW Spain)

Abstract With the aim of assessing the potability of drinking water, 31 different springs sited along the road to Santiago “The French Way” in Galicia (NW Spain) were studied. Twenty-one parameters, according to Spanish Legislation have been determined by Official Methods. It was observed that the parameters: pH, nitrate, ammonia, total coliforms, fecal coliforms and fecal streptococcus did not always comply with the levels established by Spanish Legislation. The bacteriological characters were the most restrictive of the sanitary quality of drinking water, only 19% of the springs were drinkable during all the study. According to the Factorial Analysis in Principal Component applied to the obtained results, it was concluded that the parameters: conductivity, hardness, dry residue, nitrate and fecal coliforms can be very indicative for assessing water sanitary quality.

Spatiotemporal characterization of groundwater contamination as a result of urban effects.

We investigated the effects of urban drainage on thewater quality of springs feeding drinking waterfountains in Lugo, a city in northwest Spain. Theparameters determined were electrical conductivity,dry residue, pH, dissolved O2, NO3-,NO2-, NH4+, Cl-, organicmatter, turbidity, colour, Fe, Mn, Cu and Zn. The datawere analysed with the aid of principal componentsanalysis and cluster analysis. The first two axesextracted by principal components analysis of thesamples-by-variables matrix represented (a) salinecontamination, strongly influenced by degree ofdilution, and (b) organometallic contamination,strongly influenced by redox conditions.Within-location temporal variation in water qualitywas probably largely due to seasonal variation inrainfall amounts.