Concentrations of mercury and other elements in ewes' milk: Effect of lactation stage

Essential Trace and Toxic Element Content in Lacaune Sheep Milk during Lactation

The aim of this study was to investigate the concentrations of essential trace and toxic elements in the milk of Lacaune sheep during lactation in intensive rearing systems. This research was conducted with 30 Lacaune sheep that were monitored in the early (60 days of lactation), medium (120 days of lactation), and late (180 days of lactation) stages of lactation. The sheep were fed a pelleted feed mixture (1 kg/day), a cereal mixture (600 g/day), and alfalfa hay (ad libitum). The essential (Fe, Zn, Cu, Co, Mn, Mo, Se, Cr, and Ni) and toxic element (heavy metals: Cd, Pb, As, and Hg) concentrations in the feed and milk were determined using an inductively coupled plasma mass spectrometer. Significant variations in the main essential trace and toxic elements, except for the Mo, Se, Ni, As, and Hg concentrations, were found in the milk of Lacaune sheep during lactation. As lactation progressed, in the late stage of lactation, significantly higher concentrations of Co, Mn, Mo, Cr, and Pb were found, while Zn and Cu in the milk of Lacaune sheep decreased significantly (4.15 and 0.21 mg/kg) compared to their concentrations in the early stage of lactation (5.66 and 0.43 mg/kg). Significantly lower concentrations of Fe and higher concentrations of Cd were found in the medium stage (0.23 mg/kg and 1.08 µg/kg) of lactation compared to both the early and late stages of lactation. An analysis of the correlation coefficients between the essential trace and toxic elements in Lacaune sheep milk during lactation determined a significantly positive correlation between Fe:Cr, Fe:Mn, Fe:Co, Fe:Se, Zn:Ni, Zn:Se, Cr:Mn, Cr:Co, Cr:Se, Cr:Mo, Mn:Co, Mn:Pb, Co:Ni, Co:Se, Ni:Se, Se:Mo, Se:Pb, and Cd:Pb. A significantly negative correlation was also found between Cu:Mn, Zn:Mo, Cg:Hg, and Hg:Pb. Based on the obtained results, it is recommended that the influence of the stage of lactation, as well as the breed of sheep, should be included when designing experiments. In general, sheep milk is rich in essential trace elements, but it also contains a very low content of toxic elements, which provides justification for increasing the breeding of Lacaune sheep and indicates the convenience of consuming their milk without risking the consumer's health.

Mutagens in raw ewe milk in Orava region, northern Slovakia: metals

The aim of this work was to determine the concentrations of selected mutagenic elements (As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Se) in raw ewe milk from undisturbed environment in Orava region, northern Slovakia. There are possible sources of some of the analyzed metals which may be distributed from the metallurgical plants located in the Ostrava region, Czech Republic, and Katowice, Poland. In total, forty milk samples were analyzed in June and August using an inductively coupled plasma optical emission spectrometry. The differences in elements concentrations between the seasonal periods were not significant except of iron (p < 0.0001). The concentrations of most of the metals in ewe milk were low and under the permissible or recommended limits. However, arsenic and selenium concentrations were elevated and could pose a risk of the mutagenic effect, particularly in children. The frequency of element occurrence in June was as follows: Se > Fe > As > Cu > Mn > Ni > Co > Pb > Cr > Cd, and in August: Se > Fe = As > Cu > Mn > Pb > Co > Ni > Cr > Cd. The correlation analysis revealed very strong positive correlation between Cu:Pb (p < 0.05), very strong negative correlation between Fe:Se (p < 0.05). The strong correlations were also found between other elements. The present study showed that milk produced in the relatively undisturbed environment might contain various mutagenic elements. The relationships between the elements might result in the additive or synergistic effects of elements and increase the risk of their mutagenic effects even in low concentrations. Therefore, attention must be paid to the monitoring of metals in the areas where food sources destined especially for child nutrition are produced.

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.

Spatio-temporal monitoring of mercury and other stable metal(loid)s and radionuclides in a Croatian terrestrial ecosystem around a natural gas treatment plant

The natural gas industry bears a certain contamination risk to human and biota due to, among others, mercury, arsenic, and naturally occurring radioactive material content in gas. We tracked multiple stabile metal(loid)s and radionuclides within the natural gas treatment plant Molve, Croatia, ecosystem during the last decade through a comprehensive monitoring of soil, earthworms, moss, livestock (blood, milk, hair, urine, and feces from cows), and wildlife animals (brain, muscle, liver, and kidney of European hare and pheasant). The level of mercury and other stable metal(loid)s has shown temporal variation, but without an obvious trend. The found spatial differences in soil and earthworms were based on the differing soil characteristics of the sampled locations and exceeded the maximal allowable concentration of arsenic and zinc for agricultural soil. The status of essential copper, selenium, and zinc in cows, hares, and pheasants inclined towards deficiency. The measured stable metal(loid) levels in soil and animal samples were generally in the same range of values reported in earlier decades from the same area or non-polluted areas across Europe. The consumption of local cow and game products (e.g., milk, meat) can be considered safe for human health, although game offal is advised to be avoided as a food item due to the low risk of lead and cadmium's adverse effects. Although the activity concentrations of some radionuclides in moss were higher than reported for pristine areas, transfer from soil to moss was assessed as average (except for lead-210). Radiological risk to human and biota around the gas treatment plant Molve was estimated as negligible.

Temporal and seasonal changes in mercury accumulation in Tatra chamois from West Carpathians

The main aim of this study was to determine the concentration of total mercury (T-Hg) in different tissues, hair, and faeces from a long-lived animal that actively lives in the subalpine and alpine zone within temperate climate zone throughout the year. Levels of T-Hg in samples from naturally deceased Tatra chamois (n = 72) from the Tatra Mountains (Slovakia) were determined using direct mercury analyses on the basis of dry weight. The mercury concentrations in hair samples were compared over the last three decades. Seasonal changes in mercury concentration and differences in the amounts of mercury in various tissues, hairs, and faeces between age and sex groups were also studied. The highest mercury concentrations in organs were found in the kidneys of Tatra chamois, with mean values of 0.45 ± 0.07 μg/g (dry weight) for adults (n = 18) and 0.39 ± 0.12 μg/g (dry weight) for juveniles (n = 6). These values are considerably high compared to expected Hg levels in wild ungulates from foothill and mountain areas in the temperate zone. Juveniles had higher levels of T-Hg in their muscles (0.011 ± 0.001 μg/g dry weight, n = 10) and faeces (0.189 ± 0.025 μg/g dry weight, n = 7) when compared to adults that had 0.007 ± 0.001 μg/g dry weight of T-Hg in muscles (n = 29) and 0.113 ± 0.015 μg/g dry of T-Hg weight in faeces (n = 19). T-Hg concentrations in individual tissues (heart, kidney, liver, lungs, spleen, tongue, muscle, bone), hairs, and faeces were not significantly different between males and females. Mercury levels in the hair of Tatra chamois have increased significantly since the 1990s (median value of T-Hg: 0.025 μg/g dry weight) with the highest values presenting during the 2000s (0.029 μg/g dry weight). Since 2010 (0.016 μg/g dry weight), levels have declined when compared to those observed during the 1990s and 2000s. Therefore, we can conclude that T-Hg deposition in alpine areas of the Tatra Mountains shows a declining trend since the 2010s. T-Hg concentrations in the heart, muscle, and hair were higher in summer compared to winter. Seasonal changes in mercury concentrations are likely most related to the seasonal availability of food, but may also be related to moulting periods, and this correlation must be explored further.