Reduced sperm quality in relation to oxidative stress in red deer from a lead mining area

The Impact of Pb from Ammunition on the Vegetation of a Bird Shooting Range

Hunting with lead ammunition represents a source of heavy metal pollution to the environment that can be potentially high at the local scale. Intensive hunting of small game species can concentrate high levels of ammunition discharging in small areas. This type of hunting is a relevant economic resource for private landowners in some regions of Spain, and current legislation allows the use of lead ammunition in these scenarios. It becomes, therefore, highly relevant to study whether this activity may pose concerns to the conservation of the environment in the areas where it takes place. Using a red-legged partridge (Alectoris rufa) shooting range as a study area, we examined the effect of intensive hunting on this species on the vegetation present. We found significantly higher lead levels in the sprouts of plants of shooting areas related to control sites of the same property where partridge shooting does not occur. We found differences in the presence of lead between sprouts of different plant species. In addition, old sprouts of existing vegetation in shooting areas also showed higher lead levels than newly emerged sprouts of the same plants. These results demonstrate the impact of lead ammunition on vegetation in terms of persistence over time and differences between species. Further analyses using chemical and ecotoxicological data are necessary to evaluate the extent of environmental pollution risks. Our results provide new support in favor of the use of alternative ammunition, with particular emphasis on scenarios where hunting activity is intensive.

Impact of Oxidative Stress on Male Reproduction in Domestic and Wild Animals

Oxidative stress occurs when the levels of reactive oxygen species (ROS) overcome the antioxidant defenses of the organism, jeopardizing several biological functions, including reproduction. In the male reproductive system, oxidative stress not only impairs sperm fertility but also compromises offspring health and survival, inducing oxidative damage to lipids, proteins and nucleic acids. Although a clear link between oxidative stress and male fertility disorders has been demonstrated in humans and laboratory rodents, little information is available about the implications of impaired redox homeostasis in the male fertility of domestic and wild animals. Therefore, this review aims to provide an update regarding the intrinsic and extrinsic factors that are associated with oxidative stress in the male reproductive system and their impact on the reproductive performance of domestic and wild animals. The most recent strategies for palliating the detrimental effects of oxidative stress on male fertility are reviewed together with their potential economic and ecological implications in the livestock industry and biodiversity conservation.

Detrimental effects of long-term exposure to heavy metals on histology, size and trace elements of testes and sperm parameters in Kermani Sheep

Exposure to endocrine-disrupting chemicals (EDCs) has been hypothesized as a cause of declining sheep reproductive efficiency. Understanding the long-term effects of EDCs such as heavy metals on reproductive health requires investigation in 'real life' of sheep that are reared in industrial areas. The aim of this study was to evaluate the effect of long-term exposure of Kermani rams to high levels of environmental heavy metals probably emitted from a copper smelter at KhatoonAbad in ShahreBabak, Kerman province. Testicular characteristics were determined in randomly-selected rams (3-4 years old) at 4 directions (south, north, east, and west) and 4 distances (10, 20, 30, and 40 km) from the smelter. Testicular trace element contents, size, serum testosterone, histological attributes and seminal characteristics, except semen volume, were affected by both the direction and the distance from the smelter (P < 0.05). Testicular contents of Pb, Cd, Cr, and Ni, and sperm abnormalities were higher at 10 km south from the smelter and lower at 40 km west. Other parameters were higher at 40 km west and lower at 10 km south. Interestingly, the testicular contents of Cu at 10 km south were lower and associated with higher sperm abnormalities in the rams reared closer to the smelter. The highest weight, length and circumference of the testis were found at 40 km west. The lowest concentration of testosterone was observed at 10 km south, being 92.6% lower than the highest values obtained at 40 km west. The diameter of seminiferous tubules and epithelial height at 10 km south were 8.9% and 27.5% lower than the highest values obtained at 40 km west. A positive correlation between Pb, Cd, Cr and Ni contents in the testis with sperm abnormalities, and a negative correlation between these elements with the other parameters were found. It was concluded that long-term exposure to heavy metals might have been a cause of decreased fertility in rams and probably other living species in this region.

Metalliferous Mining Pollution and Its Impact on Terrestrial and Semi-terrestrial Vertebrates: A Review

Metalliferous mining, a major source of metals and metalloids, has severe potential environmental impacts. However, the number of papers published in international peer-reviewed journals seems to be low regarding its effects in terrestrial wildlife. To the best of our knowledge, our review is the first on this topic. We used 186 studies published in scientific journals concerning metalliferous mining or mining spill pollution and their effects on terrestrial and semi-terrestrial vertebrates. We identified the working status of the mine complexes studied, the different biomarkers of exposure and effect used, and the studied taxa. Most studies (128) were developed in former mine sites and 46 in active mining areas. Additionally, although several mining accidents have occurred throughout the world, all papers about effects on terrestrial vertebrates from mining spillages were from Aznalcóllar (Spain). We also observed a lack of studies in some countries with a prominent mining industry. Despite >50% of the studies used some biomarker of effect, 42% of them only assessed exposure by measuring metal content in internal tissues or by non-invasive sampling, without considering the effect in their populations. Most studied species were birds and small mammals, with a negligible representation of reptiles and amphibians. The information gathered in this review could be helpful for future studies and protocols on the topic and it facilitates a database with valuable information on risk assessment of metalliferous mining pollution.

Response of male reproductive function to environmental heavy metal pollution in a free-living passerine bird, Passer montanus

Heavy metals affect male reproductive function by impairing reproductive organs, disturbing reproductive hormone levels or directly affecting sperm quality. However, little attention has been given to the effect of environmental heavy metals on reproductive function in wild male birds. The present study investigated the alterations of reproductive function in male tree sparrows (Passer montanus) exposed to environments contaminated by heavy metals in terms of testis parameters, reproductive hormone levels and sperm movement characteristics. Two plots, Baiyin (BY, mainly polluted by copper, zinc, lead and cadmium) and Liujiaxia (LJX, a relatively unpolluted area) were selected as sampling sites. The results showed that tree sparrows from BY (1) accumulated higher levels of cadmium in the testes, (2) showed lower superoxide dismutase (SOD) activity and malondialdehyde level, with higher total antioxidant capacity and apoptosis level in the testes, (3) showed higher plasma levels of estrogen, follicle stimulating hormone and luteinizing hormone (LH), and (4) had better sperm movement performance. Additionally, we found that testis size, SOD activity in testes and LH levels were decisive factors in sperm movement performance in tree sparrows. Heavy metal concentrations in testes negatively correlated with testis size, SOD activity in testes, and estrogen levels in tree sparrows. The present study indicates that heavy metals accumulating in testes of tree sparrows adversely affected some key indicators of male reproductive function. However, testicular function, reproductive hormone levels and sperm quality showed adaptive responses that tended to partially compensate for the negative effects in the heavy metal polluted area. This study further indicated that the regulation of testicular function and reproductive hormone levels was the main factor for better sperm quality in tree sparrows exposed to environments contaminated by heavy metals.

Low-level lead exposure is associated with aberrant sperm quality and reproductive hormone levels in Chinese male individuals: Results from the MARHCS study low-level lead exposure is associated with aberrant sperm quality

Studies in animals suggest an adverse effect of high-level lead exposure on male reproductive outcomes. However, evidence of the effects of low-level lead exposure is inconsistent. The purpose of our study was to explore the relationship between low-level lead exposure from daily environmental contaminants and semen quality in a community population without occupational exposure. We recruited 751 students in the Male Reproductive Health in Chongqing College Students (MARHCS) study and 190 community males from Bishan, Chongqing. Eight urinary metals (Pb, Cd, As, Cu, Zn, Ni, Mn, and Cr), semen quality, and serum sex hormones were detected. Even if the blood lead concentration was below the US lead poisoning standard for children (100 μg/L), a significant dose-response relationship was found between lead exposure and a decrease in semen quality. Multilinear regression showed that urinary Pb was negatively associated with sperm concentration, total sperm count, progressive motility and total sperm motility (regression coefficient: -0.074, -0.103, -0.024, and -0.014, respectively; p: <0.001, <0.001, 0.007, and <0.001, respectively), accompanied by decreased serum follicle-stimulating hormone, serum testosterone and the testosterone/luteinizing hormone ratio (β coefficient: -0.090, -0.082, and -0.020, respectively; p: 0.002, <0.001, and 0.021, respectively). Logistic regression also indicated that the risk of having abnormal semen quality was higher in the high Pb group (OR: 2.501, 95% CI: 1.411, 4.435, p = 0.002) than in the low Pb group after adjusting for confounders, with a dose-response relationship in the trend test (p = 0.007). Our results revealed an inverse association between Pb exposure at low levels and semen quality.

Genomic instability in adult men involved in processing electronic waste in Northern China

BACKGROUND

Managing and recycling electronic waste (e-waste), while useful and necessary, has resulted in significant contamination of several environments in China. The area around Tianjin, China has become one of the world's largest e-waste disposal centers, where electronics are processed by manually disassembly or burning, which can result in serious exposure of workers to a multitude of toxicants.

OBJECTIVE

The present study assessed potential genomic damage in workers involved in recycling e-waste.

METHODS

To detect cytogenetic and DNA damage, chromosomal aberrations (CA), cytokinesis blocking micronucleus (CBMN) and the comet assay were performed. Concentrations of some trace elements, markers of oxidative stress and polychlorinated biphenyls (PCBs) in whole blood or serum were measured, and relationships among the markers described above, age, and duration of exposure were analyzed. The profiles of expression of genes in lymphocytes in peripheral blood were assessed to determine the status of the regulation of genes involved in genome stability.

RESULTS

Concentrations of 28 PCB congeners in the whole blood of the exposed group were significantly (P<0.001) greater than those in the control individuals. Frequency of CA (8.01%) and CBMN (26.3‰) in lymphocytes and the level of DNA damage in the lymphocytes and spermatozoa of the exposed men were also significantly (P<0.0001) greater than those of the controls. There were significant relationships between CA, CBMN, DNA damage and duration of exposure. Concentrations of malondialdehyde (MDA) and lead (Pb) in the blood serum were significantly greater, but activities of superoxide dismutase (SOD), glutathione (GSH) and concentrations of calcium (Ca) and magnesium (Mg) were lower in the serum of the exposed men. MDA, Pb, Ca and Mg were associated with the duration of exposure to handling e-waste. In males involved in handling of e-waste, there were 13 genes - ATM, ATR, ABL1, CHEK1, CHEK2, GADD45A, CDK7, GTSE1, OGG1, DDB1, PRKDC, XRCC1 and CCNH - for which expression of mRNA was up-regulated and 7 genes - BRCA1, GTF2H1, SEMA4A, MRE11A, MUTYH, PNKP and RAD50 - for which the expression of mRNA was down-regulated.

CONCLUSIONS

A strong correlation between indicators of damage of DNA, which could result in instability of the genome, and duration of processing e-waste was observed. If proper procedures are not followed, there are significant risks to the health of the individuals involved in such activities.

Trace elements in the liver of captive and free-ranging European bison (Bison bonasus L.)

European bison is classified as a vulnerable species because of many threats. We analyzed the content of toxic and essential elements (Ag, Al, As, Ba, Be, Cd, Co, Cr, Cu, Hg, Mg, Mn, Na, Ni, Pb, Se, Th, Tl, U, V, and Zn) in the livers of 30 captive and free-ranging European bison from the Bison Breeding Center in Smardzewice and from Białowieża Primeval Forest in Poland. The contents of toxic elements were lower than reported previously in European Bison and were similar to those of wild ungulates from non-polluted areas. Accumulation of Cd and Cr was related to the age of animals. We compared the mineral status between captive and free-ranging European bison to verify whether the maintenance type could affect concentrations of trace elements in the liver. The concentration of Mn and Zn differed between captive and free-ranging group. Our results were compared to the reference values of essential elements for cattle. All animals from this study were Se-deficient and more than 80% of them have Cu deficiency. Deficiency of Mn was present in 20% of captive and 37% of free-ranging animals whereas Zn in 37% and 3% respectively. Statistical analysis confirmed that Mn and Zn deficiencies were related o the maintenance of animals (p<0.05). We revealed that mineral deficiencies could be an additional threat to the Polish population of European bison. Thus, the monitoring of essential minerals is necessary and future work is required to optimize the supplementation and foddering for preventing the occurrence of mineral deficiencies.

A comparison of selenium concentrations in selected organs of wild boar (Sus scrofa) from industrialized and non-industrialized regions of Poland

The aim of this study was to compare selenium concentration in the liver and kidneys of wild boar inhabiting industrialized and non-industrialized regions of Poland. Selenium concentrations in organs were determined using spectrofluorometric method. In all the animals studied, Se concentrations were a few times lower than in kidneys which may indicate too low content of this element either in the boar's diet or the presence of a poorly absorbable form of Se. No statistically significant differences were noted in the mean Se concentrations in the liver and kidney of wild boar from industrialized and non-industrialized areas. In the case of wild boar, it seems that the level of selenium in their organs is more dependent on geochemical conditions in the specific feeding ground than on the scale of regional industrialization, and that this situation is most likely related to the specificity of wild boar feeding.

Effects of Lead Exposure on Sperm Quality and Reproductive Success in an Avian Model

Lead (Pb) poisoning via ingestion of shot pellets is a frequent cause of death in wild birds and also has a wide range of subclinical effects. Here we report on the sublethal effects Pb exposure has on the breeding performance of red-legged partridges (Alectoris rufa). We studied the effects of Pb exposure on sperm quality, reproductive success, egg properties, laying performance, antioxidant levels, and carotenoid-based coloration. Birds were exposed by oral gavage to one or three No. 6 Pb shot pellets (2.8 mm in diameter, mean mass ± SD: 109 ± 7.97 mg). We show that exposure to three pellets (330 mg) reduced the hatching rate of females and decreased the acrosome integrity and sperm motility of males. In addition, females exposed to 1 pellet (110 mg) produced heavier eggs and chicks, whereas males exposed to 1 pellet presented an increase in sperm vigor. Sperm viability, concentration, progressiveness or fecundation rate were not affected by Pb treatment. Pb exposure increased circulating antioxidant levels in males, whereas the percentage of carotenoid-pigmented eye-ring area decreased in exposed females. Several sperm parameters showed positive relationships with coloration and antioxidant levels, suggesting that males displaying redder ornaments may be more capable of protecting sperm from oxidative stress in the event of sublethal Pb exposure.

Heavy metal bioaccumulation and histopathological alterations in wild Arctic hares (Lepus arcticus) inhabiting a former lead-zinc mine in the Canadian high Arctic: A preliminary study

A preliminary study was undertaken to determine post-mining baseline accumulation of selected trace metals, and histopathological alterations in free-living arctic hares (Lepus arcticus) inhabiting the vicinity of a former lead-zinc mine located on North Baffin Island in the Canadian High Arctic. Trace metal analysis included measurement of As, Cd, Fe, Pb and Zn in tissues, and histopathological assessment comprised of evaluation and scoring the severity of metal-induced hepatic and renal lesions. Metal contents in hepatic and renal tissues from hares from the mine area compared with the reference locations did not differ significantly suggesting that the animals are not uniformly exposed to background levels of metals in the environment. However, relatively higher accumulation pattern of Pb and Cd were noted in liver tissues of hare from the mine area compared to the background area, but did not induce increased lesions. Surface soils near the mine area contained relatively higher levels of trace metals (Zn>Mn>Pb>Cd>As) compared to reference soils, and with soil levels of Cd showing strong correlation with Cd accumulation in kidney tissues. Generally, both case and reference animals showed similar but varying severities of hepatic and renal lesions at the sublethal level, notably vascular congestion, occasional large hepatocyte nuclei, binucleate hepatocytes, yellow-brown pigmentation in the cytoplasm of hepatocytes and clustering of lymphocytes. Only hares with relatively higher accumulation of Pb from the mine area showed evidence of renal edema and hemorrhage of the capsular surface. This study constitutes the first assessment of metal induced histopathological alterations in arctic hares exposed to a historical mining area in the high arctic.

Effects of nickel exposure on testicular function, oxidative stress, and male reproductive dysfunction in Spodoptera litura Fabricius

Nickel is an environmental pollutant that adversely affects the male reproductive system. In the present study, the effects of nickel exposure on Spodoptera litura Fabricius were investigated by feeding larvae artificial diets containing different doses of nickel for three generations. Damage to testes and effects on male reproduction were examined. The amount of nickel that accumulated in the testes of newly emerged males increased as the nickel dose in the diet increased during a single generation. Nickel exposure increased the amount of thiobarbituric acid reactive substances and decreased the amount of glutathione in treatment groups compared with the control. The activity levels of the antioxidant response indices superoxide dismutases, catalase, and glutathione peroxidase in the testes showed variable dose-dependent relationships with nickel doses and duration of exposure. Nickel doses also disrupted the development of the testes by decreasing the weight and volume of testes and the number of eupyrene and apyrene sperm bundles in treatment groups compared with the control. When the nickel-treated males mated with normal females, fecundity was inhibited by the higher nickel doses in all three generations, but fecundity significantly increased during the second generation, which received 5 mg kg(-1) nickel. Hatching rates in all treatments significantly decreased in a dose-dependent manner in the three successive generations. The effects of nickel on these parameters correlated with the duration of nickel exposure. Results indicate assays of testes may be a novel and efficient means of evaluating the effects of heavy metals on phytophagous insects in an agricultural environment.

Differences in the fatty-acid composition of rodent spermatozoa are associated to levels of sperm competition

Sperm competition is a prevalent phenomenon that drives the evolution of sperm function. High levels of sperm competition lead to increased metabolism to fuel higher sperm velocities. This enhanced metabolism can result in oxidative damage (including lipid peroxidation) and damage to the membrane. We hypothesized that in those species experiencing high levels of sperm competition there are changes in the fatty-acid composition of the sperm membrane that makes the membrane more resistant to oxidative damage. Given that polyunsaturated fatty acids (PUFAs) are the most prone to lipid peroxidation, we predicted that higher sperm competition leads to a reduction in the proportion of sperm PUFAs. In contrast, we predicted that levels of sperm competition should not affect the proportion of PUFAs in somatic cells. To test these predictions, we quantified the fatty-acid composition of sperm, testis and liver cells in four mouse species (genus Mus) that differ in their levels of sperm competition. Fatty-acid composition in testis and liver cells was not associated to sperm competition levels. However, in sperm cells, as predicted, an increase in sperm competition levels was associated with an increase in the proportion of saturated fatty-acids (the most resistant to lipid peroxidation) and by a concomitant decrease in the proportion of PUFAs. Two particular fatty acids were most responsible for this pattern (arachidonic acid and palmitic acid). Our findings thus indicate that sperm competition has a pervasive influence in the composition of sperm cells that ultimately may have important effects in sperm function.

Increased chromatin fragmentation and reduced acrosome integrity in spermatozoa of red deer from lead polluted sites

Vertebrates are constantly exposed to a diffuse pollution of heavy metals existing in the environment, but in some cases, the proximity to emission sources like mining activity increases the risk of developing adverse effects of these pollutants. Here we have studied lead (Pb) levels in spermatozoa and testis, and chromatin damage and levels of endogenous antioxidant activity in spermatozoa of red deer (Cervus elaphus) from a Pb mining area (n=37) and a control area (n=26). Deer from the Pb-polluted area showed higher Pb levels in testis parenchyma, epididymal cauda and spermatozoa, lower values of acrosome integrity, higher activity of glutathione peroxidase (GPx) and higher values of DNA fragmentation (X-DFI) and stainability (HDS) in sperm than in the control area. These results indicate that mining pollution can produce damage on chromatin and membrane spermatozoa in wildlife. The study of chromatin fragmentation has not been studied before in spermatozoa of wildlife species, and the sperm chromatin structure assay (SCSA) has been revealed as a successful tool for this purpose in species in which the amount of sperm that can be collected is very limited.

Cross-species coherence in effects and modes of action in support of causality determinations in the U.S. Environmental Protection Agency's Integrated Science Assessment for Lead

The peer-reviewed literature on the health and ecological effects of lead (Pb) indicates common effects and underlying modes of action across multiple organisms for several endpoints. Based on such observations, the United States (U.S.) Environmental Protection Agency (EPA) applied a cross-species approach in the 2013 Integrated Science Assessment (ISA) for Lead for evaluating the causality of relationships between Pb exposure and specific endpoints that are shared by humans, laboratory animals, and ecological receptors (i.e., hematological effects, reproductive and developmental effects, and nervous system effects). Other effects of Pb (i.e., cardiovascular, renal, and inflammatory responses) are less commonly assessed in aquatic and terrestrial wildlife limiting the application of cross-species comparisons. Determinations of causality in ISAs are guided by a framework for classifying the weight of evidence across scientific disciplines and across related effects by considering aspects such as biological plausibility and coherence. As illustrated for effects of Pb where evidence across species exists, the integration of coherent effects and common underlying modes of action can serve as a means to substantiate conclusions regarding the causal nature of the health and ecological effects of environmental toxicants.

Lead (Pb) in sheep exposed to mining pollution: implications for animal and human health

Livestock from the ancient mining area of Sierra Madrona and Alcudia Valley (Spain) is exposed to elevated levels of lead (Pb), as previous studies based on blood monitoring have revealed. Here we have studied blood, liver and muscle Pb levels in sheep in order to know if Pb exposure could represent a risk for human consumers of the meat and offal of these animals. A cross-sectional study was conducted with ≥4 years old (adults) ewes from the mining area (n=46) and a control area (n=21). Blood samples were taken before the sacrifice at the slaughterhouse, and liver and muscle samples were taken thereafter. At the same time, 2-3 year old rams (subadults, n=17) were blood sampled in the mining area. Blood, liver and muscle Pb levels were higher in the mining than in the control area. Blood Pb concentration in the mining area (n= 44, mean: 6.7μg/dl in ewes and 10.9μg/dl in rams) was above background levels (>6μg/dl) in 73.3 percent of animals. Liver Pb concentration in 68 percent of sheep from the mining area (n=32, mean: 6.16μg/g dry weight, d.w.) exceeded the minimum level associated with toxic exposure (5µg/g d.w.) and 87.5 percent of liver samples were above European Union Maximum Residue Levels (MRL) established for offal destined for human consumption (0.5µg/g w.w.~1.4µg/g d.w.). On the contrary, none of the muscle samples in ewes exceeded the EU MRL (0.1µg/g w.w.~0.34µg/g d.w.) established for meat, which may be related to the decline of blood Pb levels with age observed in the present study. These results suggest a potential health effect for sheep exposed to Pb pollution in this area and implications for food safety, but further research with lamb meat may be necessary to refine the risk assessment for human consumers.

Identification of optimal concentrations and incubation times for the study of in vitro effects of Pb in ram spermatozoa

In vitro effects of lead (Pb) on ram (Ovis aries) spermatozoa were studied to establish a threshold level that affects sperm function. Spermatozoa were incubated between 15 and 180 min with Pb concentrations ranging from 0 to 5,000 ng/mL. Sperm motility, acrosome integrity, membrane functionality and sperm viability were all negatively affected by Pb and incubation time. Acrosome integrity was linearly affected by Pb levels at an incubation time of 30 min, and 50 ng/mL was the lowest Pb level producing such effect. These experimental conditions can be appropriate for in vitro studies of the mechanisms of action of Pb on spermatozoa.

Expression of immunoregulatory genes and its relationship to lead exposure and lead-mediated oxidative stress in wild ungulates from an abandoned mining area

Lead (Pb) is a highly toxic metal that can induce oxidative stress and affect the immune system by modifying the expression of immunomodulator-related genes. The aim of the present study was to investigate the association between Pb exposure and the transcriptional profiles of some cytokines, as well as the relationship between Pb exposure and changes in oxidative stress biomarkers observed in the spleen of wild ungulates exposed to mining pollution. Red deer and wild boar from the mining area studied had higher spleen, liver, and bone Pb levels than controls, indicating a chronic exposure to Pb pollution. Such exposure caused a depletion of spleen glutathione levels in both species and disrupted the activity of antioxidant enzymes, suggesting the generation of oxidative stress conditions. Deer from the mining area also showed an induced T-helper (Th )-dependent immune response toward the Th 2 pathway, whereas boar from the mining area showed a cytokine profile suggesting an inclination of the immune response toward the Th 1 pathway. These results indicate that environmental exposure to Pb may alter immune responses in wild ungulates exposed to mining pollution. However, evidence of direct relationships between Pb-mediated oxidative stress and the changes detected in immune responses were not found. Further research is needed to evaluate the immunotoxic potential of Pb pollution, also considering the prevalence of chronic infectious diseases in wildlife in environments affected by mining activities.

Chronic effects of lead (Pb) on bone properties in red deer and wild boar: relationship with vitamins A and D3

Here we study the occurrence of abnormalities on bone tissue composition and turnover mechanisms through the Pb-mediated disruption of vitamins A and D in wild ungulates living in a lead (Pb)-polluted mining area. Red deer (Cervus elaphus) and wild boar (Sus scrofa) from the mining area had significantly higher liver and bone Pb levels than controls, which were associated with the depletion of liver retinyl esters and the corresponding increase of free retinol levels both in deer and boar from the mining area. Pb-exposed adult deer had lower carbonate content in bone mineral than controls, which was associated with the increased free retinol percentage. In wild boar, the degree of bone mineralization was also positively associated with higher burdens of retinyl esters. These results suggest that Pb-associated changes in bone composition and mineralization is likely influenced by the depletion of vitamin A in wildlife exposed to environmental Pb pollution.

The impact of lead and cadmium on selected motility, prooxidant and antioxidant parameters of bovine seminal plasma and spermatozoa

The aim of this study was to investigate the effects of lead (Pb) and cadmium (Cd) content on basic motility characteristics (motility-MOT, progressive motility-PROG) as well as selected markers of the prooxidant-antioxidant balance (catalase-CAT, glutathione-GSH, malondialdehyde-MDA) in bovine seminal plasma and spermatozoa. Twenty five semen samples were collected from breeding bulls and used in the study. Motility analysis was carried out using the Computer Assisted Sperm Analysis (CASA) system. The samples were centrifuged, fractions of seminal plasma and spermatozoa were separated, lysates were prepared from the sperm cell fractions. Pb and Cd concentrations were determined by the voltametric method (ASV), antioxidants and MDA were analyzed by UV/Vis spectrophotometry. The analysis showed that the average concentration of Pb in the seminal plasma was 0.23 ± 0.02 μg/mL, while its amount in the sperm cells was significantly higher (0.41 ± 0.07 μg/mL; P < 0.05). The average Cd content in bovine seminal fractions was similar and non-significant: 0.09 ± 0.01 μg/mL in the seminal plasma and 0.11 ± 0.01 μg/mL in spermatozoa (P > 0.05). The correlation analysis revealed that both heavy metals were significantly negatively correlated with MOT and PROG (P < 0.05; P < 0.01; P < 0.001), CAT (P < 0.05; P < 0.01) as well as GSH (P < 0.05; P < 0.01) but significantly positively associated with MDA as the marker of lipid peroxidation (P < 0.05; P < 0.01). Moreover the samples were categorized in three quality groups (Excellent, Good, Moderate) according to their motility values. The lowest Pb, Cd and MDA concentrations but the best antioxidant characteristics were found in samples of the best quality, moderate quality samples exhibited the highest Pb, Cd and MDA content together with the worst antioxidant capacity. This study demonstrates that Pb and Cd are serious toxic elements, which are able to increase the risk of seminal oxidative stress development and a subsequent decrease of male fertility.

Mercury exposure and mechanism of response in large game using the Almadén mercury mining area (Spain) as a case study

Mercury (Hg) accumulation, transfer, defense mechanism and adverse effects were studied in red deer (Cervus elaphus) and wild boar (Sus scrofa) from the Almadén mining district (Spain), the largest (285,000 t of Hg) and the oldest (more than 2000 years) Hg mine/refining operation site in the world. Red deer (n=168) and wild boar (n=58) liver, kidney, bones (metacarpus), testis and muscle were analyzed for total Hg and selenium (Se) within a range of distances to the Almadén mining district. The highest Hg concentrations were found in kidney (0.092 and 0.103 μg/g d.w. for red deer and wild boar, respectively) followed by the levels in liver (0.013 and 0.023 μg/g d.w. for red deer and wild boar, respectively). A significant correlation (r=-0.609, p=0.007) was found between Hg concentrations and distance to the Almadén Hg mining district. However, both red deer and wild boar closest to the mining area still showed mercury concentrations well below the concentration associated with clinical signs of Hg poisoning. Highest Se concentrations were found in kidney (2.60 and 6.08 μg/g in red deer and wild boar, respectively) and testis (2.20 μg/g in red deer). For selenium, differences between red deer and wild boar were statistically significant (p<0.05) in all tissues, concentrations being higher in wild boar than in red deer. In the diagnosis of Se deficiency, the vast majority of the examined red deer livers were deficient. A significant correlation was found between Hg and Se in kidney (r=0.386, p>0.001 for red deer and r=0.567, p=0.005 for wild boar). Liver GSSG concentrations were negatively correlated to total mercury and Hg:Se molar ratio in male deer, which could indicate a hormetic response to Hg exposure. Moreover, a positive association was found between the antioxidant element Se and antioxidant vitamins in red deer tissues.

Blood Pb and δ-ALAD inhibition in cattle and sheep from a Pb-polluted mining area

The effects of Pb pollution on cattle and sheep raised in an ancient mining area were studied through the use of blood Pb (PbB) levels and δ-aminolevulinic acid dehydratase (δ-ALAD) activity. Lead levels in livestock blood from the mining area (n=110) were significantly elevated when compared to the controls (n=79). In 91.4% of cattle (n=58) and 13.5% of sheep (n=52) sampled in the mining area, PbB levels corresponded to subclinical exposure (6-35 μg/dl). Two young cattle (<2 years) from the mining area (n=5) had PbB levels indicative of clinical poisoning (>35 μg/dl). Elevated PbB was also accompanied by δ-ALAD activity inhibition in blood, which confirms that measurable effects of Pb poisoning were taking place. Observed PbB levels suggest that a potential risk to human consumers of beef from the Pb polluted areas may also exist, as has been shown previously for game meat from the same mining area.

Interactions between endogenous and dietary antioxidants against Pb-induced oxidative stress in wild ungulates from a Pb polluted mining area

Certain physiologic disorders, attributed to lead (Pb) exposure are related to the generation of oxidative stress. Organisms rely on a complex antioxidant system, composed of endogenously produced compounds such as glutathione (GSH), superoxide dismutase (SOD) and GSH peroxidase (GPX); and dietary antioxidants such as vitamins A and E. The aim of this work was to study the interactions between both groups of antioxidants and to evaluate their role in fighting Pb-induced oxidative stress in wild ungulates living in a Pb mining area. We studied red deer (n=54) and wild boar (n=60) from mining and control sites. Liver Pb, copper (Cu) and selenium (Se) levels were measured in liver and bone. Levels of GSH, oxidized GSH (GSSG), lipid peroxidation (TBARS), α-tocopherol, free retinol and retinyl esters, and the activities of SOD and GPX were measured in liver. Wild boar and red deer from the mining sites had higher bone (geometric means: 7.36 vs. 1.23μg/g dw for boar; and 0.46 vs. 0.11μg/g dw for deer) and liver Pb levels (0.81 vs. 0.24μg/g dw for boar; and 0.35 vs. 0.11μg/g dw for deer) than the controls. Pb exposure in deer was associated with lower GSH, α-tocopherol and retinyl esters, and higher free retinol and TBARS. A similar effect on vitamin A balance was observed in wild boar, but this was accompanied with an increase in GSH and α-tocopherol. GPX activity and Se levels were higher in wild boar (mean in controls: 670IU/mg protein and 1.3μg/g dw, respectively) than in red deer (150IU/mg protein and 0.3μg/g). These differences may indicate that red deer is more sensitive to Pb-induced oxidative stress than wild boar. Both endogenous and nutritional antioxidants may be negatively affected by Pb exposure, and their interactions are essential to fight against Pb-mediated oxidative damage.

Alterations in vitamin A and E levels in liver and testis of wild ungulates from a lead mining area

In animals, exposure to metal pollution can induce oxidative stress via several mechanisms. This stress might then cause adverse effects on functions such as male reproductive capacity. Antioxidant vitamins A and E play an important role in maintaining organism functions under stressed conditions. This study assessed the effect of different metals and metalloids on levels of vitamins A and E in livers and testis (n = 67 and 36) of red deer and in livers (n = 22) of wild boar. The study compared animals residing within and outside a polluted mining area. Red deer from mined areas showed significant reductions in liver retinyl docosahexaenoate and retinyl docosapentaenoate. Free retinol, α-tocopherol, and retinyl palmitate in the testis were also lower. This might indicate that increased internal usage of these antioxidants is occurring as deer try to maintain the integrity and function of reproductive tissue. Wild boar from mined areas also showed significant reductions in liver retinyl stearate but increased free retinol levels. This might suggest that vitamin A is being mobilized to a greater degree to cope with the induced oxidative stress caused by exposure to metal pollution. Additionally, a significant negative relationship between liver α-tocopherol and bone lead (Pb) in boar might indicate some long-term effects of Pb on antioxidant levels. Results suggest that vitamin A and E status can be altered as a consequence of exposure to Pb pollution and that complex differences in this response probably exist between species.

Should legislation regarding maximum Pb and Cd levels in human food also cover large game meat?

Game meat may be contaminated with metals and metalloids if animals reside in anthropogenically polluted areas, or if ammunition used to kill the game contaminates the meat. Muscle tissue from red deer and wild boar shot in Ciudad Real province (Spain) in 2005-06 was analysed for As, Pb, Cu, Zn, Se and Cd. Samples were collected from hunting estates within and outside an area that has been historically used for mining, smelting and refining various metals and metalloids. Meat destined for human consumption, contained more Pb, As and Se (red deer) and Pb (boar) when harvested from animals that had resided in mined areas. Age related accumulation of Cd, Zn and As (in deer) and Cd, Cu and Se (in boar) was also observed. Two boar meat samples contained high Pb, at 352 and 2408 μg/g d.w., and these were likely to have been contaminated by Pb ammunition. Likewise, 19-84% of all samples (depending on species and sampling area) had Pb levels > 0.1 μg/g w.w., the EU maximum residue level (MRL) for farm reared meat. Between 9 and 43% of samples exceeded comparable Cd limits. Such data highlight a discrepancy between what is considered safe for human consumption in popular farmed meat (chicken, beef, lamb), and what in game may often exist. A risk assessment is presented which describes the number of meals required to exceed current tolerable weekly intakes (PTWIs) for Pb and Cd, and the potential contribution of large game consumption to such intake limit criteria.