Long-term effects of lead poisoning on bone mineralization in vultures exposed to ammunition sources

Lead poisoning of raptors: state of the science and cross-discipline mitigation options for a global problem

Lead poisoning is an important global conservation problem for many species of wildlife, especially raptors. Despite the increasing number of individual studies and regional reviews of lead poisoning of raptors, it has been over a decade since this information has been compiled into a comprehensive global review. Here, we summarize the state of knowledge of lead poisoning of raptors, we review developments in manufacturing of non-lead ammunition, the use of which can reduce the most pervasive source of lead these birds encounter, and we compile data on voluntary and regulatory mitigation options and their associated sociological context. We support our literature review with case studies of mitigation actions, largely provided by the conservation practitioners who study or manage these efforts. Our review illustrates the growing awareness and understanding of lead exposure of raptors, and it shows that the science underpinning this understanding has expanded considerably in recent years. We also show that the political and social appetite for managing lead ammunition appears to vary substantially across administrative regions, countries, and continents. Improved understanding of the drivers of this variation could support more effective mitigation of lead exposure of wildlife. This review also shows that mitigation strategies are likely to be most effective when they are outcome driven, consider behavioural theory, local cultures, and environmental conditions, effectively monitor participation, compliance, and levels of raptor exposure, and support both environmental and human health.

Bone lead measurements of live condors in field to assess cumulative lead exposure

Lead poisoning remains the leading cause of diagnosed death for critically endangered California condors, which are annually monitored for lead exposure via blood tests. Blood tests are generally reflective of acute lead exposure. Since condors are victims to both chronic and acute lead exposure, measuring bone, which in humans is reflective of years to decades worth of exposure, is a valuable biomarker. In this study, we measured bone Pb of the tibiotarsus of 64 condors in vivo using a portable x-ray fluorescence device. The average uncertainty for measurements, typically reflective of how effective the device performed, was found to be 3.8 ± 2.2 µg/g bone mineral. The average bone lead level was found to be 26.7 ± 24.5 µg/g bone mineral. Bone lead correlated significantly with a sum of all blood lead measures over the lifetime of each condor. In the future, bone lead can potentially be used to inform treatment planning and address the chronic health implications of lead in the species.

Decrypting the skeletal toxicity of vertebrates caused by environmental pollutants from an evolutionary perspective: From fish to mammals

The rapid development of modern society has led to an increasing severity in the generation of new pollutants and the significant emission of old pollutants, exerting considerable pressure on the ecological environment and posing a serious threat to both biological survival and human health. The skeletal system, as a vital supportive structure and functional unit in organisms, is pivotal in maintaining body shape, safeguarding internal organs, storing minerals, and facilitating blood cell production. Although previous studies have uncovered the toxic effects of pollutants on vertebrate skeletal systems, there is a lack of comprehensive literature reviews in this field. Hence, this paper systematically summarizes the toxic effects and mechanisms of environmental pollutants on the skeletons of vertebrates based on the evolutionary context from fish to mammals. Our findings reveal that current research mainly focuses on fish and mammals, and the identified impact mechanisms mainly involve the regulation of bone signaling pathways, oxidative stress response, endocrine system disorders, and immune system dysfunction. This study aims to provide a comprehensive and systematic understanding of research on skeletal toxicity, while also promoting further research and development in related fields.

Blood lead levels in an endangered vulture decline following changes in hunting activity

Lead ammunition stands out as one of the most pervasive pollutants affecting wildlife. Its impact on bird populations have spurred efforts for the phase-out of leaded gunshot in several countries, although with varying scopes and applications. Ongoing and future policy changes require data to assess the effectiveness of adopted measures, particularly in the current context of biodiversity loss. Here, we assessed the long-term changes in blood lead (Pb) levels of Egyptian vultures from the Canary Islands, Spain, which have been severely affected by Pb poisoning over the past two decades. During this period, the reduction in hunting pressure and changes in legislation regarding firearms usage for small game hunting likely contributed to a decrease in environmental Pb availability. As anticipated, our results show a reduction in Pb levels, especially after the ban on wild rabbit hunting with shotgun since 2010. This effect was stronger in the preadult fraction of the vulture population. However, we still observed elevated blood Pb levels above the background and clinical thresholds in 5.6% and 1.5% of individuals, respectively. Our results highlight the positive impact of reducing the availability of Pb from ammunition sources on individual health. Nonetheless, the continued use of Pb gunshot remains an important source of poisoning, even lethal, mainly affecting adult individuals. This poses a particular concern for long-lived birds, compounding by potential chronic effects associated with Pb bioaccumulation. Our findings align with recent studies indicating insufficient reductions in Pb levels among European birds of prey, attributed to limited policy changes and their uneven implementation. We anticipated further reductions in Pb levels among Egyptian vultures with expanded restrictions on hunting practices, including a blanket ban on Pb shot usage across all small game species.

Exposure to Sublethal Concentrations of Lead (Pb) Affects Ecologically Relevant Behaviors in House Sparrows (Passer domesticus)

Global contamination of environments with lead (Pb) poses threats to many ecosystems and populations. While exposure to Pb is toxic at high concentrations, recent literature has shown that lower concentrations can also cause sublethal, deleterious effects. However, there remains relatively little causal investigation of how exposure to lower concentrations of environmental Pb affects ecologically important behaviors. Behaviors often represent first-line responses of an organism and its internal physiological, molecular, and genetic responses to a changing environment. Hence, better understanding how behaviors are influenced by pollutants such as Pb generates crucial information on how species are coping with the effects of pollution more broadly. To better understand the effects of sublethal Pb on behavior, we chronically exposed adult wild-caught, captive house sparrows (Passer domesticus) to Pb-exposed drinking water and quantified a suite of behavioral outcomes: takeoff flight performance, activity in a novel environment, and in-hand struggling and breathing rate while being handled by an experimenter. Compared to controls (un-exposed drinking water), sparrows exposed to environmentally relevant concentrations of Pb exhibited decreases in takeoff flight performance and reduced movements in a novel environment following 9-10 weeks of exposure. We interpret this suite of results to be consistent with Pb influencing fundamental neuro-muscular abilities, making it more difficult for exposed birds to mount faster movements and activities. It is likely that suppression of takeoff flight and reduced movements would increase the predation risk of similar birds in the wild; hence, we also conclude that the effects we observed could influence fitness outcomes for individuals and populations altering ecological interactions within more naturalistic settings.

Trace elements and heavy metals in black vultures (Coragyps atratus) and turkey vultures (Cathartes aura) in the southeastern United States

Many vulture species worldwide are declining at alarming rates due to a variety of anthropogenic causes, including exposure to pollutants and pharmaceuticals through consumption of contaminated carrion. However, little is known about the extent to which vultures are exposed to various contaminants as well as toxicity thresholds for trace elements and heavy metals. Our objective was to quantify levels of trace elements and heavy metals within black vulture (Coragyps atratus) and turkey vulture (Cathartes aura) tissues to determine the extent to which populations in the Southeastern United States are exposed to carrion that contains high levels of contaminants. We collected 34 black vulture liver samples and examined differences in trace element and heavy metal concentrations between sexes and age classes (adult and juvenile). Further, we collected 81 blood and 42 feather samples from additional black and turkey vultures and compared differences between species and age classes. We found similar element concentrations between juvenile and adult black vultures with the exception of Cu, where levels were higher in juveniles compared to adults. However, we did observe substantial differences in element concentrations between species for both blood and feather samples, with black vultures generally having higher concentrations of most elements. Our data revealed higher element levels in both species compared to toxicity thresholds found in other bird of prey species, such as blood and liver toxicity threshold suggestions for Pb poisoning in Falconiformes. Further, while average contaminant levels were generally low, extreme outliers were observed for some elements, including Pb, suggesting some individuals were exposed to high levels of potentially toxic elements. More research is needed to better understand contaminant exposure in black and turkey vultures across a broader geographic region, as well as elucidate toxicity thresholds and non-lethal impacts of contaminant exposure in these species.

Ecosystem productivity drives the breeding success of an endangered top avian scavenger in a changing grazing pressure context

Environmental conditions and resource availability shape population dynamics through direct and indirect effects of climate, biological interactions and the human modification of landscape. Even when a species seems dependent on predictable anthropogenic food resources or subsidies, ecosystem-level factors can still determine population dynamics across taxa. However, there is still a knowledge gap about the cascade effects driven by climate, vegetation functioning, resource availability and governmental policies on key aspects of species reproduction for top scavengers. Here we put to good use 22 years (2000-2021) of extensive population monitoring from the endemic Canary Egyptian vulture (Neophron percnopterus majorensis) on the Fuerteventura Island (Canary Islands, Spain) to study the relative importance of demographic factors, ecosystem conditions and availability of anthropogenic food sources on breeding success. Our results suggest that ecosystem-level primary productivity, the number of livestock animals present on the island and Density-dependent processes determine the temporal changes in the breeding success of this species. We firstly accounted for a top-down effect of livestock on island vegetation, where overgrazing directly reduces landscape-level vegetation biomass. We, consequently, found a bottom-up effect between vegetation and the Egyptian vulture's breeding success. In this context, minimal changes in ecological conditions can impact the species inhabiting these ecosystems, with direct consequences on a key population stage, such as breeding season, when energy requirements are higher. These results are especially relevant because cascading and indirect effects of ecosystem processes and governmental policies are often overlooked when pursuing conservation goals of endangered species.

Insularity determines nestling sex ratio variation in Egyptian vulture populations

Variation in offspring sex ratio, particularly in birds, has been frequently studied over the last century, although seldom using long-term monitoring data. In raptors, the cost of raising males and females is not equal, and several variables have been found to have significant effects on sex ratio, including food availability, parental age, and hatching order. Sex ratio differences between island populations and their mainland counterparts have been poorly documented, despite broad scientific literature on the island syndrome reporting substantial differences in population demography and ecology. Here, we assessed individual and environmental factors potentially affecting the secondary sex ratio of the long-lived Egyptian vulture Neophron percnopterus. We used data collected from Spanish mainland and island populations over a ca. 30-year period (1995-2021) to assess the effects of insularity, parental age, breeding phenology, brood size, hatching order, type of breeding unit (pairs vs. trios), and spatial and temporal variability on offspring sex ratio. No sex bias was found at the population level, but two opposite trends were observed between mainland and island populations consistent with the island syndrome. Offspring sex ratio was nonsignificantly female-biased in mainland Spain (0.47, n = 1112) but significantly male-biased in the Canary Islands (0.55, n = 499), where a male-biased mortality among immatures could be compensating for offspring biases and maintaining a paired adult sex ratio. Temporal and spatial variation in food availability might also have some influence on sex ratio, although the difficulties in quantifying them preclude us from determining the magnitude of such influence. This study shows that insularity influences the offspring sex ratio of the Egyptian vulture through several processes that can affect island and mainland populations differentially. Our research contributes to improving our understanding of sex allocation theory by investigating whether sex ratio deviations from parity are possible as a response to changing environments comprised by multiple and complexly interrelated factors.

The importance of in-year seasonal fluctuations for biomonitoring of apex predators: A case study of 14 essential and non-essential elements in the liver of the common buzzard (Buteobuteo) in the United Kingdom

Trace elements are chemical contaminants spread in the environment by anthropogenic activities and threaten wildlife and human health. Many studies have investigated this contamination in apex raptors as sentinel birds. However, there is limited data for long-term biomonitoring of multiple trace elements in raptors. In the present study, we measured the concentrations of 14 essential and non-essential trace elements in the livers of the common buzzard (Buteo buteo) collected in the United Kingdom from 2001 to 2019 and investigated whether concentrations have changed during this period. In addition, we estimated the importance of selected variables for modelling element accumulations in tissues. Except for cadmium, hepatic concentrations of harmful elements in most buzzards were lower than the biological significance level of each element. Hepatic concentrations of certain elements, including lead, cadmium, and arsenic, varied markedly seasonally within years. Their peak was in late winter and trough in late summer, except copper which showed an opposite seasonal pattern. In addition, lead in the liver consistently increased over time, whereas strontium showed a decreasing trend. Hepatic concentrations of cadmium, mercury, and chromium increased with age, whereas selenium and chromium were influenced by sex. Hepatic concentrations of arsenic and chromium also differed between different regions. Overall, our samples showed a low risk of harmful effects of most elements compared to the thresholds reported in the literature. Seasonal fluctuation was an important descriptor of exposure, which might be related to the diet of the buzzard, the ecology of their prey, and human activities such as the use of lead shot for hunting. However, elucidating reasons for these observed trends needs further examination, and biomonitoring studies exploring the effects of variables such as age, sex, and seasonality are required.

Light pollution enhances ground-level exposure to airborne toxic chemicals for nocturnally migrating passerines

Anthropogenic activities generate different forms of environmental pollution, including artificial light at night (ALAN) and airborne toxic chemicals (ATCs). Nocturnally migrating birds are attracted to ALAN during migration and if ALAN occurs in unison with ATC, the chances of ground-level ATC contamination occurring at stopover sites could increase. Here, we document the relationship between ALAN and ATC within the contiguous United States based on 479 toxic chemicals from 15,743 releasing facilities. Using weekly diurnal estimates of relative abundance for 165 nocturnally migrating passerine (NMP) bird species, we assess how the species richness and relative abundance of NMP species are correlated with ALAN and ATC across the annual cycle. The concentration of ATC increased with increasing ALAN levels, except at the highest ALAN levels. The species richness of NMP species was positively correlated with ATC during the non-breeding season and migration, and negatively correlated during the breeding season. The relative abundance of NMP species was negatively correlated with ATC during the breeding and non-breeding seasons and the correlation did not differ from zero during migration. Through the disorienting influence of ALAN, our findings suggest large numbers of NMP species are being exposed to higher ATC concentrations at stopover sites. Outside of migration, large numbers of NMP species that winter along the US Gulf Coast are being exposed for an extended period of time to higher ATC concentrations. Initiatives designed to decrease ALAN during migration have the potential to reduce the acute and chronic effects of ATC contamination, lower the maternal transfer of toxic chemicals to eggs, and decrease the biologically mediated transport of toxic chemicals across regions. However, these initiatives will not benefit species that experience prolonged ATC exposure during the non-breeding season along the US Gulf Coast, a region that could be a significant source of ATC contamination for North American birds.

Profile of Selected Mineral Elements in Tibiotarsal Bone of the White-Tailed Sea Eagle in Its Natural Habitat

Mineral bone composition (dry matter, bones ash, P, Ca, Zn, Mn, Mg, and Cu) and Pb levels of tibiotarsi of seven White-Tailed Sea Eagles were assessed. Lead intoxication in different bird species including waterfowl and raptors is being studied worldwide. The bones were analyzed for Pb by mass spectrometry with excitation in inductively coupled plasma (ICP-MS Elan DRC II) and for bone composition by Atomic Emission Spectrometer (Agilent 4100 Microwave Plasma). Pb levels ranging from 3.54 µg/g to 74.6 µg/g DM suggest that some of the investigated birds might have been intoxicated by Pb. Results of this analysis were divided into two groups of bones, with bone Pb levels higher and lower than Pb toxicity levels, and mineral bone compositions of both groups were compared. The present study shows the differentiation of bone mineral composition among seven examined White-Tailed Sea Eagles, considered a specific species in raptors. Pb intoxication may not have a major influence on mineral bone composition in raptors. It also suggests that assessing bone composition of raptor bones may help finding the possible cause of their deaths.

Heavy metal exposure and behavioral assessment of vultures in a captive environment

Heavy metals are a heterogeneous group of metals that can cause detrimental biological disruptions in vultures. Heavy metals play a threatening role and affect vulture populations around the globe. However, various conservation organizations are working for the captive breeding of these endangered animals so that they can reintroduce these captive-bred animals back to their natural environment. This research study was conducted at Changa Manga Vulture Conservatory, Punjab, with the help of Punjab Wildlife Department. A non-invasive technique was used to collect vulture feathers and fecal samples to study the exposure of heavy metals. The behavior of vultures in captivity was also recorded. Samples were chemically digested in aqua regia and analyzed for the detection of five heavy metal concentrations such as chromium (Cr), cadmium (Cd), lead (Pb), zinc (Zn), and magnesium (Mg) using flame atomic absorption spectroscopy (FAAS). Among the selected heavy metals, non-essential metals such as Pb, Cr, and Cd were recorded in the least concentration, whereas essential metals Zn and Mg were recorded in the highest concentration. Behavioral studies showed that vultures in captivity become excessively hostile and afraid of any human interaction; they flew to the top of the trees if they felt any danger. It was concluded in the study that the higher levels of both essential and non-essential metals recorded in feathers and fecal samples might be due to the type of feed, even though a controlled food is provided to vultures in captivity. However, regular monitoring of the environment can bring improvements to the health of vultures in captivity and help to find accurate sources of contamination.

High lead exposure and clinical signs of toxicosis in wild Nile crocodiles (Crocodylus niloticus) from a World Heritage site: Lake St Lucia estuarine system, South Africa

Lead (Pb) exposure is a widespread wildlife conservation threat, but impacts on reptile populations remain poorly documented. In this study, we examined Pb exposure and accumulation in a wild population of Nile crocodiles (Crocodylus niloticus) at Lake St Lucia, South Africa. Recreational angling has occurred in the area since the 1930s and incidental ingestion of Pb fishing weights has previously been identified as a major source of Pb poisoning in the local crocodile population. In 2019, we sampled blood and tail fat tissues from wild (n = 22) and captive (n = 3) crocodiles at Lake St Lucia to investigate potential impacts of chronic Pb exposure on crocodilian health. Lead was detected in blood samples of all wild crocodiles, although concentrations varied widely between individuals (86-13,100 ng ml^-1). The incidence of Pb poisoning was higher in male crocodiles, with mean blood lead (BPb) concentrations in males (3780 ± 4690 ng ml^-1) significantly (p < 0.001) higher compared to females (266 ± 230 ng ml^-1). Blood Pb concentrations were correlated with concentrations measured in tail fat tissue (n.d - 4175 ng g^-1 wet wt.). Although most of the crocodiles sampled appeared to be in good physical condition, highly elevated BPb concentrations (>6000 ng ml^-1) were associated with markedly suppressed packed cell volumes (4.6-10.8%) and severe deterioration in tooth condition. These findings suggest that anaemia and tooth loss may be clinical signs of long-term environmental exposure to Pb. Although previously undocumented in crocodilians, these symptoms are consistent with Pb poisoning observed in birds and mammals, and suggest that crocodilians may be more susceptible to the long-term toxic effects of Pb than previously thought. In light of these findings, we suggest that the impact of accumulated Pb on crocodilian fitness, reproduction and mortality requires urgent attention.

Method to assess the potential magnitude of terrestrial European avian population reductions from ingestion of lead ammunition

Current estimates of terrestrial bird losses across Europe from ingestion of lead ammunition are based on uncertain or generic assumptions. A method is needed to develop defensible European-specific estimates compatible with available data that does not require long-term field studies. We propose a 2-step method using carcass data and population models. The method estimates percentage of deaths diagnosed as directly caused by lead poisoning as a lower bound and, as an upper bound, the percentage of possible deaths from sublethal lead poisoning that weakens birds, making them susceptible to death by other causes. We use these estimates to modify known population-level annual mortality. Our method also allows for potential reductions in reproduction from lead shot ingestion because reductions in survival and reproduction are entered into population models of species with life histories representative of the most groups of susceptible species. The models estimate the sustainability and potential population decreases from lead poisoning in Europe. Using the best available data, we demonstrate the method on two taxonomic groups of birds: gallinaceous birds and diurnal raptors. The direction of the population trends affects the estimate, and we incorporated such trends into the method. Our midpoint estimates of the reduction in population size of the European gallinaceous bird (< 2%) group and raptor group (2.9–7.7%) depend on the species life history, maximum growth rate, population trend, and if reproduction is assumed to be reduced. Our estimates can be refined as more information becomes available in countries with data gaps. We advocate use of this method to improve upon or supplement approaches currently being used. As we demonstrate, the method also can be applied to individual species of concern if enough data across countries are available.

Old World Vultures Reflect Effects of Environmental Pollutants Through Human Encroachment

African wildlife face challenges from many stressors including current and emerging contaminants, habitat and resource loss, poaching, intentional and unintentional poisoning, and climate-related environmental change. The plight of African vultures exemplifies these challenges due to environmental contaminants and other stressors acting on individuals and populations that are already threatened or endangered. Many of these threats emanate from increasing human population size and settlement density, habitat loss from changing land use for agriculture, residential areas, and industry, and climate-related changes in resource availability. Environmental chemicals that are hazardous include legacy chemicals, emerging chemicals of concern, and high-volume-use chemicals that are employed as weed killers and in other agricultural applications. Furthermore, there are differences in risk for species living in close proximity to humans or in areas affected by habitat loss, climate, and industry. Monitoring programs are essential to track the status of nesting pairs, offspring survival, longevity, and lifetime productivity. This is important for long-lived birds, such as vultures, that may be especially vulnerable to chronic exposure to chemicals as obligate scavengers. Furthermore, their position in the food web may increase risk due to biomagnification of chemicals. We review the primary chemical hazards to Old World vultures and the interacting stressors affecting these and other birds. Habitat is a major consideration for vultures, with tree-nesters and cliff-nesters potentially experiencing different risks of exposure to environmental chemicals. The present review provides information from long-term monitoring programs and discusses a range of these threats and their effects on vulture populations. Environ Toxicol Chem 2022;41:1586-1603. © 2022 SETAC.

Detoxification Role of Metabolic Glutathione S-Transferase (GST) Genes in Blood Lead Concentrations of Jamaican Children with and without Autism Spectrum Disorder

Glutathione S-transferases (GST) are involved in the detoxification of exogenous chemicals including lead (Pb). Using data from 344 pairs of autism spectrum disorder (ASD) cases and age- and sex-matched typically developing (TD) controls (2−8 years old) from Jamaica, we investigated the interaction between three GST genes and ASD status as determinants of blood Pb concentrations (BPbCs). We found that ASD cases had lower geometric mean BPbCs than TD children (1.74 vs. 2.27 µg/dL, p < 0.01). Using a co-dominant genetic model, ASD cases with the Ile/Val genotype for the GSTP1 Ile105Val polymorphism had lower GM BPbCs than TD controls, after adjusting for a known interaction between GSTP1 and GSTT1, child’s parish, socioeconomic status, consumption of lettuce, fried plantains, and canned fish (Ile/Val: 1.78 vs. 2.13 µg/dL, p = 0.03). Similarly, among carriers of the I/I or I/D (I*) genotype for GSTT1 and GSTM1, ASD cases had lower adjusted GM BPbCs than TD controls (GSTT1 I*: 1.61 vs. 1.91 µg/dL, p = 0.01; GSTM1 I*: 1.71 vs. 2.04 µg/dL, p = 0.01). Our findings suggest that genetic polymorphisms in GST genes may influence detoxification of Pb by the enzymes they encode in Jamaican children with and without ASD.

Human dietary exposure to metals in the Niger delta region, Nigeria: Health risk assessment

The contamination profile and the human health risk assessment of various heavy metals (Cd, Cr, Mn, Ni and Pb) in vegetable oils, palm oils, butter and shea butter purchased from the Nigerian market were evaluated. Univariate and multivariate analyses including the principal component analysis (PCA), hierarchical cluster analysis (HCA) and heat map visualization were used to evaluate correlation, similarity and source of metals. Dietary intake and dermal absorption through the application in skin were also assessed. The heavy metals 5th and 95th percentile interval range (in mg/kg) were 0.003-0.208, 0.003-0.392, 0.003-1.344, 0.003-0.369 and 0.006-0.531 for Cd, Cr, Mn, Ni and Pb, respectively. Concentrations of Cr and Mn were significantly different across sample categories, being the levels of Mn and Ni positively correlated in both oil and butter samples. The result of PCA, HCA and heat map revealed the profile of heavy metals in oils was different from that of butters, with Pb mainly associated to oils, and Cd, Cr, Mn and Ni to butters. In some samples, the international maximum levels for Cd, Ni and Pb in edible oils were exceeded. Cadmium and Pb dietary intake through Nigerian oils and butters should not be considered negligible for human health protection.

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.

Lead contamination in tissues of large avian scavengers in south-central Europe

Lead poisoning from spent ammunition is known to affect many avian species. Birds of prey ingest lead when feeding on game shot with lead gunshot or bullets. Raptors with scavenging habits are particularly vulnerable to ingesting lead in areas with intensive hunting and are good indicators of the risk of poisoning from lead ammunition. To assess how much facultative and obligate avian scavengers suffer lead contamination in south-central Europe, between 2005 and 2019 we collected and analysed 595 tissue samples from 252 carcasses of 4 species (golden eagle, bearded vulture, griffon vulture, cinereous vulture). Lead concentrations in organs showed a similar pattern across species with long and small bones revealing the highest median values (5.56 and 6.8 mg/kg w.w., respectively), the brain the lowest (0.12), and the liver and kidney the intermediate (0.47 and 0.284). Overall, 111 individuals (44.0%) had lead concentrations above background thresholds in at least one tissue (i.e. >2 mg/kg w.w. in soft tissues, >8.33 in bone) and 66 (26.2%) had values indicating clinical poisoning (>6 mg/kg w.w. in liver, >4 in kidney, >16.6 in bone). Tissue lead concentrations and incidence of clinical and sub-clinical poisoning were higher in golden eagles and griffon vultures than in bearded and cinereous vultures, likely due to different feeding habits. In all species we found a rapid increase in lead values with age, but differences between age classes were significant only in the golden eagle. Birds with lead fragments in their digestive tract, as detected by X-rays, had higher median lead concentrations, suggesting that hunting ammunition is the main source of lead poisoning. Our results imply that lead impacts the demography of these long-lived species with delayed sexual maturity and low reproduction rate. A rapid transition towards lead-free bullets and gunshot is therefore required across Europe.

Influences of lead exposure on its accumulation in organs, meat, eggs and bone during laying period of hens

Elevating levels of environmental lead (Pb) results in serious hazards to health of animals and human beings. In this study, daily diet with three different levels of Pb (Pb nitrate at doses of 1, 10, and 100 mg/kg body weight) were fed to ISA Brown layers. It showed that the kidney and liver have the relatively high Pb concentration (2.34 and 0.51 ppm) after culture, while the meat has the Pb concentration as low as 0.07 ppm (lower than the standard of Codex Alimentarius). It was also confirmed that egg laying worked as a potential pathway for hens to excrete Pb as Pb concentrations in eggshell and yolk increased from 0.10 to 3.11 ppm. However, the Pb concentration in egg white remains at a safe level (<0.10 ppm). Furthermore, even the intake of low dose Pb can cause a decline of bone mineral density and bone strength. Raman spot and mapping analysis indicated that carotenoids content in humerus from the hens of high dose group increased significantly, which hence can be applied as an indicator for resist stress. The degradation of bone quality will further damage the health of laying hens. Therefore, Pb exposure not only toxifies organs and reduces physiological features (e.g., body weight and laying rate) instantly, but also hurts poultry via degrading bone quality in long term. Additionally, the probability of excessive Pb in poultry meat is less than those of viscera and eggs, indicating its low risk to food safety.

Sex-related and spatial variation in trace elements in feathers of the Kentish plover (Charadrius alexandrinus) from different coastal areas of the Iberian Peninsula

This study investigated the sex-related and spatial variation in trace elements concentrations in feathers of the Kentish plover (Charadrius alexandrinus) inhabiting different coastal locations in the Iberian Peninsula. Feathers were sampled in a total of 50 breeding birds from 7 different locations: 3 on the Mediterranean coast (n=18), 1 on the Atlantic coast of Andalusia (n=9) and 3 on the NW Atlantic coast (n=23). The feathers were analyzed to determine the concentrations of Al, Cr, Mn, Cu, Zn, As, Se, Cd, Hg and Pb. All of the trace elements were present at detectable concentrations, and the mean concentrations of Al, Zn and Cu were highest of those considered. The coastal section had a significant effect on 5 elements (Mn, Cu, As, Cd and Pb). The mean concentrations of almost all of the trace elements were highest in the birds from Andalusia, intermediate in the birds from the Mediterranean area and, in general, lowest in the birds from the NW Atlantic coast. Females showed significant higher Mn concentrations and high levels of exogenous elements (Al and As) in contrast with males. Less preening activity during the day of female birds, when they are occupied in incubating eggs, could favour higher concentrations of exogenous trace elements. The high levels of several trace elements observed in the samples from Mediterranean and Atlantic coast of Andalusia may pose a serious threat to these populations.

Long-Term Accumulation of Metals in the Skeleton as Related to Osteoporotic Derangements

The concentrations of metals in the environment are still not within the recommended limits as set by the regulatory authorities in various countries because of human activities. They can enter the food chain and bioaccumulate in soft and hard tissues/organs, often with a long half-life of the metal in the body. Metal exposure has a negative impact on bone health and may result in osteoporosis and increased fracture risk depending on concentration and duration of metal exposure and metal species. Bones are a long-term repository for lead and some other metals, and may approximately contain 90% of the total body burden in birds and mammals. The present review focuses on the most common metals found in contaminated areas (mercury, cadmium, lead, nickel, chromium, iron, and aluminum) and their effects on bone tissue, considering the possibility of the long-term bone accumulation, and also some differences that might exist between different age groups in the whole population.

Integrating active and passive monitoring to assess sublethal effects and mortality from lead poisoning in birds of prey

The ingestion of lead (Pb) ammunition is the most important exposure pathway to this metal in birds and involve negative consequences to their health. We have performed a passive monitoring of Pb poisoning in birds of prey by measuring liver (n = 727) and blood (n = 32) Pb levels in individuals of 16 species found dead or sick in Spain between 2004 and 2020. We also performed an active monitoring by measuring blood Pb levels and biomarkers of haem biosynthesis, phosphorus (P) and calcium (Ca) metabolism, oxidative stress and immune function in individuals (n = 194) of 9 species trapped alive in the field between 2016 and 2017. Passive monitoring results revealed some species with liver Pb levels associated with severe clinical poisoning (>30 μg/g d.w. of Pb): Eurasian griffon vulture (27/257, 10.5%), red kite (1/132, 0.8%), golden eagle (4/38, 10.5%), and Northern goshawk (1/8, 12.5%). The active monitoring results showed that individuals of bearded vulture (1/3, 33.3%), Eurasian griffon vulture (87/118, 73.7%), Spanish imperial eagle (1/6, 16.7%) and red kite (1/18, 5.6%) had abnormal blood Pb levels (>20 μg/dL). Blood Pb levels increased with age, and both monitoring methods showed seasonality in Pb exposure associated with a delayed effect of the hunting season. In Eurasian griffon, blood Pb concentration was associated with lower δ-ALAD activity in blood and P levels in plasma, and with higher blood lipid peroxidation and plasma carotenoid levels in agreement with other experimental and field studies in Pb-exposed birds. The study reveals that Pb poisoning is a significant cause of death and sublethal effects on haem biosynthesis, P metabolism and oxidative stress in birds of prey in Spain.

High Frequency of Lead Exposure in the Population of an Endangered Australian Top Predator, the Tasmanian Wedge-Tailed Eagle (Aquila audax fleayi)

Lead poisoning, mainly through incidental ingestion of lead ammunition in carcasses, is a threat to scavenging and predatory bird species worldwide. In Australia, shooting for animal control is widespread, and a range of native scavenging species are susceptible to lead exposure. However, the prevalence of lead exposure in Australia's scavenging and predatory birds is largely unknown. We evaluated the degree to which the Tasmanian wedge-tailed eagle (Aquila audax fleayi), an endangered Australian raptor and facultative scavenger, showed evidence of lead exposure. We detected lead in 100% of femur and liver tissues of 109 eagle carcasses opportunistically collected throughout Tasmania between 1996 and 2018. Concentrations were elevated in 10% of 106 liver (>6 mg/kg dry wt) and 4% of 108 femur (>10 mg/kg dry wt) samples. We also detected lead in 96% of blood samples taken from 24 live nestlings, with 8% at elevated concentrations (>10 μg/dL). Of the liver samples with elevated lead, 73% had lead^207/206 isotope ratios within the published range of lead-based bullets available in Tasmania. These first comprehensive data on lead exposure of an Australian raptor are comparable to those for raptor studies elsewhere that identify lead-based ammunition exposure as a conservation threat. Our findings highlight the importance of further research and efforts to address lead contamination throughout the Tasmanian ecosystem and in other Australian regions. Environ Toxicol Chem 2021;40:219-230. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. This article has been contributed to by US Government employees and their work is in the public domain in the USA.

Lead contamination in raptors in Europe: A systematic review and meta-analysis

Lead contamination is a widely recognised conservation problem for raptors worldwide. There are a number of studies in individual raptor species but those data have not been systematically evaluated to understand raptor-wide lead exposure and effects at a pan-European scale. To critically assess the extent of this problem, we performed a systematic review compiling all published data on lead in raptors (1983-2019) and, through a meta-analysis, determined if there was evidence for differences in exposure across feeding traits, geographical regions, between hunting and non-hunting periods, and changes over time. We also reviewed the impact of lead on raptors and the likely main source of exposure. We examined 114 studies that were unevenly distributed in terms of time of publication and the countries in which studies were performed. Peer-reviewed articles reported data for 39 raptor species but very few species were widely monitored across Europe. Obligate (vultures) and facultative scavengers (golden eagle, common buzzard and white-tailed sea eagle) accumulated the highest lead concentrations in tissues and generally were the species most at risk of lead poisoning. We found no evidence of a spatial or decadal trend in lead residues, but we demonstrated that high lead blood levels relate to hunting season. Exposure at levels associated with both subclinical and lethal effects is common and lead from rifle bullets and shot is often the likely source of exposure. Overall, our review illustrates the high incidence and ubiquity of lead contamination in raptors in Europe. However, we did not find studies that related exposure to quantitative impacts on European raptor populations nor detailed studies on the impact of mitigation measures. Such information is urgently needed and requires a more harmonised approach to quantifying lead contamination and effects in raptors across Europe.

Dust and bullets: Stable isotopes and GPS tracking disentangle lead sources for a large avian scavenger

Lead intoxication is an important threat to human health and a large number of wildlife species. Animals are exposed to several sources of lead highlighting hunting ammunition and lead that is bioavailable in topsoil. Disentangling the role of each in lead exposure is an important conservation issue, particularly for species potentially affected by lead poisoning, such as vultures. The identification of lead sources in vultures and other species has been classically addressed by means of stable-isotope comparisons, but the extremely varied isotope signatures found in ammunition hinders this identification when it overlaps with topsoil signatures. In addition, assumptions related to the exposure of individual vultures to lead sources have been made without knowledge of the actual feeding grounds exploited by the birds. Here, we combine lead concentration analysis in blood, novel stable isotope approaches to assign the origin of the lead and GPS tracking data to investigate the main foraging grounds of two Iberian griffon vulture populations (N = 58) whose foraging ranges differ in terms of topsoil lead concentration and intensity of big game hunting activity. We found that the lead signature in vultures was closer to topsoil than to ammunition, but this similarity decreased significantly in the area with higher big game hunting activity. In addition, attending to the individual home ranges of the tracked birds, models accounting for the intensity of hunting activity better explained the higher blood lead concentration in vultures than topsoil exposure. In spite of that, our finding also show that lead exposure from topsoil is more important than previously thought.

Development and characterization of magnetic eggshell membranes for lead removal from wastewater

An increasing concern for natural resources preservation and environmental safety is the removal of heavy metals from contaminated water. It is essential to develop simple procedures that use ecofriendly materials with high removal capacities. In this context, we have synthesized a new hybrid material in which eggshell membranes (ESMs) act as nucleation sites for magnetite nanoparticles (MNPs) precipitation in the presence of an external magnetic field. As a result, ESM was transformed into a magnetic biomaterial (MESM) in order to combine the Pb adsorption abilities of both MNPs and ESM and to facilitate collection of the bioadsorbant using an external magnetic field. This green co-precipitation method produced long strands of bead-like 50 nm superparamagnetic MNPs decorating the ESM fibers. When MESM were incubated in Pb(NO₃)₂ solutions, the hybrid material displayed a 2.5-fold increase in binding constant with respect to that of ESM alone, and a 10-fold increased capacity to remove Pb ions from aqueous solution. The manufactured MESMs present a maximum loading capacity of 0.066 ± 0.009 mg Pb/mg MNPs at 25 °C, which is increased up to 0.15 ± 0.05 mg Pb/mg MNPs at 45 °C. Moreover, the MESM system is very stable, since incubation in 1% HCl solution resulted in rapid Pb desorption, while MNP release from the MESM during the same period was negligible. Altogether, these results suggest that MESM could be utilized as an efficient nanoremediation agent for separation/removal of heavy metal ions or other charged pollutants from contaminated waters, with facile recovery for recycling.

Feeding Ecology Drives Lead Exposure of Facultative and Obligate Avian Scavengers in the Eastern United States

Lead poisoning of scavenging birds is a global issue. However, the drivers of lead exposure of avian scavengers have been understood from the perspective of individual species, not cross-taxa assemblages. We analyzed blood (n = 285) and liver (n = 226) lead concentrations of 5 facultative (American crows [Corvus brachyrhynchos], bald eagles [Haliaeetus leucocephalus], golden eagles [Aquila chrysaetos], red-shouldered hawks [Buteo lineatus], and red-tailed hawks [Buteo jamaicensis]) and 2 obligate (black vultures [Coragyps atratus] and turkey vultures [Cathartes aura] avian scavenger species to identify lead exposure patterns. Species and age were significant (α < 0.05) predictors of blood lead exposure of facultative scavengers; species, but not age, was a significant predictor of their liver lead exposure. We detected temporal variations in lead concentrations of facultative scavengers (blood: median = 4.41 µg/dL in spring and summer vs 13.08 µg/dL in autumn and winter; p = <0.001; liver: 0.32 ppm in spring and summer vs median = 4.25 ppm in autumn and winter; p = <0.001). At the species level, we detected between-period differences in blood lead concentrations of bald eagles (p = 0.01) and red-shouldered hawks during the winter (p = 0.001). During summer, obligate scavengers had higher liver lead concentrations than did facultative scavengers (median = 1.76 ppm vs 0.22 ppm; p = <0.001). These data suggest that the feeding ecology of avian scavengers is a determinant of the degree to which they are lead exposed, and they highlight the importance of dietary and behavioral variation in determining lead exposure. Environ Toxicol Chem 2020;39:882-892. © 2020 SETAC.

Relationship between blood lead levels and physiological stress in mute swans (Cygnus olor) in municipal beaches of the southern Baltic

Lead is one of the non-essential metals that can become a serious environmental threat to the human population and wildlife causing various toxic impairments and pathologies. Waterfowl are especially sensitive to lead exposure as they stay in areas with a high risk of lead pollution due to hunting and fishing pressures. This study aims to determine recent blood lead levels in 45 live mute swans in the southern Baltic, in the Gulf of Gdańsk and to test the hypothesis that birds with elevated lead levels have a higher physiological stress. Mean concentration of lead in blood was 0.239 μg/g (range 0.028-0.675 μg/g). Almost half of the individuals examined in this study had increased blood Pb levels above the threshold level (0.23 μg/g), however none of them showed behavioural signs of Pb poisoning. Although the dominant food of mute swans staying at municipal beaches is bread delivered by people, which has low lead levels, lead was found in all blood samples taken from mute swans. In the study area, another possible source of lead poisoning, other than from ammunition, is connected with various anthropogenic activities, such as municipal sewage works. Moreover, poor diet results in greater susceptibility to absorption of lead and this may have an additional influence on elevated lead levels in blood of these birds. The Pb level was increased with heterophils to lymphocytes (H/L) ratio, which is used as a measure of longer-term physiological stress. The mean lead level in blood was higher in young birds than in adults, which may be a consequence of adults forcing them to take less calorific food from water plants containing elevated levels of lead in the area studied. However, it is difficult to disentangle this from other factors that may influence sensitivity to lead poisoning.

Lead Toxicity: Health Hazards, Influence on Food Chain, and Sustainable Remediation Approaches

Lead (Pb) toxicity has been a subject of interest for environmental scientists due to its toxic effect on plants, animals, and humans. An increase in several Pb related industrial activities and use of Pb containing products such as agrochemicals, oil and paint, mining, etc. can lead to Pb contamination in the environment and thereby, can enter the food chain. Being one of the most toxic heavy metals, Pb ingestion via the food chain has proven to be a potential health hazard for plants and humans. The current review aims to summarize the research updates on Pb toxicity and its effects on plants, soil, and human health. Relevant literature from the past 20 years encompassing comprehensive details on Pb toxicity has been considered with key issues such as i) Pb bioavailability in soil, ii) Pb biomagnification, and iii) Pb- remediation, which has been addressed in detail through physical, chemical, and biological lenses. In the review, among different Pb-remediation approaches, we have highlighted certain advanced approaches such as microbial assisted phytoremediation which could possibly minimize the Pb load from the resources in a sustainable manner and would be a viable option to ensure a safe food production system.

Impacts of lead exposure and chelation therapy on bone metabolism during different developmental stages of rats

OBJECTIVE

To explore the impacts of Pb exposure and the dimercaptosuccinic acid (DMSA) chelation therapy on bone metabolisms in young rats of different ages, as well as the potential mechanisms.

METHOD

Young rats were exposed to 0.05%-0.1% Pb acetate for 19 days, during infanthood (postnatal day, PND2-20), childhood (PND21-39) and adolescenthood (PND40-58) respectively. In each developmental stage, rats were further divided into three subgroups: lead-exposed, one-course and two-course DMSA chelation therapy subgroups. Blood/bone lead concentrations, serum calciotropic hormones concentrations, and mRNA and protein expressions of bone turnover markers in the serum and bones were measured. Bone microstructures were analyzed using Micro-CT.

RESULTS

Compared with lead-exposed during childhood and adolescenthood, increases in blood/bone lead levels, and the changes of blood/bone lead and trabecular bone microstructures after one-course DMSA chelation were most significant in rats lead-exposed during infanthood (P < .05). The serum osteocalcin (OC) concentrations, mRNA/protein expressions of OC and runt-related transcription factor 2 (RUNX2) in bones all decreased after Pb exposure, along with significant increases in serum C-terminal telopeptide of type I collagen (CTX) concentrations (P < .05). These effects were accompanied by changes of serum parathormone (PTH) and 1,25-dihydroxyvitamin D₃ (1,25-(OH₂)-D₃) concentrations. DMSA chelation partially reversed the changes of bone microarchitectures, bone formation and resorption markers, and calciotropic-hormones, and the efficiency was greatest when the therapy was provided during infanthood.

CONCLUSION

Developmental Pb exposure impaired bone microstructures and interfered bone metabolism, and the exposure effect was more obvious during infanthood than during childhood and adolescenthood. Lead effects were partially reversed by chelation therapy, and the efficacy may be most significant when the therapy was provided at younger ages.

Environmental exposure to non-essential trace elements in two bat species from urbanised (Tadarida teniotis) and open land (Miniopterus schreibersii) areas in Italy

Bats are particularly suited as bioindicators of trace element pollution due to their longevity and their position in the trophic chain. In this study, the concentrations of ten non-essential trace elements (Al, As, Ba, Cd, Hg, Pb, Sb, Sr, Th, Tl) were determined in the tissues (whole body, skin-fur, skinned body, liver, kidney and bone) of lactant Tadarida teniotis from a nursery colony in Rome. A large number of bats from this nursery died before fledging and had bone deformities and fractures. The concentrations of non-essential trace elements in bone and whole body were also analysed in adult specimens of Miniopterus schreibersii from a colony located in a natural park in Northern Italy. In lactant T. teniotis, the Pb concentration decreased in the following order: bone>liver>skinned body>whole body>skin-fur>kidney, and exceeded the toxic threshold associated with negative effects reported for different mammalian species. The levels of the other non-essential trace elements were within a range indicative of low environmental contamination in both species. Significant interspecies differences (P < 0.05) were observed for concentrations of Pb and Ba, higher in the bones of T. teniotis, and of Cd, Hg and Sr, higher in the bones of M. schreibersii. In lactant T. teniotis, the different sources of Pb exposure, through inhalation and/or food, may represent a potential threat to the colony of this synanthropic European bat.

Regulations on lead ammunition adopted in Europe and evidence of compliance

The transition to non-lead ammunition has been enforced by regulations on use and possession of lead shot and rifle bullets. Here we review the scientific and technical literature about this regulatory process in Europe and give some notes of its effectiveness to reduce this source of lead contamination in aquatic and terrestrial environments. Presently, lead shot use has been legally restricted in 23 European countries. Two, Denmark and The Netherlands, have a total ban of lead gunshot use in all types of habitats, 16 countries have a total ban in wetlands and/or for waterbird hunting, and 5 have a partial ban implemented only in some wetlands. The legal regulation of lead bullets is limited to some German regions. This review also highlights the need to know the level of compliance with the ban on lead ammunition and the subsequent benefits for the susceptible species and for game meat safety.

Ascorbic Acid Supplementation Prevents the Detrimental Effects of Prenatal and Postnatal Lead Exposure on the Purkinje Cell and Related Proteins in the Cerebellum of Developing Rats

We investigated the effects of lead (Pb) and ascorbic acid co-administration on rat cerebellar development. Prior to mating, rats were randomly divided into control, Pb, and Pb plus ascorbic acid (PA) groups. Pregnant rats were administered Pb in drinking water (0.3% Pb acetate), and ascorbic acid (100 mg/kg) via oral intubation until the end of the experiment. Offspring were sacrificed at postnatal day 21, the age at which the morphology of the cerebellar cortex in developing pups is similar to that of the adult brain. In the cerebellum, Pb exposure significantly reduced Purkinje cells and ascorbic acid prevented their reduction. Along with the change of the Purkinje cells, long-term Pb exposure significantly reduced the expression of the synaptic marker (synaptophysin), γ-aminobutyric acid (GABA)-synthesizing enzyme (glutamic acid decarboxylase 67), and axonal myelin basic protein while ascorbic acid co-treatment attenuated Pb-mediated reduction of these proteins in the cerebellum of pups. However, glutamatergic N-methyl-D-aspartate receptor subtype 1 (NMDAR1), anchoring postsynaptic density protein 95 (PSD95), and antioxidant superoxide dismutases (SODs) were adversely changed; Pb exposure increased the expression of NMDAR1, PSD95, and SODs while ascorbic acid co-administration attenuated Pb-mediated induction. Although further studies are required about the neurotoxicity of the Pb exposure, the results presented here suggest that developmental Pb exposure disrupted normal development of Purkinje cells by increasing glutamatergic and oxidative stress in the cerebellum. Additionally, ascorbic acid co-treatment is beneficial in attenuating prenatal and postnatal Pb exposure-induced maldevelopment of Purkinje cells in the developing cerebellum.

Probing into farmers' perceptions of a globally endangered ecosystem service provider

Society's perception of ecosystem services is a key issue in conservation, particularly for endangered species providing services linked to human activities. Misperceptions may lead to wildlife-human conflicts with the risk of disappearance of the species involved. We contrasted farmers' perceptions with highly accurate quantitative data of an endangered vulture species, which provide ecosystem services. We combined surveys of 59 farmers with data from 48 GPS-tagged Canarian Egyptian vultures (Neophron percnopterus majorensis endemic to the Spanish Canary Islands) to disentangle factors influencing consistency between farmers' awareness of vulture occurrence on their properties and vulture behavior. Egyptian vultures were perceived as the main providers of scavenging services and the most beneficial avian scavenger. Consistency between farmers' perceptions (surveys) and vulture use of their farms (GPS data) was higher in the morning, in older males, and at farms with lower livestock numbers, located near vulture communal roosts, and visited more frequently by vultures. Our results underline the potential influence of modern livestock husbandry in disconnecting people from ecosystems, and how appreciation could be even lower for scarce or threatened ecosystem service providers.

Putative impacts of phytogenic additives to ameliorate lead toxicity in animal feed

Lead (Pb) is a toxic heavy metal and an environmental pollutant, particularly because of its anthropogenic activity. The main impacts of Pb is recognized to cause injurious influences of various levels of the tropic chain, due to bio-accumulated lead causes many health issues such as intoxication of different body organs, such as kidneys and liver, and reproductive and nervous systems. Industrial lead toxicity has reduced as a result of the attempts to decrease the lead levels in the surrounding work environment. Conversably, health risks related with long-term environmental exposure to a low dose of Pb have been steadily demonstrated. Long-term exposure to lead toxicity caused inflammatory infiltration, degenerative changes in testicular tissues, reduction in spermatocytes, necrosis of hepatocytes, degeneration in renal tubules, and renal epithelium hypertrophy. Hence, we need an influential approach to vanquish lead toxicity. This consequence has emerged the necessity for potentially safe represent remedy, favorably keeping both enhancement and chelating of the antioxidant competences. Many antioxidants have been used for chelating heavy toxic pollutants such as lead and oxidative stress released in excess during lead exposure. Several studies have stated the noticeable gathering of herbal singly or in combination in modulating lead-induced disturbances, therefore proposing great promise in enhancing health status and welfare of man as well as animals. For this, in the current review, we tried to discuss the enormous harmful influences of lead toxicity on the animal model and the disturbing truth that this detrimental toxic substance can be found quite simply in the surroundings and amplitude.

Suitability of anodic stripping voltammetry for routine analysis of venous blood from raptors

Lead (Pb) poisoning is a significant threat faced by raptors. Hence, rapid Pb diagnosis has become a priority during the admission of raptors in wildlife recovery centers, and bench-top analyzers, such as LeadCare II ®, are routinely employed for this purpose. However, this device has been designed for conducting analyses of human blood Pb levels (BLLs), and the validity of this methodology for whole blood from raptors has, to date, rarely been assessed. In addition, a recent recall by the US Food and Drug Administration has recommended discontinuing the use of this analyzer for human venous blood because it may underestimate the BLL. We evaluated the precision of BLL measurements taken with LeadCare II by comparing them with those obtained with inductively coupled plasma mass spectrometry (ICP-MS). Our sample contained venous blood from 105 raptors belonging to 4 species. The results showed a good correlation between the 2 techniques (Spearman's r = 0.927, p < 0.0001). The mean BLL with ICP-MS was 19.6 μg/dL; it was found to be 18.7 μg/dL with LeadCare II. A Bland-Altman analysis indicated that the bias between the mean differences was only 0.5 μg/dL, but it had a high standard deviation of bias (5.7 μg/dL) and 95% limits of agreement from -10.75 to 11.74 μg/dL. The present results indicated that LeadCare II has an overall sensitivity of 71.8% and a positive predictive value of 76.3%. The specificity of LeadCare II for detecting animals with low BLL (<3.4 μg/dL) was 96.4%, and the negative predictive value (the probability that a value below the limit of detection of LeadCare II has a true correspondence with the actual value) was 100%. The present results indicated that, although LeadCare II might be imperfect in the estimation of BLLs in raptors, it performs reasonably well and might be employed in the clinical setting to assess patients potentially suffering from Pb poisoning. Environ Toxicol Chem 2019;38:737-747. © 2018 SETAC.

What do we know about lead contamination in wild vultures and condors? A review of decades of research

Vultures and condors (hereafter vultures) make up one the most threatened avian guilds in the world due to a variety of human-mediated impacts and disturbances. In fact, 70% of vulture species are currently suffering impacted by significant conservation threats, with lead contamination being particularly important. Unfortunately, lead contamination in vulture species remains poorly studied in many regions of the world. We reviewed the existing scientific knowledge about this threat to vultures. We found 62 scientific articles studying lead contamination in vultures. Seventy-two percent of these articles were from North America and Europe, with the rest corresponding to Asia (13%), South America (8%), and Africa (7%). Most (92%) were published recently (2001-2018). Published articles included information on 13 vulture species out of a total of 23 from both the Old (9) and New World (4). Eighty-eight percent of the articles showed individuals with lead concentrations above threshold levels in some tissues sampled, with New World (Cathartidae) vultures more affected than Old World vultures (Accipitridae). The most suspected but rarely probed source of lead was lead ammunition, but other sources such as pollution or industry were also reported. It is concerning that lead contamination is considered a major threat for just 8% (2/23) of the vulture species categorized by the IUCN Red list. Our review shows that lead contamination is an important threat for several vulture species worldwide, but remains undiagnosed and not well-recognized in some species and geographical areas. The effect of this contaminant on vulture demography is not well known but merits particular attention since it may be leading to population declines in several species.

Heavy-metal concentrations in feathers of cinereous vulture (Aegypius monachus L.) as an endangered species in Turkey

The aim of this study is to find out the certain heavy-metal levels in the feathers of cinereous vulture (Aegypius monachus L.), which is a threatened species. The feathers of the cinereous vultures were collected from the breeding areas in Sündiken and Türkmenbaba Mountains. To avoid misleading results, vanes and calamuses of the rectrices were evaluated separately in terms of their As, Cd, Cr, Cu, Hg, Ni, Pb and Zn contents. ICP-OES was used to analyse the metal levels in feathers which belonged to 43 different individuals. All of the heavy-metal concentrations except for Cu were higher in vanes than in calamuses. The mean levels of Cd (0.254 ± 1.589 μg/g d.w. in the calamus and 0.334 ± 0.156 μg/g d.w. in the vane), Cr (6.536 ± 6.378 μg/g d.w. in the vane), Ni (11.886 ± 10.891 μg/g d.w. in the vane) and Pb (5.671 ± 3.884 μg/g d.w. in the vane) exceeded the threshold values for the birds. As a result, we recommend further studies to understand the effects of the heavy metals on the population of the species.

Hunting with lead ammunition is not sustainable: European perspectives

Much evidence demonstrates the adverse effects of lead ammunition on wildlife, their habitats and human health, and confirms that the use of such ammunition has no place within sustainable hunting. We identify the provisions that define sustainable hunting according to European law and international treaties, together with their guidance documents. We accept the substantial evidence for lead's actual and potential effects on wildlife, habitats and health as persuasive and assess how these effects relate to stated provisions for sustainability and hunting. We evaluate how continued use of lead ammunition negatively affects international efforts to halt loss of biodiversity, sustain wildlife populations and conserve their habitats. We highlight the indiscriminate and avoidable health and welfare impacts for large numbers of exposed wild animals as ethically unsustainable. In societal terms, continued use of lead ammunition undermines public perceptions of hunting. Given the existence of acceptable, non-toxic alternatives for lead ammunition, we conclude that hunting with lead ammunition cannot be justified under established principles of public/international policy and is not sustainable. Changing from lead ammunition to non-toxic alternatives will bring significant nature conservation and human health gains, and from the hunter's perspective will enhance societal acceptance of hunting. Change will create opportunities for improved constructive dialogue between hunting stakeholders and others engaged with enhancing biodiversity and nature conservation objectives.

Characterization and imaging of lead distribution in bones of lead-exposed birds by ICP-MS and LA-ICP-MS

Lead (Pb) poisoning in raptors and water birds is a serious problem in many countries. However, only a small fraction of Pb poisoning has been detected in birds. Bone specimens may be useful indices of Pb exposure because bones contain ∼90% of the total Pb body burden. The original purpose of this study was to comprehensively analyze Pb accumulation in various bone types using inductively coupled plasma-mass spectrometry (ICP-MS). Since our results showed that Pb accumulation differed greatly depending on bone type, a secondary objective was defined, aiming to investigate the fine Pb distribution and its relation to bone structure and bone marrow by using laser ablation (LA)-ICP-MS. Our findings suggested that bone samples (1) consisting of trabecular tissue and (2) those that contain bone marrow could accumulate high levels of Pb following acute exposure. The shorter turnover time of trabecular bone can cause a rapid accumulation of Pb, and bone marrow may have an important role for internal exposure of Pb to bone tissue. Pb is accumulated in bones via blood flow, and bone marrow receives blood from outside the bones. In conclusion, bone samples provide valuable information on Pb exposure and could be useful to investigate and understand mortalities related to suspected Pb poisoning.

Food predictability and social status drive individual resource specializations in a territorial vulture

Despite increasing work detailing the presence of foraging specializations across a range of taxa, limited attention so far has been given to the role of spatiotemporal variation in food predictability in shaping individual resource selection. Here, we studied the exploitation of human-provided carrion resources differing in predictability by Canarian Egyptian vultures (Neophron percnopterus majorensis). We focussed specifically on the role of individual characteristics and spatial constraints in shaping patterns of resource use. Using high-resolution GPS data obtained from 45 vultures tracked for 1 year, we show that individual vultures were repeatable in both their monthly use of predictable and semi-predicable resources (feeding station vs. farms) and monthly levels of mobility (home range size and flight activity). However, individual foraging activities were simultaneously characterized by a high degree of (temporal) plasticity in the use of the feeding station in specific months. Individual rank within dominance hierarchy revealed sex-dependent effects of social status on resource preference in breeding adults, illustrating the potential complex social mechanisms underpinning status-dependent resource use patterns. Our results show that predictable food at feeding stations may lead to broad-scale patterns of resource partitioning and affect both the foraging and social dynamics within local vulture populations.

Association between hunting and elevated blood lead levels in the critically endangered African white-backed vulture Gyps africanus

Lead (Pb) toxicity caused by the ingestion of Pb ammunition fragments in carcasses and offal is a threat to scavenging birds across the globe. African vultures are in critical decline, but research on whether Pb exposure is contributing to declines is lacking. In Africa, recreational hunting represents an important economic activity; however, Pb in leftover hunted carcasses and gut piles represents a dangerous food source for vultures. It is therefore important to establish whether recreational hunting is associated with Pb exposure in African vultures. We explored this issue for the critically endangered white-backed vulture (Gyps africanus) in Botswana by examining their blood Pb levels inside and outside of the hunting season, and inside and outside of private hunting areas. From 566 birds captured and tested, 30.2% birds showed elevated Pb levels (10 to <45 μg/dl) and 2.3% showed subclinical exposure (≥45 μg/dl). Higher blood Pb levels were associated with samples taken inside of the hunting season and from within hunting areas. Additionally, there was a significant interaction between hunting season and areas, with Pb levels declining more steeply between hunting and non-hunting seasons within hunting areas than outside them. Thus, all our results were consistent with the suggestion that elevated Pb levels in this critically endangered African vulture are associated with recreational hunting. Pb is known to be highly toxic to scavenging birds and we recommend that Pb ammunition in Botswana is phased out as soon as possible to help protect this rapidly declining group of birds.

Patterns and trends in lead (Pb) concentrations in bald eagle (Haliaeetus leucocephalus) nestlings from the western Great Lakes region

Most studies examining bald eagle (Haliaeetus leucocephalus) exposure to lead (Pb) have focused on adults that ingested spent Pb ammunition during the fall hunting season, often at clinical or lethal levels. We sampled live bald eagle nestlings along waterbodies to quantify Pb concentrations in 3 national park units and 2 nearby study areas in the western Great Lakes region. We collected 367 bald eagle nestling feather samples over 8 years during spring 2006-2015 and 188 whole blood samples over 4 years during spring 2010-2015. We used Tobit regression models to quantify relationships between Pb concentrations in nestling feathers and blood using study area, year, and nestling attributes as covariates. Pb in nestling feather samples decreased from 2006 to 2015, but there was no trend for Pb in blood samples. Pb concentrations in nestling feather and blood samples were significantly higher in study areas located closer to and within urban areas. Pb in feather and blood samples from the same nestling was positively correlated. Pb in feathers increased with nestling age, but this relationship was not observed for blood. Our results reflect how Pb accumulates in tissues as nestlings grow, with Pb in feathers and blood indexing exposure during feather development and before sampling, respectively. Some nestlings had Pb concentrations in blood that suggested a greater risk to sublethal effects from Pb exposure. Our data provides baselines for Pb concentrations in feathers and blood of nestling bald eagles from a variety of waterbody types spanning remote, lightly populated, and human-dominated landscapes.

Metals in Feathers of African Penguins (Spheniscus demersus): Considerations for the Welfare and Management of Seabirds Under Human Care

Bird feathers have been proven to be reliable indicators of metal exposure originating from contaminated food and polluted environments. The concentrations of 15 essential and non-essential metals were investigated in African penguins (Spheniscus demersus) feathers from a Northwestern Italian zoological facility. These birds are exclusively fed with herring from the northeast Atlantic Ocean. Certain elements, such as Hg and Cd, reflected the bioaccumulation phenomena that occur through the marine food chain. The levels of Cr, Mn, and Ni were comparable to those registered in feathers of birds living in polluted areas. These results are important for comparative studies regarding the health, nutrition and welfare of endangered seabirds kept under human care.