Distribution of lead in selected organs and its effect on reproduction parameters of pheasants (Phasianus colchicus) after an experimental per oral administration

Toxicity and bioremediation of the lead: a critical review

Lead is a naturally occurring, bluish-gray metal that is found in small quantities in the earth's crust. The existing literature demonstrates that non-biodegradable character and continuous use results in accumulation of lead concentration in the environment and causes various ill effects such as neurotoxicity, change in psychological and behavioral development of different organisms. Nowadays the most effective technique in the revival of the environment is bioremediation and it is environmentally friendly and cost-effective. Bacterial strains such as Oceanobacillus profundus and Lactobacillus acidophilus ATCC4356 have the ability to reduce lead 97% and 73.9%, respectively. Similarly some species of algae and fungal strains also showed lead removal efficiency as 74% (spirulina), 97.1% (Chlorella kessleri), 95.5% (Penicillium janthinillum) and 86% (Aspergillus flavus). Biodegradation of lead by various microbes would be the most efficient and sustainable approach. This review focuses on toxicity, fate of lead in the environment and its microbial degradation.

Difference in concentration of lead (Pb) in meat from pheasants killed using lead and iron (Fe) shotgun ammunition

The use of lead shotgun ammunition for hunting has been banned in a few jurisdictions and habitats, principally to protect wild birds from poisoning by ingestion of spent lead shot. The EU and UK REACH processes have recently considered bans on lead ammunition throughout the European Union and United Kingdom, including assessments of possible health benefits from reduced human dietary exposure to lead from game meat. Comparisons of the mean lead concentrations in meat from gamebirds killed using lead and non‑lead shotgun ammunition have not been published. We compared lead concentrations in meat from wild-shot pheasants from which lead shotgun pellets were recovered (n = 27) with those from which iron pellets were recovered (n = 20), having removed all pellets from the meat before analysis. The mean concentration of lead in meat from pheasants killed using lead shot was 2.10 mg/kg w.w., which is >20 times the European Union's maximum permitted level for the lead concentration in meat from domesticated animals. For pheasants killed using iron shot the mean was 0.07 mg/kg w.w., which is below the maximum permitted level.

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.

How contaminated with ammunition-derived lead is meat from European small game animals? Assessing and reducing risks to human health

Small game animals are generally hunted with lead gunshot which often fragments causing elevated lead concentrations in meat and presenting health risks to frequent consumers and vulnerable groups. We reviewed three decades of European data on lead concentrations in the meat of gamebirds, rabbits and hares across countries with various restrictions on lead gunshot use. Mean meat lead concentrations decreased to a low level in Denmark, the only country in the study with a total ban on lead gunshot use. In contrast, elsewhere in Europe meat lead concentrations increased over time, an unexplained and previously undescribed finding. The only regulatory restriction associated with a decrease in meat lead concentrations was the Danish total ban on lead gunshot use. We calculated an arithmetic mean lead concentration in small game meat of 5.205 ppm w.w. (2011-2021) from across Europe. EU and UK regulators are considering banning lead ammunition for all hunting to protect human and wildlife health. The mean value we found for small game meat (2011-2021) was fourteen times higher than that used in a recent EU-wide risk assessment.

Physiological factors influencing female fertility in birds

Fertility is fundamental to reproductive success, but not all copulation attempts result in a fertilized embryo. Fertilization failure is especially costly for females, but we still lack a clear understanding of the causes of variation in female fertility across taxa. Birds make a useful model system for fertility research, partly because their large eggs are easily studied outside of the female's body, but also because of the wealth of data available on the reproductive productivity of commercial birds. Here, we review the factors contributing to female infertility in birds, providing evidence that female fertility traits are understudied relative to male fertility traits, and that avian fertility research has been dominated by studies focused on Galliformes and captive (relative to wild) populations. We then discuss the key stages of the female reproductive cycle where fertility may be compromised, and make recommendations for future research. We particularly emphasize that studies must differentiate between infertility and embryo mortality as causes of hatching failure, and that non-breeding individuals should be monitored more routinely where possible. This review lays the groundwork for developing a clearer understanding of the causes of female infertility, with important consequences for multiple fields including reproductive science, conservation and commercial breeding.

Toxic elements in blood of red-necked nightjars (Caprimulgus ruficollis) inhabiting differently polluted environments

Toxic metals have been widely reported in avian tissues due to their well-known accumulation capacity and adverse effects. However, rare earth elements (REE) and other minor elements (ME) are becoming a new threat due to their use in modern technology. Presently, exposure data are limited and no studies have been reported in wildlife. The order Caprimulgiformes is among the most understudied groups of birds lacking blood ecotoxicological data. One major constraint is the small blood sample volume that can be collected to ensure animal welfare, which limits analyses. In order to shed light on these collective issues, we sampled 48 red-necked nightjars (Caprimulgus ruficollis) inhabiting three different scenarios of contaminant exposure (agricultural-urban area, n = 15; mining area, n = 17; and control area, n = 16) in southeastern Spain, and report for the first time concentrations of 50 elements (i.e. trace elements, ATSDR's list toxic elements, REE and ME) using a recently developed technique able to analyze them by ICP-MS in very small volumes of blood (130 μL). Concentrations of As, Cd, Pb and Mn were significantly higher in individuals captured at the mining area compared to the other sites. Lead levels in the mine site were of particular concern since it was in the range of blood concentrations related to subclinical/clinical effects in other species, and in our study were associated with decreased hematocrit values (up to 44% hematocrit depression at blood concentrations >1000 ng/ml w.w.). Moreover, additive effects related to metal cocktail exposure in the mining area could be expected. Age and gender-related differences in blood concentrations were found for some elements. Even though most REE and ME concentrations were close to the LOQ, some of these emerging contaminants may trigger sublethal effects that, together with the ATSDR's list toxic elements, need to be carefully evaluated in a future study.

Effects of lead from ammunition on birds and other wildlife: A review and update

Poisoning of wild birds following ingestion of lead from ammunition has long been recognised and considerable recent research has focused on terrestrial birds, including raptors and scavengers. This paper builds upon previous reviews and finds that both the number of taxa affected and geographical spread of cases has increased. Some lead may also be absorbed from embedded ammunition fragments in injured birds which risk sub-lethal and welfare effects. Some papers suggest inter-specific differences in sensitivity to lead, although it is difficult to disentangle these from other factors that influence effect severity. Sub-lethal effects have been found at lower blood lead concentrations than previously reported, suggesting that previous effect-level 'thresholds' should be abandoned or revised. Lead poisoning is estimated to kill a million wildfowl a year in Europe and cause sub-lethal poisoning in another ≥ 3 million. Modelling and correlative studies have supported the potential for population-level effects of lead poisoning in wildfowl, terrestrial birds, raptors and scavengers.

Wildlife, human and environmental costs of using lead ammunition: An economic review and analysis

A proposed European Union (EU)-wide restriction on the use of lead gunshot for shooting in and over wetlands estimated that the societal benefits of a restriction outweighed costs, despite few identified benefits being quantified economically. A subsequent Annex XV Investigation Report on the evidence of impacts of lead ammunition in terrestrial environments concluded that additional measures to control its use are warranted, although to date this has not been further evaluated. To help inform this process, we review the literature and undertake new analyses to estimate the costs of continued use of lead ammunition associated with impacts on wildlife, people and the environment. We estimate minimum annual direct costs across the EU and Europe of c. €383 million-€960 million and €444 million-€1.3 thousand million respectively. The value that society places on being able to avoid these losses, estimated using a 'willingness to pay' approach, was c. €2.2 thousand million for wildfowl alone. Our estimated costs of the continued use of lead ammunition across the EU appear to be considerably greater than the likely costs of switching to non-toxic alternative ammunition types, although these have not been formally estimated in full.

Avian Stress-Related Transcriptome and Selenotranscriptome: Role during Exposure to Heavy Metals and Heat Stress

Selenium, through incorporation into selenoproteins, is one of the key elements of the antioxidant system. Over the past few years there has been increased interest in exploring those molecular mechanisms in chicken, responsible for the development of this protection system. In more detail, Cd/Pb poisoning and heat stress increase oxidation, mRNA levels of inflammatory proteins, and apoptotic proteins. Selenium seems to enhance the antioxidant status and alleviates these effects via upregulation of antioxidant proteins and other molecular effects. In this review, we analyze avian transcriptome key elements with particular emphasis on interactions with heavy metals and on relation to heat stress.

CHOP/caspase-3 signal pathway involves in mitigative effect of selenium on lead-induced apoptosis via endoplasmic reticulum pathway in chicken testes

Lead (Pb) is an environmental pollutant. Selenium (Se) has alleviative effect on Pb poisoning. However, mitigative effect of Se on Pb-induced apoptosis has not been unclear via endoplasmic reticulum (ER) pathway in chicken testes. The aim of this study was to investigate mitigative effect of Se on apoptosis induced by Pb poisoning via ER pathway in chicken testes. Sixty male chickens (7-day-old) were randomly divided into the control group offered drinking water (DW) and basic diet (BD) (0.49 mg/kg Se), the Se group offered DW and BD containing Na₂SeO₃ (SeBD) (1.00 mg/kg Se), the Pb group offered DW containing (CH₃OO)₂Pb (PbDW) (350.00 mg/L Pb) and BD, and the Pb + Se group offered PbDW and SeBD; and were fed for 90 days. The following contents were performed as follows: histology; antioxidant indexes (reduced glutathione (GSH), malondialdehyde (MDA), glutathione peroxidase (GPx), glutathione S-transferase (GST), and superoxide dismutase (SOD)); mRNA expressions of ER-related genes (glucose-related protein 78 (GRP78), protein kinase-like ER kinase (PERK), eukaryotic initiation factor 2α (eIF2α), activating transcription factor 4 (ATF4), and enhancer-binding protein homologous protein (CHOP)); and apoptosis-related genes (cysteine-aspartic protease (caspase)-3 and caspase-12) in chicken testes. The results indicated that Pb poisoning caused histological changes; increased MDA content; decreased the content of GSH and the activities of GPx, GST, and SOD; and upregulated mRNA expressions of the above five ER-related genes and two apoptosis-related genes in the chicken testes. Se alleviated Pb-induced oxidative stress, ER stress, and apoptosis via CHOP/caspase-3 signal pathway in the chicken testes.

Lead exposure affects health indices in free-ranging ducks in Argentina

Numerous experiments under controlled conditions and extensive investigation of waterfowl die-offs have demonstrated that exposure to lead from spent gunshot is highly detrimental to the health of waterfowl. However, few studies have focused on examining the more subtle sub-lethal effects of lead toxicity on ducks in non-experimental settings. In our study, the health of ducks exposed to varying amounts of lead under natural conditions was assessed by correlating individual lead exposure with relevant indices of health. Based on hunter-killed wild ducks in Argentina, we measured spleen mass, body condition, examined bone marrow smears, and determined Ca and P in bone tissue. In free-ranging live-trapped ducks we determined basic hematology and aminolevulinic acid dehydratase activity. Using multivariate analyses, we found that, when controlling for the potential confounding effect of site type, year, duck species, body mass and age, lead levels in the liver were negatively associated with body condition and spleen mass. Spleen mass was also lower in ducks with higher lead levels in their bones. In live ducks, high blood lead levels were associated with low packed cell volume and red cell morphologic abnormalities. These findings suggest that, despite the lack of recorded lead-induced mortality in the region, lead exposure results in less conspicuous but still significant impacts on the health of ducks, which could have serious implications for their conservation. Moreover, this evidence further supports the need for urgently banning lead shot in the region.