Current situation of lead (Pb) exposure in raptors and waterfowl in Japan and difference in sensitivity to in vitro lead exposure among avian species.

Although lead (Pb) poisoning in wild birds has been considered a serious problem in Japan for over 30 years, there is little information about Pb exposure and its sources throughout Japan except for Hokkaido. Furthermore, to identify and effectively prioritize the conservation needs of highly vulnerable species, differences in sensitivity to Pb exposure among avian species need to be determined. Therefore, we investigated the current situation of Pb exposure in raptors (13 species, N = 82), waterfowl (eight species, N = 44) and crows (one species, N = 6) using concentration and isotope analysis. We employed blood or tissue samples collected in various Japanese facilities mainly in 2022 or 2023. We also carried out a comparative study of blood δ-ALAD sensitivity to in vitro Pb exposure using blood of nine avian species. Pb concentrations in the blood or tissues displayed increased levels (>0.1 µg/g blood) in two raptors (2.4%), ten waterfowl (23%) and one crow (17%). Among them, poisoning levels (>0.6 µg/g blood) were found in one black kite and one common teal. The sources of Pb isotope ratios in ten blood samples with high Pb levels were determined as deriving from shot pellets (N = 9) or rifle bullets (N = 1). In the δ-ALAD study, red-crowned crane showed the highest sensitivity among the nine tested avian species and was followed in order by five Accipitriformes species (including white-tailed and Steller's sea eagle), Blakiston's fish owl, Muscovy duck and chicken, suggesting a genetically driven variance in susceptibility. Further studies on contamination conditions and exposure sources are urgently needed to inform strict regulations on the usage of Pb ammunition. Furthermore, detailed examinations of δ-ALAD sensitivity, interspecific differences, and other factors involved in the variability in sensitivity to Pb are required to identify and prioritize highly sensitive species.

Quantification of the tissue distribution and accumulation of the neonicotinoid pesticide clothianidin and its metabolites in maternal and fetal mice.

Neonicotinoids (NNs) are commonly used pesticides that have a selective agonistic action on insect nicotinic acetylcholine receptors. Recent evidence has shown that NNs have adverse effects in the next generation of mammals, but it remains unclear how NNs transferred from dams to fetuses are distributed and accumulated in fetal tissues. Here, we aimed to clarify the tissue distribution and accumulation properties of the NN clothianidin (CLO) and its 6 metabolites in 7 tissues and blood in both dams and fetuses of mice administered CLO for a single day or for 9 consecutive days. The results showed that the total concentrations of CLO-related compounds in the brain and kidney were higher in fetuses than in dams, whereas in the liver, heart, and blood they were lower in fetuses. The multi-day administration increased the total levels in heart and blood only in the fetuses of the single administration group. In addition, dimethyl metabolites of CLO showed fetus/dam ratios >1 in some tissues, suggesting that fetuses have higher accumulation property and are thus at higher risks of exposure to CLO-related compounds than dams. These findings revealed differences in the tissue-specific distribution patterns of CLO and its metabolites between dams and fetuses, providing new insights into the assessment of the developmental toxicity of NNs.

Metals and arsenic distribution in stray dogs' tissues around a lead-zinc mine in Kabwe, Zambia.

Metal contamination poses a threat to human, animal, and environmental health. The purpose of the current study was to assess the accumulation of toxic and trace metal concentrations in tissues of stray dogs in Kabwe, a town known for lead pollution due to a long history of lead and zinc mining. Brain, spleen, heart, stomach, stomach content, small intestine, kidney, liver, and bone samples were collected from 29 stray dogs (14 from locations within 3 km of the mine and 15 from sites 7 km away from the mine) after necropsy. Inductively coupled plasma mass spectrometry was used to analyze toxic metals, arsenic (As), cadmium (Cd), and lead (Pb), and trace elements, copper (Cu) and zinc (Zn). The lungs (0.117 ± 0.114 mg/kg dry weight), kidney (7.515 ± 8.830 mg/kg dry weight), and bone (41.68 ± 66.83 mg/kg dry weight) were found to have the highest concentrations of As, Cd, and Pb, respectively. In contrast, higher Cu and Zn concentrations were measured in the liver than in other tissues. In all tissues analyzed, tissues sampled from dogs near the mine had significantly higher mean concentrations of Cd and Pb than dogs far away. Neither sex nor age-related differences were observed in the distribution of metals in most tissues. There were significant associations among toxic (Pb and Cd) and trace metals (Cu and Zn). In the kidney, Cd positively correlated with Pb (ρ = 0.534) and Zn (ρ = 0.600), whereas in the liver, Cu correlated with Zn (ρ = 0.565). The current study's findings suggest that environmental pollution is still a problem in Kabwe, and environmental remediation is needed to address the pollution.

Association between Chronic Environmental Lead (Pb) Exposure and Cytokines in Males and Females of Reproductive Age from Kabwe, Zambia.

Lead (Pb) poisoning remains a great public health challenge globally known to induce a wide range of ailments in both children and adults. The current study investigated the association of chronic environmental Pb exposure and immunomodulatory cytokines tumor necrosis factor alpha (TNF-α) and interleukin-8 (IL-8) in adult males and females living in Kabwe, Zambia. The standard human cytokine/chemokine Milliplex assay was used to quantify plasma cytokines from four groups categorized as low (<10 µg/dL) and high (>10 µg/dL) blood lead level (BLL) groups, namely, low BLL female (n = 47; BLL = 3.76 µg/dL), low BLL Male (n = 43; BLL = 4.13 µg/dL), high BLL female (n = 21; BLL = 23.5 µg/dL), and high BLL male (n = 18; BLL = 23.7 µg/dL), respectively. The low BLL group was associated with increased TNF-α levels, and the high BLL group was associated with reduced TNF-α levels in female subjects. No associations between BLL and the levels of IL-8 and TNF-α cytokines were observed in either females or males, respectively. A negative correlation between BLL and TNF-α was found in female subjects, suggesting that an increase in BLL accompanied by a reduction in TNF-α. The reduced levels of circulating TNF-α in female subjects suggest that chronic Pb exposure could predispose females to immune and inflammation-related disorders than their male counterparts. Further studies are recommended to ascertain the impact of chronic Pb exposure on immunomodulatory cytokines, especially in females.

Characteristics of tissue distribution, metabolism, effects on brain catecholamines, and environmental exposure of frogs to neonicotinoid insecticides.

Pesticide exposure is considered to be one important factor responsible for declining amphibian populations worldwide. The usage of neonicotinoid insecticides (NNIs) has markedly increased in recent years, and there are concerns regarding the effects of NNI-induced toxicity on the development and behavior of amphibians. However, there have been few reports on the metabolism, distribution, and neurotoxicity of NNIs in amphibians. In this study, we exposed the Western clawed frog (Silurana tropicalis) to clothianidin (CLT) in water. After 24 h of exposure, the highest concentrations were detected in the skin, indicating that frogs are at a high risk of absorbing CLT through their skin along with water. Excretion of CLT was estimated based on the concentrations of CLT metabolites in the water until 48 h of exposure. The findings showed that frogs had higher CLT metabolic ability than zebrafish. Serotonin levels in the brain were lower in the high-concentration CLT exposure group than in the control group, although the difference was not statistically significant. This suggested that catecholamine-related effects of CLT on the brain cannot be disregarded. In addition, quantitative analyses of NNI residue in wild frogs, soil, and water in agricultural areas in Hokkaido, Japan, were performed and four NNIs were detected. These results indicated the possible risk of NNI-induced toxicity in frogs. This is the first report of the characteristics of tissue distribution and metabolism of NNIs in frogs, which may facilitate the design of appropriate conservation programs for amphibians.

Investigation of dichlorodiphenyltrichloroethane (DDT) on xenobiotic enzyme disruption and metabolomic bile acid biosynthesis in DDT-sprayed areas using wild rats.

Dichlorodiphenyltrichloroethane (DDT) is an organochlorine insecticide used worldwide. Several studies have reported the toxic effects of DDT and its metabolites on steroid hormone biosynthesis; however, its environmental effects are not well understood. This study examined wild rats collected in DDT-sprayed areas of South Africa and quantified plasma metabolites using liquid chromatography quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS). Fold change analysis of the metabolome revealed the effect of DDT on bile acid biosynthesis. Gene expression of the related enzyme in rat liver samples was also quantified. Significant association was found between DDT and gene expression levels related to constitutive androstane receptor mediated enzymes, such as Cyp2b1 in rat livers. However, our results could not fully demonstrate that enzymes related to bile acid biosynthesis were strongly affected by DDT. The correlation between DDT concentration and gene expression involved in steroid hormone synthesis in testis was also evaluated; however, no significant correlation was found. The disturbance of metabolic enzymes occurred in rat liver in the target area. Our results suggest that DDT exposure affects gene expression in wild rats living in DDT-sprayed areas. Therefore, there is a need for DDT toxicity evaluation in mammals living in DDT-sprayed areas. We could not find an effective biomarker that could reflect the mechanism of DDT exposure; however, this approach can provide new insights for future research to evaluate DDT effects in sprayed areas.

Accumulation of Metals in the Environment and Grazing Livestock near A Mongolian Mining Area.

The Mongolian economy is supported by rich deposits of natural resources, such as copper, coal, and gold. However, the risk of heavy metal pollution to livestock and human have been recently discussed. This research collected various samples from soil and animal (sheep, goat, horse, cow, and camel), blood and organs (kidney and liver) in the Mongolian countryside. These samples were processed, and the concentration of metals was quantified using inductively coupled plasma-mass spectrometry (ICP/MS). As previously reported, arsenic was found at high levels of accumulation in soil. Selenium is another concern, as median concentration in one area exceeded the maximum allowable level. Cadmium and selenium were found to be highly accumulated in animal kidney. This research revealed the current pollution level in Mongolia based on evaluation of soil and animals. The concentration in animals could not indicate that animals had severe effects because of heavy metal exposure. However, kidney is eaten in Mongolia, and so there is a direct connection to human health, and this research suggested the possible risks posed by each edible animal. In particular, evaluation of metals in livestock is rare in Mongolia. This result can contribute to animal and human health in Mongolian communities.

Characteristics of cytochrome P450-dependent metabolism in the liver of the wild raccoon, Procyon lotor.

Wildlife is exposed to a wide range of xenobiotics in the natural environment. In order to appropriately assess xenobiotic-induced toxicity in wildlife, it is necessary to understand metabolic capacities. Carnivores, in general, have low metabolic abilities, making them vulnerable to a variety of chemicals. Raccoons (Procyon lotor) in the wild have been found to have high levels of xenobiotics. However, little is known about the metabolic capacity of the cytochrome P450 (CYP) enzymes in this species. Thus, this study used liver samples to investigate the characteristics of CYP enzymes in wild raccoons. In 22 wild raccoons, CYP concentrations in hepatic microsomes were examined. To better understand the properties of CYP-dependent metabolism, in vitro metabolic activity studies were performed using ethoxyresorufin, pentoxyresorufin and testosterone as substrates. In addition, three raccoons were fed commercial dog food in the laboratory for one week, and the effects on CYP-dependent metabolism were investigated. In comparison to other mammalian species, raccoons had very low concentrations of CYP in their livers. In an in vitro enzymatic analysis, raccoons' ethoxyresorufin O-deethylase (EROD) and pentoxyresorufin O-depentylase (PROD) metabolic capacities were less than one-fifth and one-tenth of rats', respectively. These results indicate the possible high risk in raccoons if exposed to high levels of environmental xenobiotics because of their poor CYP activity. In this study, the features of CYP-dependent metabolism in wild raccoons are described for the first time.

Methylation profiles of global LINE-1 DNA and the GSTP1 promoter region in children exposed to lead (Pb).

Lead (Pb) exposure has adverse health effects and altered DNA methylation may contribute to Pb toxicity. LINE-1 is an interspersed repeated DNA that is used as a surrogate marker for estimating genomic DNA methylation levels, and GSTP1 is an isozyme that detoxifies xenobiotics like Pb, and its expression is inhibited by methylation. Thus, to assess the effects of Pb exposure on global hypomethylation and gene-specific promoter hypermethylation, we examined DNA methylation at LINE-1 repetitive elements and the GSTP1 promoter region. Blood samples were obtained from children (N = 123) living in Pb-polluted areas (as exposed children) and children (N = 63) living in Pb-unpolluted areas (as control children) in Kabwe, Zambia. ICP-MS was used to determine blood lead levels (BLLs), and pyrosequencing and a fluorescence-based polymerase chain reaction assay were used to determine levels of LINE-1 methylation and GSTP1 promoter methylation, respectively. Inverse association was found between BLLs and LINE-1 methylation (ß = - 0.046, p = 0.006). The highest quartile of BLL had significant hypomethylation of LINE-1 (p for trend = 0.03), suggesting the higher the BLL, the lower LINE-1 methylation. GSTP1 methylation levels did not differ significantly between the two areas (p = 0.504), nor was it associated with Pb poisoning risk (OR = 1.03, p = 0.476), indicating GSTP1 methylation may not be a reliable biomarker of Pb exposure in healthy people. Therefore, Pb-related health problems could result from global DNA methylation changes due to high BLLs.

Estimation of the Effects of Neonicotinoid Insecticides on Wild Raccoon, Procyon lotor, in Hokkaido, Japan: Urinary Concentrations and Hepatic Metabolic Capability of Neonicotinoids.

Toxicological effects of neonicotinoid insecticides (NNIs) have been reported for mammals, such as humans, rats, and mice. However, there are limited reports on their toxic effects on wild mammals. To predict NNI-induced toxic effects on wild mammals, it is necessary to determine the exposure levels and metabolic ability of these species. We considered that raccoons could be an animal model for evaluating NNI-induced toxicities on wildlife because they live near agricultural fields and eat crops treated with NNIs. The objective of the present study was to estimate the effects of NNI exposure on wild raccoons. Urinary concentrations of NNI compounds (n = 59) and cytochrome P450-dependent metabolism of NNIs (n = 3) were evaluated in wild raccoons captured in Hokkaido, Japan, in 2020. We detected either one of the six NNIs or one metabolite, including acetamiprid, imidacloprid, clothianidin, dinotefuran, thiacloprid, thiamethoxam, and desmethyl-acetamiprid in 90% of raccoons (53/59); the average cumulative concentration of the seven NNI compounds was 3.1 ng/ml. The urinary concentrations were not much different from those reported previously for humans. Furthermore, we performed an in vitro assessment of the ability of raccoons to metabolize NNIs using hepatic microsomes. The amounts of NNI metabolites were measured using liquid chromatography-electrospray ionization-tandem mass spectrometry and compared with those in rats. Raccoons showed much lower metabolic ability; the maximum velocity/Michaelis-Menten constant (Vmax /Km ) values for raccoons were one-tenth to one-third of those for rats. For the first time, we show that wild raccoons could be frequently exposed to NNIs in the environment, and that the cytochrome P450-dependent metabolism of NNIs in the livers of raccoons might be low. Our results contribute to a better understanding of the effects of NNIs on raccoons, leading to better conservation efforts for wild mammals. Environ Toxicol Chem 2022;41:1865-1874. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Glutathione S-transferase gene polymorphisms in association with susceptibility to lead toxicity in lead- and cadmium-exposed children near an abandoned lead-zinc mining area in Kabwe, Zambia.

Interindividual genetic variations determine human's susceptibility to heavy metal-induced toxicity. Thus, we analyzed blood concentrations of lead (Pb) and cadmium (Cd) in 140 lead-exposed children. Genotyping of the glutathione S-transferase (GST) genes, GSTM1, GSTT1, and GSTP1 genes, was carried out to investigate their possible association with heavy metal concentrations and the risk of susceptibility to Pb toxicity. Exposure to both heavy metals was prevalent among the children. The blood Pb level ranged from 3.30 to 74.0 µg dL-1 with an average value of 26.8 µg dL-1 that is five times above its reference level. The average Cd level (0.22 µg L-1) was below its reference level. The metal-gene interaction showed positive correlation between GSTT1 null genotype and Pb and Cd levels (ß = 0.11; p = 0.02 and ß = 0.10; p = 0.01, respectively). More pronounced effects (ß = 0.19; p < 0.01 and ß = 0.25; p = 0.04) were found for the mixture of the three putative genes with blood Pb concentration. The susceptibility analysis using 10 µg dL-1 as blood Pb cutoff level showed a high risk of Pb toxicity (OR = 2.54; 95% CI: 1.02-6.32, p = 0.04) for children carrying the GSTP1 Ile/Val genotype. Further, the combined effect of GSTP1 Ile/Val with GSTT1 null genotype was more pronounced and showed an increased risk of susceptibility to Pb toxicity (OR = 11.7; 95% CI: 1.36-102.1, p = 0.02). In summary, this study suggests that GSTT1 null and GSTP1 Ile/Val genotypes are the main genetic factors, and individual and specific combinations of GSTP1 Ile/Val with GSTM1 and GSTT1 GST polymorphisms are associated with susceptibility to Pb toxicity.

Effects of zinc on tissue uptake and toxicity of lead in Sprague Dawley rat.

Lead (Pb) exposure occurs together with other metals including zinc (Zn). This study investigated the impact of Zn on Pb tissue accumulation and Pb-induced toxicities. Animals (n=6 rats per group) were exposed to lead acetate (PbAc) or a combination of PbAc and zinc acetate (ZnAc) under the following groups: control (deionized water), low PbAc [12 mg/kg PbAc (3 mg PbAc/rat/day)], low PbAc-ZnAc [12 mg/kg PbAc (3 mg PbAc/rat/day) + 0.2 mg ZnAc/rat/48 hr], high PbAc [120 mg/kg (30 mg PbAc/rat/day)], and high PbAc-ZnAc [120 mg/kg (30 mg PbAc/rat/day) + 1 mg ZnAc/rat/48 hr] for 8 weeks. A significant reduction in body weight gain was observed in the high PbAc group relative to the control group. Muscles and testes both had reduced and increased Pb uptake in low PbAc-ZnAc and high PbAc-ZnAc groups compared to PbAc only groups, respectively. Bone Pb levels in the high PbAc-ZnAc group were lower than the high PbAc group. Zinc co-administration attenuated Pb-induced inhibition of delta aminolaevulinic acid dehydratase enzyme and enhanced catalase enzyme activity at a high level of exposure. Moreover, ZnAc seems to have minimized the effects of Pb-induced mRNA dysregulation in antioxidant and antiapoptotic enzymes encoding genes. Heme oxygenase-1 was downregulated in the kidney and brain in the low PbAc group. Liver glutathione peroxidase and thioredoxin reductase-1 were downregulated in the high PbAc group. These findings suggest that zinc co-administration with lead may partially mitigate against Pb-induced toxicities.

Bioaccumulation of DDT and other organochlorine pesticides in amphibians from two conservation areas within malaria risk regions of South Africa.

The threat to wildlife from chemical exposure exists regardless of the presence of conservation boundaries. An issue exacerbated by the use of environmentally persistent insecticides for vector control and long-range transport of legacy persistent organic pollutants. In this comparative study between two important conservation regions in South Africa, Kruger National Park (KNP) and Ndumo Game Reserve (NGR), we assessed organochlorine pesticide (OCP) accumulation in several anuran species collected from within the conservation regions. The two conservation regions differ in size and subsequent proximity of collection sites to OCP input sources. Detectable concentrations of OCPs were present in ∼ half the frogs analysed from KNP and ∼all frogs from NGR and total OCP loads were similar between regions, where measured in the same species. The OCP profiles in KNP frogs were representative of legacy pesticides likely introduced via long-range transport, whereas NGR profiles showed influence of current use of DDT consistent with close proximity to sources. This indicates amphibians can accumulate OCPs within conservation regions and that the exposure of non-target organisms inside conservation regions to current use pesticides has a strong association with proximity to sources. These results serve to inform conservation management decision making with regard to the non-target organism effects of chemical interventions such as vector control pesticide use in and around conservation regions.

Assessment of LeadCare® II analysis for testing of a wide range of blood lead levels in comparison with ICP-MS analysis.

The LeadCare® testing system, which utilizes anodic stripping voltammetry (ASV) methodology, has been widely used worldwide for cost-effective blood lead level (BLL) screening. However, some concerns have recently been issued regarding inaccurate results obtained using LeadCare®. Hence, we aimed to evaluate the accuracy of BLL measured by LeadCare® II (BLLLC) by comparison with ICP-MS (BLLIM) by the Passing-Bablok regression, Deming regression, and Bland-Altman analyses by using 994 venous blood samples. BLLLC ranged from 3.3 to 162.3 µg/dL, while BLLIM ranged from 0.8 to 154.8 µg/dL. Although BLLLC and BLLIM exhibited a strong and positive correlation, BLLLC values were generally greater than BLLIM values, indicative of the overestimation of the LeadCare® analysis. A large positive bias of 19.15 ± 8.26 µg/dL and 29.25 ± 14.04 µg/dL for BLLLC compared with BLLIM were recorded in the BLLLC range of 45.0-64.9 µg/dL and for ≥65.0 µg/dL, respectively. In contrast, a bias of ≤0.3 µg/dL was observed at a BLLLC of less than 10.0 µg/dL. Blood copper, cadmium, and iron levels did not exhibit an effect on the bias of BLLLC, indicative of the minimal potential interferences of the metals; these interferences are a cause for concern with the ASV method. In conclusion, LeadCare® analysis is thought to be a good tool for screening purposes at a lower BLL around the reference level of 5 µg/dL in the initial stage; however, conversion or retesting using a laboratory analyzer is recommended at a higher BLL for appropriate clinical evaluation and research.

Clinical biochemical parameters associated with the exposure to multiple environmental metals in residents from Kabwe, Zambia.

Lead (Pb) interferes with various bodily functions. Although high blood Pb (Pb-B) levels in residents from Kabwe, Zambia have been reported, the accumulation pattern of other metals remains unknown. The study was designed to determine the Pb-B, blood cadmium (Cd-B), and zinc (Zn-B) values of 504 representative samples from Kabwe, as well as the potential associated adverse health effects. The Pb-B level ranged from 0.79 to 154.75 µg/dL and generally increased in areas near the mine. A significant elevation of Cd-B was observed in two areas (0.37 ± 0.26 and 0.32 ± 0.30 µg/L) where the two highest mean Pb-B levels were recorded. By contrast, the Zn-B values did not differ greatly with respect to area. Some blood biochemical parameters relating to hepatic and renal functions were out of the normal range in approximately 20-50% of studied adult participants. The δ-aminolevulinic acid dehydratase (δ-ALAD) activity was significantly inhibited in the two areas contaminated by Pb and Cd. A significant negative relationship was observed between metal levels and clinical parameters, e.g., between Pb-B and δ-ALAD for all the age categories and between Cd-B and the estimated glomerular filtration rate for all the age categories except 0-4 years. The elevated Cd-B in areas near the mine relative to the other areas suggested the potential adverse health effects of Cd and/or the interaction of Pb and Cd. A significant association of metal levels with clinical parameters also indicated the effects of metal exposure on hematopoietic, hepatic, and renal systems.

Dichlorodiphenyltrichloroethane (DDT) levels in rat livers collected from a malaria vector control region.

Dichlorodiphenyltrichloroethane (DDT) is an organochlorine insecticide that has been used for indoor residual spraying for the control of mosquito-borne diseases including malaria. However, due to its toxicity and environmental persistence, there are concerns about its potential deleterious effects in humans and wildlife. Therefore, the current study aimed to monitor and estimate the level of DDTs in human communities. The accumulation of DDT and its metabolites was evaluated in house rat (as sentinel) livers collected in an area where DDT was sprayed. DDTs were measured using a gas chromatography / Electron Capture Detector. The results revealed high concentrations of DDTs in the rat livers and the levels of DDTs were similar to findings reported from the same area in 2014.

Linking organochlorine exposure to biomarker response patterns in Anurans: a case study of Müller's clawed frog (Xenopus muelleri) from a tropical malaria vector control region.

Organochlorine pesticides are highly persistent in aquatic ecosystems. Amphibians, specifically anurans, play an intricate part in the aquatic food web, and have very permeable skin which makes them prone to bioaccumulation of persistent pollutants. In this study the bioaccumulation of various legacy organochlorine pesticides (OCPs)-including dichlorodiphenyltrichloroethane (DDT), currently used for malaria vector control (MVC)-was assessed along with a set of biomarker responses in Müller's clawed frog Xenopus muelleri collected from the lower Phongolo River floodplain in South Africa. Possible relationships between bioaccumulation and biomarkers (of exposure, oxidative stress biomarkers, and cellular energy allocation) alongside their temporal changes were investigated. The OCP concentrations showed a significant increase over time for the duration of the study. The increase correlated negatively with rainfall from the region. DDT levels were well below expected effects levels with p,p-DDE being the main contributing metabolite. The results of this study indicate OCPs actively accumulate at sub-lethal levels in aquatic frogs from the study area, while showing possible relations towards some of the biochemical stress responses measured. Most notable were negative relationships indicated between p,p-DDE and acetylcholinesterase, malondialdehyde, and carbohydrates and protein energy availability. Levels of DDT were not found to be significantly higher than other legacy pesticides in the frog tissue, although evidence of newly introduced DDT in the frog tissue was found. Further investigation about sub-lethal effects of these pesticides on anurans is required to gain better insight into their full impact on animal livelihood.

Assessment of DDT contamination in house rat as a possible bioindicator in DDT-sprayed areas from Ethiopia and South Africa.

Ethiopia and South Africa are among the few countries to still implement indoor residual spraying with dichloro-diphenyl-trichloroethane (DDT) for malaria vector control. In this study, we investigated the levels and ecological risks of DDT and its metabolites in liver tissues of house rat, as a sentinel animal, for providing an early warning system for public health and wildlife intervention from Ethiopia and South Africa. The results showed that ΣDDT concentration ranged from 127 to 9155 µg/kg wet weight, and the distribution order of DDT and its metabolites in the analyzed liver samples was p,p'-DDD > p,p'-DDE >> p,p'-DDT, o,p'-DDT, and o,p'-DDD. The risk assessment indicated a potential adverse impact on humans, especially for pregnant women and children, because they spend majority of their time in a DDT-sprayed house. The ecological assessment also showed a concern for birds of prey and amphibians like frogs. This study is the first report on DDT contamination in liver tissues of house rats from Ethiopia and South Africa, and henceforth, the data will serve as a reference data for future studies.

Contamination status and accumulation characteristics of heavy metals and arsenic in five seabird species from the central Bering Sea.

Seabirds are marine top predators and accumulate high levels of metals and metalloids in their tissues. Contamination by metals in the highly productive offshore region has become a matter of public concern. It is home to 80% of the seabird population in the U.S.A., 95% of northern fur seals (Callorhinus ursinus), and major populations of Steller sea lions (Eumetopias jubatus), walruses (Odobenus rosmarus) and whales. Here, the concentrations of eight heavy metals (Hg, Cd, Cr, Co, Ni, Cu, Zn and Pb) and a metalloid (As) in the liver and kidneys of the northern fulmar (Fulmarus glacialis), thick-billed murre (Uria lomvia), short-tailed shearwater (Puffinus tenuirostris), tufted puffin (Fratercula cirrhata) and horned puffin (Fratercula corniculata) collected in the Bering Sea were measured. As proxies of trophic level and habitat, nitrogen (δ15N) and carbon (δ13C) stable isotope ratios of breast muscles were also measured. Hepatic Hg concentration was high in northern fulmar, whereas Cd level was high in tufted puffin and northern fulmar. The Hg concentration and δ15N value were positively correlated across individual birds, suggesting that Hg uptake was linked to the trophic status of consumed prey. Furthermore, Hg concentration in our study was higher than those of the same species of seabirds collected in 1990.

Contamination Levels and Sources of Heavy Metals and a Metalloid in Surface Soils in the Kumasi Metropolis, Ghana.

BACKGROUND: Environmental contamination with heavy metals and metalloids due to industrial, smelting and mining activities have become common in large and growing cities. Kumasi is one of the most industrialized cities in Ghana and experiences metal pollution due to recent and past activities. Although metals are naturally abundant in the area, their accumulation in soils could potentially lead to adverse effects on local ecosystems. OBJECTIVES: The aims of this study were to determine the distribution, enrichment, geoaccumulation and sources of metals in Kumasi soils and to estimate the contamination factor (CF) and pollution load index (PLI) of these metals in soils. METHODS: Concentrations of eight heavy metals and a metalloid were determined in 112 soil samples randomly collected from 31 sampling sites in the area. In addition, 5 soil samples were collected from a pristine site (Kwame Nkrumah University of Science and Technology Botanical Gardens) for data comparison, to determine the local background values for metal concentrations and to evaluate the extent of metal pollution in the study area. RESULTS: Heavy metals such as zinc (Zn), lead (Pb), cadmium (Cd) and chromium (Cr) were enriched in 65, 32, 58 and 93% of the sampling sites, respectively, and geo-accumulation indexes for Cr, Zn, Cd, mercury (Hg) and Pb showed moderate to extreme contamination in 100, 97, 77, 65 and 45% of the sampling sites, respectively. Principal component and cluster analyses revealed that industrial activities including mining were the major sources of metals in Kumasi soils with high metal input in the community of Suame. Distribution maps revealed hotspots of Cd, nickel (Ni), arsenic (As), cobalt (Co), copper (Cu) and Pb in Suame. The highest CFs for Cu, Cd, Ni, As, Co and Pb highlighted anthropogenic inputs in Suame, while Hg was highest in Mbrom, Zn in Suntreso, and Cr in Aboabo. CONCLUSIONS: The PLI of metals revealed Suame as the most polluted study site, while Anomangye and Bomso were the least polluted.