The Phongolo River Floodplain (PRF) is South Africa's largest floodplain, unique in being the... more The Phongolo River Floodplain (PRF) is South Africa's largest floodplain, unique in being the only large floodplain able to sustain permanent waters throughout the dry season (Kyle, 2002). This highly productive region contains around 90 floodplain associated pans which are rich in biodiversity and is known to be of high ecological and socio-economic importance (Dube et al., 2017). The floodplain is surrounded by informal settlements and rural communities which are reliant on these aquatic resources, not only for domestic use or agricultural purposes such as watering livestock and subsistence farming, but also for subsistence fisheries as a source of protein (Coetzee et al., 2015). A recent study by Coetzee et al. (2015) indicated that several fish species in the study area are important sources of protein within artisanal fishery practices. Contamination due to the introduction of pesticides into aquatic ecosystems is of great concern, as many banned (World Health Organisation (WHO, 2002)) organochlorine pesticides (OCPs) are persistent in the environment and this is reflected by the fact that although many OCPs are no longer used, they still remain present in many, if not all aquatic ecosystems (Gerber et al., 2016). Implementation of effective long term management plans rely directly on fully understanding chemical compounds as well as their risks to both ecosystems and humans, where these aspects can be assessed using; (1) stable isotopes and trophic magnification factors (TMF's) and (2) human health risk assessments via exposure through consumption (Verhaert et al., 2013, Verhaert et al., 2017)
Dichlorodiphenyltrichloroethane (DDT) is an organochlorine insecticide used worldwide. Several st... more 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.
Teuri Island, Hokkaido in Japan is an important place for seabirds breeding. We measured the conc... more Teuri Island, Hokkaido in Japan is an important place for seabirds breeding. We measured the concentrations of heavy metals (Hg, Cd, Cr, Co, Ni, Cu, Zn, and Pb) and a metalloid (As) in rhinoceros auklet (Cerorhinca monocerata) (n = 7), thick-billed murre (Uria lomvia) (n = 2), spectacled guillemot (Cepphus carbo) (n = 6), slaty-backed gull (Larus schistisagus) (n = 15), jungle crow (Corvus macrorhynchos) (n = 3), Japanese anchovy (Engraulis japonica) (n = 6) and Atka mackerel (Pleurogrammus azonus) (n = 2). Spectacled guillemot had high As concentrations, with its source being their feeding habitat. Concentration of Hg in kidney of jungle crow was higher than other seabird species at Teuri.
Bulletin of Environmental Contamination and Toxicology, Mar 15, 2018
Many countries with incidence of malaria, including those surrounding Maputo bay, use DDT to redu... more Many countries with incidence of malaria, including those surrounding Maputo bay, use DDT to reduce mosquitoes. This study is the first to estimate the human health risk associated with consumption of marine fish from Maputo Bay contaminated with DDTs. The median for ∑DDTs was 3.8 ng/g ww (maximum 280.9 ng/g ww). The overall hazard ratio (HR) for samples was 1.5 at the 75 th percentile concentration and 28.2 at the 95 th percentile. These calculations show increased potential cancer risks due to contamination by DDTs, data which will help policy makers perform a risk-benefit analysis of DDT use in malaria control programs in the region.
It is reported that seabirds accumulate high levels of metals, prompting concerns regarding poiso... more It is reported that seabirds accumulate high levels of metals, prompting concerns regarding poisoning. The present study investigated the accumulation patterns of metals in tissues among four species of seabirds (Fratercula corniculata, Uria lomvia, Puffinus tenuirostris, and Fulmarus glacialis). Furthermore, we focused on Slaty-backed Gulls, which accumulated high levels of cadmium and mercury, and compared the areal differences. Geographic variation of metal levels could also contribute to differences in metal accumulation levels in these bird species. Therefore, the concentrations of metals in seabirds are considered to reflect their habitat. There are differences in the accumulation pattern among the seabird species. The high accumulation of metals could affect seabirds even if they do not show any symptoms.
Lead (Pb) exposure occurs together with other metals including zinc (Zn). This study investigated... more 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.
Bulletin of Environmental Contamination and Toxicology, Dec 29, 2016
Concentrations of 10 trace elements (Hg, As, Cd, Pb, Co, Cr, Cu, Ni, Se and Zn) were determined i... more Concentrations of 10 trace elements (Hg, As, Cd, Pb, Co, Cr, Cu, Ni, Se and Zn) were determined in different tissues (liver, kidney, muscle, heart and brain) of African sacred ibis (Threskiornis aethiopicus), Hamerkop (Scopus umbretta), marabou stork (Leptoptilos crumeniferus) and great white pelican (Pelecanus onocrotalus) inhabiting the Ethiopian Rift Valley region. There were differences in trace element patterns among the bird species. Significantly (p < 0.05) higher concentrations of Cd (5.53 µg/g dw ± 2.94) in kidney and Hg (0.75 µg/g ww ± 0.30) in liver were observed in the great white pelican compared to the other species, and liver concentrations of these two elements showed positive correlations with trophic level. Concentrations of toxic elements (As, Cd, Pb and Hg) in liver were below their respective toxicological thresholds, indicating that the data may provide baseline information for future studies.
Abstract The current study aimed to validate the possible ameliorative effects of Spirulina (Arth... more Abstract The current study aimed to validate the possible ameliorative effects of Spirulina (Arthrospira platensis) on lead poisoning and obesity using C57BL/6J mice. After a treatment period, we performed metal analyses, as well as hematocrit and plasma biochemical parameter measurements, and assayed oxidative stress markers and erythrocyte δ-aminolevulinic acid dehydratase (ALAD) activity. Our results highlighted the effectiveness of Spirulina in improving anemia status with the normalization of hematocrit levels and ALAD activity ratios, even in mice that exhibited obesity in addition to lead poisoning. Spirulina treatment also decreased epididymal white adipose tissue weight and increased plasma high-density lipoprotein levels, which are normally reduced after lead exposure. However, most of the studied plasma biochemical parameters and oxidative stress markers did not show large changes after treatment, likely because of the short duration of treatment. Further studies with longer-term exposures are required to validate the usefulness of Spirulina suggested in the present study.
Comparative Biochemistry and Physiology C-toxicology & Pharmacology, Feb 1, 2020
Worldwide use of anticoagulant rodenticides (ARs) for rodents control has frequently led to secon... more Worldwide use of anticoagulant rodenticides (ARs) for rodents control has frequently led to secondary poisoning of non-target animals, especially raptors. In order to suggest some factors that may help considering the mechanism of the incidents, this study focused on the avian vitamin K 2, 3-epoxide reductase (VKOR) that is the target protein of ARs. We addressed the interspecific differences in VKOR activity and inhibition related to amino acid sequence and mRNA expression of VKORC1 and VKORC1-like1 (VKORC1L1). Poultry have been considered to be more tolerant to ARs than mammals. However, VKOR activity of owls, hawks, falcon and surprisingly, canaries, was lower and inhibited by warfarin more easily than that of chickens and turkeys. The amino acid sequence of VKORC1 and VKORC1L1 implied that the value of Ki for VKOR activity to ARs could depend on the amino acid at position 140 in the TYX warfarin-binding motif in VKORC1, and other amino acid mutations in VKORC1L1. The mRNA expression ratio of VKORC1:VKORC1L1 differed between turkey (8:1) and chicken (2:3) liver. VKORC1L1 has been reported to be resistant to warfarin compared to VKORC1. Hence, both the Ki of specific VKORC1 and VKORC1L1, and the mRNA expression ratio would cause avian interspecific difference of the VKOR inhibition. Our study also suggested the high inhibition of VKOR activities in raptors and surprisingly that in canaries as well.
Environmental Science and Pollution Research, Sep 1, 2017
Ethiopia and South Africa are among the few countries to still implement indoor residual spraying... more Ethiopia and South Africa are among the few countries to still implement indoor residual spraying with dichlorodiphenyl-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 DDTsprayed 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.
Background. Environmental contamination with heavy metals and metalloids due to industrial, smelt... more 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.
Indoor residual spraying and indiscriminate pesticide usage underlines relevance of this study. •... more Indoor residual spraying and indiscriminate pesticide usage underlines relevance of this study. • 22 OCPs in different tissues of 4 bird species were monitored. • List ParagraphPotential ecological risk to birds associated with exposure to p,p'-DDE. • Further ecotoxicological study using a wide range of species and sample size is necessary.
Food Additives & Contaminants: Part A, Sep 20, 2017
Organochlorine pesticides such as dichlorodiphenyltrichloroethane (DDT) have been used in agricul... more Organochlorine pesticides such as dichlorodiphenyltrichloroethane (DDT) have been used in agriculture and for disease control purposes over many decades. Reports suggest that DDT exposure may result in a number of adverse effects in humans. In the KwaZulu-Natal Province of South Africa, DDT is sprayed annually in homes (indoor residual spraying) to control the mosquito vector of malaria. In the northern part of the Province, samples of free-range chicken meat (n = 48) and eggs (n = 13), and commercially-produced chicken meat (n = 6) and eggs (n = 11) were collected and analysed. Of the free-range chicken meat samples, 94% (45/48) contained DDTs (ΣDDTs median 6.1 ng/g ww, maximum 79.1 ng/g ww). Chicken egg contents were also contaminated (ΣDDTs in freerange eggs median 9,544 ng/g ww, maximum 96,666 ng/g ww; and in commercial eggs median 1.3 ng/g ww, maximum 4.6 ng/g ww). The predominant DDT congener detected was p,p'-DDE in both free-range meat (> 63%) and eggs (> 66%), followed by p,p'-DDT and then p,p'-DDD. Based on estimated daily intake values, calculated human risk ratios (carcinogenic) values were >1 for DDTs detected in both free-range chicken products. Consumption of free-range eggs poses a particularly high health risk.
High burden of DDTs due to its use in agriculture and public health may cause toxic effects (i.e.... more High burden of DDTs due to its use in agriculture and public health may cause toxic effects (i.e., eggshell thinning and survival of young birds) to Ethiopian bird species.
Environmental Science and Pollution Research, Aug 23, 2015
The physical and chemical characteristics of surface sediments from a leading conservation area, ... more The physical and chemical characteristics of surface sediments from a leading conservation area, namely the Kruger National Park, were determined in order to identify potential stressors in the systems that may contribute to overall deterioration in sediment quality within the reserve, leading to potential threats to the aquatic biota conserved within these stretches of river. Sediment samples were collected during four surveys (two low flow and two high flow) from 2009 to 2011. Samples were analysed for organic content, grain size determination, metals and various organochlorine pesticides. Results indicated that the Olifants River sediments did not show any great improvement over the years and point towards the continued input of pollutants into this system. Sediment quality in the Luvuvhu and Letaba Rivers is better than that of sediments from the Olifants River in terms of metals, but metal concentrations are still comparable and point towards anthropogenic inputs of metals into these rivers. Even though the data indicate that these systems are being contaminated with both metals and organochlorine pesticides (OCPs), levels were still below contaminated sediments from around the globe. Sediment Quality Index scores showed that the sediment quality of these rivers is in a relatively good state. High metal concentrations were the drivers behind lowered sediment quality, and in some cases certain OCPs played a role. Both metals and OCP concentrations were highly correlated with finer grain sizes. Sediment assessments are not routinely applied in South Africa resulting in very little reference or background data available for the area. The metal concentrations for the study area were generally lower than those for other studies in more polluted regions. The study also contributes to the available knowledge on surrounding metal pollution in riverine sediments in South Africa.
The Phongolo River Floodplain (PRF) is South Africa's largest floodplain, unique in being the... more The Phongolo River Floodplain (PRF) is South Africa's largest floodplain, unique in being the only large floodplain able to sustain permanent waters throughout the dry season (Kyle, 2002). This highly productive region contains around 90 floodplain associated pans which are rich in biodiversity and is known to be of high ecological and socio-economic importance (Dube et al., 2017). The floodplain is surrounded by informal settlements and rural communities which are reliant on these aquatic resources, not only for domestic use or agricultural purposes such as watering livestock and subsistence farming, but also for subsistence fisheries as a source of protein (Coetzee et al., 2015). A recent study by Coetzee et al. (2015) indicated that several fish species in the study area are important sources of protein within artisanal fishery practices. Contamination due to the introduction of pesticides into aquatic ecosystems is of great concern, as many banned (World Health Organisation (WHO, 2002)) organochlorine pesticides (OCPs) are persistent in the environment and this is reflected by the fact that although many OCPs are no longer used, they still remain present in many, if not all aquatic ecosystems (Gerber et al., 2016). Implementation of effective long term management plans rely directly on fully understanding chemical compounds as well as their risks to both ecosystems and humans, where these aspects can be assessed using; (1) stable isotopes and trophic magnification factors (TMF's) and (2) human health risk assessments via exposure through consumption (Verhaert et al., 2013, Verhaert et al., 2017)
Dichlorodiphenyltrichloroethane (DDT) is an organochlorine insecticide used worldwide. Several st... more 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.
Teuri Island, Hokkaido in Japan is an important place for seabirds breeding. We measured the conc... more Teuri Island, Hokkaido in Japan is an important place for seabirds breeding. We measured the concentrations of heavy metals (Hg, Cd, Cr, Co, Ni, Cu, Zn, and Pb) and a metalloid (As) in rhinoceros auklet (Cerorhinca monocerata) (n = 7), thick-billed murre (Uria lomvia) (n = 2), spectacled guillemot (Cepphus carbo) (n = 6), slaty-backed gull (Larus schistisagus) (n = 15), jungle crow (Corvus macrorhynchos) (n = 3), Japanese anchovy (Engraulis japonica) (n = 6) and Atka mackerel (Pleurogrammus azonus) (n = 2). Spectacled guillemot had high As concentrations, with its source being their feeding habitat. Concentration of Hg in kidney of jungle crow was higher than other seabird species at Teuri.
Bulletin of Environmental Contamination and Toxicology, Mar 15, 2018
Many countries with incidence of malaria, including those surrounding Maputo bay, use DDT to redu... more Many countries with incidence of malaria, including those surrounding Maputo bay, use DDT to reduce mosquitoes. This study is the first to estimate the human health risk associated with consumption of marine fish from Maputo Bay contaminated with DDTs. The median for ∑DDTs was 3.8 ng/g ww (maximum 280.9 ng/g ww). The overall hazard ratio (HR) for samples was 1.5 at the 75 th percentile concentration and 28.2 at the 95 th percentile. These calculations show increased potential cancer risks due to contamination by DDTs, data which will help policy makers perform a risk-benefit analysis of DDT use in malaria control programs in the region.
It is reported that seabirds accumulate high levels of metals, prompting concerns regarding poiso... more It is reported that seabirds accumulate high levels of metals, prompting concerns regarding poisoning. The present study investigated the accumulation patterns of metals in tissues among four species of seabirds (Fratercula corniculata, Uria lomvia, Puffinus tenuirostris, and Fulmarus glacialis). Furthermore, we focused on Slaty-backed Gulls, which accumulated high levels of cadmium and mercury, and compared the areal differences. Geographic variation of metal levels could also contribute to differences in metal accumulation levels in these bird species. Therefore, the concentrations of metals in seabirds are considered to reflect their habitat. There are differences in the accumulation pattern among the seabird species. The high accumulation of metals could affect seabirds even if they do not show any symptoms.
Lead (Pb) exposure occurs together with other metals including zinc (Zn). This study investigated... more 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.
Bulletin of Environmental Contamination and Toxicology, Dec 29, 2016
Concentrations of 10 trace elements (Hg, As, Cd, Pb, Co, Cr, Cu, Ni, Se and Zn) were determined i... more Concentrations of 10 trace elements (Hg, As, Cd, Pb, Co, Cr, Cu, Ni, Se and Zn) were determined in different tissues (liver, kidney, muscle, heart and brain) of African sacred ibis (Threskiornis aethiopicus), Hamerkop (Scopus umbretta), marabou stork (Leptoptilos crumeniferus) and great white pelican (Pelecanus onocrotalus) inhabiting the Ethiopian Rift Valley region. There were differences in trace element patterns among the bird species. Significantly (p < 0.05) higher concentrations of Cd (5.53 µg/g dw ± 2.94) in kidney and Hg (0.75 µg/g ww ± 0.30) in liver were observed in the great white pelican compared to the other species, and liver concentrations of these two elements showed positive correlations with trophic level. Concentrations of toxic elements (As, Cd, Pb and Hg) in liver were below their respective toxicological thresholds, indicating that the data may provide baseline information for future studies.
Abstract The current study aimed to validate the possible ameliorative effects of Spirulina (Arth... more Abstract The current study aimed to validate the possible ameliorative effects of Spirulina (Arthrospira platensis) on lead poisoning and obesity using C57BL/6J mice. After a treatment period, we performed metal analyses, as well as hematocrit and plasma biochemical parameter measurements, and assayed oxidative stress markers and erythrocyte δ-aminolevulinic acid dehydratase (ALAD) activity. Our results highlighted the effectiveness of Spirulina in improving anemia status with the normalization of hematocrit levels and ALAD activity ratios, even in mice that exhibited obesity in addition to lead poisoning. Spirulina treatment also decreased epididymal white adipose tissue weight and increased plasma high-density lipoprotein levels, which are normally reduced after lead exposure. However, most of the studied plasma biochemical parameters and oxidative stress markers did not show large changes after treatment, likely because of the short duration of treatment. Further studies with longer-term exposures are required to validate the usefulness of Spirulina suggested in the present study.
Comparative Biochemistry and Physiology C-toxicology & Pharmacology, Feb 1, 2020
Worldwide use of anticoagulant rodenticides (ARs) for rodents control has frequently led to secon... more Worldwide use of anticoagulant rodenticides (ARs) for rodents control has frequently led to secondary poisoning of non-target animals, especially raptors. In order to suggest some factors that may help considering the mechanism of the incidents, this study focused on the avian vitamin K 2, 3-epoxide reductase (VKOR) that is the target protein of ARs. We addressed the interspecific differences in VKOR activity and inhibition related to amino acid sequence and mRNA expression of VKORC1 and VKORC1-like1 (VKORC1L1). Poultry have been considered to be more tolerant to ARs than mammals. However, VKOR activity of owls, hawks, falcon and surprisingly, canaries, was lower and inhibited by warfarin more easily than that of chickens and turkeys. The amino acid sequence of VKORC1 and VKORC1L1 implied that the value of Ki for VKOR activity to ARs could depend on the amino acid at position 140 in the TYX warfarin-binding motif in VKORC1, and other amino acid mutations in VKORC1L1. The mRNA expression ratio of VKORC1:VKORC1L1 differed between turkey (8:1) and chicken (2:3) liver. VKORC1L1 has been reported to be resistant to warfarin compared to VKORC1. Hence, both the Ki of specific VKORC1 and VKORC1L1, and the mRNA expression ratio would cause avian interspecific difference of the VKOR inhibition. Our study also suggested the high inhibition of VKOR activities in raptors and surprisingly that in canaries as well.
Environmental Science and Pollution Research, Sep 1, 2017
Ethiopia and South Africa are among the few countries to still implement indoor residual spraying... more Ethiopia and South Africa are among the few countries to still implement indoor residual spraying with dichlorodiphenyl-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 DDTsprayed 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.
Background. Environmental contamination with heavy metals and metalloids due to industrial, smelt... more 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.
Indoor residual spraying and indiscriminate pesticide usage underlines relevance of this study. •... more Indoor residual spraying and indiscriminate pesticide usage underlines relevance of this study. • 22 OCPs in different tissues of 4 bird species were monitored. • List ParagraphPotential ecological risk to birds associated with exposure to p,p'-DDE. • Further ecotoxicological study using a wide range of species and sample size is necessary.
Food Additives & Contaminants: Part A, Sep 20, 2017
Organochlorine pesticides such as dichlorodiphenyltrichloroethane (DDT) have been used in agricul... more Organochlorine pesticides such as dichlorodiphenyltrichloroethane (DDT) have been used in agriculture and for disease control purposes over many decades. Reports suggest that DDT exposure may result in a number of adverse effects in humans. In the KwaZulu-Natal Province of South Africa, DDT is sprayed annually in homes (indoor residual spraying) to control the mosquito vector of malaria. In the northern part of the Province, samples of free-range chicken meat (n = 48) and eggs (n = 13), and commercially-produced chicken meat (n = 6) and eggs (n = 11) were collected and analysed. Of the free-range chicken meat samples, 94% (45/48) contained DDTs (ΣDDTs median 6.1 ng/g ww, maximum 79.1 ng/g ww). Chicken egg contents were also contaminated (ΣDDTs in freerange eggs median 9,544 ng/g ww, maximum 96,666 ng/g ww; and in commercial eggs median 1.3 ng/g ww, maximum 4.6 ng/g ww). The predominant DDT congener detected was p,p'-DDE in both free-range meat (> 63%) and eggs (> 66%), followed by p,p'-DDT and then p,p'-DDD. Based on estimated daily intake values, calculated human risk ratios (carcinogenic) values were >1 for DDTs detected in both free-range chicken products. Consumption of free-range eggs poses a particularly high health risk.
High burden of DDTs due to its use in agriculture and public health may cause toxic effects (i.e.... more High burden of DDTs due to its use in agriculture and public health may cause toxic effects (i.e., eggshell thinning and survival of young birds) to Ethiopian bird species.
Environmental Science and Pollution Research, Aug 23, 2015
The physical and chemical characteristics of surface sediments from a leading conservation area, ... more The physical and chemical characteristics of surface sediments from a leading conservation area, namely the Kruger National Park, were determined in order to identify potential stressors in the systems that may contribute to overall deterioration in sediment quality within the reserve, leading to potential threats to the aquatic biota conserved within these stretches of river. Sediment samples were collected during four surveys (two low flow and two high flow) from 2009 to 2011. Samples were analysed for organic content, grain size determination, metals and various organochlorine pesticides. Results indicated that the Olifants River sediments did not show any great improvement over the years and point towards the continued input of pollutants into this system. Sediment quality in the Luvuvhu and Letaba Rivers is better than that of sediments from the Olifants River in terms of metals, but metal concentrations are still comparable and point towards anthropogenic inputs of metals into these rivers. Even though the data indicate that these systems are being contaminated with both metals and organochlorine pesticides (OCPs), levels were still below contaminated sediments from around the globe. Sediment Quality Index scores showed that the sediment quality of these rivers is in a relatively good state. High metal concentrations were the drivers behind lowered sediment quality, and in some cases certain OCPs played a role. Both metals and OCP concentrations were highly correlated with finer grain sizes. Sediment assessments are not routinely applied in South Africa resulting in very little reference or background data available for the area. The metal concentrations for the study area were generally lower than those for other studies in more polluted regions. The study also contributes to the available knowledge on surrounding metal pollution in riverine sediments in South Africa.
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