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1.
Artigo em Inglês | MEDLINE | ID: mdl-33477475

RESUMO

Lead (Pb) is a metal toxicant of great public health concern. The present study investigated the applicability of the rat incisor in Pb exposure screening. The levels of lead in teeth (Pb-T) in the crown and root of incisors in laboratory Pb-exposed Sprague Dawley rats were quantified using inductively coupled plasma mass spectrometry (ICP-MS). The crown accumulated much Pb-T than the root of the Sprague Dawley rat incisor. The levels of lead in blood (Pb-B) were positively correlated with the Pb-T in the crown and root incisors of the Sprague Dawley rats. As an application of the Pb-T crown results in experimental rats, we subsequently analyzed the Pb-T in the crown incisors of Pb-exposed wild rats (Rattus rattus) sampled from residential sites within varying distances from an abandoned lead-zinc mine. The Pb-T accumulation in the crown of incisors of R. rattus rats decreased with increased distance away from the Pb-Zn mine. Furthermore, the Pb-T was strongly correlated (r = 0.85) with the Pb levels in the blood. Laser ablation ICP-MS Pb-T mappings revealed a homogenous distribution of Pb in the incisor with an increased intensity of Pb-T localized in the tip of the incisor crown bearing an enamel surface in both Sprague Dawley and R. rattus rats. These findings suggest that Pb-T in the crown incisor may be reflective of the rat's environmental habitat, thus a possible indicator of Pb exposure.

2.
Chemosphere ; 262: 127788, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33182082

RESUMO

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.


Assuntos
Exposição Ambiental/análise , Poluentes Ambientais/análise , Metais/análise , Adulto , Cádmio/análise , Coleta de Dados , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos , Exposição Ambiental/estatística & dados numéricos , Monitoramento Ambiental/métodos , Taxa de Filtração Glomerular , Humanos , Fígado/química , Registros , Valores de Referência , Adulto Jovem , Zâmbia , Zinco
3.
Aquat Toxicol ; 227: 105607, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32861022

RESUMO

The ubiquitous contamination of environmental lead (Pb) remains a worldwide threat. Improper Pb mine waste disposal from an abandoned lead-zinc mine has recently unearthed widespread Pb poisoning in children in Kabwe Zambia. Although the adverse effects of Pb on human health have begun to receive attention, the ecotoxicological effects on aquatic vertebrates still need further investigation. In addition, there is paucity in the knowledge on the behavioural and molecular subcellular responses in larval zebrafish exposed to Pb within the range of environmental relevant concentration (average 3 µg/L with maximum of 94 µg/L) on aquatic organisms such as zebrafish. The adverse effects of environmentally relevant levels of Pb on larval zebrafish was evaluated by measuring swimming behaviour under alternating dark and light conditions. Larval zebrafish acutely exposed to environmentally relevant Pb exhibited neuro-behavioural alteration including enhanced hyperactivity under light conditions evidenced by increased distanced covered and speed compared to the control. The alteration of entire behavioral profiles was further associated with the disturbed expression patterns of mRNA level of key genes associated with antioxidant (HO-1, Ucp-2 and CoxI), proapoptotic gene (TP53), and antiapoptotic gene (Bcl-2). To our knowledge, this is the first report on the effects of environmentally relevant Pb levels from Kabwe, Zambia and their adverse neurobehavioural effects and subcellular molecular oxidative responses in larval zebrafish acutely exposed within a 30 min period. The current results would be beneficial in our understanding of the effects of low Pb levels acutely discharged into an aquatic environment and the life of aquatic organisms.


Assuntos
Chumbo/toxicidade , Poluentes Químicos da Água/toxicidade , Peixe-Zebra/fisiologia , Animais , Antioxidantes/metabolismo , Apoptose/efeitos dos fármacos , Humanos , Larva/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Testes de Toxicidade Aguda
4.
Environ Sci Technol ; 54(22): 14474-14481, 2020 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-32490671

RESUMO

We investigated the potential effects of different land use and other environmental factors on animals living in a contaminated environment. The study site in Kabwe, Zambia, is currently undergoing urban expansion, while lead contamination from former mining activities is still prevalent. We focused on a habitat generalist lizards (Trachylepis wahlbergii). The livers, lungs, blood, and stomach contents of 224 lizards were analyzed for their lead, zinc, cadmium, copper, nickel, and arsenic concentrations. Habitat types were categorized based on vegetation data obtained from satellite images. Multiple regression analysis revealed that land use categories of habitats and three other factors significantly affected lead concentrations in the lizards. Further investigation suggested that the lead concentrations in lizards living in bare fields were higher than expected based on the distance from the contaminant source, while those in lizards living in green fields were lower than expected. In addition, the lead concentration of lungs was higher than that of the liver in 19% of the lizards, implying direct exposure to lead via dust inhalation besides digestive exposure. Since vegetation reduces the production of dust from surface soil, it is plausible that dust from the mine is one of the contamination sources and that vegetation can reduce exposure to this.

5.
Environ Res ; 188: 109759, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32554272

RESUMO

BACKGROUND: Lead (Pb) is a well-known toxic heavy metal which can have serious public health hazards. As of today, there is no safe threshold for Pb exposure, especially for children. Lead exposure has been associated with adverse health outcomes involving epigenetic mechanisms, such as aberrant DNA methylation. The objective of the present study was to elucidate the associations between blood lead levels (BLLs) and gene-specific promoter DNA methylation status in environmental Pb-exposed children from Kabwe, Zambia. METHODS: A cross-sectional study was conducted using 2 to 10-year-old children from high Pb exposed area (N = 102) and low Pb exposed area (N = 38). We measured BLLs using a LeadCare II analyzer and investigated the methylation status of the ALAD and p16 gene promoters by methylation-specific PCR. RESULTS: The mean BLLs were 23.7 µg/dL and 7.9 µg/dL in high Pb exposed and low Pb exposed children, respectively. Pb exposure was correlated with increased methylation of the ALAD and p16 genes. The promoter methylation rates of ALAD and p16 in high Pb exposed children were 84.3% and 67.7%, and 42.1% and 44.7% in low Pb exposed children, respectively. Significantly increased methylation was found in both genes in high Pb exposed children compared with low Pb exposed children (p < 0.05). Children with methylated ALAD and p16 genes showed an increased risk of Pb poisoning (odd ratio >1) compared to the unmethylated status. CONCLUSIONS: This study for the first time tries to correlate promoter methylation status of the ALAD and p16 genes in environmental Pb-exposed children from Kabwe, Zambia as a representative. The result suggests that Pb exposure increases aberrations in ALAD and p16 gene methylation, which may be involved in the mechanism of Pb toxicity.


Assuntos
Intoxicação por Chumbo , Chumbo , Criança , Pré-Escolar , Estudos Transversais , Metilação de DNA , Genes p16 , Humanos , Chumbo/toxicidade , Intoxicação por Chumbo/epidemiologia , Intoxicação por Chumbo/genética , Sintase do Porfobilinogênio/genética , Zâmbia
6.
Chemosphere ; 243: 125412, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31995873

RESUMO

Childhood lead (Pb) poisoning has devastating effects on neurodevelopment and causes overt clinical signs including convulsions and coma. Health effects including hypertension and various reproductive problems have been reported in adults. Historical Pb mining in Zambia's Kabwe town left a legacy of environmental pollution and childhood Pb poisoning. The current study aimed at establishing the extent of Pb poisoning and exposure differences among family members in Kabwe as well as determining populations at risk and identify children eligible for chelation therapy. Blood samples were collected in July and August 2017 from 1190 household members and Pb was measured using a portable LeadCare-II analyser. Participants included 291 younger children (3-months to 3-years-old), 271 older children (4-9-years-old), 412 mothers and 216 fathers from 13 townships with diverse levels of Pb contamination. The Blood Lead Levels (BLL) ranged from 1.65 to 162  µg/dL, with residents from Kasanda (mean 45.7  µg/dL) recording the highest BLL while Hamududu residents recorded the lowest (mean 3.3  µg/dL). Of the total number of children sampled (n = 562), 23% exceeded the 45  µg/dL, the threshold required for chelation therapy. A few children (5) exceeded the 100  µg/dL whereas none of the parents exceeded the 100  µg/dL value. Children had higher BLL than parents, with peak BLL-recorded at the age of 2-years-old. Lead exposure differences in Kabwe were attributed to distance and direction from the mine, with younger children at highest risk. Exposure levels in parents were equally alarming. For prompt diagnosis and treatment, a portable point-of-care devise such as a LeadCare-II would be preferable in Kabwe.


Assuntos
Exposição Ambiental/análise , Intoxicação por Chumbo/epidemiologia , Chumbo/sangue , Chumbo/toxicidade , Adulto , Criança , Pré-Escolar , Poluição Ambiental/análise , Pai , Feminino , Humanos , Lactente , Masculino , Mineração , Mães , Registros , Reprodução , Manejo de Espécimes , Zâmbia/epidemiologia
7.
Chemosphere ; 212: 994-1001, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30286556

RESUMO

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.


Assuntos
Aves/metabolismo , Osso e Ossos/efeitos dos fármacos , Osso e Ossos/metabolismo , Chumbo/metabolismo , Chumbo/toxicidade , Espectrometria de Massas , Imagem Molecular , Animais , Carga Corporal (Radioterapia) , Poluentes Ambientais/metabolismo , Poluentes Ambientais/toxicidade
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