Geospatial approach to investigate spatial clustering and hotspots of blood lead levels in children within Kabwe, Zambia.

BACKGROUND: Communities around Kabwe, Zambia are exposed to lead due to deposits from an old lead (Pb) and zinc (Zn) mining site. Children are particularly more vulnerable than adults, presenting with greatest risk of health complications. They have increased oral uptake due to their hand to mouth activities. Spatial analysis of childhood lead exposure is useful in identifying specific areas with highest risk of pollution. The objective of the current study was to use a geospatial approach to investigate spatial clustering and hotspots of blood lead levels in children within Kabwe. METHODS: We analysed existing data on blood lead levels (BLL) for 362 children below the age of 15 from Kabwe town. We used spatial autocorrelation methods involving the global Moran's I and local Getis-Ord Gi*statistic in ArcMap 10.5.1, to test for spatial dependency among the blood lead levels in children using the household geolocations. RESULTS: BLL in children from Kabwe are spatially autocorrelated with a Moran's Index of 0.62 (p < 0.001). We found distinct hotspots (mean 51.9 µg/dL) in communities close to the old lead and zinc-mining site, lying on its western side. Whereas coldspots (mean 7 µg/dL) where observed in areas distant to the mine and traced on the eastern side. This pattern suggests a possible association between observed BLL and distance from the abandoned lead and zinc mine, and prevailing winds. CONCLUSION: Using geocoded data for households, we found clustering of childhood blood lead and identified distinct hotspot areas with high lead levels for Kabwe town. The geospatial approach used is especially valuable in resource-constrained settings like Zambia, where the precise identification of high risk locations allows for the initiation of targeted remedial and treatment programs.

Land Use in Habitats Affects Metal Concentrations in Wild Lizards Around a Former Lead Mining Site.

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.

Blood lead levels and aberrant DNA methylation of the ALAD and p16 gene promoters in children exposed to environmental-lead.

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.

Lead intoxicated children in Kabwe, Zambia.

Kabwe is a lead contaminated mining town in Zambia. Kabwe has extensive lead contaminated soil and children in Kabwe ingest and inhale high quantities of this toxic dust. The aim of this paper is to analyze the health impact of this exposure for children. Health data from three existing studies were re-analyzed. Over 95% of children living in the most affected townships had high blood lead levels (BLLs) > 10µg/dL. Approximately 50% of those children had BLLs ≥ 45µg/dL. The existing data clearly establishes the presence of a severe environmental health crisis in Kabwe which warrants immediate attention.

Metallothionein from Wild Populations of the African Catfish Clarias gariepinus: From Sequence, Protein Expression and Metal Binding Properties to Transcriptional Biomarker of Metal Pollution.

Anthropogenic pollution with heavy metals is an on-going concern throughout the world, and methods to monitor release and impact of heavy metals are of high importance. With a view to probe its suitability as molecular biomarker of metal pollution, this study has determined a coding sequence for metallothionein of the African sharptooth catfish Clarias gariepinus. The gene product was recombinantly expressed in Escherichia coli in presence of Zn(II), Cd(II), or Cu, and characterised by Electrospray Ionisation Mass Spectrometry and elemental analysis. C. gariepinus MT displays typical features of fish MTs, including 20 conserved cysteines, and seven bound divalent cations (Zn(II) or Cd(II)) when saturated. Livers from wild C. gariepinus fish collected in all three seasons from four different sites on the Kafue River of Zambia were analysed for their metal contents and for MT expression levels by quantitative PCR. Significant correlations were found between Zn and Cu levels and MT expression in livers, with MT expression clearly highest at the most polluted site, Chililabombwe, which is situated in the Copperbelt region. Based on our findings, hepatic expression of MT from C. gariepinus may be further developed as a major molecular biomarker of heavy metal pollution resulting from mining activities in this region.

Sediment Metal Contamination in the Kafue River of Zambia and Ecological Risk Assessment.

Zambia's Kafue River receives wastes from various sources, resulting in metal pollution. This study determined the degree of contamination of 13 metals (Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Cd, Hg and Pb) in Kafue River sediment and the associated ecological risks at six sites in three different seasons. The level of contamination for most metals showed significant site and seasonal differences. The contamination factor and pollution load index indicated that concentrations of most metals particularly copper (Cu), cobalt (Co), manganese (Mn) and arsenic (As) were very high at sites within the Copperbelt mining area. The geoaccumulation index showed an absence of anthropogenic enrichment with Cd and Hg at all the study sites and extreme anthropogenic enrichment with Cu at sites in the Copperbelt mining area. Potential ecological risk showed that Cu and As were likely to cause adverse biological effects to aquatic organisms in the Copperbelt mining region of the Kafue River.

Pathological and molecular diagnosis of the 2013 African swine fever outbreak in Lusaka, Zambia.

African swine fever (ASF) is a highly contagious and fatal hemorrhagic viral disease of domestic pigs. The disease is widespread in sub-Saharan Africa and has repeatedly been introduced into other continents. The current study describes the diagnostic investigations of a hemorrhagic disease that was reported in pigs in Lusaka (October 2013), Zambia. Necropsy, histopathology, and molecular diagnosis using polymerase chain reaction and sequence analysis confirmed the disease to be ASF. The sequences obtained showed high similarity to previously isolated ASF viruses. Consistent surveillance and rapid diagnosis of the disease is recommended to prevent future outbreaks and economic losses as there is currently no vaccine against the disease.

The zoonotic potential of avian influenza viruses isolated from wild waterfowl in Zambia.

Whilst remarkable progress in elucidating the mechanisms governing interspecies transmission and pathogenicity of highly pathogenic avian influenza viruses (AIVs) has been made, similar studies focusing on low-pathogenic AIVs isolated from the wild waterfowl reservoir are limited. We previously reported that two AIV strains (subtypes H6N2 and H3N8) isolated from wild waterfowl in Zambia harbored some amino acid residues preferentially associated with human influenza virus proteins (so-called human signatures) and replicated better in the lungs of infected mice and caused more morbidity than a strain lacking such residues. To further substantiate these observations, we infected chickens and mice intranasally with AIV strains of various subtypes (H3N6, H3N8, H4N6, H6N2, H9N1 and H11N9) isolated from wild waterfowl in Zambia. Although some strains induced seroconversion, all of the tested strains replicated poorly and were nonpathogenic for chickens. In contrast, most of the strains having human signatures replicated well in the lungs of mice, and one of these strains caused severe illness in mice and induced lung injury that was characterized by a severe accumulation of polymorphonuclear leukocytes. These results suggest that some strains tested in this study may have the potential to infect mammalian hosts directly without adaptation, which might possibly be associated with the possession of human signature residues. Close monitoring and evaluation of host-associated signatures may help to elucidate the prevalence and emergence of AIVs with potential for causing zoonotic infections.

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.

Geographic information system-based source estimation of copper pollution in Lake Itezhi-tezhi and metal-accumulation profiles in Oreochromis spp. from both field and laboratory studies.

The Copperbelt region, upstream of the Kafue River, including Lake Itezhi-tezhi (ITT), in Zambia has extensive copper (Cu) mines. In our field study, geographic information system analysis in lake sediment indicated that the northern part of the lake, i.e., the Copperbelt region, could be the source of Cu pollution. Concentrations of Cu in stomach contents between fish species were not significantly different. However, Oreochromis spp. liver showed significantly greater Cu concentrations than those in other fish species. Log liver [Cu], standard length, and nitrogen stable isotope ratio were positively correlated only in Oreochromis spp. In the laboratory study, O. niloticus and O. latipes were exposed to Cu for 4 days, and recovery phases ≤ 28 days were examined. O. niloticus showed significantly greater concentrations of Cu compared with O. latipes at all sampling points. Significantly greater concentrations of Hg in Schilbe intermedius liver than for other fish species were observed, whereas O. macrochir showed significantly greater concentrations of cadmium. In conclusion, the northern part of the lake could be the source of Cu pollution in Lake ITT. Diet may not be the reason for high Cu accumulation in Oreochromis spp. Results from both field and laboratory studies imply that Oreochromis spp. contain high concentrations of Cu under normal physiological conditions.

Metal contaminated soil from mining area caused metal accumulation and biological responses in rats.

In order to assess the effects of metal contamination on wildlife, we collected wild black rats (Rattus sp.) from mining areas (Kabwe and Chingola) and a control area (Lusaka) in Zambia and compared metal and metallothionein (MT) levels in their tissues. Furthermore, we exposed metal-contaminated soil from Kabwe to laboratory Wistar rats (Rattus norvegicus) for one year in order to determine the accumulation factors and effects of metals caused by soil exposure. Results of both the field and laboratory studies suggested that metal-contaminated soil caused accumulation and biological responses such as elevation of MT-2 mRNA expression levels in rats.

Accumulation and biological effects of metals in wild rats in mining areas of Zambia.

The lead-zinc (Pb-Zn) mine in Kabwe City and the copper-cobalt (Cu-Co) mine in the Copperbelt Province are major mining areas in Zambia. To examine the effects of metal pollution on wildlife, wild black rats (Rattus rattus and Rattus tanezumi) were captured in Kabwe and Chingola (in the Copperbelt Province), and in Lusaka (a noncontaminated site). Wild black rats in Kabwe accumulated significantly higher concentrations of Pb and Cd in various organs than rats from Lusaka. In Chingola, significantly higher concentrations of Cu, Co, Pb, and Cd were accumulated in wild black rats than in rats from Lusaka. These results were in accordance with metal accumulation patterns in soil. From toxicological aspects, concentrations of Pb and Cd in rats were generally low. However, metallothionein-1 (MT-1) and metallothionein-2 (MT-2) mRNA expression levels in wild black rats from Kabwe were significantly higher than those in rats from Lusaka. A generalized linear model (GLM) showed that concentrations of Zn and Cu had positive effects on the MT-1 and MT-2 mRNA expression. These results suggest that wild black rats in Zambian mining sites were exposed to metals that accumulated in their organs, causing biological responses such as MT mRNA induction. GLM indicated that heme oxygenase-1 (HO-1) mRNA expression could be a marker for Cr exposure.

Highly pathogenic avian influenza H5N1 virus outbreak among Cape cormorants (Phalacrocorax capensis) in Namibia, 2022.

In January 2022, significant mortality was observed among Cape cormorants (Phalacrocorax capensis) on the west coast of Namibia. Samples collected were shown to be positive for H5N1 avian influenza by multiplex RT-qPCR. Full genome analysis and phylogenetic analysis identified the viruses as belonging to clade 2.3.4.4b and that it clustered with similar viruses identified in Lesotho and Botswana in 2021. This is the first genomic characterization of H5N1 viruses in Namibia and has important implications for poultry disease management and wildlife conservation in the region.

Social cost of mining-related lead (Pb) pollution in Kabwe, Zambia, and potential remediation measures.

Lead (Pb) pollution has been one of the major environmental problems of worldwide significance. It is a latent factor for several fatal illnesses, whereas the exposure to lead in early childhood causes a lifetime IQ loss. The social cost is the concept to aggregate various adverse effects in a single monetary unit, which is useful in describing the pollution problem and provides foundation for the design of interventions. However, the assessment of the social cost is scarce for developing countries. In this study, we focus on the lead pollution problem of a former mining town, Kabwe, Zambia, where mining wastes abandoned near residential areas has caused a critical pollution problem. We first investigated the social cost of lead pollution that future generations born in 2025-2049 would incur in their lifetime. As the channels of the social cost, we considered the lost income from the IQ loss and the lost lives from lead-related mortality. The results showed that the social cost would amount to 224-593 million USD (discounted to the present value). Our results can be considered conservative, lower bound estimates because we focused only on well-identified effects of lead, but the social cost was still substantial. Then we examined several engineering remediation measures. The results showed that the social cost can be reduced (the benefits of remediations) more than the costs of implementing remediation measures. This study is the first to investigate the social cost of mining-related lead pollution problem in developing countries. Our interdisciplinary approach utilises the micro-level economic, health and pollution data and integrates the techniques in economics, toxicology and engineering.

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.

Metabolomic Alteration in the Plasma of Wild Rodents Environmentally Exposed to Lead: A Preliminary Study.

Lead poisoning is often considered a traditional disease; however, the specific mechanism of toxicity remains unclear. The study of Pb-induced alterations in cellular metabolic pathways is important to understand the biological response and disorders associated with environmental exposure to lead. Metabolomics studies have recently been paid considerable attention to understand in detail the biological response to lead exposure and the associated toxicity mechanisms. In the present study, wild rodents collected from an area contaminated with lead (N = 18) and a control area (N = 10) were investigated. This was the first ever experimental metabolomic study of wildlife exposed to lead in the field. While the levels of plasma phenylalanine and isoleucine were significantly higher in a lead-contaminated area versus the control area, hydroxybutyric acid was marginally significantly higher in the contaminated area, suggesting the possibility of enhancement of lipid metabolism. In the interregional least-absolute shrinkage and selection operator (lasso) regression model analysis, phenylalanine and isoleucine were identified as possible biomarkers, which is in agreement with the random forest model. In addition, in the random forest model, glutaric acid, glutamine, and hydroxybutyric acid were selected. In agreement with previous studies, enrichment analysis showed alterations in the urea cycle and ATP-binding cassette transporter pathways. Although regional rodent species bias was observed in this study, and the relatively small sample size should be taken into account, the present results are to some extent consistent with those of previous studies on humans and laboratory animals.

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.

Human Health Risk Assessment from Lead Exposure through Consumption of Raw Cow Milk from Free-Range Cattle Reared in the Vicinity of a Lead-Zinc Mine in Kabwe.

Lead (Pb) contamination in the environment affects both humans and animals. Chronic exposure to Pb via dietary intake of animal products such as milk from contaminated areas poses a health risk to consumers; therefore, the present study investigated Pb contamination in cow milk and its health risk impact on humans through consumption of milk from cattle reared in the proximity of a Pb−Zn mine in Kabwe, Zambia. Fresh milk samples were collected from cows from Kang'omba (KN), Kafulamse (KF), Mpima (MP), Mukobeko (MK), and Munga (MN) farming areas. Pb determination was performed using Graphite Flame Absorption Atomic Spectrophotometry (GFAAS). Cow milk Pb levels showed different concentration patterns according to season, distance, and location of the farms from the Pb−Zn mine. The overall mean Pb levels were ranged 0.60−2.22 µg/kg and 0.50−4.24 µg/kg in the wet and dry seasons, respectively. The mean Pb concentration, chronic daily intake (CDIs), target hazard quotients (THQs), and incremental lifetime cancer risk (ILCR) results obtained were all within the permissible limits of 20 µg/kg, 3 and 12.5 µg/kg-BW/day, <1 and 10−4 to10−6, respectively. In conclusion, although Pb was detected in milk from cows reared in Kabwe, the health risk effects of Pb exposure associated with the consumption of milk in both adults and children were negligible.

Narrative review of lead poisoning in humans caused by industrial activities and measures compatible with sustainable industrial activities in Republic of Zambia.

Lead (Pb) pollution and human exposure to Pb, is an important issue for the international community to address being associated with 0.90 million deaths from long-term effects. The Republic of Zambia is a typical mineral resource-rich country, with long-standing mining and smelting activities of metals including Pb in several parts of the country. This narrative review provides a comprehensive overview of previous papers that have assessed human exposure to Pb and related health effects in Zambia. Environmental remediation methods that should be applied locally, ways to reduce Pb exposure of the population, and issues that need to be addressed by various sectors are discussed. Environmental remediation methods using locally available and affordable materials are needed to ensure both sustainable industrial activities and pollution prevention. In the Zambian mining towns, including Kabwe, various research activities have been conducted, including environmental monitoring, human biomonitoring and health impact assessments. The town of Kabwe, which was one of Zambia's largest Pb mining area in the 20th century, continues to have formal and informal Pb-related industries and is known as one of the most polluted areas in the world. For example, despite the World Health Organization asserting that "For an individual with a blood Pb concentration ≥ 5 µg/dL, appropriate action should be taken to terminate exposure", there are reports of blood Pb levels in Kabwe children exceeding 100 µg/dL. While Pb pollution is a global issue, not many places have such continuous and comprehensive research has been conducted, and there is much to be learned from the knowledge accumulated in these areas. Because the high levels of Pb accumulation in humans and the adverse health effects were clarified, we consider that it is important to combine mining activities, which are a key industry, with measures to prevent environmental pollution.

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.