Effects of environmental lead contamination on cattle in a lead/zinc mining area: changes in cattle immune systems on exposure to lead in vivo and in vitro

Bovine lead exposure from informal battery recycling in India

We provide an estimate of annual bovine lead exposure and attributable mortality at informal lead acid battery recycling sites in India. We use Pure Earth's Toxic Sites Identification Program database, the FAO's Gridded Livestock dataset, and a Poisson plume model of lead particle air dispersion to estimate site-level mortality. We calculate that India suffers 2370 excess bovine fatalities each year, resulting in more than USD $2.1 million of economic damage. The distribution of damages by location is highly skewed. While we find most sites (86.3%) induce no mortalities, 6.2% of sites induce minor damage (1 to 5 fatalities), 4.1% induce moderate damage (6 to 20 fatalities), and 3.4% induce severe damage (21 + fatalities). These findings highlight the importance of geospatial data to prioritize mitigation efforts and identify a previously unquantified burden on the rural poor.

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.

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.

Biomonitoring of Lead Exposure in Children from Two Fishing Communities at Northern Colombia

Lead (Pb) exposure is a growing concern in developing countries, especially in vulnerable children. The objective of this study was to evaluate blood lead levels (BLL) in children from two fishing populations at Northern Colombia, Loma de Arena and Tierrabomba, as well as their association with morphometric parameters, markers of hematological status, liver function, and mRNA expression of genes related to Pb toxicity. A total of 198 blood samples were collected from participants aged 5-16 years old. The mean (± standard error) BLL for the studied sample was 3.6 ± 0.3 μg/dL, and the 97.5th percentile was 21.0 μg/dL. The participants of Loma de Arena and Tierrabomba presented BLL of 3.9 ± 0.5 and 2.9 ± 0.3 μg/dL, respectively. Children born preterm had greater BLL than those born at full term. Boys had greater BLL than girls, which also occurred for participants between 12 and 16 years old, compared with those aged 5-11 years old. The BLL were negatively correlated with body mass index in children from Loma de Arena, but an opposite behavior was observed for Tierrabomba. In Loma de Arena, the mRNA expression of interferon gamma, a pro-inflammatory cytokine, increased with the BLL, but that of δ-aminolevulinic acid dehydrogenase, a sensor for Pb poisoning, decreased. In Tierrabomba, gene expression did not change with BLL. These results show that in fishing communities, lead exposure promotes different health impacts depending on age, sex, and other site-specific factors. In any case, appropriate educational and intervention programs should be carried out to minimize Pb exposure in children.

Lead exposure activates the Nrf2/Keap1 pathway, aggravates oxidative stress, and induces reproductive damage in female mice

Lead, a common metallic contaminant, is widespread in the living environment, and has deleterious effects on the reproductive systems of humans and animals. Although numerous toxic effects of lead have been reported, the effects and underlying mechanisms of the impacts of lead exposure on the female reproductive system, especially oocyte maturation and fertility, remain unknown. In this study, mice were treated by gavage for seven days to evaluate the reproductive damage and role of Nrf2-mediated defense responses during lead exposure. Lead exposure significantly reduced the maturation and fertilization of oocytes in vivo. Additionally, lead exposure triggered oxidative stress with a decreased glutathione level, increased amount of reactive oxygen species, and abnormal mitochondrial distribution. Moreover, lead exposure caused histopathological and ultrastructural changes in oocytes and ovaries, along with decreases in the activities of catalase, glutathione peroxidase, total superoxide dismutase, and glutathione-S transferase, and increases in the levels of malonaldehyde in mouse ovaries. Further experiments demonstrated that lead exposure activated the Nrf2 signaling pathway to protect oocytes against oxidative stress by enhancing the transcription levels of antioxidant enzymes. In conclusion, our study demonstrates that lead activates the Nrf2/Keap1 pathway and impairs oocyte maturation and fertilization by inducing oxidative stress, leading to a decrease in the fertility of female mice.

Metalliferous Mining Pollution and Its Impact on Terrestrial and Semi-terrestrial Vertebrates: A Review

Metalliferous mining, a major source of metals and metalloids, has severe potential environmental impacts. However, the number of papers published in international peer-reviewed journals seems to be low regarding its effects in terrestrial wildlife. To the best of our knowledge, our review is the first on this topic. We used 186 studies published in scientific journals concerning metalliferous mining or mining spill pollution and their effects on terrestrial and semi-terrestrial vertebrates. We identified the working status of the mine complexes studied, the different biomarkers of exposure and effect used, and the studied taxa. Most studies (128) were developed in former mine sites and 46 in active mining areas. Additionally, although several mining accidents have occurred throughout the world, all papers about effects on terrestrial vertebrates from mining spillages were from Aznalcóllar (Spain). We also observed a lack of studies in some countries with a prominent mining industry. Despite >50% of the studies used some biomarker of effect, 42% of them only assessed exposure by measuring metal content in internal tissues or by non-invasive sampling, without considering the effect in their populations. Most studied species were birds and small mammals, with a negligible representation of reptiles and amphibians. The information gathered in this review could be helpful for future studies and protocols on the topic and it facilitates a database with valuable information on risk assessment of metalliferous mining pollution.

Slag dusts from Kabwe (Zambia): Contaminant mineralogy and oral bioaccessibility

The former Pb-Zn mining town of Kabwe in central Zambia is ranked amongst the worst polluted areas both in Africa and in the world. The fine dust particles from the ISF and Waelz slags deposited in Kabwe represent a health risk for the local population. Here, we combined a detailed multi-method mineralogical investigation with oral bioaccessibility testing in simulated gastric fluid (SGF; 0.4 M glycine, pH 1.5, L/S ratio of 100, 1 h, 37 °C) to evaluate the risk related to the incidental dust ingestion. The slag dust fractions contain up to 2610 mg/kg V, 6.3 wt% Pb and 19 wt% Zn. The metals are mainly bound in a slag glass and secondary phases, which formed during the slag weathering or were windblown from nearby tailing stockpiles (carbonates, Fe and Mn oxides, phosphates, vanadates). The bioaccessible fractions (BAFs) are rather high for all the main contaminants, with the BAF values generally higher for the ISF slags than for the Waelz slags: Pb (24-96%), V (21-100%) and Zn (54-81%). The results clearly indicate the potential risks related to the incidental slag dust ingestion. Even when a conservative value of the dust daily intake (100 mg/day) is considered, the daily contaminant intake significantly exceeds the tolerable daily intake limits, especially for Pb ≫ V > Zn. At higher ingestion rates, other minor contaminants (As, Cd) also become a health risk, especially for children. The slag heaps in Kabwe should be fenced to prevent local people entering and should be covered to limit the dust dispersion.

Treatment with Lead Chloride During Pregnancy and the Postnatal Period Alters Cell Proliferation and Immune Function in Swiss Albino Mice

In the current study, we investigated the effect of lead chloride (PbCl₂) administration (50 and 100 ppm) on organ and body weight as well as its bioaccumulation during pregnancy and the postnatal period in mice. We showed that lead has no effect on the body weight of mice. However, spleen weight is affected by the two doses of PbCl₂ while liver and kidney weights are altered only by the 100-ppm dose. Inductively coupled plasma atomic emission spectrometry (ICP-AES) analysis showed that lead accumulates in the blood, spleen, and thymus. Both doses of PbCl₂ significantly reduced splenocyte and thymocyte cell counts after stimulation with lipopolysaccharide (LPS) and phytohemagglutinin A (PHA), respectively. On the other hand, we showed that the levels of Th1 cytokines (interleukin-2 (IL-2), interferon gamma (IFN-γ)), and tumor necrosis factor alpha (TNF-α) were reduced in the serum of mice treated with PbCl₂ in a dose-dependent manner, as measured by ELISA. The levels of interleukin-4 (IL-4) and interleukin-10 (IL-10) were very low in untreated mice and were also reduced by treatment with PbCl₂. The levels of IL-2, IFN-γ, IL-4, IL-10, and TNF-α secretion differentially decreased in LPS-stimulated splenocytes in lead-treated mice. Using PHA-stimulated thymocytes, we observed a reduction in the levels of IL-2, IL-4, IL-10, and TNF-α in the PbCl₂-treated groups. However, IFN-γ concentration in the supernatant of these cells was not decreased when mice were treated with 50 ppm of lead.

Trace elements in the liver of captive and free-ranging European bison (Bison bonasus L.)

European bison is classified as a vulnerable species because of many threats. We analyzed the content of toxic and essential elements (Ag, Al, As, Ba, Be, Cd, Co, Cr, Cu, Hg, Mg, Mn, Na, Ni, Pb, Se, Th, Tl, U, V, and Zn) in the livers of 30 captive and free-ranging European bison from the Bison Breeding Center in Smardzewice and from Białowieża Primeval Forest in Poland. The contents of toxic elements were lower than reported previously in European Bison and were similar to those of wild ungulates from non-polluted areas. Accumulation of Cd and Cr was related to the age of animals. We compared the mineral status between captive and free-ranging European bison to verify whether the maintenance type could affect concentrations of trace elements in the liver. The concentration of Mn and Zn differed between captive and free-ranging group. Our results were compared to the reference values of essential elements for cattle. All animals from this study were Se-deficient and more than 80% of them have Cu deficiency. Deficiency of Mn was present in 20% of captive and 37% of free-ranging animals whereas Zn in 37% and 3% respectively. Statistical analysis confirmed that Mn and Zn deficiencies were related o the maintenance of animals (p<0.05). We revealed that mineral deficiencies could be an additional threat to the Polish population of European bison. Thus, the monitoring of essential minerals is necessary and future work is required to optimize the supplementation and foddering for preventing the occurrence of mineral deficiencies.

The analysis of blood lead levels changeability over the 5-year observation in workers occupationally exposed to lead

The aim of the present study was to compare a group of workers with stable lead levels with a group of workers with fluctuating lead levels in terms of selected hematological, biochemical, and immunological parameters. The examined group included male workers occupationally exposed to lead. Blood lead (PbB) levels were measured every 3 months during the 5-year observation. Based on standard deviation of mean PbB levels, the examined population was divided into two groups: low level of fluctuation (L-SD) and high level of fluctuation (H-SD) groups. The mean and maximal PbB levels were significantly higher in the H-SD group than in the L-SD group by 9 and 22%, respectively. At the same time, the maximal level of zinc protoporphyrin (ZPP) and standard deviation of mean ZPP level were higher in the H-SD group by 29 and 55%, respectively. The maximal level of hemoglobin and white blood cell (WBC) count as well as standard deviation of the mean hemoglobin level and WBC count were higher in the H-SD group by 2, 8, 58, and 24%, respectively. The expression of nuclear factor kappa-B1 gene and telomerase reverse transcriptase gene was significantly greater in the H-SD group than in the L-SD group by 11 and 28%, respectively. Workers occupationally exposed to lead do not represent a homogenous population. Some present stable lead levels, whereas others have fluctuating lead levels. These fluctuations are related to secondary changes in ZPP and hemoglobin levels as well as WBC count.

Reliability of stable Pb isotopes to identify Pb sources and verifying biological fractionation of Pb isotopes in goats and chickens

Stable Pb isotope ratios (Pb-IRs) have been recognized as an efficient tool for identifying sources. This study carried out at Kabwe mining area, Zambia, to elucidate the presence or absence of Pb isotope fractionation in goat and chicken, to evaluate the reliability of identifying Pb pollution sources via analysis of Pb-IRs, and to assess whether a threshold for blood Pb levels (Pb-B) for biological fractionation was present. The variation of Pb-IRs in goat decreased with an increase in Pb-B and were fixed at certain values close to those of the dominant source of Pb exposure at Pb-B > 5 μg/dL. However, chickens did not show a clear relationship for Pb-IRs against Pb-B, or a fractionation threshold. Given these, the biological fractionation of Pb isotopes should not occur in chickens but in goats, and the threshold for triggering biological fractionation is at around 5 μg/dL of Pb-B in goats.

Metal extent in blood of livestock from Dandora dumping site, Kenya: Source identification of Pb exposure by stable isotope analysis

Nairobi city in Kenya produces 2000 tons/day of garbage, and most of it is dumped onto the Dandora dumping site, home to a quarter-million residents. This study was conducted (1) to assess the contamination levels of nine metals and a metalloid (arsenic) in the blood of pigs, goats, sheep and cattle from Dandora, and (2) to identify a possible source of lead (Pb) pollution. Cadmium (Cd, 0.17-4.35 μg/kg, dry-wt) and Pb (90-2710 μg/kg) levels in blood were generally high, suggesting human exposure to Cd through livestock consumption and Pb poisoning among pigs (2600 μg/kg) and cattle (354 μg/kg). Results of Pb isotope ratios indicated that the major exposure route might differ among species. Our results also suggested a possibility that the residents in Dandora have been exposed to the metals through livestock consumption.

Lead poisoning in children from townships in the vicinity of a lead-zinc mine in Kabwe, Zambia

Childhood lead poisoning is a serious public health concern worldwide. Blood lead levels exceeding 5 μg dL(-1) are considered elevated. In Kabwe, the capital of Zambia's Central Province, extensive Pb contamination of township soils in the vicinity of a Pb-Zn mine and posing serious health risk to children has been reported. We investigated BLLs in children under the age of 7 years in townships around the mine; where blood samples were collected and analyzed using an ICP-MS. All of the sampled children had BLLs exceeding 5 μg dL(-1). Children in these areas could be at serious risk of Pb toxicity as 18% of the sampled children in Chowa, 57% (Kasanda) and 25% (Makululu) had BLLs exceeding 65 μg dL(-1). Eight children had BLLs exceeding 150 μg dL(-1) with the maximum being 427.8 μg dL(-1). We recommend that medical intervention be commenced in the children with BLL exceeding 45 μg dL(-1).

The effect of copper on the mRNA expression profile of xenobiotic-metabolizing enzymes in cultured rat H4-II-E cells

Copper (Cu(2+)) is an essential element that plays important roles in physiological functions of the body. However, high Cu(2+) levels can have toxic implications. This study aims to investigate the constitutive response to Cu(2+) exposure of xenobiotic-metabolizing enzymes in cultured rat liver (H4-II-E) cell lines. Rat cells were exposed to copper sulfate (0-500 μM) for 24 h. The effects of Cu(2+) on the messenger RNA (mRNA) expressions of phase I and II enzymes and regulatory elements were examined using real-time PCR. Metallothionein mRNA expression was induced in a dose-dependent manner after treatment with Cu(2+). mRNA expressions of phase I enzymes such as cytochrome P450 1A1 and 1A2 (CYP1A1 and CYP1A2) were slightly induced after exposure to low concentrations of Cu(2+); however, CYP1A1 and CYP1A2 mRNA expressions were significantly downregulated at higher Cu(2+) concentrations. These effects corresponded with expression of aryl hydrocarbon receptor mRNA. The mRNA expressions of phase II enzymes were reduced upon exposure to Cu(2+). In conclusion, phase I and II enzyme expressions were significantly modulated upon Cu(2+) exposure. These results indicated that Cu(2+) exposure had toxicological implications for cultured H4-II-E cells.