Monitoring exposure to heavy metals among children in Lake Victoria, Kenya: environmental and fish matrix

Public health assessment of Kenyan ASGM communities using multi-element biomonitoring, dietary and environmental evaluation

The Kakamega gold belt's natural geological enrichment and artisanal and small-scale gold mining (ASGM) have resulted in food and environmental pollution, human exposure, and subsequent risks to health. This study aimed to characterise exposure pathways and risks among ASGM communities. Human hair, nails, urine, water, and staple food crops were collected and analysed from 144 ASGM miners and 25 people from the ASGM associated communities. Exposure to PHEs was predominantly via drinking water from mine shafts, springs and shallow-wells (for As>Pb>Cr>Al), with up to 366 µg L-1 arsenic measured in shaft waters consumed by miners. Additional exposure was via consumption of locally grown crops (for As>Ni>Pb>Cr>Cd>Hg>Al) besides inhalation of Hg vapour and dust, and direct dermal contact with Hg. Urinary elemental concentrations for both ASGM workers and wider ASGM communities were in nearly all cases above bioequivalents and reference upper thresholds for As, Cr, Hg, Ni, Pb and Sb, with median concentrations of 12.3, 0.4, 1.6, 5.1, 0.7 and 0.15 µg L-1, respectively. Urinary As concentrations showed a strong positive correlation (0.958) with As in drinking water. This study highlighted the importance of a multidisciplinary approach in integrating environmental, dietary, and public health investigations to better characterise the hazards and risks associated with ASGM and better understand the trade-offs associated with ASGM activities relating to public health and environmental sustainability. Further research is crucial, and study results have been shared with Public Health and Environmental authorities to inform mitigation efforts.

Influence of agricultural activities and seasonality on levels of selected physico-chemical parameters and heavy metals along River Yala in Lake Victoria Basin

The aim of the work was to establish the effect of anthropogenic activities and seasonality on physico-chemical parameters and heavy metal levels of River Yala (RY) within RY Basin of Lake Victoria (LV), as well as the associated ecological risks. Analyses were done on the collected samples in order to establish the levels of EC, pH, DO, temperature, conductivity, turbidity, acidity, alkalinity, BOD, COD, DOC, TOC and heavy metals (Cu, Fe, Pb, Mn, Zn, Cr and Cd) in RY water and sediments adjacent to Agricultural Farms during dry and wet seasons. The levels in terms of μg/mL, μS/cm (EC), NTU (turbidity) of analyzed parameters in the Agricultural Farms in water ranged from 0.01±0.00 to 121.75±15.23 (Upstream pristine sources of RY - S), 0.02±0.01 to 184.83±23.43 (Nandi Tea Estate and Kaimosi Agricultural Farms - N), 0.02±0.01 to 149.67±22.77 (Subsistence Farms - Sub), 0.02±0.01 to 209.33±18.09 (Lake Agro Limited Agricutural Farms and Yala Swamp - D) and 0.01±0.00 to 164.25±30.33 (Terminal of RY - T). The levels in μg/g of analyzed parameters in sediments ranged from 7.2±1.46 to 3342.8±538.7 (S), 9.12±0.2 to 4063.2±90.4 (N), 3.15±1.14 to 5998.5±588.4 (Sub), 2.03±0.76 to 4519.8±194.9 (D) and 2.13±0.75 to 5514.4±201.4 (T). The significant differences in the levels of analyzed parameters in water between dry and wet seasons were computed as; EC (+20.54 μS/cm), alkalinity (-2.85 μg/mL), DOC (+0.24 μg/mL), Fe (+0.58 μg/mL), Pb (+0.11 μg/mL), Zn (+0.07 μg/mL) and Cd (+0.01 μg/mL) while that for Mn in sediment samples was +163.8937 μg/g. The significantly (p ≤ 0.05) positive values indicated that wet season had more impact on the levels than dry season. There was positive correlation of zinc in water and sediments during dry and wet season. Chromium correlated positively in water and sediments during wet season. Copper and cadmium correlated negatively during dry and wet season while Mn only wet season. Results of geostatistical indices (CF, Cd, mCd, PLI, Er and RI) indicated that sediments located at regions N, D and T were highly contaminated with the heavy metals. However, a wetland at the mouth of Lake Victoria cleaned the water before it drained into the lake. Therefore, despite contamination of RY through anthropogenic activities, wetland mitigation protects LV from pollution by the river, indicating the important ecological and restorative functions played by wetlands.

Human biomonitoring of heavy metals exposure in different age- and gender-groups based on fish consumption patterns in typical coastal cities of China

The study aimed to investigate heavy metals (HMs) concentrations in human hair based on fish consumption patterns in Qingdao, Xiamen, and Zhoushan. The (HMs) concentrations were determined using acid digestion and an inductively coupled plasma mass spectrometer (ICP-MS, NexION 300X, PerkinElmer). The associated health risks were investigated using risk assessment models described by the United States Environmental Protection Agency (USEPA). The order of fish HMs concentration in Qingdao was CdCrCu>Pb>Cr>As>Cd in all three study areas. The hair Zn concentration in 28 % of the studied population exceeded the safety standards. Overall, the hair HMs concentration was found to be high in middle-aged groups (19-45 and 45-59), and the hair HMs concentrations were high, especially in the case of females. A significant correlation was noticed between hair As (0.119; p < 0.05), Cr (0.231; p < 0.05),) and Cu (0.117; p < 0.05),) and fish consumption frequency. High Odd ratios (>2) were noticed for As, Cu and Zn in high fish-eating frequency. A significant non-carcinogenic risk was noticed in human Cr exposure (1.10E+00) in Xiamen, and the hazard index values indicated non-carcinogenic risk in Xiamen and Zhoushan. The carcinogenic risk for human As exposure (2.50E-05-7.09E-03) indicated a significant cancer risk.

Considerations for environmental biogeochemistry and food security for aquaculture around Lake Victoria, Kenya

The impact of population expansion through economic growth and development has been identified as one of the key drivers of both water and sediment contamination from potentially harmful elements (PHEs). This presents a major hazard not only to aquatic ecosystems but local riparian communities and beyond who rely heavily on this natural resource for drinking water and fish-a valuable source of dietary micronutrients and protein. The present study measured biogeochemical concentration of PHEs in water, sediment and fish from locations pooled into four zones within Winam Gulf and Lake Victoria area of Kenya. Captured fish were used as a sentinel receptor of lake health to evaluate potential risks to fisheries and aquaculture food security. In water, concentrations of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu) and lead (Pb) were observed above the United States Environmental Protection Agency (US EPA) maximum contamination level drinking water guidelines (MCL), with aluminium (Al) observed above the Aquatic Life Criteria in all four zones. Similarly, sediment concentrations in all four zones exceeded the US EPA Effects range low (ERL) threshold guidelines for Cu, nickel (Ni), zinc (Zn) and Pb, with Cu, Zn and Pb classed at moderate contamination levels using the contamination factor. Fish tissue concentrations from the four zones were calculated using recommended daily intakes (RDI) and for PHEs as provisional maximum tolerable intakes (PMTIs) and indicated most macro- and micronutrients were at or below 10% RDI from aquaculture and wild fish, with Se indicating a greater RDI (16-29%) in all the zones. Contributions of PHEs to PMTIs were below threshold guidelines for both aquaculture and wild fish with only Cd, Cr and Pb levels being above the PMTI thresholds. There is a need to assess the long-term effects of persistent anthropogenic PHE input into Winam Gulf and the wider Lake Victoria basin. Continued monitoring of PHEs using both historical and more recent data will enable future management policies to be implemented through improved mitigation strategies to reduce their impact on water quality, fish health and subsequent human health.

Heavy metals in fish, rice, and human hair and health risk assessment in Wuhan city, central China

The current study investigated the concentration of heavy metals (HMs) in human hair associated with fish and rice consumption in Wuhan City, central China. The mean values of As in 8/10 fish species exceeded the food safety standard of 0.015 mg/kg. The mean values (mg/kg) of HMs in rice followed a descending order of Zn (13.7)> Cu (1.9)>Cr (0.51)>As (0.11) >Cd (0.08) >Pb (0.04). The ascending order of HMs for male hair was Cd < As < Cr < Pb < Cu < Zn, while As < Cd < Cr < Pb < Cu < Zn for female. 30% of hair Cr and 22% of hair Zn contents exceeded the recommended values. The middle age (19-44) and adult (45-59) groups were the most vulnerable group, as the concentration for most elements was high in these age groups. A significant correlation was found between fish-eating frequency and hair Zn (r = 0.213; p < 0.05), and As (r = 0.204; p < 0.05). High odd ratios were found in a population with high fish-eating frequency, especially for Pb (7.19), As (3.1), Zn (3.83), and Cd (3.7). A significant non-carcinogenic risk was associated with Cr exposure through consuming herbivores, filter feeders, and omnivorous fish. The cancer risk values of Cd exposure (1.54E-04) via rice consumption and As exposure (1.25E-04) via consumption of omnivores fish indicate precautionary measures.

Health risk assessment of trace elements in the Tonle Sap Great Lake and the Tonle Sap River in Cambodia during the rainy season

To investigate the potential health risk of trace elements in the Tonle Sap Great Lake system, lake (n = 37) and river (n = 14) water samples were collected and analyzed for 19 trace elements (Ag, Al, As, B, Ba, Cd, Co, Cr, Cu, Fe, Ga, Mn, Mo, Ni, Pb, Se, Tl, U and Zn) using inductively coupled plasma mass spectrometry. As a result, Cd was not detected in any river and lake water samples. Al, Fe and Mn in lake water exceeded the regulation limits of Cambodia, USEPA and WHO. Health risk assessment using the USEPA model indicated that male and female Cambodian residents are at minimal risk of non-carcinogenic effects from single and mixed trace elements through lake and river water consumption. Nevertheless, As, Tl, Co, Ba, Mn and Cr might pose high potential health risks to consumers which requires more attention. Therefore, regular monitoring and further studies are required to investigate the pollution trends and toxic behavior of these trace elements in the Tonle Sap Great Lake system.

Health risk assessment of heavy metals in the seafood at Kalpakkam coast, Southeast Bay of Bengal

The distribution of heavy metals in the seafood intake by various age group representatives around the Kalpakkam coastal region was part of the baseline study. Totally 40 different types of fish species were estimated on heavy metals (Cu, Cr, Co, Cd, Pb, Ni, Zn, and Mn) in the coastal zone; the average concentration of heavy metals were 0.71, 0.06, 0, 0, 0.07, 0.02, 1.06 and 0.36 ppm, respectively. Individual mean bioaccumulation index (IMBI) and Metal pollution index (MPI) with heavy metals distributed around the coastal zone were compared with fish tissue and were found to be higher for Zn and Cu. The human health risk was calculated using uncertainty modeling of risk assessment of Estimated daily intake (EDI), Maximum allowable consumption rate (CRlim), Target hazard quotient (THQ), and Hazard index (HI) were estimated for different age groups. Our present values were suggestively high (>1) for both kids and adults. The cumulative cancer risk assessment based on heavy metals and the Hospital-Based Cancer Registry (HBCR) compared to the region did not exceed the recommended threshold risk limit around the Kalpakkam coastal zone. Statistical analyses such as correlation, Principal component, and Cluster investigation ensure that heavy metal concentrations do not pose a major risk to occupants.

Bioaccumulation of Toxic Metals in Children Exposed to Urban Pollution and to Cement Plant Emissions

Cement plants located in urban areas can increase health risk. Although children are particularly vulnerable, biomonitoring studies are lacking. Toenail concentration of 24 metals was measured in 366 children (6-10 years), who live and attend school in a city hosting a cement plant. Living addresses and schools were geocoded and attributed to exposed or control areas, according to modeled ground concentrations of PM10 generated by the cement plant. Air levels of PM10 and NO2 were monitored. PM10 levels were higher in the exposed, than in the control area. The highest mean PM10 concentration was recorded close to the cement plant. Conversely, the highest NO2 concentration was in the control area, where vehicular traffic and home heating were the prevalent sources of pollutants. Exposed children had higher concentrations of Nickel (Ni), Cadmium (Cd), Mercury (Hg), and Arsenic (As) than controls. These concentrations correlated each other, indicating a common source. Toenail Barium (Ba) concentration was higher in the control- than in the exposed area. The location of the attended school was a predictor of Cd, Hg, Ni, Ba concentrations, after adjusting for confounders. In conclusion, children living and attending school in an urban area exposed to cement plant emissions show a chronic bioaccumulation of toxic metals, and a significant exposure to PM10 pollution. Cement plants located in populous urban areas seem therefore harmful, and primary prevention policies to protect children health are needed.

Human Health Risk Assessment of Trace Metals in the Commonly Consumed Fish Species in Nakuru Town, Kenya

The present study was conducted to determine daily intake of cadmium (Cd), copper (Cu), and lead (Pb) and to assess noncarcinogenic human health risk caused by these trace metals in the commonly consumed fish species (Oreochromis niloticus, Rastrineobola argentea, Lates niloticus, and Protopterus aethiopicus) in Nakuru town, Kenya. Trace metal determination in the composite samples of the commonly consumed fish species was done using flame atomic absorption spectrophotometer. Cd, Cu, and Pb content in the muscle tissues of the commonly consumed fish species ranged from 0.11 ± 0.045 to 1.11 ± 0.931 mg kg-1 for Cd, 0.48 ± 0.013 to 3.00 ± 0.009 mg kg-1 for Cu, and 3.42 ± 0.045 to 12.78 ± 0.108 mg kg-1 for Pb. Cu concentrations were within Food and Agriculture Organization (FAO) recommended limits for this trace metal in fish. In contrast, Cd and Pb had values above their respective permissible limits in fish. The assessment of human exposure to trace metals indicated that exposure doses of Cd and Cu were safe for fish consumers. Conversely, target hazard quotient (THQ) values of Pb suggested possible health risks for consumers of the commonly consumed fish species in Nakuru town, Kenya.

Biomonitoring of Metals in Children Living in an Urban Area and Close to Waste Incinerators

The impact of waste incinerators is usually examined by measuring environmental pollutants. Biomonitoring has been limited, until now, to few metals and to adults. We explored accumulation of a comprehensive panel of metals in children free-living in an urban area hosting two waste incinerators. Children were divided by georeferentiation in exposed and control groups, and toenail concentrations of 23 metals were thereafter assessed. The percentage of children having toenail metal concentrations above the limit of detection was higher in exposed children than in controls for Al, Ba, Mn, Cu, and V. Exposed children had higher absolute concentrations of Ba, Mn, Cu, and V, as compared with those living in the reference area. The Tobit regression identified living in the exposed area as a significant predictor of Ba, Ni, Cu, Mn, and V concentrations, after adjusting for covariates. The concentrations of Ba, Mn, Ni, and Cu correlated with each other, suggesting a possible common source of emission. Exposure to emissions derived from waste incinerators in an urban setting can lead to body accumulation of specific metals in children. Toenail metal concentration should be considered a noninvasive and adequate biomonitoring tool and an early warning indicator which should integrate the environmental monitoring of pollutants.

A comparison of blood and toenails as biomarkers of children's exposure to lead and their correlation with cognitive function

This study sought to compare lead (Pb) concentrations in toenails and blood and to investigate the association of each biomarker with children's cognitive function. Toenails and whole blood samples were collected from 224 twelve-year-old children, and their full-scale intelligence quotient (FSIQ) was assessed using the Wechsler Intelligence Scale for Children-4th edition. Inductively coupled plasma-mass spectrometry was used to determine blood (BPb) and toenail (TPb) Pb concentrations. Log BPb and Log TPb were significantly correlated (r² = 0.49, p < 0.001). In unadjusted analyses, both log-transformed BPb and TPb were significantly associated with decreased FSIQ, but BPb accounted for approximately quadruple the FSIQ scores' variability than log-transformed TPb (model R² = 0.12 and R² = 0.03, respectively). After adjusting for neighborhood deprivation, caregiver intelligence (assessed with the Wechsler Abbreviated Scale of Intelligence-2nd edition), and child BMI, BPb remained significantly associated with decreased FSIQ, while TPb did not (p = 0.16). These results suggest that while concentrations of Pb in blood and toenails are correlated, TPb does not predict cognitive outcomes at these exposure levels. With caution and in conjunction with BPb, TPb may be used as a population-based biomarker of Pb exposure.

Child Exposure to Lead in the Vicinities of Informal Used Lead-Acid Battery Recycling Operations in Nairobi Slums, Kenya

BACKGROUND

Child exposure to lead from informal used lead-acid battery (ULAB) recycling operations is a serious environmental health problem, particularly in developing countries.

OBJECTIVES

We investigated child exposure to lead in the vicinities of ULAB recycling operations in the Dandora, Kariobangi and Mukuru slums in Nairobi between January and August 2015.

METHODS

Top soil (n = 232) and floor dust (n = 322) samples were collected from dwelling units (n = 120) and preparatory schools (n = 44) and analyzed using an inductively coupled plasma-optical emission spectrometer at the Mines and Geological Department Laboratory in the Ministry of Mining, Nairobi. From the obtained lead levels in soil and house dust, child blood lead levels were subsequently predicted using the Integrated Exposure Uptake Biokinetic Model for Lead in Children (IEUBK), Windows version.

RESULTS

Lead loadings in all the floor dust samples from the Dandora, Kariobangi and Mukuru slums exceeded the United States Environmental Protection Agency (USEPA) guidance value for lead on floors with a range of 65.2 - 58,194 μg/ft2. Control floor dust samples recorded lower lead loadings compared to the Dandora, Kariobangi and Mukuru slums. Lead concentration in 70.7% of the soil samples collected from waste dumps, industrial sites, residential areas, playgrounds and preparatory schools in Dandora, Kariobangi and Mukuru exceeded the respective USEPA guidance values for lead in soils. Lead concentration in 100% of control soil samples were below the respective USEPA limits. The IEUBK model predicted that nearly 99.9% of children ≤ 7 years old living near informal ULAB recycling operations in Dandora, Kariobangi and Mukuru were at risk of being lead poisoned, with predicted blood lead levels (BLL) above the Centers for Disease Control (CDC) reference value for blood lead. A total of 99.9% of exposed children living in the Mukuru slums are likely to have BLL above 34 μg/dL.

CONCLUSIONS

There is a need for coordinated efforts to decrease lead emissions from informal battery recycling in Nairobi slums and to remediate existing soils, particularly around battery workplaces and dumpsites. The BLL of local children should be clinically tested and appropriate intervention measures taken.

Assessment of essential and nonessential dietary exposure to trace elements from homegrown foodstuffs in a polluted area in Makedonska Kamenica and the Kočani region (FYRM)

The main purpose of the present study is to assess human dietary exposure to essential and non-essential trace elements via consumption of selected homegrown foodstuffs. Twelve essential and non-essential trace elements (Cd, Co, Cu, Cr, Hg, Mo, Ni, Pb, Sb, Se, Zn and As) were detected in various homegrown foodstuffs. Detailed questionnaires were also applied among a sample of the local population to collect information on sociodemographic characteristics. The results of the present study clearly indicate that the majority of the trace elements are at highly elevated levels in the studied foodstuffs, in comparison to international recommendations. The maximum measured levels of ETE and NETE are as follows [μgkg(-1)]: Cd 873, Co 1370, Cu 21700, Cr 59633, Hg 26, Mo 6460, Ni14.5, Pb 11100, Sb 181, Se 0.30, Zn 102 and As 693. Additionally, age, body mass index and gender were significantly associated with levels of dietary exposure. Further research is warranted on the potential health implication of this exposure.

CAPSULE ABSTRACT

The study merges the accumulation of ETE and NETE in home-grown foodstuffs and reflects considerably high health risks for inhabitants.

Chromium Distribution and Spatial Variations in the Finer Sediment Grain Size Fraction and Unfractioned Surficial Sediments on Nyanza Gulf, of Lake Victoria (East Africa)

Surficial sediments collected from the Nyanza Gulf of Lake Victoria (East Africa) were used to determine spatial concentrations of Cr and determine differences in contents of the unfractioned (whole sediment) and the finer grain size sediments, establishing any changes in Cr enrichment and potential ecological risks using sediment quality guidelines. A single pollution index was also used to evaluate level of Cr contamination. The spatial mean Cr contents in the <63 µm (silt-clay) fraction were found to be significantly lower than those in the unfractioned sediments, but with a strong linear positive correlation. The study results show decreasing spatial amounts of Cr in surficial sediments of the Nyanza Gulf, when compared to a study done 20 years earlier. However, the 95% confidence limits of the overall mean Cr in unfractioned sediments exceed the threshold effect concentration (TEC), indicating the potential for Cr remobilization from sediments. In general the sediment enrichment is evidence of possible dominance of lithogenous sources of Cr in the surface lake sediments, with potential anthropogenic sources from the drainage system and nearshore urban areas. The sediments are unpolluted with respect to geoaccumulation index, and sediment enrichment factors suggest a minor to moderate enrichment of Cr in surficial sediments of three sites around the Nyanza Gulf zones and around the river mouth in the main lake.

Solar UV-treatment of water samples for stripping-voltammetric determination of trace heavy metals in Awash river, Ethiopia

We report about testing a new mobile and sustainable water sample digestion method in a preliminary field trial in Ethiopia. In order to determine heavy metals at the ultra-trace level by stripping voltammetric techniques in water samples from Awash River, we applied our new method of solar UV-assisted sample pretreatment to destroy the relevant interfering dissolved organic matter. The field tests revealed that 24 h of solar UV irradiation were sufficient to achieve the same sample pretreatment results as with classic digestion method based on intense and hard UV. Analytical results of this study suggest that both a hydroelectric power station and agrichemical applications at Koka Lake have increased the levels of the investigated metals zinc, cadmium, lead, copper, cobalt, nickel, and uranium.

Investigating relationships between biomarkers of exposure and environmental copper and manganese levels in house dusts from a Portuguese industrial city

This study reports on data obtained from a pilot survey focusing on house dust and toenail metal(loids) concentrations in residents living in the industrial city of Estarreja. The study design hereby described aims at investigating relationships between human toenails and both copper and manganese levels in settled house dusts. A total of 21 households and 30 individuals were recruited for the pilot study: 19 households corresponding to 27 residents living near the industrial complex, forming the exposed group, plus 2 households and 3 residents from residential areas with no anticipated environmental contaminants that were used for comparison. Factorial analysis was used for source identification purposes. Investigation on the potential influence of environmental factors over copper and manganese levels in the toenails was carried out via questionnaire data and multiple correspondence analysis. The results show that copper concentrations are more elevated in the indoor dusts, while manganese concentrations are more elevated in the outdoor dust samples. The geometrical relationships in the datasets suggest that the backyard soil is a probable source of manganese to the indoor dust. Copper and manganese contents in the toenail clippings are more elevated in children than in adults, but the difference between the two age groups is not statistically significant (p > 0.05). Investigation of environmental factors influencing the exposure-biomarker association indicates a probable relationship between manganese contents in indoor dust and manganese levels in toenail clippings, a result that is partially supported by the bioaccessibility estimates. However, for copper, no relationship was found between indoor dusts and the biomarkers of exposure.

Cadmium levels in a North Carolina cohort: Identifying risk factors for elevated levels during pregnancy

The objectives of this study were to examine cadmium (Cd) levels and relationships to demographics in an observational, prospective pregnancy cohort study in Durham County, North Carolina. Multivariable models were used to compare blood Cd levels across demographic characteristics. The relative risk of having a blood Cd level that exceeds the US national median (0.32 μg/l) was estimated. Overall, >60% of the women had an elevated (>0.32 μg/l) blood Cd level. Controlling for confounding variables, smoking was associated with 21% (95% CI: 15-28%) increased risk for an elevated blood Cd level. High Cd levels were also observed in non-smokers and motivated smoking status-stratified models. Race, age, education, relationship status, insurance status and cotinine level were not associated with risk of elevated Cd levels among smokers; however, older age and higher cotinine levels were associated with elevated Cd levels among non-smokers. Taken together, more than half of pregnant women in this cohort had elevated blood Cd levels. Additionally, among non-smokers, 53% of the women had elevated levels of Cd, highlighting other potential sources of exposure. This study expands on the limited data describing Cd levels in pregnant populations and highlights the importance of understanding Cd exposures among non-smokers. Given the latent health risks of both smoking and Cd exposure, this study further highlights the need to biomonitor for exposure to toxic metals during pregnancy among all women of child-bearing age.

A correlation between diet and longevity characterization by means of element profiles in healthy people over 80 years from a Chinese longevous region

Monitoring the element concentrations in the human body is of critical importance for health and longevity. In order to explore the formation mechanism of longevity from the perspective of the body's element loads, this study investigated the prominent feature of element profiles in healthy people over 80 years from Bama County (China), a famous longevous region (LR). The element profiles in nails of elderly people from the LR and a non-longevous region were determined by inductively coupled plasma mass spectrometry, using orthogonal projections to latent structures discriminant analysis (OPLS-DA) for pattern recognition. As a result, four characteristic elements closely related to the healthy elderly people from LR, including Cr, Fe, Mn, and Co, were identified. The concentrations of Cr, Fe, Mn, and Co were significantly increased in the LR group (p < 0.05). The values of fold change of Cr, Fe, Mn, and Co were 3.00, 2.46, 2.24, and 2.21, respectively. These characteristic elements could provide an important material guarantee for health and longevity of elderly people in the LR. The further correlation analysis revealed significant positive correlations between the Sr (r = 0.886), Mn (r = 0.873), Ni (r = 0.786), and Co (r = 0.738) concentrations in nails of elderly people and those in drinking water. Furthermore, significant positive correlations were found between the Se (r = 0.940), Mn (r = 0.833), and Fe (r = 0.733) concentrations in nails and their dietary intake. Consequently, the observations suggested that diet could provide extraordinary reference information in terms of reflecting the feature of element profiles in healthy elderly people over 80 years from the LR.

The level and distribution of heavy metals and changes in oxidative stress indices in humans from Lahore district, Pakistan

Human biomonitoring is a well-recognized tool for estimating the exposure of humans to environmental pollutants. However, heavy metals' pollution from anthropogenic origin is a cause for concern because of its potential accumulation in the environment and living organisms, leading to long-term toxic effects. This study was aimed to assess the concentrations of cadmium (Cd), chromium (Cr), lead (Pb), copper (Cu), nickel (Ni), cobalt (Co), manganese (Mn), iron (Fe), and zinc (Zn) in human biological samples (urine, whole blood, hair, and nails) and antioxidant response in blood samples from 48 individuals exposed to heavy metals and to compare them with different age classes and sites. The results indicated that there were metal-specific differences in concentration in exposure groups among the studied sites. The concentration of heavy metals in blood samples showed the following order : Pb > Cd > Ni > Co > Cr. In urine samples, the order was Cu > Pb > Cr > Ni > Co > Cd; in nails samples, the order was Pb > Ni > Cr > Co > Cd > Mn; and in hair samples, the trend was Pb > Ni > Cr > Mn > Cd > Co. A significant (p > 0.05) decrease in antioxidants enzymes activity was observed with increase in heavy metals concentrations. This is the first study reporting biological evidence of altered toxic metals' concentration in humans in Lahore, Pakistan, due to environmental exposure. Further research, including risk analysis studies, food chain contamination, and epidemiological and clinical investigations, are needed to assess optimal levels for dietary exposure in the study area and associated adverse health outcomes.

Human nail usage as a Bio-indicator in contamination monitoring of heavy metals in Dizajabaad, Zanjan province-Iran

BACKGROUND

Due to pedogeochemical background and anthropogenic sources, heavy metal contamination of soil is a widespread problem in some parts of Zanjan province located in North West Iran. In this study an affected area located near National Iranian Lead and Zinc Company (NILZ) was selected for detailed study.

METHODOLOGY

Thirty soil samples and eighteen leaf samples were collected and analyzed for heavy metal contamination by Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES). Both soil and plant samples were found to be basically polluted by Pb (72.60 and 97.11), Zn (546.47 and 166.61), and Cd (1.80 and 1.55) mg. kg(-1) respectively. High concentrations of these elements in soil and plant species signifies possible health risks to humans. The distribution maps drawn using Arc GIS (10) show high concentrations of these toxic metals around Dizajabaad village. To assess vulnerability and health risks of metal concentrations in human bodies' twenty nine fingernail samples were also collected from people living in this village.

RESULTS AND DISCUSSION

Analysis for different heavy metal contents of nail samples reveals very high levels of the same toxic elements (Pb = 15.15, Cd = 1.18, As = 15.47, Zn = 68.46 and Ni = 18.22 mg. kg(-1)) compared with samples collected from an unaffected area and available values indicated in the literature. Further, high concentration of heavy metals in the nail samples suggests long term exposure of inhabitants to these toxic metals.

Randomized open-label pilot study of the influence of probiotics and the gut microbiome on toxic metal levels in Tanzanian pregnant women and school children

Exposure to environmental toxins is a 21st century global health problem that is often the result of dietary intake. Although efforts are made to reduce dietary toxin levels, they are often unsuccessful, warranting research into novel methods to reduce host exposure. Food-grade microbes that can be delivered to the gastrointestinal tract and that are capable of sequestering toxins present a safe and cost-effective intervention. We sought to investigate the potential for probiotic-supplemented yogurt to lower heavy metal levels in at-risk populations of pregnant women and in children in Mwanza, Tanzania, and to examine the microbiome in relation to toxin levels. Two populations suspected to have high toxic metal exposures were studied. A group of 44 school-aged children was followed over 25 days, and 60 pregnant women were followed over their last two trimesters until birth. A yogurt containing 10¹⁰ CFU Lactobacillus rhamnosus GR-1 per 250 g was administered, while control groups received either whole milk or no intervention. Changes in blood metal levels were assessed, and the gut microbiomes of the children were profiled by analyzing 16S rRNA sequencing via the Ion Torrent platform. The children and pregnant women in the study were found to have elevated blood levels of lead and mercury compared to age- and sex-matched Canadians. Consumption of probiotic yogurt had a protective effect against further increases in mercury (3.2 nmol/liter; P = 0.035) and arsenic (2.3 nmol/liter; P = 0.011) blood levels in the pregnant women, but this trend was not statistically significant in the children. Elevated blood lead was associated with increases in Succinivibrionaceae and Gammaproteobacteria relative abundance levels in stool.

Probiotic food produced locally represents a nutritious and affordable means for people in some developing countries to counter exposures to toxic metals. Further research and field trials are warranted to explore this approach in countries where communities are located near mining sites and agricultural areas, two types of areas where toxins are likely to be elevated.

Toenail metal concentration as a biomarker of occupational welding fume exposure

In populations exposed to heavy metals, there are few biomarkers that capture intermediate exposure windows. We sought to determine the correlation between toenail metal concentrations and prior 12-month work activity in welders with variable, metal-rich, welding fume exposures. Forty-eight participants, recruited through a local union, provided 69 sets of toenail clippings. Union-supplied and worker-verified personal work histories were used to quantify hours welded and respirator use. Toenail samples were digested and analyzed for lead (Pb), manganese (Mn), cadmium (Cd), nickel (Ni), and arsenic (As) using ICP-MS. Spearman correlation coefficients were used to examine the correlation between toenail metal concentrations. Using mixed models to account for multiple participation times, we divided hours welded into three-month intervals and examined how weld hours correlated with log-transformed toenail Pb, Mn, Cd, Ni, and As concentrations. Highest concentrations were found for Ni, followed by Mn, Pb and As, and Cd. All the metals were significantly correlated with one another (rho range = 0.28-0.51), with the exception of Ni and As (rho = 0.20, p = 0.17). Using mixed models adjusted for age, respirator use, smoking status, and BMI, we found that Mn was associated with weld hours 7-9 months prior to clipping (p = 0.003), Pb was associated with weld hours 10-12 months prior to clipping (p = 0.03) and over the entire year (p = 0.04). Cd was associated with weld hours 10-12 months prior to clipping (p = 0.05), and also with the previous year's total hours welded (p = 0.02). The association between Ni and weld hours 7-9 months prior to clipping approached significance (p = 0.06). Toenail metal concentrations were not associated with the long-term exposure metric, years as a welder. Results suggest Mn, Pb, and Cd may have particular windows of relevant exposure that reflect work activity. In a population with variable exposure, toenails may serve as useful biomarkers for occupational metal fume exposures to Mn, Pb, and Cd during distinct periods over the year prior to sample collection.

Potentially toxic contamination of sediments, water and two animal species in Lake Kalimanci, FYR Macedonia: relevance to human health

The objectives of the research were: (1) to examine the concentrations of metals in Vimba melanops and Rana temporaria and (2) to evaluate the potential risks of the contaminated organisms to human health in Makedonska Kamenica region. Analyses identified high levels of Cr, Hg, Ni and Pb in studied animals, which also exceeded their permissible levels in food. In sediment and soil samples, levels of Cd, Cu, Cr, Pb, Zn and As were perceived, while Cd, Cu, Ni, Pb, Se and As were increased in water samples. Results of transfer factor revealed that the examined animals had higher bioaccumulation rate from surrounding waters than from sediments or soils. The accomplished Health Risk Index disclosed that studied animals can have considerably high health risks for inhabitants. Conclusively, they could be considered as highly contaminated with metals and can consequently harm human health, especially children in their early development stages.

Dynamics of metal uptake and depuration in a parasitized cyprinid fish (Rastrineobola argentea)

Infestation of fish by endoparasites may potentially influence metal uptake and elimination by the host. We quantified the metal uptake rate constant (k(u)) and efflux rate constants (k(e)) of radiolabeled Cd and Co in the cyprinid fish Rastrineobola argentea experimentally infected with the parasite Ligula intestinalis. During 24h, the accumulation of Cd and Co increased linearly with no evident steady state in uninfected fish, infected fish and in the parasite. Following aqueous exposures, the k(u) for Cd in parasites was about 3× higher than that of infected fish and 6× higher than for the uninfected fish. The k(u) for Co was up to 15× higher in the parasites than that of infected fish and 7.5× higher than for the uninfected fish. The k(e) for excretion of Cd were consistently higher for the uninfected fish than for the infected fish and also higher for uninfected fish than the parasite. The k(e) for Co for the uninfected fish was 1.4-2.0× lower than in the infected fish, but higher for parasites compared to uninfected fish (1.3-2.3×). Pulse-chase feeding experiments with radiolabeled copepods showed that Cd assimilation efficiency from food was higher in infected fish, while Co was assimilated more effectively by uninfected fish. The observed differences in metal dynamics between infected and uninfected R. argentea in the laboratory concord with differences in metal concentrations measured in natural populations in Lake Victoria. Our findings provide evidence that L. intestinalis infection enhances Cd accumulation, but depletes the essential Co in the cyprinid fish R. argentea. We conclude that the combined stress of parasites and pollution changes metal risks to fish hosts in a metal specific manner.

Human exposure pathways of heavy metals in a lead-zinc mining area, Jiangsu Province, China

Heavy metal pollution is becoming a serious issue in developing countries such as China, and the public is increasingly aware of its adverse health impacts in recent years. We assessed the potential health risks in a lead-zinc mining area and attempted to identify the key exposure pathways. We evaluated the spatial distributions of personal exposure using indigenous exposure factors and field monitoring results of water, soil, food, and indoor and outdoor air samples. The risks posed by 10 metals and the contribution of inhalation, ingestion and dermal contact pathways to these risks were estimated. Human hair samples were also analyzed to indicate the exposure level in the human body. Our results show that heavy metal pollution may pose high potential health risks to local residents, especially in the village closest to the mine (V1), mainly due to Pb, Cd and Hg. Correspondingly, the residents in V1 had higher Pb (8.14 mg/kg) levels in hair than those in the other two villages. Most of the estimated risks came from soil, the intake of self-produced vegetables and indoor air inhalation. This study highlights the importance of site-specific multipathway health risk assessments in studying heavy-metal exposures in China.

Assessing human exposure risk to cadmium through inhalation and seafood consumption

The role of cadmium (Cd) bioaccessibility in risk assessment is less well studied. The aim of this study was to assess human health risk to Cd through inhalation and seafood consumption by incorporating bioaccessibility. The relationships between trophically available Cd and bioaccessibility were constructed based on available experimental data. We estimated Cd concentrations in human urine and blood via daily intake from seafood consumption and inhalation based on a physiologically-based pharmacokinetic (PBPK) model. A Hill-based dose-response model was used to assess human renal dysfunction and peripheral arterial disease risks for long-term Cd exposure. Here we showed that fish had higher bioaccessibility (~83.7%) than that of shellfish (~73.2%) for human ingestion. Our results indicated that glomerular and tubular damage among different genders and smokers ranged from 18.03 to 18.18%. Our analysis showed that nonsmokers had 50% probability of peripheral arterial disease level exceeding from 3.28 to 8.80%. Smoking populations had 2-3 folds higher morbidity risk of peripheral arterial disease than those of nonsmokers. Our study concluded that the adverse effects of Cd exposure are exacerbated when high seafood consumption coincides with cigarette smoking. Our work provides a framework that could more accurately address risk dose dependency of Cd hazard.

Element profiles in hair and nails of children reflect the uptake from food and the environment

The present study evaluated if the element profiles in hair and nails of children from the Lake Victoria region in Kenya reflect uptake from food and the environment. To this purpose, the element concentrations in hair and nails were related to element concentrations measured in food items, water, and soil. The highest intake of most elements occurred via ingestion of the fish Rastrineobola argentea, which is consumed in higher quantities than other fish and food items. Element concentrations in hair and nails were correlated to food and soil in element-specific patterns. Multivariate analysis combining principal component analysis and multidimensional scaling enabled us to cluster individuals from specific sites and to relate differences between sites to food-consumption patterns and environmental exposures. Site-specific differences in macroelement concentrations among the children were attributed to patterns of food consumption, while those in microelement concentrations reflected differences in geochemical background. It is concluded that the simultaneous analysis of elements in human hair and nails allows separation of populations based on food consumption and geochemical background.

Parasites modify sub-cellular partitioning of metals in the gut of fish

Infestation of fish by parasites may influence metal accumulation patterns in the host. However, the subcellular mechanisms of these processes have rarely been studied. Therefore, this study determined how a cyprinid fish (Rastrineobola argentea) partitioned four metals (Cd, Cr, Zn and Cu) in the subcellular fractions of the gut in presence of an endoparasite (Ligula intestinalis). The fish were sampled along four sites in Lake Victoria, Kenya differing in metal contamination. Accumulation of Cd, Cr and Zn was higher in the whole body and in the gut of parasitized fish compared to non-parasitized fish, while Cu was depleted in parasitized fish. Generally, for both non-parasitized and parasitized fish, Cd, Cr and Zn partitioned in the cytosolic fractions and Cu in the particulate fraction. Metal concentrations in organelles within the particulate fractions of the non-parasitized fish were statistically similar except for Cd in the lysosome, while in the parasitized fish, Cd, Cr and Zn were accumulated more by the lysosome and microsomes. In the cytosolic fractions, the non-parasitized fish accumulated Cd, Cr and Zn in the heat stable proteins (HSP), while in the parasitized fish the metals were accumulated in the heat denatured proteins (HDP). On the contrary, Cu accumulated in the HSP in parasitized fish. The present study revealed specific binding of metals to potentially sensitive sub-cellular fractions in fish in the presence of parasites, suggesting interference with metal detoxification, and potentially affecting the health status of fish hosts in Lake Victoria.

Determination of select trace elements in hair of college students in Jinzhou, China

Select trace elements (Fe, Cu, Zn, Al, K, Na, Ba, Sb, Pb, As) were determined by ICP-AES after nitric acid-perchloric acid wet digestion in samples of scalp hair of University students. Some metal-to-metal intercorrelations were found. The more often the hair was dyed and marcelled, the higher were the contents of iron, copper, potassium, sodium, barium, lead, and arsenic. Copper levels increased with the degree of myopia, while zinc, lead, aluminum, iron, and potassium decreased with the myopic degree. Copper, zinc, iron, and arsenic levels were lower in white hair, while sodium and lead were higher. The levels of the elements were generally higher in the hair samples of students who drink and smoke. The hair metal contents were found to be influenced by alcohol use and smoking. Hair element analyses thus could be used as noninvasive means of detecting unhealthy lifestyles in college students.