Average Lead Concentration Research Articles

Determination of Heavy Metals in Cocoa Products Consumed in Nairobi County Kenya

Cocoa is an important cash crop obtained from the beans of the Theobroma cacao tree belonging to the family Malvaceae. Its products are rich in several classes of phenolic compounds such as Flavanols, procyanidins, and anthocyanins. These compounds are attributed to copious health benefits. In addition to the bioactive compounds, cocoa contains heavy metals whose origin and levels depend on natural and anthropogenic activities. Beyond permissible limits, these metals are linked to deleterious damage to several systems in the human body. This study aims to determine the concentration of some heavy metals in Cocoa products and compare the levels with the permissible exposure limits stipulated by international health agencies. This was achieved by wet digestion of the strategically sampled cocoa products and their analysis using the atomic absorption spectrometry technique. The average concentration of Lead (Pb), Copper (Cu), Zinc (Zn), and Manganese (Mn) in cocoa powder was 0.154±0.021, 0.270±0.037, 0.794±0.063, and 0.334±0.015 respectively. The average concentration of Pb, Cu, Zn, and Mn in cocoa butter was 0.329±0.008, 0.028±0.038, 0.116±0.075, and 0.124±0.008 respectively. The average concentration of Pb, Cu, Zn, and Mn in chocolate milk was 0.463±0.003, 0.042±0.066, 0.296±0.015, and 0.162±0.010 respectively. Cadmium levels were below the detection limit in all the samples. The results obtained in all the samples were within the WHO and KEBS permissible levels in food products.

The Effect of Cord Blood Lead Level on Neonatal Growth Parameters at a Tertiary Care Center in Southern India

Context: Environmentally prevalent lead is a potentially hazardous metal. Depending on its absorption and desorption, lead causes detrimental effects. The growth of fetus and newborn is seriously impacted in utero due to lead exposure in mothers. Aims: (1) To determine the lead levels in cord blood and (2) to determine the relationship of blood lead levels with anthropometry in newborns. Settings and Design: Cross-sectional study, department of pediatrics for 6-month period (May 2022 to October 2022). Subjects and Methods: The study included term and preterm babies above 28 weeks of gestation, born to mothers without risk factors. Cord blood samples from 83 newborns were analyzed for lead levels by inductively coupled plasma optical emission spectrometry. Statistical Analysis: Taking power as 80% and alpha error as 5%, sample size (n = 83) was obtained using regression methods. Results: The average lead concentration in the cord blood was detected to be 0.4 μg/dL (0.05–1.90 μg/dL). Using Pearson’s correlation coefficient, decrease in birth weight with increasing lead levels was statistically significant (P = 0.0005, r = −0.464). The correlation between gestational age, length, head circumference, chest circumference of newborn, and cord blood lead level (r = −0.364, P = 0.001); (r = −0.343, P = 0.001); (r = −0.435, P = 0.0005); and (r = 0.446, P = 0.0005), respectively, was highly significant. A moderately significant correlation was found between abdominal circumference and cord blood lead level (r = −0.343, P = 0.001). Conclusions: Reduction in neonatal anthropometric measurements, especially the birth weight, length, chest circumference, and head circumference, was noted with increasing lead levels in umbilical cord blood.

Dependence of bioavailability of lead compounds in soils on the type and source of contamination (the example of Mexico City and mining area of Parral, Mexico)

Evaluation and monitoring of soil contamination with heavy metals relies in most cases on their bulk concentrations whereas the risks of negative effects on human health depend upon the content of their bioavailable forms. The paper presents the study of the dependence of lead bioavailability in the surface soil horizons upon the contamination type and source. Two territories in Mexico with sharp difference of the source of pollution: Mexico City megapolis where the lead in soils originates from the ethyl gasoline burning and mining district in the south of Chihuahua State where the mine tailings are the source of the toxic elements including lead. Bulk lead concentrations were measured by the X-ray fluorescence method, bioavailability was estimated by the method imitating the effect of the stomach and intestine solutions. The research has shown that both in Mexico City (especially in its central part) and in the mining district in the Chihuahua State bulk lead concentrations are several times higher than the background values. The soils of the mining district have average bulk lead concentrations 787,5 mg/kg and show the average bioavailability values 64% whereas in the Mexico City megapolis average bulk concentrations of lead are lower - 324,7 mg/kg but bioavailability reaches 83% and in some samples even 100%. These results support the conclusion that despite lower bulk lead concentrations in Mexico City the risk of its negative effect on humans is higher than in the mining district polluted with the wastes of mining industry. The explanation of the observed tendency is that the chemical form of lead has a major influence on its bioavailability. Dependence of bioavailability upon the bulk concentrations within each study territory has not been established.

Analytical Procedure for Determination of Lead in Blood and Urine by Atomic Absorption Spectrometry

Lead is one of the natural constituents of earth found in soils, plants, and water. Lead predominantly a concern for neurological toxic effect particularly in children due to its irreversible neurological damage. The common spectroscopic methods in trace element analysis in biological fluids are dithizone extraction, polarography, spectral analysis, atomic absorption spectrometry (AAS), inductively coupled plasma atomic emission spectrometry. A graphite furnace atomic absorption spectrophotometer is a valuable, simpler, and cost-effective spectrometric technique for the identification of lead absorbance in the human system. The GF-AAS method can be employed for the measurement of lead percentage in whole blood and urine, and the results acquired are helpful in biological monitoring and clinical diagnostic of work related to surrounding lead exposure. The paper reports the average lead concentration, and calibration graphs for standards as well as absorbance against lead concentration, which will be productive in future for analytical determination of lead in blood and urine.

A Determining and comparing lead and cadmium concentration in Sediments of the Coast of Benghazi – Libya

This study was designed to measure the content of lead and cadmium in coastal sediments in the coastal city of Benghazi as an indicator of the pollution of these areas with these metals. The study included measuring the average concentration of lead and cadmium metals in the study areas, which included each Sidi Khalifa, Galiana, and Garyounis, at different distances. The obtained results showed that the average concentration of lead and cadmium is 1.263 ppm and 0.304 ppm, respectively, in all study areas. The results of the statistical analysis (SPSS-26) show that there are significant differences at a probability level of less than 0.05, indicating that the studied sediments contain lead and cadmium in all study areas, and the lowest concentration of lead and cadmium was present in the sediment samples collected at a distance of 2 m. From the coast of the city of Benghazi.

Lead concentration in human hair in Russia: a systematic review

BACKGROUND: Extensive measures to reduce lead concentrations in the biosphere are implemented in many countries, therefore, the world community predicts a decrease in the quantitative content of lead in the environment. The concentration of lead in human hair is considered as an indicator of environmental pollution, therefore, systematized information on this indicator in the subjects of the Russian Federation is necessary to assess the effectiveness of environmental measures.
 MATERIAL AND METHODS: This is a systematic review following PRISMA guidelines. We performed a systematic search and qualitative synthesis of scientific literature on hair concentrations of lead across Russia between 2011 and 2021. PubMed and eLIBRARY.RU were the main sources of scientific information in English and Russian, respectively. Initial search returned 1748 matches. Thirty-seven papers remained for qualitative synthesis after screening and eligibility analysis.
 RESULTS: During the study period, the results of studies on 27 subjects of the Russian Federation were published, which is one third of all subjects of the federation. No heterogeneity was observed in sample preparation while methods of laboratory analysis varied between the settings and included inductively coupled plasma mass spectrometry, atomic absorption spectrometry and inversion voltammetry. The sample sizes ranged from 5 to 5908 individuals. The average lead concentrations varied between 0.01 and 6.54 mg/kg. The greatest concentrations of lead were reported in the Orenburg (6.54 mg/kg) and Chita Regions (4.35 mg/kg).
 CONCLUSION: Two-thirds of all subjects of the Russian Federation for the period 20112021 are not covered by the study, so there are no data on the concentration of lead in the hair of the population of these regions. Further data collection should be performed using representative and sufficient sample samples while presentation of the results should contain detailed information on methods of data collection and analysis to ensure reproducibility and comparability of the findings.

Assessment of Heavy Metal Pollution Status in Surface Soil of a Nigerian University

The problem of urban soil contamination with heavy metals due to rapid urbanization and industrialization has been a major concern in recent years. A university can be considered as a product of industrialization and urbanization which is associated with different activities that may induce heavy metals pollution into the environment. Therefore, this research work assessed the contamination level of chromium (Cr), copper (Cu), lead (Pb), zinc (Zn) and manganese (Mn) in surface soils of Afe-Babalola university (ABUAD) using various indices. Soil samples were taken from ten (10) different functional sites in the university. These samples were taken to the laboratory and analyzed for chromium (Cr), copper (Cu), lead (Pb), zinc (Zn) and manganese (Mn) using standard method. The mean concentrations of copper (Cu), chromium (Cr) and lead (Pb) were up to 0.75, 0.66 and 0.36 mg/g respectively, while manganese (Mn) and zinc (Zn) were 1.37 and 0.49 mg/g respectively. The average concentration of manganese (Mn) was comparable to its corresponding natural background value, but the average concentration of chromium (Cr), copper (Cu), zinc (Zn) and lead (Pb) were higher. They were approximately of the ratio 1:7, 1:2, 1:3 and 1:2 respectively compared to their corresponding natural background value. The multivariate statistical analyses indicated that vehicles, power generating sets, petrol station, machine workshops, production plants and emissions from outdoor roasted food spots were the major sources of heavy metals contamination on the universitys’ soil. The results from contamination indices and assessment showed that the contamination level of soils within the university can generally be classified as moderately contaminated. Therefore, periodic assessment of the sources and associated ecological risks of the heavy metals is highly recommended. This is to enable decision-makers to effectively manage the environment in the manner that will preserve public and ecosystem health.

Analysis of heavy metal content and microbiological quality of fish and giant prawns chatch in Percut Watershed, Percut Sei Tuan District, Province of North Sumatra

The purpose of this research was to determine the content of heavy metals and microbiological quality, and compare to the requirements of the quality standard values according to SNI 2729:2013 and SNI 2705:2014, as well as to determine the value of the Bioaccumulation Factor (BAF) and the maximum consumption limit of fish and giant prawns heavy metal-concentrated. This researh used survey and random sampling methods, i.e taking research samples (tilapia, broom fish, and giant prawns) at 3 (three) observation stations, including Station 1 Amplas, Station 2 Denai, and Station 3 Percut. Heavy metal content (Pb and Cd) and microbiological quality (E.coli and Salmonella, sp) were analysed. Data analysis was done by inference and calculated using Microsoft office Excel (Microsoft Inc., USA) descriptively. The results showed that all samples in each observation did not meet the quality standard value requirements according to SNI 2729:2013 and SNI 2705:2014. The average heavy metal content of Lead (Pb) was 0,3 mg/kg in tilapia and broom fish, and 0,5 mg/kg in giant prawns. The content of heavy metal Cadmium (Cd), were 0,1 mg/kg in tilapia and broom fish, and 0,5 mg/kg in giant prawns. All samples also showed positive in containing E.coli and Salmonella, sp. The value of Bioaccumulation Factor (BAF) of heavy metals (Pb and Cd) in all samples was 1, meaning that the sample's ability to accumulate heavy metals (Pb and Cd) was high. The maximum limit for consumption of concentrated samples of heavy metals in tilapia was 0,196 kg/week, broom fish was 0,221 kg/week, and giant prawns was 0,203 kg/week.

The Brown Hare (Lepus europaeus) as a Biomonitor for the Presence of Lead and Cadmium in Vojvodina, Serbia

Summary Lead (Pb) and cadmium (Cd) are heavy metals considered possible contaminants of water, soil and air (especially when occurring as a consequence of human activities in agriculture or industry), and can be found in the liver or kidneys of animals, thus serving as indicators of pollution. Vojvodina is a northern province of the Republic of Serbia which boasts very intensive agricultural production, especially crop production. The brown hare is well-adapted and abundant in Vojvodina. As a complete herbivore, it has the potential to be a good biomonitor for the presence of lead and cadmium in the chosen biotope. A total of 60 samples of hare livers were collected and analyzed immediately after hunting. The average concentration of lead in all the liver samples analyzed was 851.43 µg/kg of wet tissue. The lead concentrations determined at three different sites in Vojvodina (namely Odžaci in Bačka, Rusko selo in Banat and Kraljevci in Srem) were not statistically significant. However, the average lead concentrations at all the sites were above the permitted level (500 µg/kg of wet tissue). The maximum amount of lead determined was 2,302 µg/kg of wet tissue, i.e. almost five times above the permitted level. The cadmium concentrations in all the samples analyzed ranged from 12.90 to 1183.00 µg/kg of wet tissue. The average cadmium concentrations determined at three different sites were found statistically significant, suggesting a local source of contamination. The average cadmium concentrations at sites I, II and III were 65.57, 205.91 and 413.99 µg/kg of wet tissue, respectively. The average cadmium concentrations determined at the sites considered were below the permitted level, although exceeding the legal limit in some of the samples analyzed.

The European Hare (Lepus europaeus) as a Biomonitor of Lead (Pb) and Cadmium (Cd) Occurrence in the Agro Biotope of Vojvodina, Serbia

Simple SummaryHeavy metals such as lead and cadmium are pollutants and can be found in different biotopes. Hares, due to their natural habitat, numbers, range and choice of food are good bioindicators of the occurrence of heavy metals. Vojvodina, northern province of Republic of Serbia, has intensive agriculture with about 77.8% of agricultural land. In such agricultural biotope, we discovered that out of the two studied heavy metals in the liver of hare’s it seems that the occurrence of lead is more of the importance. In the majority of locations the cadmium concentrations were in the permitted level by Serbian legislative. However, the situation with the occurrence of lead was completely different. Only on the two out of seventeen locations average concentrations were in the permitted level.The aim of this study was to investigate the occurrence of two heavy metals, lead and cadmium, in European hare liver samples, collected in agro biotope of northern Serbian province Vojvodina. Heavy metals such as lead (Pb) and cadmium (Cd) do not have any biological function in the animal body; however, they can be found due to the pollution in the environment. For the purpose of this study, in 196 samples from 17 different locations hare livers were analyzed for the occurrence of lead and cadmium. All samples were taken from hares harvested during the regular hunting season. The average value for lead in all analyzed samples was 884 µg/kg fresh weight (fw), with the range 59–3700 µg/kg fw. Only samples from two locations had the average concentration of lead which was within the permitted limit by the Serbian regulation. The average cadmium level in all samples was 243 µg/kg fw. The range of all samples was from 0 to 1414 µg/kg fw. Our research indicates that out of two investigated heavy metals, the occurrence of lead is more common and at a higher concentration in the agricultural development region of Vojvodina.

Determination of Heavy Metals in Soil around Amasoma Community in Bayelsa State, Nigeria

Aims: Anthropogenic activities such as crude oil exploration and exploitation has led to the suspicion of heavy metals contamination in the study area. This study investigated the concentration of zinc, nickel, lead and cadmium in the soil extracted from the area where Scent Leaf (Ocimum gratissimum) and Pawpaw tree (Carica papaya) are grown in Amassoma community, Bayelsa State, Nigeria.
 Study Design: Scent leaf (Ocimum gratissimum) and Pawpaw tree (Carica papaya) soils from where these plants are grown were randomly collected for heavy metal analysis from within Amassoma community in Southern Ijaw Local Government Area of Bayelsa State, Nigeria
 Place and Duration of Study: This study was carried out in Biological Sciences, Faculty of Science, Niger Delta University, Wilberforce Island, Amassoma, Bayelsa State between March 2019 to September 2019
 Methodology: Scent leaf (Ocimum gratissimum) and Pawpaw tree (Carica papaya) soils were digested and analyzed for heavy metals using Atomic Absorption Spectrophotometer (AAS, model S471096). The method used was wet-ashing method for the analysis.
 Results: the concentrations of Lead (Pb), Nickel (Ni), Cadmium (Cd), and Zinc (Zn), in pawpaw soil and scent leaf soil. From the sample data analysis, the average lead (Pb) contents in pawpaw soil and scent leaf soil were 1.283 mg/kg and 1.44 mg/kg respectively. The average Cadmium (Cd) in pawpaw soil and scent leaf soil were 0.256 mg/kg and 0.256 mg/kg respectively. The average Nickel (Ni) compositions in pawpaw soil and scent leaf soil were 4.71 mg/kg and 5.09 mg/kg respectively. While the Average Zinc (Zn) in pawpaw soil and scent leaf soil is 2.280 mg/kg and 2.160 mg/kg respectively. The soil analyzed for heavy metals were below the threshold target values recommended by the WHO.
 Conclusion: The Scent leaf (Ocimum gratissimum) and Pawpaw tree (Carica papaya) soils analyzed for heavy metals were below the permissible limit recommended by WHO for soil safety. The result from the present study revealed that there may not be soil contamination as a result of the selected heavy metals, however, It is recommended that caution should be taken in regulating the anthropogenic activities that may tend to elevate the level of heavy metals in the surrounding to prevent contamination of soil over time which could be detrimental to the health of the populace.

Production of Thin Pb<sub>x</sub>Sn<sub>1–x</sub>Te Films by “Hot Wall” Method for Creating IR-Photodetectors

Alloys of lead and tin telluride (PbxSn1–xTe) are materials with good thermoelectric properties, as well as semiconductors that can be used as long-wave infrared detectors. Polycrystalline telluride of PbxSn1–xTe (0.05 £ x £ 0.80) alloys has been synthesized by direct fusion technique. Thin films of these materials have been obtained by the hot wall method depositing Сorning 7059 on glass substrates at Tsub = (200–350) oC and vacuum of about 10–5 Torr. The microstructure of the films has been investigated by XRD, SEM and EDX methods. The X-ray spectra of thin films have been in satisfactorily agreement with the spectra of the powder target and indicated the absence of binary phases. The films have shown a natural cubic crystalline structure. While increasing the lead content, the unit cell parameter of the crystal also increases. The established linear relationship between the unit cell parameter and the elemental composition corresponds to Vegard's law. The SEM analysis has shown that the films are polycrystalline, have a columnar structure, are tightly packed and have good mechanical adhesion. The grain size depends on the chemical composition and temperature of the substrate. The electrical measurements have shown that the grown films are non-degenerate semiconductors of p-type conductivity. The conductivity of the films was in the range of σ = (3 × 101)–(1 × 104) Ω–1×cm–1. An increase of lead concentration leads to a decrease in electrical conductivity. Hall mobility in the grown thin films increases in the range of changes in the lead content from ~10 to ~23 at. %, and decreases with a further increase to ~33 at. %. At the same time, the strongest dependence of the decrease in mobility on an increase in temperature increase is observed for films with a high lead content and is explained by the predominant scattering of charge carriers by vibrations of the crystal lattice. For a sample with an average lead concentration, an alternative effect of two scattering mechanisms is observed in the temperature dependence of the mobility: by impurity ions and by phonons.

The use of statistical methods to assess groundwater contamination in the Lower Tano river basin, Ghana, West Africa.

In this study, descriptive statistics, correlation matrix, multiple regression model, and geostatistical models were used to assess the contamination of groundwater with respect to trace elements in the Lower Tano river basin, Ghana, West Africa. A total number of 48 boreholes drilled across the basin with depths ranging from 18 to 60m were used as data sources in this study. The results of the descriptive statistics showed that the average lead, iron, and aluminium concentrations exceeded the WHO permissible limits of 0.3mg/L, 0.01mg/L, and 0.2mg/L respectively. Furthermore, copper, chromium, aluminium, zinc, manganese, nickel, iron, arsenic, electrical conductivity, and total dissolved solids were found to be extreme and highly positively skewed. Even though significant correlations exist among some variables, the statistical results showed that the quality of the boreholes drilled across the basin was mainly originating from geogenic and anthropogenic sources. In addition, each pair of correlated physical parameters and trace elements in the drilled boreholes were predicted using multiple regression models. Likewise, geostatistical modelling was used to assess the spatial analysis of each pair of correlated physical parameters and trace elements in the drilled boreholes. The cross-validation results revealed kriging model, as the most precise model for the spatial distribution maps for the correlated physical parameters, and correlated trace elements concentration in the boreholes drilled across the study region. The semivariogram models showed that most of the correlated physical parameters and correlated trace elements were weak moderately and strongly spatially dependent, suggesting fewer agronomic influences. The results of the spatial analysis were consistent with the multiple regression model and the Pearson correlation matrix.

Radon potential mapping in Jangsu-gun, South Korea using probabilistic and deep learning algorithms

The adverse health effects associated with the inhalation and ingestion of naturally occurring radon gas produced during the uranium decay chain mean that there is a need to identify high-risk areas. This study detected radon-prone areas using a geographic information system (GIS)-based probabilistic and machine learning methods, including the frequency ratio (FR) model and a convolutional neural network (CNN). Ten influencing factors, namely elevation, slope, the topographic wetness index (TWI), valley depth, fault density, lithology, and the average soil copper (Cu), calcium oxide (Cao), ferric oxide (Fe2O3), and lead (Pb) concentrations, were analyzed. In total, 27 rock samples with high activity concentration index values were divided randomly into training and validation datasets (70:30 ratio) to train the models. Areas were categorized as very high, high, moderate, low, and very low radon areas. According to the models, approximately 40% of the study area was classified as very high or high risk. Finally, the radon potential maps were validated using the area under the receiver operating characteristic curve (AUC) analysis. This showed that the CNN algorithm was superior to the FR method; for the former, AUC values of 0.844 and 0.840 were obtained using the training and validation datasets, respectively. However, both algorithms had high predictive power. Slope, lithology, and TWI were the best predictors of radon-affected areas. These results provide new information regarding the spatial distribution of radon, and could inform the development of new residential areas. Radon screening is important to reduce public exposure to high levels of naturally occurring radiation.

Heavy Metals in the Bottom Sediments of the Black Sea Northwestern Shelf in Recent Years

Purpose. The study is aimed at investigating metal accumulation in the 0–2 cm layer of the bottom sediments of the Black Sea northwestern shelf over 2000–2020, and at identifying the sea bottom areas subjected to the increased anthropogenic load through comprehensive assessment of the degree of their pollution taking into account their granulometric composition. Methods and Results. The bottom sediments were sampled annually from the 0–2 cm depth at the same stations. The detected metal concentrations were compared with their content in the Earth crust and the background values. The dynamics and trends of the individual metals’ content in the shelf bottom sediments were assessed for the whole period of observations. The notion of the average characteristic concentration of an element is introduced; the procedure for its calculation is represented. The pollution of bottom sediments was analyzed with the regard for the element average characteristic concentration in the bottom sediments of various granulometric types. Increase in the average content of lead, zinc and chromium was revealed from the beginning of the observation period to 2020. The seasonal dynamics of these elements was found in the whole water area under study (as well as the iron content at some areas). Conclusions. Multiple cases of the lead, manganese and chrome concentrations exceeding their content in the Earth crust were recorded; as for zinc and copper, such cases were few and sporadic. The tendencies in variation of the bottom sediments content were determined: the average long-term values of the lead concentration increased by 1.2 times, those of zinc – by 1.6 times, and those of chrome – by 2 times; the concentrations of iron, manganese and copper remained essentially the same. Seasonal dynamics of the zinc, chromium, lead and iron content was shown. For a number of metals, the cases when their absolute content exceeded their average characteristic concentration in the corresponding type of the bottom sediments had been found. The regions subjected to a multi-faceted anthropogenic load were identified; the areas of possible local inflow of the monitored elements were revealed. The bottom sediments sampled in 2019 were the most polluted.

Tyazhelyye metally v donnykh osadkakh shel'fa severo-vostochnoy chasti Chernogo morya v sovremennyy period

Purpose. The study is aimed at investigating metal accumulation in the 0–2 cm layer of the bottom sediments of the Black Sea northwestern shelf over 2000–2020, and at identifying the sea bottom areas subjected to the increased anthropogenic load through comprehensive assessment of the degree of their pollution taking into account their granulometric composition. Methods and Results. The bottom sediments were sampled annually from the 0–2 cm depth at the same stations. The detected metal concentrations were compared with their content in the Earth crust and the background values. The dynamics and trends of the individual metals’ content in the shelf bottom sediments were assessed for the whole period of observations. The notion of the average characteristic concentration of an element is introduced; the procedure for its calculation is represented. The pollution of bottom sediments was analyzed with the regard for the element average characteristic concentration in the bottom sediments of various granulometric types. Increase in the average content of lead, zinc and chromium was revealed from the beginning of the observation period to 2020. The seasonal dynamics of these elements was found in the whole water area under study (as well as the iron content at some areas). Conclusions. Multiple cases of the lead, manganese and chrome concentrations exceeding their content in the Earth crust were recorded; as for zinc and copper, such cases were few and sporadic. The tendencies in variation of the bottom sediments content were determined: the average long-term values of the lead concentration increased by 1.2 times, those of zinc – by 1.6 times, and those of chrome – by 2 times; the concentrations of iron, manganese and copper remained essentially the same. Seasonal dynamics of the zinc, chromium, lead and iron content was shown. For a number of metals, the cases when their absolute content exceeded their average characteristic concentration in the corresponding type of the bottom sediments had been found. The regions subjected to a multifaceted anthropogenic load were identified; the areas of possible local inflow of the monitored elements were revealed. The bottom sediments sampled in 2019 were the most polluted.

Lead contamination status and assessment of potential risk to human health of commercial foods in Guangzhou City in 2017-2019

To investigate lead contamination in commercial foods in Guangzhou City, and to assess the health risk of dietary lead exposure in the residents. Food samples were collected in 11 districts in Guangzhou City from 2017 to 2019.The samples were tested for lead by using inductively coupled plasma mass spectrometry. The dietary exposure to lead of residents of different age groups in Guangzhou was calculated in combination with the intake of foods from the food consumption survey of Guangzhou residents in 2011, and the margin of exposure(MOE) method was used to evaluate the health risk of the population. A todal of 3130 food samples of 15 categories were collected. The overall lead detection rate was 82.11%, the exceeding rate was 0.13%, and the average lead content was 0.031 mg/kg. The highest lead levels were found in bivalve, edible fungi and flour and flour products. Excessive levels of lead were found in bivalve, eggs and egg products, and flour and flour products. The average daily dietary intake of lead in people aged 3-6, 7-17, 18-59 and over 60 in Guangzhou were 0.368, 0.377, 0.326 and 0.337 μg/kg, respectively. Daily lead exposure of population with high consumption(P95) in various age groups through foods were 1.091, 1.079, 0.906 and 0.925 μg/kg, respectively. Brassica and leafy vegetables, rice and its products and meat were the main sources of dietary lead exposure, accounting for 53.28% of the total dietary lead exposure. The average MOE of lead in all age groups were greater than 1, but the P95 of MOE value of people aged 3-6 and 7-17 were 0.55 and 0.56, respectively, which presented certain health risks. There was a certain amount of lead exceeding the standard in commercial foods in Guangzhou. The average level of dietary lead exposure for residents of all ages posed a low risk to population health, but the dietary lead exposure risk of high-food consumers aged 3-6 and 7-17 posed certain health risks that deserve significant attention.

Rapid and simple lead service line detection screening protocol using water sampling.

Many water systems are challenged with uncertainty regarding service line material type. This work investigated using a simple drinking water flushed sampling approach and a more complicated and invasive sequential profile sampling approach to predict whether homes had an existing lead service line (LSL). Homes that never had an LSL (control groups) and homes with LSLs (study groups) in two communities having different degrees of corrosion control were sampled. Using control groups' results, community-specific "threshold" lead levels were determined and compared to results from study groups. The flushed sampling maximum lead concentration (FMC) of lead accurately predicted 100% and 60% of LSL sites for the community with poor and good corrosion control, respectively. The weighted average sequential profile lead concentration (WASLC) increased the 40% not identified as LSL sites by fully flushed samples to 100%. The WASLC closely followed by the maximum sequential profile lead concentration were most reliable in identifying LSLs.

Water quality assessment, multivariate analysis and human health risks of heavy metals in eight major lakes in Kenya

This study evaluates water quality, concentrations and health risks of heavy metals (HMs) in eight major lakes in Kenya namely Naivasha, Elementaita, Nakuru, Baringo, Bogoria, Turkana, Victoria and Magadi. Water quality was assessed using water quality index (WQI) and pollution evaluation index (PEI), while human health risk associated with ingestion and dermal contact of HMs was assessed using hazard quotients (HQ) and hazard index (HI). Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were used to deduce the probable sources of the HMs. The average concentration of aluminium (Al), molybdenum (Mo), manganese (Mn), nickel (Ni), arsenic (As), zinc (Zn), selenium (Se), lead (Pb), chromium (Cr), mercury (Hg), cobalt (Co) and cadmium (Cd) in the eight lakes was 824.6, 66.1, 58.9, 16.2, 8.40, 7.84, 6.91, 4.65, 2.66, 0.86, 0.78 and 0.46, respectively, all in μg/L. Al, Mn, As, and Mo were relatively high in Rift Valley lakes and exceeded the maximum permissible levels for drinking water. Notably, high HM concentrations were recorded at the entry points of rivers and areas with high human activities. Lake Magadi had the highest average WQI of 158.8 followed by lake Elementaita (128.4), Bogoria (79.5), Nakuru (73.3), Turkana (57.6), Victoria (52.3), Baringo (42.6) and Naivasha (25.5). Lake Magadi also had the highest average PEI of 40.0 followed by Elementaita (30.1), Bogoria (16.2), Nakuru (15.7), Victoria (10.8), Baringo (9.57), Turkana (9.53) and Naivasha (5.12). Based on WQI, Lake Naivasha water was excellent for drinking, Lake Victoria, Turkana, Baringo, Nakuru, and Bogoria had good water, but water from Lake Elementaita and Magadi was of poor quality. PEI classified the lakes as minimally polluted except Lake Magadi. Multivariate analysis concluded that Pb, Cr, Ni and Se had anthropogenic sources, mainly agricultural and urban runoff, but other HMs had natural influence. Although the HMs did not pose any health risks through dermal contact, HQingestion was >1 for adults and children consuming water from Lake Elementaita, Nakuru, Bogoria and Magadi due to non-carcinogenic risks associated with As, Zn and Mo. These results are important for formulating the necessary remediation policies to improve water quality in the eight lakes.

Heavy metal concentrations in the edible tissues of some commercial fishes caught along the Eastern Black Sea coast of Turkey and the health risk assessment

Concentrations of some metals were determined in muscle tissue of five marine fish species (Engraulis encrasicolus, Sarda sarda, Mullus barbatus, Trachurus mediterraneus, and Merlangius merlangus) caught from the Eastern Black Sea coast of Turkey in 2017. Heavy metals were analyzed by using inductively coupled plasma-optical emission spectrometry after the muscle tissues of fish were digested by acids. The metal accumulation differences between species were investigated statistically. The levels of aluminum, cadmium, chromium, copper, iron, manganese, lead, and zinc in the muscles of fish were 3.27, 0.12, 0.27, 2.04, 9.97, 1.00, 0.95, and 10.65 µg/g, respectively. The highest levels of aluminum, cadmium, chromium, and manganese were detected in E. encrasicolus; the highest levels of lead and zinc were accumulated in T. mediterraneus and the highest concentration of iron and copper was found in S. sarda. The average lead concentration values were found to be above the limit values determined by national and international standards due to anthropogenic inputs such as mining activities and agricultural wastes. In addition, potential risks associated with human consumption were evaluated using quality indices such as estimated daily intake and target hazard ratio. According to these indexes, a potential risk in terms of human health has not been identified due to consuming fish tissues.