Characteristics and sources of Pb exposure via household dust from the urban area of Shanghai, China

Distribution of urinary trace element exposure and dietary sources in women over 50 in an agricultural region- A community-based KoGES cohort study

BACKGROUND

There is a noticeable lack of information on the levels of both non-essential and essential trace elements in women aged over 50. The main objective of this study is to investigate trace element concentrations and explore the influence of sociodemographic factors and dietary sources of exposure in this demographic.

METHODS

We analyzed 19 trace elements, including manganese, cobalt, copper, zinc, molybdenum, chromium, nickel, arsenic, strontium, cadmium, tin, antimony, cesium, barium, tungsten, mercury, thallium, lead, and uranium, using ICP-MS and mercury analyzer. Urine samples were obtained from a cohort of 851 women aged over 50 who participated in the 8th KoGES-Ansung study (2017-2018). Multiple linear models were employed to explore associations between urinary trace element concentrations and sociodemographic factors and dietary sources of exposure. We used K-means clustering to discern patterns of exposure to trace elements and identify contributing factors and sources.

RESULTS

Our findings indicate higher concentrations of molybdenum (Mo), arsenic (As), cadmium (Cd), and lead (Pb) in our study population compared to women in previous studies. The study population were clustered into two distinct groups, characterized by lower or higher urinary concentrations. Significant correlations between age and urinary concentrations were observed in Ni. Smoking exhibited positive associations with urinary Cd and As. Associations with dietary sources of trace elements were more distinct in women in the high-exposure group. Urinary antimony (Sb) was positively linked to mushroom and egg intake, As to mushroom and fish, and Hg to egg, dairy products, fish, seaweed, and shellfish.

CONCLUSIONS

Our study underscores the significant gap in understanding urinary concentrations of trace elements in women aged over 50. With higher concentrations of certain elements compared to previous studies and significant correlations between age, smoking, and specific food sources, it is imperative to address this gap through targeted dietary source-specific risk management.

Domestic dogs as sentinels of children lead exposure: Multi-pathway identification and source apportionment based on isotope technique

Environmental lead exposure poses risks to children' health, thus exposure sources and pathways identification remain important concern and research scope. Due to sharing the same environment, domestic animals, especially dogs, have been used as useful sentinels to identify human lead exposure. However, more evidence is needed on whether domestic dogs could be used to identify the lead exposure pathways and sources of children. Thus, this study investigated the dietary habits, behaviors, and household environment of children and dogs in a typical coal-fired area in China. The lead levels and lead isotope ratios (Acronym: LIRs, expressed as ²⁰⁸Pb/²⁰⁶Pb and ²⁰⁷Pb/²⁰⁶Pb) in dogs' and children's blood, as well as in environmental media (food, PM_2.5, indoor/outdoor dust, drinking water and soil) were measured to explore the predominant lead pollution sources and exposure pathways of children. The results showed that the LIRs of children's blood (²⁰⁸Pb/²⁰⁶Pb = 2.0703 ± 0.0076, ²⁰⁷Pb/²⁰⁶Pb = 0.8501 ± 0.0052) were similar to those of dogs' blood (²⁰⁸Pb/²⁰⁶Pb = 2.0696 ± 0.0085, ²⁰⁷Pb/²⁰⁶Pb = 0.8499 ± 0.0052), as well as similar to the LIRs of environmental media, i.e. children's food (²⁰⁸Pb/²⁰⁶Pb = 2.0731 ± 0.0057, ²⁰⁷Pb/²⁰⁶Pb = 0.8491 ± 0.0036) and coal (²⁰⁸Pb/²⁰⁶Pb = 2.0683 ± 0.017, ²⁰⁷Pb/²⁰⁶Pb = 0.8515 ± 0.01). Children and dogs had similar lead exposure pathways, but the contributions of each exposure pathway were different, i.e., 83.1% vs. 76.9% for children and dogs via food ingestion, 1.4% vs. 5.6% via particulate matter exposure, and 15.5% vs. 17.5% via household dust exposure, respectively. The contribution of food via ingestion to lead exposure remains dominant, and coal combustion is a main lead exposure source for children and domestic dogs.

Trends in elemental Pb concentrations within atmospheric PM2.5 and associated risk to human health in major cities of China

High concentrations of elemental lead (Pb) in the atmosphere pose a serious threat to human health. This study presents and summarizes data obtained from relevant literature on Pb concentrations within fine particulate matter (PM_2.5) recorded in major cities in China from 2008 to 2019. An environmental health risk assessment model was then used to evaluate the health hazards of inhaling Pb among adults and children in China. Owing to the promulgation and implementation of a series of air pollution control measures, the Pb concentrations within PM_2.5 measured in major cities in China showed a downward trend after peaking in 2013. The concentrations were higher in winter than in summer, and higher in northern cities than in southern cities. Although the Pb concentrations in most cities did not exceed the limit (500 ng/m³) set by China, they remained much higher than concentrations recorded in developed countries. The results of the environmental health risk analysis showed that the non-carcinogenic risk from atmospheric Pb exposure was higher in children than in adults (adult females > adult males), while the carcinogenic risk was higher in adults than in children. This study shows that even if the health risk of Pb in PM_2.5 does not exceed the acceptable limit, stricter Pb pollution control measures are required to safeguard population health due to the dangers of Pb.

Distribution, sources and health risks of heavy metals in indoor dust across China

The potential effects of heavy metals on human health have attracted increasing attention as most people spend up to 90% of their time indoors. Human exposure to heavy metals in indoor dust have only been characterised for limited regions in China, and full-scale data for different functional areas are not available. Therefore, this review analysed the concentrations, contamination characteristics, and potential health risks of seven heavy metals (including zinc (Zn), lead (Pb), copper (Cu), chromium (Cr), nickel (Ni), arsenic (As), and cadmium (Cd)) in indoor dust at 3392 sampling sites in 55 cities across 27 provincial regions of China based on literature data. Results revealed that the median heavy metal concentrations in indoor dust throughout China decreased in the following order: Zn > Pb > Cu > Cr > Ni > As > Cd. Traffic emissions and decorative materials are the primary sources of heavy metal pollution in indoor dust. No considerable non-carcinogenic risk was found for Zn, Cu, Cr, Ni, and Cd in indoor dust, while Pb and As exhibited potential non-carcinogenic risks to children, primarily distributed in cities across Southern China. Meanwhile, the carcinogenic risks posed by Cr and Ni were higher than those posed by As and Cd, especially in Southern China. Therefore, effective measures in Southern China should prioritised for controlling Pb, Cr, Ni and As pollution in indoor dust to reduce human health risk. This review is useful for policy decision-making and protecting human from exposure to heavy metals in indoor dust across China.

Single and combined associations of blood lead and essential metals with serum lipid profiles in community-dwelling adults

Background

Although several studies have examined the relationships between lead (Pb) exposure and serum lipid profiles, the associations of the metal mixture, including lead (Pb) and essential metals with lipid profiles, remain unclear.

Objective

To investigate the associations of the metal mixture including Pb and essential metals [magnesium (Mg), manganese (Mn), copper (Cu), iron (Fe), zinc (Zn), and calcium (Ca)] with serum lipid profiles [total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C)], as well as the potential interactions among the metals.

Methods

Nine hundred and ninety-eight Chinese community-dwelling adults completed a questionnaire and underwent checkups of anthropometric parameters, serum lipid profile levels (TC, TG, LDL-C, and HDL-C), and blood metal concentrations (Pb, Mg, Mn, Cu, Fe, Zn, and Ca). The multivariable linear regression, weighted quantile sum (WQS) regression, and Bayesian kernel machine regression (BKMR) were applied to evaluate the single and combined associations of blood Pb and essential metals with serum lipid profiles.

Results

In the multivariable linear regression model, the blood Pb was positively associated with TC, LDL-C, and HDL-C (p < 0.05, all), and the blood Mg were positively associated with serum TC, LDL-C, and Ln TG (p < 0.05, all). In the WQS regression and BKMR models, the metal mixture of blood Pb and the essential metals was positively associated with all of the serum lipid profiles. In addition, an inverse U-shaped association of Pb with Ln TG and the positive interactive effect between blood Pb and Mg levels on TC and LDL-C were found.

Conclusion

The levels of blood Pb, together with the essential metals, especially Mg levels, are suggested to be considered when assessing dyslipidemia risk. However, more evidence is still needed to validate the conclusions.

Lead exposure dose-dependently affects oxidative stress, AsA-GSH, photosynthesis, and mineral content in pakchoi (Brassica chinensis L.)

Lead (Pb) is a heavy metal pollutant and negatively affects agriculture and ecosystems. Pb can cause oxidative stress and abnormal plant growth. The ascorbic acid-glutathione (AsA-GSH) cycle mainly exists in chloroplasts and resists oxidative stress, scavenges reactive oxygen radicals, and maintains normal photosynthesis. However, the dosage related effects of Pb on pakchoi photosynthesis, via oxidative stress and the AsA-GSH system, remains unclear. In this study, various Pb dosage stress models were tested (low: 300 mg/kg; medium: 600 mg/kg; high: 900 mg/kg). Pb stress induced a dose-dependent increase in Pb content in pakchoi leaves (P < 0.05). Principal component analysis showed that Se, B, and Pb were significantly and negatively correlated. Pb stress also increased MDA content and decreased antioxidant enzymes SOD, GSH-Px, and T-AOC activities (P < 0.05). We also found that Vc content, as well as the GSH/GSSG ratio, decreased. Additionally, Pb stress destroyed chloroplast structure, decreased photosynthesis indicators Pn, Tr, Gs, Ci and VPD, and attenuated Fv/Fm and Fv/Fo (P < 0.05). In the high-dose group, the contents of chlorophyll a, chlorophyll b, and carotenoids decreased significantly, while the expression of chloroplast development genes (GLK, GLN2) decreased (P < 0.05). Our data suggest that Pb stress leads to dosage-dependent, aberrant photosynthesis by inhibiting the AsA-GSH system in pakchoi. This study expands the Pb toxicology research field and provides indications for screening antagonists.

Effect of the interaction of fulvic acid with Pb(II) on the distribution of Pb(II) between solid and liquid phases of four minerals

Lead (Pb) is one of the top metal pollutants worldwide, and its distribution between liquid and solid phases of soils is strongly controlled by its adsorption on minerals, organic matter, and their composites. This paper presented the effect of fulvic acid (FA) coexistence on the distribution of Pb(II) at the solid-liquid interface of four minerals, which provided reference for how to use humic substances to remove toxic Pb(II) in soils. The free Pb²⁺ of suspensions, measured by Pb ion selective electrode, was used to characterize the complexation of FA with Pb²⁺ at various pH. The adsorption isotherms of Pb(II) by montmorillonite, kaolinite, goethite, and gibbsite with and without FA were studied with batch experiments. Results indicated that the free Pb²⁺ decreased and complexed Pb(II) increased with the increase of FA concentration in Pb(II)-FA solutions, whether the initial concentration of Pb(II) was 0.1 or 1 mM. Pb²⁺ hydrolysis was low and the free Pb²⁺ concentration in pure lead solution without FA was generally unchanged with increasing solution pH at pH < 6.0. But free Pb²⁺ decreased with the increase of pH in the presence of FA, suggesting that the complexation ability of FA with Pb²⁺ increased with the increase of solution pH. The adsorption of Pb(II) by the minerals without FA followed the order: montmorillonite > kaolinite ≈ goethite > gibbsite at pH5.0. The Pb(II) adsorption by montmorillonite and kaolinite significantly enhanced with 1 g/L FA, while significantly inhibited with 3 g/L FA at low initial Pb(II) concentration. However, the effect of FA on Pb(II) adsorption by montmorillonite was greater than that of kaolinite, which was mainly related to the crystal layer structure, adsorption area, and cation exchange capacity of the minerals. The Pb(II) adsorption by goethite and gibbsite was significantly enhanced by the addition of both 1 g/L and 3 g/L FA, and the enhancement was more evident in goethite system. The effect of FA on the distribution of Pb(II) between solid and liquid phases of the minerals was determined by the factors such as the initial concentration ratio of FA to Pb(II), the adsorption capacity of minerals for FA, and the number of soluble complexes of FA with Pb²⁺. Therefore, the distribution of FA between solid and liquid of four minerals affected the distribution of Pb(II) between solid and liquid phases of the minerals greatly. The results can provide an important reference for understanding the distribution of Pb(II) and the dynamics and mobility of active components in polluted soils.

Concentrations of Pb and Other Associated Elements in Soil Dust 15 Years after the Introduction of Unleaded Fuel and the Human Health Implications in Pretoria, South Africa

Leaded fuel has been reported to contain certain amounts of toxic trace metals such as Pb and Cadmium (Cd), which may have negative impacts on humans and the environment. Unleaded fuel was introduced to South Africa in 2006 with the aim of reducing and eventually eliminating the negative impact of leaded fuel on the environment. However, trace metals are usually nonbiodegradable, and it may therefore be necessary to monitor their presence in the environment so as to evaluate their possible impact on human health. The present study evaluated the levels of Pb and other heavy metals in soil samples collected from petrol (gas) filling stations and from busy roads just around the filling stations in Pretoria, South Africa, fifteen years after the introduction of unleaded fuel. A total of twenty-four (24) soil samples were analysed for lead (Pb), chromium (Cr), copper (Cu), zinc (Zn), arsenic (As), iron (Fe), manganese (Mn), nickel (Ni), titanium (Ti), and cadmium (Cd) using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The results showed that the concentrations of the trace metals were in the following ranges: Pb, 0.08 ± 0.02−188.36 ± 15.32 ug/g; Mn, 5.35 ± 0.34−6842.43 ± 1.35 ug/g; Zn, 1.82 ± 0.22−9814.89 ± 22.32 ug/g; As, 0.21 ± 0.00−8.42 ± 2.44 ug/g; Cu, 10.51 ± 3.41−859 ± 0.09 ug/g; Cr, 5.80 ± 2.21−417.70 ± 9.08 ug/g; Ti, 19.94 ± 4.99−1036.12 ± 1.49 ug/g; and Fe, 3.06 ± 7.87−674.07 ± 12.22 mg/g. The highest concentrations from all the elements were recorded for Fe in all the collected soil samples. The concentrations of Pb in the soils collected from sites associated with high traffic and industrial areas were higher than for those from all other sites, and the differences were significant (p < 0.05). The pollution index (PI), which is the anthropogenic influence of the trace metals, and the geoaccumulation (Igeo), which allows for the removal of possible variations as regards the studied element in the soil due to the possible differences in the background value, showed that some samples were enriched anthropogenically. The PI for Ni, Pb, Cu, and Cr indicated highly anthropogenically contaminated soils, especially at sites associated with high traffic volumes and in industrial areas. The Igeo showed moderately polluted areas for Pb and Cu in high-traffic areas. The exposure routes for the toxic trace metals that were of concern in the study were either through ingestion or dermal contact. The calculated hazard quotient showed both noncarcinogenic and carcinogenic risks for Fe and Mn via ingestion and through dermal contact for both children and adults, respectively. The concentrations of Pb were high and similar to those that were previously reported in the study and pointed to vehicular emission as one of the contributors. The study also noticed an increase in the presence of Mn and Fe in all soil samples.

Source Apportionment and Health Risk Assessment of Heavy Metals in Endemic Tree Species in Southern China: A Case Study of Cinnamomum camphora (L.) Presl

As a developed economic region in China, the problem of heavy metals (HMs) pollution in the Yangtze River Delta has become increasingly prominent. As an important evergreen broad-leaved tree species in southern China, the camphor tree cannot only be used as a street tree but also its various tissues and organs can be used as raw materials for Chinese herbal medicine. In order to explore whether heavy metal contamination in the region threatens the safety of camphor trees as pharmaceutical raw materials, we collected the bark and leaves of the tree most commonly used for pharmaceuticals in Yixing City. Based on the determination of HMs content, the health risks after human intake are evaluated, the sources and contributions of HMs are analyzed, and then the health risks of pollution sources are spatially visualized. The results showed that under the influence of human activities, the camphor trees in the study area had obvious enrichment of HMs, and the over-standard rate of Pb in the bark was as high as 90%. The non-carcinogenic risks of bark and leaves are acceptable, but the carcinogenic risks are not acceptable. The bark had the highest average carcinogenic risk, approaching six times the threshold. The results of Pb isotope ratio analysis showed that the average contribution rate of industrial activities to HMs in camphor trees in the study area was the highest, reaching 49.70%, followed by fossil fuel burning (37.14%) and the contribution of natural sources was the smallest, only 13.16%. The locations of the high-risk areas caused by the three pollution sources in the study area are basically similar, mainly concentrated in the northwest, northeast, and southeast, which are consistent with the distribution of industries and resources in the study area. This study can provide a reference for the precise prevention of HMs pollution of camphor and the safe selection of its pharmaceutical materials.