A global perspective of the current state of heavy metal contamination in road dust

Metals and metalloids pollution levels, partitioning, and sources in the environmental compartments of a small urban catchment in Moscow megacity

This study examines the contamination levels and sources of 32 metals and metalloids (MMs) in environmental compartments (roadside soil, road dust, and river suspended sediments) of a small urbanized river catchment located in Moscow megacity. MMs partitioning between particle size fractions (PM1000, PM1-10, and PM1) was analyzed by ICP-MS and ICP-AES methods. The pollution level of particle size fractions with MMs decreases in the following series: road dust > suspended sediments > soils. Absolute principal component analysis with multiple linear regression (PCA/APCS-MLR) shows that in both relatively coarse (PM1-10) and fine (PM1) fractions, traffic emissions are the primary contributors to pollution, whereas natural sources are dominant providers of chemical elements in bulk samples (PM1000). The predominance of fractions with a diameter over 10 μm in all three studied compartments indicates that the mineral matrix of all compartments is formed predominantly by natural material. Across all compartments and their fractions, Sb, Cd, Zn, Mo, W, Sn, Cu, Pb, and Bi are consistently accumulated. PM1 and PM1-10 particles of road dust and suspended sediments also absorb Ni and Cr, suspended sediments retain Mn and As, and soils additionally accumulate As. Anthropogenic influence is more pronounced in PM1 and PM1-10 particles compared to bulk samples due to a large impact of industrial sources, traffic, construction activities, and waste storage. Polluted soils are an additional source of MMs to PM1 and PM1-10 of road dust and PM1-10 of suspended sediments, and road dust acts as a source of MMs to PM1-10 of soils.

Genome-wide identification and expression analysis of SpUGE gene family and heterologous expression-mediated Arabidopsis thaliana tolerance to Cd stress

The UDP-glucose 4-epimerase (UGE) enzyme plays a critical role in plant growth and responses to abiotic stressors, such as heavy metal exposure. However, UGE-mediated remodeling of cell wall polysaccharides in response to these stressors remains poorly understood in willow. This study investigated the structure, function, and expression patterns of the UGE gene family in willow, focusing on cadmium treatment to elucidate how SpUGE1 enhances Cd resistance. Six SpUGE genes were identified through whole-genome sequencing and bioinformatics analysis, and they were mapped across five chromosomes. Quantitative PCR analysis revealed that, with the exception of SpUGE3, all genes showed their highest relative expression in the leaves. Under Cd treatment, members of the SpUGE gene family displayed varying levels of responsiveness, with SpUGE1 showing a marked increase in expression over time. In transgenic Arabidopsis thaliana overexpressing SpUGE1, the cellulose, hemicellulose, lignin, and pectin content significantly increased, with cellulose levels rising by >50 % and pectin by approximately 30 %. This overexpression conferred enhanced Cd resistance by increasing cell wall thickness through elevated cell wall polysaccharides, which reduced Cd uptake. Consequently, Cd content in the cell wall, chloroplasts, and mitochondria was significantly lower than that in wild-type plants, reducing cellular damage and improving Cd resistance. Overall, this study provides valuable theoretical and experimental insights into the role of the SpUGE1 gene family in willow.

Association between multiple metals exposure and metabolic dysfunction-associated fatty liver disease among Chinese adults

BACKGROUND

Previous research has investigated the hepatotoxicity of single metal exposure. However, there is limited evidence about metal mixture and their association with metabolic dysfunction-associated fatty liver disease (MAFLD), particularly in the Chinese population.

OBJECTIVE

To investigate the individual and combine effects of 20 metals on MAFLD in a large population in China.

METHODS

This study included 3651 participants from the Medical Physical Examination Center of Tongji Hospital, Wuhan, China. MAFLD was identified based on ultrasonic graphic evidence of hepatic steatosis and the presence of overweight/obese, diabetes mellitus, or metabolic dysregulation. Inductively coupled plasma mass spectrometry (ICP-MS) was used to determine urinary concentrations of 20 metals. Logistic regression was used to assess the relationship between individual metal and MAFLD, with results presented as odds ratios (ORs) and 95 % confidence intervals (CIs). Weighted quantile sum (WQS) regression was performed to evaluate the combine effect of metals.

RESULTS

The prevalence of MAFLD among the participants was 32.1 % (1173/3651). In singe-metal analysis, high exposure to zinc (OR =1.42; 95 % CI = 1.27, 1.59) and selenium (OR = 1.23; 95 % CI = 1.10, 1.39) were positively associated with MAFLD. No significant association was found for other metals. WQS regression analysis showed that urinary metal mixture was positively associated with MAFLD (OR = 1.32, 95 % CI: 1.15, 1.51), with zinc (50.4 %) being the largest contributor, followed by barium (10.8 %).

CONCLUSIONS

In conclusion, our finding suggested that exposure to the mixture of metals was positively correlated with MAFLD, with zinc being the major contributor.

Heavy metal levels of outdoor dust from the Eastern Mediterranean Sea region and assessment of the ecological and health risk

As a result of some chemical element (heavy metals) pollution of dust, environmental pollution of dust has become an increasing concern, necessitating an assessment of risks to both ecology and human health, particularly in urban areas. Most of these pollutants settle on the outdoors and eventually become part of the outdoor dust. These will have negative long-term repercussions on ecosystems and human health. In this research, energy dispersive X-ray fluorescence (EDXRF) spectrometry analytical method was used to assess the pollution characteristics of the eight heavy metals (HMs): Mn, Cu, As, Hg, Ni, Cr, Zn, and Pb in the East Mediterranean Sea area. The concentration of As, Mn, Cr, Cu, Hg, Ni, Pb, and Zn analyzed in outdoor dust samples varied from 0.94 to 19.52 mg kg-1, 190.08 to 1019.7 mg kg-1, 20.46 to 45.9 mg kg-1, 19.5 to 62.56 mg kg-1, 0.01 to 0.93 mg kg-1, 10.48 to 40.64 mg kg-1, 12. 6 to 36.1 mg kg-1, and 48.96 to 112.41mg kg-1, respectively. HMs have been detected in the outdoor dust samples analyzed in the study, and, as a result, mean concentrations followed the order Mn > Zn > Cu > Cr > Ni > Pb > As > Hg, respectively. The ecological risk was observed at various contamination levels, with As and Hg pollution being the most severe. The highest hazard quotient (HQ) for adults and children was determined as a result of As and Cr, respectively. According to the US-EPA health risk threshold, the cancer risk in the study area is negligible.

The chemical composition and sources of road dust, and of tire and road wear particles-A review

To gain better understanding of how the transition to electric vehicles affects road dust (RD) composition, and potential health and environmental risks, it is crucial to analyze the chemical composition of RD and identify its sources. Sources of RD include wear of tire tread (TT), brake wear (BW) and road wear (RW). A relevant component of RD are tire and road wear particles (TRWPs). This literature review compiles data on the chemical bulk composition of RD sources, RD in Asia, Europe and North America and TRWP as a RD component. The focus is on elements such as Cd, Co, Cr, Cu, Ni, Pb, V, and Zn. Although the comparability of global RD data is limited due to differences in sampling and analytical methods, no significant differences in the composition from Asia, Europe, and North America were found for most of the investigated elements studied, except for Cd, Co, and V. Sources of RD were analyzed using elemental markers. On average TT, BW, and RW contributed 3 %, 1 %, and 96 %, respectively. The highest concentrations of TT (9 %) and BW (2 %) were observed in the particle size fraction of RD ≤ 10 μm. It is recommended that these results be verified using additional marker compounds. The chemical composition of TRWPs from different sources revealed that (i) TRWPs isolated from a tunnel dust sample are composed of 31 % TT, 6 % BW, and 62 % RW, and (ii) test material from tire test stands show a similar TT content but different chemical bulk composition likely because e.g., of missing BW. Therefore, TRWPs from test stands need to be chemically characterized prior to their use in hazard testing to validate their representativeness.

Sources and human health risks associated with potentially toxic elements (PTEs) in urban dust: A global perspective

Long-term exposure to urban dust containing potentially toxic elements (PTEs) poses detrimental impacts on human health. However, studies estimating human health risks in urban dusts from a global perspective are scarce. We evaluated data for twelve PTEs in urban dusts across 59 countries from 463 published articles, including their concentrations, input sources, and probabilistic risks to human health. We found that 34.1 and 60.3% of those investigated urban dusts have been heavily contaminated with As and Cd, respectively. The input of PTEs was significantly correlated with economic structure due to emissions of industrial activities and traffic emissions being the major sources. Based on the Monte Carlo simulation, we found that the mean hazard index below the safe threshold (1.0) could still cause non-negligible risks to human health. Arsenic and Cr were the major PTEs threatening human health, and relatively high risk levels were observed in cities in China, Korea, Chile, Malaysia, and Australia. Importantly, our analysis suggested that PTEs threaten the health of approximately 92 million adults and 280 million children worldwide. Overall, our study provides important foundational understanding and guidance for policy decision-making to reduce the potential risks associated with PTE exposure and to promote sustainable development of urban economies.

Phytochemicals Involved in Mitigating Silent Toxicity Induced by Heavy Metals

Heavy metals (HMs) are natural elements present in the Earth's crust, characterised by a high atomic mass and a density more than five times higher than water. Despite their origin from natural sources, extensive usage and processing of raw materials and their presence as silent poisons in our daily products and diets have drastically altered their biochemical balance, making them a threat to the environment and human health. Particularly, the food chain polluted with toxic metals represents a crucial route of human exposure. Therefore, the impact of HMs on human health has become a matter of concern because of the severe chronic effects induced by their excessive levels in the human body. Chelation therapy is an approved valid treatment for HM poisoning; however, despite the efficacy demonstrated by chelating agents, various dramatic side effects may occur. Numerous data demonstrate that dietary components and phytoantioxidants play a significant role in preventing or reducing the damage induced by HMs. This review summarises the role of various phytochemicals, plant and herbal extracts or probiotics in promoting human health by mitigating the toxic effects of different HMs.

Porphyrinuria in Autism Spectrum Disorder: A Review

Numerous studies demonstrated that the number of children with autism spectrum disorder (ASD) has increased remarkably in the past decade. A portion of ASD etiology, however, is attributed to environmental issues and genetic disorders. We highlighted a scoping review to principally evaluate the current information on mercury exposure in ASD children and to reveal knowledge gaps. Elevated porphyrins concentration in the urinary system related to mercury exposure, such as precoproporphyrin (prcP), coproporphyrin (cP), and pentacarboxyporphyrin (5cxP), was shown in comparison with controls. Moreover, high levels of urinary porphyrins have been elevated in response to heavy metal exposure. The related pattern (increased prcP, cP, and 5cxP) with Hg exposure may be used as biomarkers in the characteristics of ASD symptoms. However, this review highlighted the data gaps because the control groups were not genderand age-matched for ASD children.

Multi-year monitoring of atmospheric dust fall as a sink for lead in an agro-industrial and petrochemical city of Argentina. Geo-accumulation and ecological risk assessment

A multi-year monitoring data set of potentially harmful elements (PHEs), which are present in the chemical composition of atmospheric settleable particulate matter (SPM) in the urban, industrial and port areas in Bahía Blanca, was studied in order to assess potential ecological risk. The selected PHEs were metal elements of local and regional environmental importance (Cd, Cr, Cu, Ni, Pb, and Zn). Seventeen sampling campaigns were carried out between April 2013 and September 2019. After the microwave-assisted acid digestion of samples, the total contents of the PHEs were determined by ICP-OES. The annual dry deposition rate, the indexes associated with the potential ecological risk (RI) and the degree of geo-accumulation (Igeo) of each PHE were calculated. The results indicated that: (a) there are 3 groups (I, II, III) of PHEs with differentiated concentration levels, ranked I (Pb > Zn > Cu) > II (Cr ≈ Ni) > III (Cd) (p < 0.01) in all the studied areas; (b) the median of the total deposition rate was 1 mg cm-2. month-1 with a significant relative contribution of Pb; (c) a considerable increase in geo-accumulation of Pb indicated that SPM was functioning as a sink for Pb, and also reflected a significant progressive increase in the potential ecological risk in all sites (p < 0.01); and (d) there were chemometrically identified potential sources of Pb, Cu and Zn emissions that would be associated mainly to the resuspension of dust from geogenic, industrial and urban origin, and to a lesser extent, to other gaseous emissions of the industrial sector. This work highlights three major aspects of environmental assessment: (a) the value of continuous monitoring as an important tool to detect long-term trends; (b) the importance of the role of dust fall as a useful environmental indicator of lead geo-accumulation; and (c) the great utility of geo-accumulation and potential ecological risk indices as rapid quantitative assessment tools of environmental pollution.

Zinc (Zn) mitigates copper (Cu) toxicity and retrieves yield and quality of lettuce irrigated with Cu and Zn-contaminated simulated wastewater

Owing to a competitive interaction, zinc (Zn) contained in highly Cu-contained wastewater was hypothesized to mitigate Cu toxicity-induced negative effects on the growth and quality of lettuce. Thus, growth, metal accumulation and biochemical responses of lettuce irrigated with simulated wastewater (SW, control), Cu-contaminated SW (CuSW, 20 mg Cu L-1), Zn-contaminated SW (ZnSW, 100 mg Zn L-1) and both Cu- and Zn-contaminated SW (CuZnSW, 20 mg Cu and 100 mg Zn L-1) were evaluated. Results revealed that irrigation with CuSW negatively affected growth (dry matters, root length and plant height) and quality (low mineral concentrations) of lettuce, which were associated with higher Cu uptake. Irrigation with Zn + Cu-contaminated SW retrieved Cu toxicity and improved root and shoot dry matters and root length by 13.5%, 46% and 19%, respectively compared to that with alone Cu-contaminated SW. Moreover, CuZnSW improved lettuce leaf quality compared to CuSW and increased concentrations of Mg (30%), P (15%), Ca (41%), Mn (24%) and Fe (23%). Moreover, compared to CuSW, CuZnSW improved flavonoids (54%), total polyphenolic compounds (1.8-fold), polyphenolic acids (77%) and antiradical activities (16.6%). Most importantly, Zn addition boosted up lettuce Cu tolerance index by 18% under Cu-contaminated SW treatment. Pearson's correlation analysis among various growth and mineral parameters demonstrated that shoot Zn concentration was positively related to elemental concentrations, phytochemical contents and antioxidant activity under Cu-contaminated environment. Thus, it is concluded that Zn supplementation retrieves negative effects of Cu toxicity to lettuce grown with Cu-contaminated wastewater.

Remediation methods of heavy metal contaminated soils from environmental and geotechnical standpoints

Heavy metal contaminated soil (HMCS) threatens world health and sustainable growth, owing to which numerous remediation methods have been devised. Meanwhile, environmental sustainability and geotechnical serviceability of remediated HMCS are important considerations for reusing such soils and achieving sustainable development goals; therefore, these considerations are critically reviewed in this article. For this purpose, different onsite and offsite remediation methods are evaluated from environmental and geotechnical standpoints. It was found that each remediation method has its own merits and limitations in terms of environmental sustainability and geotechnical serviceability; generally, sustainable green remediation (SGR) and cementation are regarded as effective solutions for the problems related to the former and latter, respectively. Overall, the impact of remediation techniques on the environment and geotechnical serviceability is a developing area of study that calls for increased efforts to improve the serviceability, sustainability, reusability and environmental friendliness of the remediated HMCS.

Effects of cadmium stress on fruits germination and growth of two herbage species

Cadmium (Cd) pollution is a global environmental problem. It is of great significance to find a kind of pasture that can grow normally in a cadmium environment, especially in the Tibetan Plateau. We studied the fruit germination and fruit growth of Elymus sinsubmuticus S.L. Chen and Elymus tangutorum (Nevski), native plants of the Tibetan Plateau, in different cadmium environments. The results showed that with increased cadmium stress, the fruit germination rate, final germination rate, fruit-vigor, average germination time, and germination-speed index for the two grass species gradually decreased, and the 50% germination time for the seed gradually increased. Root length, biomass, and the number of leaves decreased in both species. We quantified the fruit germination and growth of plants in the cadmium environment and found that E. sinosubmuticus S.L. Chen had better fruit germination and fruit growth, and it had the development potential of cadmium pollution control.

Pollution and Health Risk Assessments of Potentially Toxic Elements in the Fine-Grained Particles (10−63 µm and <10 µm) in Road Dust from Apia City, Samoa

Fine road dust is a major source of potentially toxic elements (PTEs) pollution in urban environments, which adversely affects the atmospheric environment and public health. Two different sizes (10−63 and <10 μm) were separated from road dust collected from Apia City, Samoa, and 10 PTEs were analyzed using inductively coupled plasma mass spectrometry (ICP-MS). Fine road dust (<10 μm) had 1.2−2.3 times higher levels of copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd), antimony (Sb), lead (Pb), and mercury (Hg) than 10−63 μm particles. The enrichment factor (EF) value of Sb was the highest among PTEs, and reflected significant contamination. Cu, Zn, and Pb in road dust were also present at moderate to significant levels. Chromium (Cr), cobalt (Co), and nickel (Ni) in road dust were mainly of natural origins, while Cu, Zn, Sb, and Pb were due to traffic activity. The levels of PTEs in road dust in Samoa are lower than in highly urbanized cities, and the exposure of residents in Samoa to PTEs in road dust does not pose a noncarcinogenic health risk. Further studies of the effects of PTEs contamination in road dust on the atmosphere and living organisms are needed.

Heavy Metal Pollution and Risk Assessment of Surface Dust in the Arid NW China

High concentrations of heavy metals (HMs) in urban surface dust (USD) can be extremely hazardous to urban ecology and human health. Oasis cities are located at the edge of deserts and are more exposed to salt/sandstorms, and they face a significantly higher accumulation of USD than wet or semi-humid areas. However, systematic studies on the pollution and risk assessment of HMs in USD in oasis cities have rarely been conducted. This study systematically analyzed the enrichment status, spatial distribution, pollution levels, health risks, and sources of HMs in USD in a typical oasis city (Changji city). The results showed that the average concentrations of Pb, Ni, As, Cd, Hg, and Cu in the USD of Changji city were 46.83, 26.35, 9.92, 0.21, 0.047, and 59.33 mg/kg, respectively, and the results of the pollution index evaluation showed moderate Pb, Hg, and Cu pollution, mild Cd pollution, and no Ni or As pollution. The spatial distribution of HM concentrations in the USD was substantially heterogeneous. High values of Pb, Hg, and Cu concentrations were mainly observed in areas with relatively intensive transportation and commercial activities, and high values of Cd and Ni were observed in industrial areas. The health risk assessment showed that HMs do not pose non-carcinogenic risks to humans at their current level, but they pose a carcinogenic risk to children, with As contributing the largest carcinogenic and non-carcinogenic risks. The source identification of HMs showed that the main pollution of HMs were traffic sources for Pb and Cu, industrial sources for Ni and Cd, natural sources for As, and coal-fired sources for Hg. According to the results of the quantitative analysis with the positive matrix factorization, the contribution of pollution sources followed this order: industrial sources (31.08%) > traffic sources (26.80%) > coal-fired sources (23.31%) > natural sources (18.81%).