The environmental impacts of heavy metals in soil, certain plants and wastewater near industrial area of Brahmanbaria, Bangladesh

Cytogenotoxicity evaluation of heavy metals detected in extracts and infusion of Baccharis trimera, potential bioaccumulator plant

Heavy metals (HMs) are natural components of the Earth's crust that might originate from natural and anthropogenic sources. In excess quantities, the presence of these metals is harmful for both environment and human health. Taking this into account, various investigators examined bioaccumulator species in order to reduce environmental toxicity, among these Baccharis trimera. Therefore, the present study aimed to determine the capacity of B. trimera to bioaccumulate HMs and assess consequent cytogenotoxicity following exposure. B. trimera vegetative parts were collected from two groups (1) control, in which plants were cultivated in soil exposed to distilled water, and (2) exposed, in which plants were cultivated in soil exposed to HMs including manganese (Mn), iron (Fe), lead (Pb), copper (Cu), cobalt (Co), zinc (Zn), and chromium (Cr). HMs were quantified in cultivation soil and extracts (aqueous and ethanolic) as well as infusion of B. trimera vegetative parts. Root lengths and cytogenotoxic effects were determined using Allium cepa test. Results demonstrated that all HMs studied were absorbed and bioaccumulated by B. trimera. Root lengths were decreased when exposed to ethanolic extract of B. trimera cultivated in soil exposed to HMs solution, which was the extract that exhibited the highest cytogenotoxicity values. Thus, data demonstrated that B. trimera might serve as a bioaccumulator for the reduction of environmental toxicity associated with the presence of certain HMs.

The Associations between Exposure to Multiple Heavy Metals and Total Immunoglobulin E in U.S. Adults

Immunoglobulin E (IgE) is a type of immunoglobulin, and elevated serum total IgE is often present in allergic diseases. Exposure to environmental heavy metals has been markedly linked to allergic diseases, leading to elevated total IgE levels. However, studies concerning the effects of multiple metal exposures on total IgE levels are limited. Therefore, the current study seeks to explore the correlation between heavy-metal co-exposure and total IgE levels based on the National Health and Nutrition Examination Survey (NHANES, 2005-2006). Participants possessed complete data on total IgE levels, 11 urinary metal concentrations and other covariates. The correlations between 11 metals and total IgE levels were analyzed using multiple linear regression, and total IgE levels were a continuous variable. Total IgE levels exceeding 150 kU/L were considered sensitized. Binary logistic regression analyses were employed to assess the correlation between metal exposure and the occurrence of an allergic state. Then, the association between co-exposure to the 11 metals and total IgE levels or the occurrence of sensitization status was further analyzed by Bayesian kernel machine regression (BKMR), a multi-contaminant model. There were 1429 adults with complete data included. Based on the median concentration, molybdenum (Mo) had the highest concentration (46.60 μg/L), followed by cesium (Cs), barium (Ba), lead (Pb), and mercury (Hg). And the median (interquartile range) for total IgE levels was 43.7 (17.3, 126.0) kU/L. Multiple linear regression results showed that Pb was significantly and positively associated with total IgE levels (β = 0.165; 95% CI: 0.046, 0.284). Binary logistic regression showed a significant positive correlation between urinary Pb (OR: 1.258; 95% CI: 1.052, 1.510) and tungsten (W) (OR: 1.251; 95% CI: 1.082, 1.447). Importantly, the BKMR model found a positive correlation between combined-metal exposure and total IgE levels and the occurrence of sensitization status. The mixed heavy-metal exposure was associated with increased total IgE levels, and this association may be driven primarily by the exposure of Pb and W. This study provides new insights into the relationship between heavy-metal exposure and allergic diseases. More research is needed to confirm these findings.

Cadmium, lead, and zinc immobilization in the soil using a phosphate compound with citric acid present

Low molecular weight organic acids (LMWOAs) are common in rhizospheric soil and may impede the interaction between phosphate and metals. Thus, studying how phosphate compounds impact metal immobilization in rhizospheric soil using LMWOAs is crucial. An incubation experiment examined the effects of NaH2PO4 (a P compound) (3%), various concentrations of citric acid (CA), and combinations of P and CA, on soil cadmium (Cd), lead (Pb), and zinc (Zn) immobilization using the European Community Bureau of Reference (BCR) sequential extraction method, CaCl2 extraction method, zeta potential, fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The P, low CA (2 mmol kg-1 soil) (CA2), and P-CA2 treatments reduced acid-soluble and CaCl2-extractable Cd, Pb, and Zn, indicating metal immobilization, with the P-CA2 treatment being the most effective. High CA (>5-20 mmol kg-1 soil) or a P with high CA reversed prior patterns, suggesting metal mobilization. The zeta potential study indicated that when pH increased, treatments became more negative, notably P-CA2 followed by P, suggesting that electrostatic adsorption was the predominant metal immobilization mechanism, especially in P-CA2. XRD tests, however, showed that the P treatment alone produced Cd phosphate, pyromorphite, and hopeite, indicating that sorption and precipitation were the main metal immobilization processes in the P treatment alone. In conclusion, P-CA2 was found to be the most efficient metal immobilization and redistribution treatment for contaminated soils. Rhizospheric CA may alter Cd, Pb, and Zn mineral stability. Therefore, when treating Cd, Pb, and Zn-contaminated soils with a P compound, CA should be addressed.

Associations of multiple metals with lung function in welders by four statistical models

BACKGROUND

Exposure to heavy metals has been related to decreased lung function in workers. However, due to limitations in statistical methods for mixtures, previous studies mainly focused on single or several toxic metals, with few studies involving metal exposome and lung function.

OBJECTIVES

The study aimed to evaluate the effects of co-exposure to the metal mixtures on multiple parameters of pulmonary function tests and to identify the elements that play an essential role in elastic-net regression (ENET), multivariate linear regression, bayesian kernel machine regression (BKMR), and quantile g-computation (QG-C) models.

METHODS

We have recruited 186 welders from Anhui (China) in 2019. And their end-of-shift urine and lung function measure data were collected with informed consent. The urinary concentrations of 23 metals were measured by inductively coupled urinary mass spectrometry. The lung function measures including forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1) and peak expiratory flow (PEF) were also detected as outcome indicators. Four statistical methods, ENET, multivariate linear regression, BKMR, and QG-C models were used to evaluate the associations of element mixtures on lung function comprehensively.

RESULTS

Lead and cadmium were negatively associated with FVC and FEV1, nickel and chromium were inversely associated with PEF, and strontium showed significant positive effects in linear regression models, which were consistent with the results in BKMR and QG-C models. Both BKMR and QG-C models showed a significantly negative overall effect of metal mixtures on lung function parameters (FVC, FEV1, and PEF). Meanwhile, BKMR showed the non-linear relationships of cadmium with FVC.

CONCLUSION

Multi-pollutant mixtures of metals were negatively associated with lung function. Lead, cadmium, nickel, and strontium might be crucial elements. Our findings highlight a need to prioritize workers' environmental health, and guide future research into the toxic mechanisms of metal-mediated lung function injury.