In vitro toxicity of arsenic rich waters from an abandoned gold mine in northeast Portugal

Molecular and cell phenotype programs in oral epithelial cells directed by co-exposure to arsenic and smokeless tobacco

Chronic arsenic exposure can lead to various health issues, including cancer. Concerns have been mounting about the enhancement of arsenic toxicity through co-exposure to various prevalent lifestyle habits. Smokeless tobacco products are commonly consumed in South Asian countries, where their use frequently co-occurs with exposure to arsenic from contaminated groundwater. To decipher the in vitro molecular and cellular responses to arsenic and/or smokeless tobacco, we performed temporal multi-omics analysis of the transcriptome and DNA methylome remodelling in exposed hTERT-immortalized human normal oral keratinocytes (NOK), as well as arsenic and/or smokeless tobacco genotoxicity and mutagenicity investigations in NOK cells and in human p53 knock-in murine embryonic fibroblasts (Hupki MEF). RNAseq results from acute exposures to arsenic alone and in combination with smokeless tobacco extract revealed upregulation of genes with roles in cell cycle changes, apoptosis and inflammation responses. This was in keeping with global DNA hypomethylation affecting genes involved in the same processes in response to chronic treatment in NOK cells. At the phenotypic level, we observed a dose-dependent decrease in NOK cell viability, induction of DNA damage, cell cycle changes and increased apoptosis, with the most pronounced effects observed under arsenic and SLT co-exposure conditions. Live-cell imaging experiments indicated that the DNA damage likely resulted from induction of apoptosis, an observation validated by a lack of exome-wide mutagenesis in response to chronic exposure to arsenic and/or smokeless tobacco. In sum, our integrative omics study provides novel insights into the acute and chronic responses to arsenic and smokeless tobacco (co-)exposure, with both types of responses converging on several key mechanisms associated with cancer hallmark processes. The generated rich catalogue of molecular programs in oral cells regulated by arsenic and smokeless tobacco (co-)exposure may provide bases for future development of biomarkers for use in molecular epidemiology studies of exposed populations at risk of developing oral cancer.

Characteristics of Soil Arsenic Contamination and the Potential of Pioneer Plants for Arsenic Remediation in Gold Mine Tailings

Arsenic (As) contamination of gold mine tailings poses major threats to the natural environment and human health, necessitating adequate management measures. To investigate the soil As contamination level and the potential of pioneer plants for As remediation, the soil and plants of an abandoned gold mine tailings in the Qinling Mountains were analyzed. The level of As contamination was assessed using the single-factor pollution index and potential ecological risk index, and its bioeffectiveness was analyzed. The enrichment capability of plants was investigated using the bioaccumulation factor and translocation factor. Redundancy analysis and partial least squares regression were employed to investigate factors affecting the distribution of As in soil and plants. The results show that As in soil mainly existed in the difficult-available state, with serious contamination and extremely high ecological risk. Lythrum salicaria L. and Equisetum ramosissimum Desf. are the preferred plants for remediation of As contamination through screening pioneer plants. Soil total nitrogen (STN) and available phosphorus (SAP) are the main factors influencing the characteristics of As distribution in the soil. Soil available potassium (SAK), water content (SWC), and SAP promote the accumulation of As by plants. This study provides plant materials and new ideas for mine ecological remediation.

Remobilization of legacy arsenic from sediment in a large subarctic waterbody impacted by gold mining

Arsenic contamination from mining poses an environmental challenge due to the mobility of this redox-sensitive element. This study evaluated arsenic mobility in sediments of Yellowknife Bay (Canada), a large subarctic water body impacted by gold mining during the 20th century. Short-term measurements of arsenic flux from sediment, arsenic profiling of the water column and sediment porewater, and mass balance modelling were conducted to assess the importance of sediment as an arsenic source. Sediment arsenic fluxes were highly variable throughout Yellowknife Bay and ranged from - 65-1520 µg m^-2 day^-1. Elevated fluxes measured near the mine site were among the highest published for well-oxygenated lakes. Redox boundaries were typically 2-3 cm below the sediment surface as indicated by porewater profiles of iron, manganese, and arsenic, with arsenic maxima of 65-3220 µg L^-1 predominately as arsenite. Sediment arsenic flux was positively related to its solid-phase concentration. Modelling indicated sediment was a principal source of arsenic to the water column. Adsorption and precipitation processes in the oxidizing environment of near-surface sediments did not effectively attenuate arsenic remobilized from contaminated sediments. Internal recycling of legacy arsenic between sediment and surface water will impede a return to background conditions in Yellowknife Bay for decades.

Environmental chemistry, toxicity and health risk assessment of groundwater: Environmental persistence and management strategies

Groundwater is a significant supply of freshwater for the world's population, being used for residence, agricultural, and industrial purposes. One-third of the world's population relies on groundwater for drinking applications. Groundwater pollution is a global issue with serious consequences for human health and the environment. It needs a thorough understanding because access to safe drinking water is a basic human right. However, groundwater quality is being threatened by urbanisation, agricultural activities, industrial activities, and climate change, among others. Pollutants like hydrocarbons, toxic metals, pesticides, microplastics, nanoparticles and other emerging contaminants mean a risk to human health and sustainable socioeconomic development. To ensure sustained groundwater usage to assess, monitor, and regulate groundwater quality issues is essential. Excess withdrawal alters groundwater flow together with contaminants like uranium, radon, radium, salinity, arsenic and fluoride, resulting in mediocre water quality. Consequently, chemical and biological contaminants owing to domestic, industrial, and agricultural practices alter water quality and threaten human health. Controlling and management of groundwater pollution and related health risks require developing vulnerability, hazard, and risk maps.