Health Risk from Toxic Metals in Wild Rice Grown in Copper Mining-Impacted Sediments

Northern wild rice is of great dietary and cultural importance to the Native American population in the Upper Peninsula of Michigan. Millions of tons of mine tailings were discharged into Lake Superior and other inland lakes during the copper mining boom in the early 20th century in this area. This includes L’Anse Bay, located within the Keweenaw Bay Indian Community (KBIC) reservation. Since wild rice restoration is being encouraged by the KBIC, we investigated the distribution of toxic metals in sediments, water, and wild rice and their potential impact on human health from two locations. Sand Point sloughs on L’Anse Bay and a nearby inland lake, Lake Plumbago, were sampled for sediment, water, and wild rice, and the potential human health risk from dietary exposure to toxic metals in wild rice was assessed. Arsenic stood out as the element that had the highest bioaccumulation at both locations. Risk calculations showed that the hazard index (HI) value for wild rice seeds from both sites was high. Data indicate both carcinogenic and noncarcinogenic risks for As from wild rice in Sand Point sloughs and Lake Plumbago, and carcinogenic risks for Cd and Cr at Lake Plumbago

Impact of EDDS Dosage on Lead Phytoextraction in Contaminated Urban Residential Soils

Lead (Pb) contamination in soils of residential properties due to peeling and chipping of Pb-based paint can cause human health problems. Phytoextraction is a green technology that has the potential to remediate soil Pb. The efficiency of phytoextraction is dependent on the geochemical forms of Pb in soil. A biodegradable chelating agent, ethylenediaminedisuccinic acid (EDDS), was previously shown to enhance Pb removal by facilitating phytoextraction. In this study, EDDS was tested at various concentrations for its potential in mobilizing Pb in urban residential soils in Jersey City, New Jersey, and San Antonio, Texas. Results show that the concentrations of plant-available forms of Pb increased with the increasing dosage of EDDS from 2 to 30 mmol/L. The addition of EDDS at 30 mmol/L resulted in the conversion of up to 61.2% and 68.9% of the total Pb to plant-available forms in Jersey City and San Antonio soils, respectively. Further analysis showed that, after EDDS application, carbonate-bound Pb, oxide-bound Pb, organic-bound Pb, and residual silicate-bound Pb were transformed to plant-available forms. Higher doses of EDDS performed better than lower doses in transforming soil Pb forms, especially for the oxide-bound Pb. Strong correlations between Pb concentrations measured on-site using a portable X-ray Fluorescence Analyzer (p-XRF) and those obtained in the laboratory using Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) confirmed that p-XRF is a reliable rapid, convenient technology to measure Pb levels in situ

Valorization of Spent Vetiver Roots for Biochar Generation

Vetiver root is widely used to produce essential oils in the aromatherapy industry. After the extraction of oil, the roots are disposed of as waste. The central objective of this research was to explore the conversion of this waste into a resource using a circular economy framework. To generate biochar, vetiver roots were pyrolyzed at different temperatures (300, 500, and 700 °C) and residence times (30, 60, and 120 min). Analysis showed the root biochar generated at 500 °C and held for 60 min had the highest surface area of 308.15 m2/g and a yield of 53.76%, in addition to other favorable characteristics. Comparatively, the surface area and the yield of shoot biochar were significantly lower compared to those of the roots. Repurposing the spent root biomass for environmental and agronomic benefits, our circular economy concept prevents the plant tissue from entering landfills or the waste stream

Evaluating soil Arsenic toxicity using an in vitro cell culture model and exploring the Pteris vittata microbiome in Arsenic mitigation using phytotechnology

Arsenic is one of the most toxic environmental pollutants, classified as a Class I carcinogen. Anthropogenic activities such as industrial and agricultural applications have led to an increase in arsenic contamination of soils. The work presented here is a systematic approach to evaluating and mitigating the health impacts of arsenic and exploring the role of the root microbiome of the arsenic hyperaccumulating plant, the Chinese Brake fern (Pteris vittata L.), in enhanced arsenic uptake and tolerance. This research deals with three aspects of soil arsenic pollution, 1. Determine the human health impact of arsenic due to contact exposure using a human skin cell culture model, 2. Develop a novel phytoremediation technique to mitigate arsenic exposure through rice consumption, and 3. Exploring the plant-microbe interactions in enhancing arsenic tolerance and uptake by the hyperaccumulator, P. vittata. We used human skin cell culture and soil geochemical techniques to determine the effect of soil arsenic exposure through dermal contact. Immokalee soil from Florida was spiked with four concentrations of arsenic based on ten-year use of arsenical pesticides. Our data indicated that keratinocyte cells were more susceptible to arsenic-induced cellular transformation than fibroblasts. In addition, higher concentrations of soil arsenic impacted specific cellular responses such as cell viability, cell migration, and epithelial-to-mesenchymal transition, and induced changes in the expression of proteins related to these functions. The in-vitro model developed in this study can be used as a quick, inexpensive, and reliable approach to determine the toxicity of soil contaminants. Exposure to arsenic from a diet of contaminated rice is a widespread problem and a serious concern in several parts of the world. We developed a crop rotation method of alternating rice with the arsenic hyperaccumulator, P. vittata, to reduce arsenic concentrations in rice grains. Our results show that at the end of two crop rotation cycles, there was a 67% and 35% decrease in arsenic in rice grains and soil, respectively. Interactions between hyperaccumulators and metal(oid)-resistant microbes in the rhizosphere have generated much research interest due to their application potential in plant-based environmental remediation techniques. We compared root endophytic, rhizospheric and bulk soil microbial communities between P. vittata and non-accumulator Pteris ensiformis Burm. Arsenic-tolerant bacteria like Steroidobacter, Cohnella, and Streptomyces were present in the root endophytes of P. vittata but absent in P. ensiformis. These findings suggest that the arsenic hyperaccumulator specifically recruits a microbial community that enhances its tolerance and uptake of arsenic. The root microbiome of hyperaccumulators could provide valuable insight into improving the efficiency of metal uptake in plants growing in polluted soil

Health Risk from Toxic Metals in Wild Rice Grown in Copper Mining-Impacted Sediments

Northern wild rice is of great dietary and cultural importance to the Native American population in the Upper Peninsula of Michigan. Millions of tons of mine tailings were discharged into Lake Superior and other inland lakes during the copper mining boom in the early 20th century in this area. This includes L’Anse Bay, located within the Keweenaw Bay Indian Community (KBIC) reservation. Since wild rice restoration is being encouraged by the KBIC, we investigated the distribution of toxic metals in sediments, water, and wild rice and their potential impact on human health from two locations. Sand Point sloughs on L’Anse Bay and a nearby inland lake, Lake Plumbago, were sampled for sediment, water, and wild rice, and the potential human health risk from dietary exposure to toxic metals in wild rice was assessed. Arsenic stood out as the element that had the highest bioaccumulation at both locations. Risk calculations showed that the hazard index (HI) value for wild rice seeds from both sites was high. Data indicate both carcinogenic and non-carcinogenic risks for As from wild rice in Sand Point sloughs and Lake Plumbago, and carcinogenic risks for Cd and Cr at Lake Plumbago

Is Arsenic in Rice a Major Human Health Concern?

Arsenic (As) is a toxic metalloid associated with various negative human health impacts including cancer, skin lesions, cardiovascular diseases, and diabetes. Arsenic contamination of groundwater and soil is a major human health issue, particularly in South and Southeast Asia. Use of As-contaminated groundwater from shallow tube wells for irrigation of paddy rice, the staple food for people in this region, is one of the causes of As-related health impacts. The anaerobic growing conditions of flooded rice paddies and the unique physiology of the rice plants lead to increased As levels in rice. The World Health Organization (WHO) has set advisory levels of As in polished (i.e., white) rice grain at 0.2 mg/kg, but the EU and USA are yet to set legal standards for As in rice and rice-based products. Strategies for lowering As accumulation in rice revolve around two approaches—agronomic and biotechnological. Agronomic approaches, such as mineral supplementation of soil using iron, phosphorus, sulfur, silicon, water management, soil aeration practices, and the use of biological agents, are designed to lower As solubility, and uptake by rice. Rotation of the rice crop with As accumulating plants could also result in lowering soil As. Biotechnological approaches involve producing transgenic rice varieties by altering the expression of genes involved in As uptake, translocation, and sequestration in the plant. These approaches, combined with proper diet management and creating public awareness on potential health risks resulting from chronic exposure to As in rice, could play a key role in risk reduction

Human health risk mitigation from arsenic in rice by crop rotation with a hyperaccumulator plant

Exposure to arsenic (As) from a diet of contaminated rice is a widespread problem and a serious concern in several parts of the world. There is a need to develop sustainable, effective, and reliable strategies to reduce As accumulation in rice. Our goal was to develop and test a simple crop rotation method of alternating rice with the As hyperaccumulator plant, Chinese brake fern (Pteris vitatta L.), to reduce As concentrations in rice grains. A greenhouse column study was performed for 2 years using As-contaminated rice paddy soil from West Bengal. Rice was grown under flooded conditions and irrigated with As-contaminated water to simulate field conditions. Chinese brake fern was grown between two rice cycles in experimental columns, while control columns were left unplanted. Our results show that at the end of two cycles, there was a statistically significant decrease in soil As concentrations in the treatment columns compared to the control columns. After one rotation with the fern, there was a significant decline in As concentrations in rice grains in treatment plants and a concomitant decline in both noncarcinogenic and carcinogenic health risks. Our results indicate that there could be substantial benefit in implementing this simple crop rotation model to help lower human health risks from As exposure via rice ingestion

Comparative assessment of bacterial diversity and composition in arsenic hyperaccumulator, Pteris vittata L. and non-accumulator, Pteris ensiformis Burm

The use of arsenic (As) for various industrial and agricultural applications has led to worldwide environmental contamination. Phytoremediation using hyperaccumulators is a sustainable soil As mitigation strategy. Microbial processes play an important role in the tolerance and uptake of trace elements such as in plants. The rhizospheric and endophytic microbial communities are responsible for accelerating the mobility of trace elements around the roots and the production of plant growth-promoting compounds and enzymes. Several studies have reported that the As hyperaccumulator, Pteris vittata L. (PV) influences the microbial community in its rhizosphere and roots. Deciphering the differences in the microbiomes of hyperaccumulators and non-accumulators is crucial in understanding the mechanism of hyperaccumulation. We hypothesized that there are significant differences in the microbiome of roots, rhizospheric soil, and bulk soil between the hyperaccumulator PV and a non-accumulator of the same genus, Pteris ensiformis Burm. (PE), and that the differential recruitment of bacterial communities provides PV with an advantage in As contaminated soil. We compared root endophytic, rhizospheric, and bulk soil microbial communities between PV and PE species grown in As-contaminated soil in a greenhouse setting. There was a significant difference (p \u3c 0.001) in the microbiome of the three compartments between the ferns. Differential abundance analysis showed 328 Amplicon Sequence Variants (ASVs) enriched in PV compared to 172 in PE. The bulk and rhizospheric soil of both ferns were abundant in As-resistant genera. However, As-tolerant root endophytic genera were present in PV but absent in PE. Our findings show that there is a difference between the bacterial composition of an As hyperaccumulator and a non-accumulator species grown in As-contaminated soil. These differences need to be further explored to develop strategies for improving the efficiency of metal uptake in plants growing in As polluted soil

Using Scratch Wound Assay To Study The Effect Of Soil Arsenic On Human Dermal Fibroblasts Cell Migration Due To Contact Exposure

The scratch wound assay was performed on Normal Human Primary Dermal Fibroblasts (HDFa) cells to observe the effect on cell migration due to contact exposure to arsenic-contaminated Immokalee soil. The cell migration was observed through a microscope for 72 h. HDFa cells were seeded in 48-well plate. On day 3, treatment media was added (n=8). The cells were treated with four concentrations of soil As (45, 225, 450, and 900 mg/kg) and two controls - Negative control (NC; Pure media) and control (C; 0 mg/kg soil As) for 72 h. A scratch was made using a pipette tip. The wound healing was observed through timelapse for 72 hours using EVOS FL Auto microscope. Images were taken every 30 mins for 72 h. The percentage recovery of scratch was calculated using Image J (https://imagej.nih.gov/ij/

Using Scratch Wound Assay To Study The Effect Of Soil Arsenic On Human Keratinocyte Cell Migration Due To Contact Exposure

The scratch wound assay was performed on Human immortalized keratinocytes (HaCaT) cells to observe the effect on cell migration due to contact exposure to arsenic-contaminated Immokalee soil. The cell migration was observed through a microscope for 72 h. HaCaT cells were seeded in 48-well plate. On day 3, treatment media was added (n=8). The cells were treated with four concentrations of soil As (45, 225, 450, and 900 mg/kg) and two controls - Negative control (NC; Pure media) and control (C; 0 mg/kg soil As) for 72 h. A scratch was made using a pipette tip. The wound healing was observed through timelapse for 72 hours using EVOS FL Auto microscope. Images were taken every 30 mins for 72 h. The percentage recovery of scratch was calculated using Image J (https://imagej.nih.gov/ij/