Trace element bioaccumulation in edible red seaweeds (Rhodophyta): A risk assessment for consumers

Single-drop electrodeposition of nanoneedle-like bismuth on disposable graphene electrode for on-site electrochemical detection of cadmium and lead

A novel cost-effective disposable porous graphene electrode (P-GE) modified with bismuth nanoneedles (nano-BiNDs) is proposed as a "mercury-free" sensor for detecting heavy metals through smartphone-assisted electrochemical sensing. The P-GE was fabricated using screen-printing. Nano-BiNDs were generated on the P-GE by potentiostatic electrodeposition. Using an optimal potential of -1.20 V (vs. pseudo-Ag/AgCl) and a deposition time of 200 s, the nano-BiNDs had an average length and width of 189 ± 5 nm and 20 ± 2 nm, respectively. The analytical performances of the fabricated sensing platform were demonstrated by detecting Cd2+ and Pb2+ using square-wave anodic stripping voltammetry (SWASV) under optimized conditions. In the optimal conditions, the fabricated sensor exhibited sharp, well-defined stripping peaks for Cd2+ and Pb2+ with excellent peak-to-peak separation. The linear detection ranges were from 0.01 to 50 μg mL-1 for Cd2+ and 0.006-50 μg mL-1 for Pb2+. The detection limits for Cd2+ and Pb2+ were 3.51 and 2.10 ng mL-1, respectively. The developed portable sensor demonstrated high sensitivity, good repeatability, reproducibility, and anti-interference properties. The proposed portable sensor quantified Cd2+ and Pb2+ in commercial seaweed products with good accuracy, consistent with the results obtained using the standard ICP-OES method.

Survey of arsenic content in edible seaweeds and their health risk assessment

Since humans are especially sensitive to arsenic exposure, predominantly through diet, a strict control of the most widely consumed seaweeds is mandatory. Total arsenic contents and arsenic species in twenty-five different seaweeds from five different origins were studied. Seaweeds selected, included Phaeophyta (brown seaweed), Chlorophyta (green seaweed) and Rhodophyta (red seaweed) genera. The highest arsenic content appears in the Phaeophyta seaweed in the range from 11 to 162 mg kg-1 dried weight. Arsenosugars were found to be the predominant species of arsenic in most seaweeds, being up to 99.7% of total arsenic in some samples. The arsenic dietary intakes for seaweeds studied were assessed and the Target Hazard Quotients (THQ) and the Target Cancer Risk (TCR) were calculated, taking into account inorganic arsenic contents (iAs). iAs species in seaweeds showed low risk of arsenic intake except for Hizikia fusiforme samples.

Assessing metal(loid)s-Induced long-term spatiotemporal health risks in Coastal Regions, Bay of Bengal: A chemometric study

Despite sporadic and irregular studies on heavy metal(loid)s health risks in water, fish, and soil in the coastal areas of the Bay of Bengal, no chemometric approaches have been applied to assess the human health risks comprehensively. This review aims to employ chemometric analysis to evaluate the long-term spatiotemporal health risks of metal(loid)s e.g., Fe, Mn, Zn, Cd, As, Cr, Pb, Cu, and Ni in coastal water, fish, and soils from 2003 to 2023. Across coastal parts, studies on metal(loid)s were distributed with 40% in the southeast, 28% in the south-central, and 32% in the southwest regions. The southeastern area exhibited the highest contamination levels, primarily due to elevated Zn content (156.8 to 147.2 mg/L for Mn in water, 15.3 to 13.2 mg/kg for Cu in fish, and 50.6 to 46.4 mg/kg for Ni in soil), except for a few sites in the south-central region. Health risks associated with the ingestion of Fe, As, and Cd (water), Ni, Cr, and Pb (fish), and Cd, Cr, and Pb (soil) were identified, with non-carcinogenic risks existing exclusively through this route. Moreover, As, Cr, and Ni pose cancer risks for adults and children via ingestion in the southeastern region. Overall non-carcinogenic risks emphasized a significantly higher risk for children compared to adults, with six, two-, and six-times higher health risks through ingestion of water, fish, and soils along the southeastern coast. The study offers innovative sustainable management strategies and remediation policies aimed at reducing metal(loid)s contamination in various environmental media along coastal Bangladesh.

Bioaccessibility of toxic heavy metals/metalloids in edible seaweeds: Exposure and health risk assessment

This study assesses the health risk due to heavy metals/metalloids (HMs/Ms) in edible seaweeds (Caulerpa racemosa, Kappaphycus alvarezii, and Ulva lactuca) through an in vitro bioaccessibility study. The percentage of bioabsorbed HMs/Ms in unprocessed and processed C. racemosa, U. lactuca, and K. alvarezii ranged from 3 % to 46 %, 3 % to 42 %, and 3 % to 40 %, respectively. The levels of HMs/Ms in seawater, sediment, and seaweeds were below the levels recommended by the European Commission (EC) and World Health Organization/Food and Agriculture Organization (WHO/FAO). The maximum accumulation of HMs/Ms was found during monsoons and post-monsoon seasons, and Cd, Pb, Hg, Cr, As, and Pb were predominant in all the samples. Tukey's post hoc test and t-test confirmed that thermal processing significantly reduced HMs/Ms in seaweeds. On the basis of the bioabsorption of HMs/Ms, the TTHQ values were found to be < 1, and the LCR values were within the acceptable limit (10-06 to 10-04), indicating no carcinogenic risks through seaweeds.

Trace metals and macrominerals in common seaweeds in the Marchica (a restored lagoon, Mediterranean Sea): Nutritional value and health risk assessment

This study investigated the contents of macrominerals (Na, K, Ca, Mg and P) and essential trace metals (Fe, Mn, Cu, Zn and Se) in four species of seaweeds (Gracilaria sp., Alsidium corallinum, Caulerpa prolifera, and Chaetomorpha sp.) from Marchica Lagoon. The contents of macrominerals with mean values (% dw) can be sequenced in this descending order, [Ca > Mg > Na > K > P] for Caulerpa prolifera, and the decreasing sequence [K > Ca > Mg > P > Na] for Chaetomorpha sp. In red seaweeds, Gracilaria sp. and Alsidiumcorallinum followed these orders: [K > Ca > Na > Mg > P] and [K > Na > Ca > Mg > P] respectively. The essential trace metals mean values (mg kg-1) followed the decreasing order [Fe > Mn > Zn > Cu > Se] for Alsidiumcorallinum, Chaetomorpha sp. and Gracilaria sp., and the following order [Fe > Mn > Zn > Se > Cu] for Caulerpa prolifera. Based on the calculated recommended dietary allowance (RDA), targeted hazard quotient (THQ) and the hazard index (HI), the studied seaweeds did not pose any health risk for human consumption.

Metal and metalloid bioaccumulation in dried red seaweed Hypnea musciformis and health risk assessment for consumers

This study measured 22 metal and metalloid concentrations in Hypnea musciformis from the Bakkhali River estuary and Saint Martin's Island, Bangladesh and determined their potential impact on consumption. Student t-tests showed a significant variation in metal concentrations between the two sampling sites (p < 0.05). Mean concentrations of Co (2.49 ± 0.05 mg/kg), Fe (793.29 ± 11.76 mg/kg), Mn (368.72 ± 4.87 mg/kg), Pb (3.82 ± 0.02 mg/kg), V (11.23 ± 0.20 mg/kg) and Zn (16.60 ± 0.28 mg/kg) were higher in samples collected from the Bakkhali River estuary compared to Saint Martin's Island, while mean concentrations of Ca (484.18 ± 4.68 mg/kg), Cd (2.44 ± 0.03 mg/kg), Mg (2112.70 ± 17.80 mg/kg), Mo (1.57 ± 0.06 mg/kg), Sr (2377.57 ± 29.98 mg/kg), and Ti (258.27 ± 4.62 mg/kg) were higher in samples collected from Saint Martin's Island. Eight heavy metals (Pb, Cd, Zn, Cu, Ni, Mn, Cr, Fe) were used to assess potential health risks for adults, but no potential health risk was detected (HQ value>1). This study reveals positive Se-HBV for H. musciformis collected from both sampling sites, indicating no potential risks involved with Hg toxicity.

Integrative Evaluation of the Ecological Hazards by Microplastics and Heavy Metals in Wetland Ecosystem

This study was performed to evaluate the impact of microplastics and heavy metals (Pb, Cd, Cr, Cu, Zn, Ni) on sediments, water, aquatic plants (Pistia stratiotes, Alternanthera philoxeroides, and Ipomoea carnea), and fish (Labeo rohita) samples collected from five different sites in the Bajwat wetlands in Sialkot, Pakistan. The concentrations of Pb, Cd, and Cr were above the permissible limits devised by WHO in all the ecosystem components (i.e. sediments, water, plants, and fish) at all sites. The maximum amount of microplastic particles (2317 microplastic particles per kg of sediments) was recorded at Site 1. The filaments were the most commonly found type of microplastics. Plants and fish samples also showed considerable concentration of metals. The multivariate statistical analysis revealed anthropogenic sources of elevated concentrations of metal elements which could cause adverse biological effects in the ecosystem.