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.

First report on the exposure and health risk assessment of organochlorine pesticide residues in Caulerpa racemosa, and their potential impact on household culinary processes.

Seaweeds are widely consumed as natural seafood in various Asian countries. Chemical contaminants, such as pesticide residues (PRs), can contaminate it due to its high bio-accumulation nature. Limited research exists on the presence of PRs in edible seaweeds, their decrease in levels during cooking processes, and the evaluation of hazard indices and associated health risks to humans. This study investigated the effects of different cooking methods on the levels of organochlorine pesticides in Caulerpa racemosa seaweed. It also assessed the potential health risks associated with consuming seaweed by estimating daily intake, hazard quotient, and hazard index. The PRs were reduced after different cooking methods. The impact of thermal cooking on PRs in C. racemosa was found to be notably beneficial. The PRs decreased following MWC, boiling, and steam cooking. Several PRs were analyzed, and endrin, DDT, endosulfan, and cypermethrin were found to be the most prevalent. The HQ and HI values for raw and cooked seaweeds were found to be below one, suggesting that the PRs in C. racemosa pose no risk to consumers of seaweed. In summary, thermal cooking proves to be an efficient method for minimizing PRs, while the cooking of seaweeds ensures a high level of safety during consumption.

Spatial distribution and seasonal variation of pesticide residues in the sediment, seawater, and edible seaweeds: Environmental and human health risk assessment.

This study evaluates the distribution of pesticide residues (PRs) and assesses the ecological and human health risks posed by them from seawater, sediment and edible seaweeds in the Gulf of Mannar. Results showed that hexachlorocyclohexane, heptachlor, aldrin, endrin and endosulfan were the predominant PRs. The maximum concentration of PRs was observed in the monsoon and post-monsoon seasons. Their concentrations in sediment exceeded interim sediment quality guidelines, indicating significant risks to benthic organisms. Except for endrin, the presence of other organochlorine pesticides (OCPs) was below the maximum residual limit. Human health risk assessment revealed that the estimated daily intake of PRs through seaweeds was below the acceptable daily intake. The hazard quotient and hazard ratio were <1, implying that the study seaweeds do not pose significant health risks. The presence of endrin in edible seaweeds, however, indicates safety concerns for consumers and the continued use of banned OCPs in agriculture.

Ingestion of microplastics in commercially important species along Thoothukudi coast, south east India.

Microplastics pollute the marine environment and pose a greater risk to marine organisms. The microplastics were observed in the guts of the 12 species, which varied from 0.00 to 1.80 ± 1.19 particles /individual. Most of the microplastics were fibre shaped, 0.5-1 mm sized, blue-coloured, and polyethylene polymers. The abundance of the microplastics was higher for benthic species (0.66 ± 0.13 particles/ individual) than the pelagic species (0.53 ± 0.11 particles/individual), with no significant difference (p > 0.05). According to their feeding habits and trophic level, significantly the microplastics were abundant in the herbivores (1.23 ± 0.61 particles/individual) and quaternary consumers (0.76 ± 0.16 particles/individual), respectively. The present study suggests that microplastic ingestion in commercially important species was influenced by their feeding habits irrespective of their habitat and length and weight. In addition to this, biomagnification of the microplastics (Trophic Magnification Factor, TMF = 1.02) was also observed in the commercially important species with increasing trophic level. This further indicates that the trophic level can serve as the pathway for the transfer of microplastics from lower trophic level organisms to higher trophic level organisms. The present study concludes that the occurrence of biomagnification of microplastics and the pollutants absorbed by them might harm the commercially important species from the Thoothukudi region.

Impact of textile dyes on human health and bioremediation of textile industry effluent using microorganisms: current status and future prospects.

Environmental contamination brought on by the discharge of wastewater from textile industries is a growing concern on a global scale. Textile industries produce a huge quantity of effluents containing a myriad of chemicals, mostly dyes. The discharge of such effluents into the aquatic environment results in pollution that adversely affects aquatic organisms. Synthetic dyes are complex aromatic chemical structures with carcinogenic and mutagenic properties in addition to high biological oxygen demand (BOD) and chemical oxygen demand (COD). This complex aromatic structure resists degradation by conventional techniques. The bioremediation approach is the biological clean-up of toxic contaminants from industrial effluents. Biological treatment methods produce less or no sludge and are cost-effective, efficient, and eco-friendly. Microorganisms, mostly microalgae and bacteria, and, in some instances, fungi, yeast, and enzymes decolorize textile dye compounds into simple, non-toxic chemical compounds. Following a thorough review of the literature, we are persuaded that microalgae and bacteria might be one of the potential decolorizing agents substituting for most other biological organisms in wastewater treatment. This article presents extensive literature information on textile dyes, their classification, the toxicity of dyes, and the bioremediation of toxic textile industry effluent utilizing microalgae and bacteria. Additionally, it combines data on factors influencing textile dye bioremediation, and a few suggestions for future research are proposed.

Microplastics accumulation in pelagic and benthic species along the Thoothukudi coast, South Tamil Nadu, India.

Microplastics contamination poses a serious threat to marine biota, so the current study was carried out to assess the incidence of microplastics in the gastrointestinal tracts of pelagic and benthic species collected from the six sampling sites along Thoothukudi region from January 2021 to December 2021. In the present study, benthic species (0.67 ± 0.14 MPs/indiv) showed a higher abundance of microplastics than pelagic species (0.53 ± 0.11 MPs/indiv). The dominance of microplastic shapes, sizes, colours and polymers found were comparable among both pelagic and benthic species, this being fibre (27.56% and 48.33%), 0.5-1mm (39.78% and 42.94%), blue (50% and 40.85%), and PE (46.24% and 48.18%), respectively. The present study showed that microplastics are ubiquitous in both habitats, which raises serious concerns for public health. Hence, measures focusing on reducing local emissions and plastic waste disposal should be implemented to control microplastic pollution in the marine environment.

Spatial, seasonal and ecological risk assessment of microplastics in sediment and surface water along the Thoothukudi, south Tamil Nadu, south east India.

Microplastics are a widespread environmental contaminant that raises serious concern for aquatic organisms. Hence, the present study was conducted to investigate the spatial and seasonal variation of microplastics, their characteristics, polymer types and the risk assessment caused by the microplastics in six sampling sites along the Thoothukudi region. The average microplastic abundance ranged from 32 ± 26 to 232 ± 229 items/kg and 54 ± 41 to 619 ± 377 items/l in sediment and surface water, respectively, and they exhibited a significant spatial difference among the sampling sites. The microplastic abundance also showed a significant difference among the seasons with the monsoon significantly recording the highest mean microplastic abundance in sediment (160 ± 130 items/kg) and surface water (454 ± 374 items/l). In sediment and surface water, fragment (sediment: 52.72%, surface water: 40.89%), 0.5-1 mm (sediment: 43.96%, surface water: 31.11%) and blue-coloured (sediment: 52.33%, surface water: 41.85%) microplastics were dominant with no significant difference both spatially and seasonally. Polyethylene, the dominant polymer, was observed in both the sediment and surface water, accounting for about 47.58% and 49.83%, respectively, and it showed no significant difference among the selected sites. This signifies that they are homogenously distributed along the coast and further suggests that these particles persisted in the sediment and surface water for a longer period of time. The results of the polymer hazard index show that the sediment (PHI = 1181.63) and surface water (PHI = 1018.66) were severely contaminated (hazard level V) with microplastic polymers such as PE, PP, PS, PET and PA. It was also found that the degree of the microplastic contamination in sediment (PLI = 3.57) and surface water (PLI = 3.84) was lower (hazard level I). The overall risk index (RI) for sediment (253.48) and surface water (444.74) falls under the higher risk category. From the correlation analysis, a significantly positive relationship was observed between microplastics in sediment and surface water based on each classification (abundance, shape, size, colour and polymer). This suggests that microplastics rejoin the water column from the sediment through resuspension, which occurs due to the circulation, tides and sedimentation rate. This might be the reason for the higher microplastic abundance in the surface water than in the sediment. As a result, proper management measures to reduce plastic waste disposal in the marine environment should be implemented to lessen the effects of microplastics on marine biota and on public health.

Contamination of microplastics, surface morphology and risk assessment in beaches along the Thoothukudi coast, Gulf of Mannar region.

Microplastics accumulation on beaches raises a serious concern worldwide. Hence, the present study was conducted with the focus of investigating the abundance, characteristics, risk assessment, surface morphology and elemental composition of microplastics (MPs) in the beach sediments of the Thoothukudi region, situated on the south-east coast of India, Gulf of Mannar region. The MPs abundance ranged between 19 ± 18.62 and 78.55 ± 95.17 items/kg with a mean abundance of 33.82 ± 26.11 items/kg and the spatial distribution of MPs showed insignificant variation. Fragments (59.48%), 0.5-1 mm (43.66%) and blue-coloured MPs (45.61%) were highly predominant in the sediments. Attenuated total reflection - Fourier transform infrared (ATR-FTIR) spectroscopy showed the dominance of polyethylene polymers in sediments (52.26%) and their sources could be attributed to the direct inflow of sewage, recreational and fishing activities and accidental loss. The current study revealed that microplastics (< 5 mm) are ubiquitous along the Thoothukudi coast, posing a serious threat to the marine environment and marine organisms. The ecological risk assessment of MPs in sediments was calculated by adopting 3 models: the polymer hazard index (PHI), pollution load index (PLI) and potential ecological risk assessment (RI). The overall PHIsediments = 698.96 exhibited a hazard level of IV, which was mainly due to the varying abundance of polymer composition in sediments. The value of PLIsediments is 2.51, which mainly depends on the MPs abundance in sediments and yields the hazard level of I. The ecological risk posed by MPs in beach sediments along the Thoothukudi coast (RIsediments = 241.06) falls into the medium category, indicating that steps must be taken to reduce the flow of plastics through management measures such as proper wastewater treatment practices, recycling of plastic waste and proper waste disposal. Field emission scanning electron microscopy (FESEM) images revealed that MPs surfaces were strongly weathered and energy dispersive X-ray (EDX) spectroscopy spectra showed that the presence of inorganic elements associated with the surface MPs might be derived from the surrounding environment or additives in plastics. Hence, further research has to be conducted in view of studying the combined effects of MPs pollution and organic pollutants, which will provide further understanding of the contamination of MPs in the marine environment.

Dietary intake of trace elements from commercially important fish and shellfish of Thoothukudi along the southeast coast of India and implications for human health risk assessment.

The concentrations of eight trace elements (chromium, cobalt, copper, zinc, arsenic, cadmium, mercury and lead) in14 commercially important fish and shellfish collected from Thoothukudi along the southeast coast of India was investigated using inductively coupled plasma mass spectrometry in order to assess the health risks associated with their consumption. The concentration of trace elements ranged from 0.001 to 39.5 µg/g. The estimated weekly intake of cadmium in seven fish and shellfish (0.0081-0.0996 mg/kg body weight) were above the provisional tolerable weekly intake set by the Joint FAO/WHO Expert Committee on Food Additives. The risk assessment analysis indicated that there was non- carcinogenic risk upon lifetime consumption of rock crab, C. natator (TTHQ >1) and carcinogenic risks upon lifetime consumption of S. jello, P. semisulcatus, P. sanguinolentus C. natator, Uroteuthis duvaceli, Sepia pharaonis and Cistopus indicus due to cadmium exposure indicating a potential health risk to the exposed consumers.

Concentrations of trace elements in the organs of commercially exploited crustaceans and cephalopods caught in the waters of Thoothukudi, South India.

Concentrations of trace elements (arsenic, cadmium, mercury, and lead) in tissues (muscle, gills, and digestive gland) of three commercially exploited crustaceans (Portunus sanguinolentus, Charybdis natator, and Penaeus semisulcatus) and three cephalopods (Doryteuthis sibogae, Sepia pharaonis, and Cistopus indicus) were examined. The animals were captured in the waters of Thoothukudi, and the tissues of six individuals of each species were analyzed using ICP-MS. The highest concentrations of arsenic (16.5 µg/g) and mercury (0.052 µg/g) were recorded in the digestive gland of C. natator, and cadmium (69.9 µg/g) and lead (0.351 µg/g) in the digestive gland of S. pharaonis. The edible portion of the crustaceans and cephalopods contained lower concentrations of trace elements, and these were below allowable limits set by the European Union. The edible parts of the investigated samples are safe for human consumption, but accidental contamination of the edible tissues with material from the digestive glands could lead to concerns relating to metal toxicity.