Airborne Microplastics in Indoor and Outdoor Environments of a Developing Country in South Asia: Abundance, Distribution, Morphology, and Possible Sources.

Airborne microplastics (AMPs) have been reported in indoor and outdoor air in high-income countries and are expected to be a significant contributor to daily microplastic (MP) exposure for human beings. To date, there are only a handful of studies in lower-middle-income countries. In this study, AMPs from 5000 to 50 µm were sampled across selected areas of Sri Lanka using an active sampling technique. Suspected AMPs were further characterized using Fourier transform infrared spectroscopy. MP concentrations were higher indoors compared to outdoor air (0.13-0.93, compared to 0.00-0.23 particles/m3, respectively). The types of indoor MPs were related to indoor-generating sources, and the occupant's lifestyles. The highest outdoor MP abundance was found near an industrial zone, followed by urban and inland locations in high-density areas. The dominant size range of MPs was 100-300 µm, and the only shapes observed indoors and outdoors were fibers (98%) and fragments. Polyethylene terephthalate was the most prominent MP type, followed by polyester, indicating that textile fibers could be the major source of these AMPs. This study provides the first report on AMPs in Sri Lanka. Considering population growth and industrialization, further research should evaluate possible trends and health risks upon inhalation.

Diversity of microbial communities in hot springs of Sri Lanka as revealed by 16S rRNA gene high-throughput sequencing analysis.

Characterization of hot spring microbiota is useful as an initial platform for exploring industrially important microbes. The present study focused on characterization of microbiota in four hot springs in Sri Lanka: Maha Oya; Wahava; Madunagala; and Kivlegama using high throughput 16S amplicon sequencing. Temperatures of the selected springs were ranged from 33.7 °C to 52.4 °C, whereas pH ranged from 7.2 to 8.2. Bacteria were found to be the dominant microbial group (>99%) compared to Archaea which represented less than 1% of microbiota. Four hot springs comprised of unique microbial community structures. Proteobacteria, Firmicutes, Bacteroidetes, Cloroflexi, Deinococcus and Actenobacteria were the major bacterial phyla. Moderately thermophilic genera such as Thermodesulfobacteria and Deinococcus-Thermus were detected as major genera that could be used in industrial applications operating at temperatures around 50 °C and alkaline reaction conditions.

Prevalence and Quantitative Analysis of Antibiotic Resistance Genes (ARGs) in Surface and Groundwater in Meandering Part of the Kelani River Basin in Sri Lanka.

Nearly 80% of the population in the Colombo district fulfill their major requirement from the Kelani river. Recent studies are interoperating: most groundwater and surface water in Sri Lanka are contaminated with waterborne pathogens and antibiotics. In the present study, nine antibiotic resistance genes (ARGs) were screened which were belonging to two common groups of antibiotic: penicillin - OPR D, bla TEM , bla OXA , amp a, and amp b - and tetracycline - tet A, tet M, tet B, and tet S. The results of the study reveled that the surface and groundwater of the entire lower part of the Kelani river basin were contaminated with TC and FC (98%). None of the penicillin and tetracycline group antibiotics were detected either surface or groundwater samples except the Kelani river mouth (amoxicillin (AMX) at 0.003 ± 0.001 µg/ml). The results showed that 5 to 15% of surface water samples were positive for penicillin resistance genes (bla TEM , bla OXA , OPR D, amp a, amp b) where ~ 10% of groundwater samples were positive against tetracycline resistance genes (tet A, tet M, tet S, tet B). Among the penicillin resistance genes, the bla TEM (700.576 × 102 copy/ml) was recorded as the highest concentration where the highest tet A gene (439.875 × 102 copy/ml) was detected among the tetracycline resistance genes. Therefore, water quality management and regular monitoring are essential to maintain the quality of drinking water in the meandering part of the Kelani river basin to safeguard river water consumers.

Modified, optimized method of determination of Tributyltin (TBT) contamination in coastal water, sediment and biota in Sri Lanka.

Tributyltin (TBT) is a toxic organotin compound that belongs to the group of Persistent Organic Pollutants (POPs) and it is documented to cause severe sexual disorders development in aquatic fauna. According to the present study, The TBT concentration in coastal water ranged from 303 ± 7.4 ngL-1 to 25 ± 4.2 ngL-1 wherein sediment was from 107 ± 4.1 ngKg-1 to 17 ± 1.4 ngKg-1. TBT in Perna viridis was found to range from 4 ± 1.2 ngKg-1 to 42 ± 2.2 ngKg-1 wet weight and in ascending order of the body weight. The highest TBT level in water and sediment was found in the Colombo port where the highest level of TBT in P. viridis (42 ± 2.2 ngKg-1) was recorded from the Dikkowita fishery harbor. A positive correlation between the number of male P. viridis and TBT level (p < 0.05) suggests possible reproductive impairment in aquatic animals exposed continuously to a high concentration of TBT.

Kidney developmental effects of metal-herbicide mixtures: Implications for chronic kidney disease of unknown etiology.

Chronic kidney disease of unknown etiology (CKDu) is an emerging global concern affecting several agricultural communities in the Americas and South Asia. Environmental contaminants such as heavy metals (e.g., Cd, As, Pb, and V) and organic pesticides (e.g., glyphosate) in the drinking water have been hypothesized to play a role in childhood onset and progression of this disease. However, a comprehensive analysis of chemical contaminants in the drinking water and effects of these compounds and their mixtures on kidney development and function remains unknown. Here, we conducted targeted and non-targeted chemical analyses of sediment and drinking water in CKDu affected regions in Sri Lanka, one of the most affected countries. Using zebrafish Danio rerio, a toxicology and kidney disease model, we then examined kidney developmental effects of exposure to (i) environmentally derived samples from CKDu endemic and non-endemic regions and (ii) Cd, As, V, Pb, and glyphosate as individual compounds and in mixtures. We found that drinking water is contaminated with various organic chemicals including nephrotoxic compounds as well as heavy metals, but at levels considered safe for drinking. Histological studies and gene expression analyses examining markers of kidney development (pax2a) and kidney injury (kim1) showed novel metal and glyphosate-metal mixture specific effects on kidney development. Mitochondrial dysfunction is directly linked to kidney failure, and examination of mixture specific mitochondrial toxicity showed altered mitochondrial function following treatment with environmental samples from endemic regions. Collectively, we show that metals in drinking water, even at safe levels, can impede kidney development at an early age, potentiating increased susceptibility to other agrochemicals such as glyphosate. Drinking water contaminant effects on mitochondria can further contribute to progression of kidney dysfunction and our mitochondrial assay may help identify regions at risk of CKDu.

Accumulation of Microcystin-LR in Grains of Two Rice Varieties (Oryza sativa L.) and a Leafy Vegetable, Ipomoea aquatica.

The potential transfer of microcystin-LR (MC-LR) to humans via crop plants irrigated with MC-contaminated water is causing serious concern. In this study, two Oryza sativa variants, a hybrid (BG358), a traditional (Suwandel) variety, and a leafy green vegetable crop, Ipomoea aquatica, were exposed under laboratory conditions to natural blooms of Microcystis aeruginosa sampled from a hypereutrophic lake contaminated with MC-LR (3,197.37 ± 1.04 µg/L). Field samples of O. sativa and I. aquatica were collected from farmlands that had been irrigated from a reservoir, containing MC-LR (180 µg/L). MC-LR was quantified by high performance liquid chromatography followed by photodiode-array detection (HPLC-PDA). From the laboratory study, we calculated the potential human health exposure from BG358, Suwandel and I. aquatica as 2.84 ± 0.01, 0.22 ± 0.01, and 0.06 ± 0.01 µg/kg of body weight/day, respectively, whereas the potential health exposures from BG358, Suwandel and I. aquatica collected from the field were 0.10 ± 0.01, 0.009 ± 0.005, and 0.03 ± 0.01 µg/kg of body weight/day, respectively. In certain instances, the results exceeded the World Health Organization's (WHO) tolerable daily intake of MC-LR, posing a potential health risk to humans. Thus, our results emphasize the importance of continuous screening programs for cyanotoxins in edible plants in the future to prevent the consumption of contaminated crops.

Spatial and vertical distributions of sedimentary halogenated polycyclic aromatic hydrocarbons in moderately polluted areas of Asia.

The sedimentary halogenated (chlorinated and brominated) polycyclic aromatic hydrocarbons (Cl/BrPAHs), PAHs, and elements were analyzed to investigate contamination processes and sources. Assessments were conducted in sediments from three sites: surface sediments from the Yellow Sea and sediment cores from Kandy Lake and Negombo Lagoon, Sri Lanka. Most of ClPAHs targeted were detected in all sediments. Spatial distributions of total ClPAH concentrations in the Yellow Sea showed the presence of multiple hot spots that differed from those of total PAHs. In Kandy and Negombo sediments,total ClPAH concentrations were slightly higher in surface layers than in bottom layers; the opposite trend was observed for PAHs. Principal component analysis showed that the clusters of most ClPAHs were similar to those of anthropogenically derived elements, but were far from those of PAHs. Consequently, ClPAHs in sediments appear to be persistent contaminants, which may make them appropriate as indicators of anthropogenic sources.

Isolation and identification of novel microcystin-degrading bacteria.

Of 31 freshwater bacterial isolates screened using the Biolog MT2 assay to determine their metabolism of the microcystin LR, 10 were positive. Phylogenetic analysis (16S rRNA) identified them as Arthrobacter spp., Brevibacterium sp., and Rhodococcus sp. This is the first report of microcystin degraders that do not belong to the Proteobacteria.

Species-specific concentrations of perfluoroalkyl contaminants in farm and pet animals in Japan.

The persistent metabolites of perfluorinated compounds (PFCs) which have been detected in the tissues of both humans and wildlife, and human contamination by PFCs suggest differences in the exposure patterns to these compounds. However, studies focused on identifying human exposure pathways to PFCs are scarce. To provide a preliminary assessment of PFCs in farm animals such as chicken, cattle, pigs, goats and horses, blood and liver samples were collected from various regions in Japan. Additionally, dog sera samples representing pet animals were also employed for analysis. Perfluorooctane sulfonate (PFOS) was the most prominent contaminant found in farm and pet animals, with mean sera PFOS concentrations (in decreasing order) of: chicken (5.8 ng/ml)>cattle (3.0 ng/ml)>goat (2.4 ng/ml)>horse (0.71 ng/ml)>pig (0.37 ng/ml). Chicken livers (67 ng/g) contained the highest mean PFOS concentration among the farm animals, followed by those of pigs (54 ng/g) and cattle (34 ng/g). In comparison to PFOS levels in farm animals, the detected levels of other PFCs were not significant. The high levels of PFOS found in cattle fetal livers suggest that PFOS crosses the placental barrier to enter fetal circulation. The consumption of chicken by humans might produce higher PFOS exposure in humans compared to that in farm animals; however, the current levels of PFOS in farm animals in Japan were lower than those reported in fish and wild animals. Elevated concentrations of both PFOS (25 ng/ml) and perfluorohexane sulfonate (PFHxS; 10 ng/ml) were found in dog sera, indicating that further studies are needed to identify PFC sources in the human environment.