Microplastics in Asian rivers: Geographical distribution, most detected types, and inconsistency in methodologies.

Microplastics pose a significant environmental threat, with potential implications for toxic chemical release, aquatic life endangerment, and human food chain contamination. In Asia, rapid economic growth coupled with inadequate waste management has escalated plastic pollution in rivers, positioning them as focal points for environmental concern. Despite Asia's rivers being considered the most polluted with plastics globally, scholarly attention to microplastics in the region's freshwater environments is a recent development. This study undertakes a systematic review of 228 scholarly articles to map microplastic hotspots in Asian freshwater systems and synthesize current research trends within the continent. Findings reveal a concentration of research in China and Japan, primarily investigating riverine and surface waters through net-based sampling methods. Polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET) emerge as the predominant microplastic types, frequently observed as fibers or fragments. However, the diversity of sampling methodologies and reporting metrics complicates data synthesis, underscoring the need for standardized analytical frameworks to facilitate comparative analysis. This paper delineates the distribution of microplastic hotspots and outlines the prevailing challenges and prospects in microplastic research within Asian freshwater contexts.

Analyze the toxicities of benzalkonium chloride as a COVID-19 disinfectant in physiological goldfish (Carassius auratus).

Background and Aims: Coronavirus disease-2019 (COVID-19) impacts increasing the use of disinfectants (benzalkonium chloride), which indirectly accumulate in water. The disinfectant accumulation in waters has been studied, but there has been no study of its impact on aquatic commodities, especially fish with a high sensitivity, one of which is goldfish (Carassius auratus). Benzalkonium chloride can potentially affect several body proteins, including the cytoskeleton, nervous and endocrine systems, and fish physiology. This study aimed to determine the impact of benzalkonium chloride as a disinfectant on the level of color brightness, growth, gill histopathology, and mortality in goldfish. This investigation provides input into the impact of using disinfectants to prevent COVID-19 on aquatic commodities. Materials and Methods: This study utilized goldfish specimens sourced from Tulungagung, East Java, Indonesia. The experiment involved different concentration levels of benzalkonium chloride: (T1) 0 mg/L, (T2) 0.03 mg/L, (T3) 0.06 mg/L, (T4) 0.09 mg/L, and (T5) 0.12 mg/L. The research data were subjected to an analysis of variance for analysis. In cases where significant differences were observed, Duncan's test was conducted for color brightness, growth, and mortality data. Furthermore, if the gill histopathological data yielded significant differences, additional tests were applied (Kruskal-Wallis and Mann-Whitney test). Results: The findings of this study demonstrated significant differences (p < 0.05) in the level of color brightness, growth, gill histopathology, and mortality in goldfish in response to varying concentrations of benzalkonium chloride. The relationship between the length and weight of the goldfish was analyzed using regression coefficients (b values), which were determined as 4.86, -0.04, -0.2, 0.8, and -0.07, respectively. Notably, the brightness level in the T2 group exhibited positive color results with a hue value of 11.55°, while optimal growth was observed in the T4 group, as evidenced by b value of 0.8. The gill histopathological data showed significant differences (p < 0.05). The scoring of histopathological damage in the goldfish gills ranged from 0 to 10, with higher scores indicating more severe damage. The highest total score of 10 was observed in the T5 group exposed to a concentration of 0.12 mg/L, resulting in an 85% mortality rate. This indicates that benzalkonium chloride, with its toxic compounds, can disrupt the respiratory system of fish and lead to death. Conclusion: The effects of benzalkonium chloride were evident even at a concentration of 0.03 mg/L. With increasing concentration, there was an increase in mortality rate, a decrease in growth, and a rise in histopathological damage to the gills. These findings highlight the negative impact of using conventional disinfectants on water and its organisms, emphasizing the need for further research on environmentally friendly alternatives.

Microplastics pollution in agricultural farms soils: preliminary findings from tropical environment (Klang Valley, Malaysia).

The aim of this research is to investigate the occurrence, characteristics, and potential sources of microplastic pollution at four agricultural farms in Malaysia's tropical region of Klang Valley. The mean number of microplastic particles found in the agricultural soils were 2.1 ± 0.44 to 3.4 ± 1.2 particles/kg. Farms B and D had the lowest and highest total microplastic particle counts, 1.5 and 6.0 particles/kg, respectively, which was in line with the intensity of plastic consumption at these farms. Microplastics particle sizes ranged from 16.7 to 1.246 µm, attributed to their extensive breakdown processes. The microplastic particle shapes (film, fiber, and fragment) and colors (black, white, red, and blue) from the soil samples reflected the type of plastic products used and unmanaged plastic waste at these farms. Plastic nets, mulching films, and unmanaged plastics waste constituted the major microplastics sources at these farms. Our findings confirm microplastic pollution in tropical agricultural soils as well as the need to assess the negative effects of long-term plastic use on agricultural soils.

Microplastics in Malaysian bottled water brands: Occurrence and potential human exposure.

The World Health Organization noted that there is a growing need to determine the occurrence of microplastics in bottled water and its potential risks to human health. Thus, present study analyzes microplastics in eight major bottled water brands available in Malaysia and estimates the potential human exposure. Membrane filtration method followed by visual and polymer identifications were utilized to identify microplastics particles in these eight major bottled water brands. Microplastic concentrations in bottled water samples ranged from 8 to 22 particles/L, with an average of 11.7 ± 4.6 particles/L. Particle sizes ranging between 100 and 300 µm were dominant and accounted for approximately 31% in these bottled water brands. Fragments were the most identified microplastics in bottled water with transparent color being the most prevalent. The polyethylene terephthalate (PET) and polypropylene (PP) polymer types found in this study are consistent with prior results in that microplastics in bottled water are mainly derived from packaging materials and bottle caps. The Estimated Dietary Intake (EDI) for adults was between 0.068 and 0.19 particle/kg/day, while the EDI for children was between 0.089 and 0.25 particle/kg/day. Although consumption of bottled water was estimated to have low EDI values, the potential risks to human health should be heeded due to the presence of numerous plastic additives and residual monomers in these particles, which have the potential to increase inflammatory reactions and cytotoxicity in human body. Future studies should concentrate on understanding microplastics particles less than 1.5 µm and other associated factors (bottled material quality, consumption behaviour, bottled water storage conditions, and the frequency of bottle opening and closing) to further understand the effects of these microplastics particles on human toxicological aspects.