Analysis of microplastics in ships ballast water and its ecological risk assessment studies from the Persian Gulf

Microplastics and phthalate esters in yogurt and buttermilk samples: characterization and health risk assessment

The contamination of yogurt and buttermilk (doogh), two widely consumed dairy products, with microplastics (MPs) and phthalic acid esters (PAEs), and subsequently the health effects caused by the contamination of these products on humans, is a potential concern. In this study, the abundance and characteristics of MPs as well as the PAEs concentration in different types of yogurts and buttermilk available in the Iranian market were investigated. The average abundance of MPs in different types of yogurts and buttermilk was between 0.63 and 0.76 and 0.52-0.7 items/mL, respectively. Most detected MPs in yogurt and buttermilk samples were in the size range of 1000-5000 μm with the predominant color and shape of transparent and fiber, respectively. Polyethylene terephthalate (PET) and polyamide (PA) were the dominant polymers in yogurt and buttermilk samples, respectively. The average concentrations of PAEs in different types of yogurt and buttermilk samples were between 5.79 and 11.36 and 1.46-6.93 µg/L, respectively. The findings showed that Di(2-ethylhexyl) phthalate (DEHP) levels in yogurt and buttermilk samples may have a carcinogenic risk for adults and adolescents. According to the results of this study, the intake of MPs and PAEs through high consumption of yogurt and buttermilk should be recognized as a significant source of MPs in the human body.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40201-025-00939-z.

Overview of monitoring methods and environmental distribution: Microplastics in the Indian Ocean

Microplastics are ubiquitous globally, posing a significant threat to human health. Notably, the Indian Ocean ranks second in microplastic contamination, emerging as a major source of pollution. In response to this risk, neighboring countries are actively addressing severe plastic pollution and deficiencies in waste management. Research on microplastics in Indian Ocean seawater commenced in 2016. This paper reviews the research status and trends, detailing sampling, extraction, and identification methods. We categorize 43 studies by trawl sampling and other techniques, summarizing microplastic abundance, size, shape, color, and polymer types. Microplastic distribution varies widely in the Indian Ocean, peaking in the East, West, and along the Indian coast. Fiber and debris microplastics are the most, the main colors are black, blue, white and transparent, and the polymer types are mainly PE, PP and PS. Oceanic convergence intensity affects microplastic distribution globally, intensifying accumulation. This study highlights the need for standardized microplastic sampling and analysis in Indian Ocean countries. Collaborative surveys and investigations are crucial to addressing pollution.

Onboard measurement of polyethylene microplastics on a research vessel using Raman micro-spectroscopy: A preliminary study for testing feasibility

Microplastic pollution in marine environments poses significant environmental risks due to its widespread presence. Traditional micro-imaging measurement of microplastics often rely on post-cruise laboratory analyses. In this study, we explored the feasibility of onboard microplastic measurement using Raman spectroscopy, with a focus on polyethylene (PE). A measurement system was developed, and two concentration estimation approaches were proposed. To evaluate recovery and validate the methodology, artificial microplastic samples were prepared, yielding a recovery rate of 94.8 % ± 10.4 %. Environmental samples were then analyzed using the developed system, with results validated against conventional Fourier-transform infrared (FTIR) spectroscopy. The estimated PE concentration was 583 pieces/m3 (95% confidence interval: [2, 1542] pieces/m3) using the direct approach and 1453 pieces/m3 (95% credible interval: [291, 92,837] pieces/m3) using the Bayesian approach. Both estimates were consistent with the 333 pieces/m3 obtained through validation with FTIR, indicating adequate accuracy. However, the wide confidence intervals highlight the need for improved precision. While challenges remain, this study provides a comprehensive experimental procedure and introduces a robust data analysis framework, which could offer a foundational methodology for future onboard microplastic measurement research.

Microplastic footprints in sharks and rays: First assessment of microplastic pollution in two cartilaginous fishes, hardnose shark and whitespotted whipray

Microplastic (MP) pollution is an emerging environmental problem worldwide and has caused widespread concern both in terrestrial and aquatic ecosystems due to their potential impacts on the human health, and health of aquatic organisms and the environment. Little is known about the exposure of top marine predators to MP contamination (debris 0.1μm - <5mm, also called MPs). For the first time, MPs have been characterized in carnivore demersal elasmobranch specimens of hardnose shark Carcharhinus macloti, and the whitespotted whipray Maculabatis gerrardi. The specimens were from the Persian Gulf and Sea of Oman, and MPs were extracted from their intestines, gills, and skin. MPs were found in every sampled tissue examined: this is higher pollution than previously reported for elasmobranch. The total MPs for these organs were 12.6 MPs/g body mass of sharks, and 17.8 MPs/g in the whiprays on average. The most common MPs found were fibres (59%), and filaments (35%); pointing towards fishing gears and limited wastewater treatment. Fragments, films, and foams were <2.1 %; a less abundant problem. The most abundant MPs sampled were ∼0.5 mm ≤ L< 1 mm (when the limit of detection was 0.1 mm), and blue was the most common MP color hinting intake due to visual confusion. Polycarbonate and nylon were the most abundant polymers in the MPs recovered. The overall findings show that C. macloti and M. gerrardi are vulnerable to plastic and it reflects the critical state of their habitat.

Effects of different microplastics on the physicochemical properties and microbial diversity of rice rhizosphere soil

Biodegradable plastics, as alternatives to conventional waste plastics, are increasingly applied across various fields. However, the ecological risks associated with the widespread use of biodegradable plastics remain unclear. Additionally, biodegradable plastics tend to age in the environment, leading to changes in their physicochemical properties. The ecological risks brought by the aging of microplastics have also been scarcely studied. In this study, we selected conventional microplastics (PE-MPs), biodegradable microplastics (PLA-MPs), and aged biodegradable microplastics (aging-PLA-MPs) to explore their effects on the rhizosphere soil environment of rice. The results showed that microplastics reduced the soil N and P content, with PE slightly increasing the DOC content, while PLA and aging-PLA significantly increased DOC by 21.13 and 24.04%, respectively. Microplastics also decreased soil enzyme activity, with aging-PLA having a somewhat stimulatory effect on enzyme activity compared to PLA. Furthermore, microplastics reduced the soil bacterial diversity index and altered the community structure of dominant bacterial species, with DOC content and FDA hydrolase being the main factors influencing the soil bacterial community. Bacteria were most sensitive to PLA, and the stability of the bacterial microbial network structure decreased, although aging reduced the negative impact of PLA on the bacterial community. This study contributes to our understanding of the ecological risks posed by biodegradable plastics and their aging processes on the environment.

Advancements in bilge wastewater treatment: A review for current and future trends

Bilge wastewater (BW) from ships poses a significant threat to coastal ecosystems due to its recalcitrant nature. BW is mainly composed of organic hydrocarbons and oils together with surfactants, heavy metals, and other organic compounds but oil is the sole compound regulated by international law with a discharge limit of 15 mg/L. Therefore, BW treatment is a crucial aspect of marine pollution control and environmental protection. In this sense, BW must be treated on board or shipped to treatment plants on land. While conventional methods like gravity separation and adsorption have been used to treat BW, their inability to effectively treat complex mixtures has encouraged researchers to investigate advanced alternatives. Thus, new, cost-efficient, and sustainable technologies to treat BW are required such as those based on biological approaches. Moreover, integrating bio-based methods with existing technologies can provide comprehensive and eco-friendly treatment solutions. This review compiles various documents published regarding the treatment of BW, pointing out the necessity of developing new cost-efficient and environmentally friendly approaches to treat it. To the best knowledge of the authors this is the first comprehensive review on this very latest topic. Therefore, this review will be a significant contribution to the literature in terms of conservation of the environment, reduction in water pollution, and protection of the marine ecosystems.

Abundance, characteristics and ecological risk assessment of microplastics in ship ballast water in ports around Liaodong Peninsula, China

The development of the shipping industry has led to a large volume of ballast water discharge annually. This accelerates pollutants' transfer and dispersion, such as microplastics. Currently, empirical data on microplastics in ballast water are rarely available. This study innovatively investigated the abundance, morphological characteristics (particle size, shape, and color), and polymer composition of microplastics in ballast water from ports surrounding the Liaodong Peninsula. The results revealed that the average abundance of microplastics in 13 ships' ballast water was 6071.30 ± 1313.85 items/m3. Notably, the small microplastics (0.06-2.50 mm) were most abundant, accounting for 94.52 % of the total microplastics. Transparent, fiber, and polyethylene glycol terephthalate were the most prevalent color, shape, and polymer composition of microplastics detected in the ballast water. The risk assessment indicated that these microplastics present ecological risks to organisms. These findings suggest that ship ballast water is the potential "hotspot" for marine microplastics transport.

Qualitative and quantitative assessment of microplastics derived from antifouling paint in effluent from ship hull hydroblasting and their emission into the marine environment

This study focused on microplastic (MP) contamination originating from ship paint, particularly during the hydroblasting of ship hull, to understand the emission characteristics of MPs into the marine environment. We evaluated paint particles generated from the hydroblasting of an ocean-going vessel based on their number, size, polymer type, and mass. Hydroblasting a vessel produced 4.3 × 1015 particles, predominantly comprising acrylic particles, 99.9 % of which were smaller than 5 mm. Of the 44.1 kg of antifouling (AF) paint particles generated, 36.5 kg consisted of particles smaller than 5 mm, with 18.2 kg being identified as plastic emissions. Furthermore, we calculated the MP emission factor (8.43 g/m2) for hydroblasting on AF paint by dividing the total emission by the wetted surface area (WSA) of the vessel. This factor was then extrapolated by multiplying it with the total WSA of global ships and their hull cleaning frequency to preliminarily estimate the annual global MP emissions. Consequently, a total of 665.6 tons of plastics was generated globally by hydroblasting, with approximately 550.2 tons of these being in the form of MPs. This study highlights the need for developing stricter regulations governing hydroblasting operations and waste disposal practices to protect marine environments from MP pollution.

Microplastics and phthalate esters contamination in top oceanic predators: A study on multiple shark species in the Pacific Ocean

Marine organisms, especially top predators such as sharks, are susceptible to environmental pollutants like microplastics (MPs) and phthalate esters (PAEs), leading to ecosystem risks. Research on contamination in these apex species is, however, still limited. This study investigated MPs and PAEs in multiple shark species (Isurus oxyrinchus, Alopias superciliosus, Alopias pelagicus, Carcharhinus brevipinna, and Sphyrna zygaena) off Taiwan's eastern coast. Gastric tissue analyses revealed ubiquitous microplastics (2-31 particles), which positively correlated with body lengths and weights for Isurus oxyrinchus. Blue, fiber-shaped (1-2 mm), and rayon-based MPs are likely associated with textile fiber pollution. The PAEs concentration mean was 7035 ± 6829 ng/g, ww, having DEHP and DiNP as primary compounds. This study highlights pervasive contamination in Pacific Ocean sharks, emphasizing anthropogenic impact on top oceanic predators and providing essential insights for food safety and MP accumulation.

Distribution characteristics and ecological risk analysis of microplastics in sediments and effluents related to offshore oil and gas activities in the Bohai Sea, China

Oil and gas activities are sources of marine microplastics (MPs) but have received less attention globally. This study assessed the distribution characteristics and ecological risks of MPs in 31 sediment samples and effluent samples of 5 oil and gas platforms related to offshore oil and gas activities in the Bohai Sea. The results showed that the mean abundance of MPs in sediment, produced water, and domestic sewage was 205.7 ± 151.5 items/kg d.w., 18 ± 11 items/L, and 26 ± 39 items/L, respectively. The MPs in sediments and effluents were dominated by transparent, rayon, and fibers <1 mm. Oil and gas activities may influence the abundance of MPs in the sediments. The sediments in the area were at a low level of risk, but some samples exhibited indexes beyond low levels. The mass of MPs carried by the effluents from oil and gas platforms in the Bohai Sea was less than that of other sources.

Microplastic pollution in surface sediments of Coromandel coastline, South-East Coast, India: Diversity index, carbonyl index, pollution load index, risk fraction and MPs inventory

The investigation along the Coromandel coastline of South-east India focused on assessing microplastics abundance using Simpson's diversity index (DIMP), Degradation-carbonyl index (DgCIMP), Pollution load index (PLIMP) and Ecological risk fraction (RfMP). These indices evaluated the dissemination and transportation of MPs across a 1076 km stretch divided into five zones from Chennai to Kanyakumari. During the wet season, average microplastics abundance (101 ± 36.6 items/kg dw) was lower compared to the dry season (143 ± 56.2 items/kg dw). Notably, 54% and 45% of microplastics were found in the 0.1-0.5 mm size range, with 45% and 64% being colored microplastics, and 80% and 71% being fibers during the wet and dry seasons respectively. Micro-Fourier-transform infrared spectroscopy (μFTIR) analysis showed rayon (34%) and PE (64%) dominance in ports and estuaries during both seasons. Kottaipattinam Port exhibited higher diversity indices (DIMPsh=0.56,DIMPsz=0.66,DIMPco=0.50andDIMPpo=0.65) compared to other zones, with an overall diversity index IDIMP of 0.57. Notably, among the DgCIMP values (n = 96), only 12 fell within the moderate photo-chemical oxidation range (0.16-0.35), while the majority (n = 60) surpassed 0.35 indicating higher oxidation levels, with some (n = 24) exceeding 0.50, signifying extreme oxidation. PLIMP revealed that 42% of sampling stations had very low to negligible MP contamination levels in ports and estuaries. However, ecological risk fraction RfMP values ranged from 10.2 to 13,670, with 27% of values exceeding 1500, indicating higher coastal ecological risk in 13 sampling stations.

Landscape and risk assessment of microplastic contamination in farmed oysters and seawater along the coastline of China

Microplastic (MP) pollution poses a significant threat to marine ecosystem and seafood safety. However, comprehensive and comparable assessments of MP profiles and their ecological and health in Chinese farming oysters are lacking. This study utilized laser infrared imaging spectrometer (LDIR) to quantify MPs in oysters and its farming seawater at 18 sites along Chinese coastlines. Results revealed a total of 3492 MPs in farmed oysters and seawater, representing 34 MP types, with 20-100 µm MP fragments being the dominant. Polyurethane (PU) emerged as the predominant MP type in oysters, while polysulfones were more commonly detected in seawater. Notably, oysters from the Bohai Sea exhibited a higher abundance of MPs (13.62 ± 2.02 items/g) and estimated daily microplastic intake (EDI, 2.14 ± 0.26 items/g/kg·bw/day), indicating a greater potential health risk in the area. Meanwhile, seawater from the Yellow Sea displayed a higher level (193.0 ± 110.7 items/L), indicating a greater ecological risk in this region. Given the pervasiveness and abundance of PU and its high correlation with other MP types, we proposed PU as a promising indicator for monitoring and assessing the risk MP pollution in mariculture in China. These findings provide valuable insights into the extent and characteristics of MP pollution in farmed oysters and seawater in China.

Influence of the geographic location and house characteristics on the concentration of microplastics in indoor dust

Microplastics (MPs) are known for their ubiquity, having been detected in virtually any environmental compartment. However, indoor MPs concentrations are poorly studied despite being closely related to human exposure. The present study aims to evaluate the presence of MPs in settled atmospheric dust in 60 houses distributed in 12 districts of the metropolitan city of Lima, Peru, and investigate the influence of their geographical location and house characteristics. MPs concentration ranged from 0.01 to 33.9 MPs per mg of dust. Fibers and blue were the most frequent shape and color (98 % and 69 %, respectively). Also, 82 % of the particles were between 500 μm - 5 mm in size. A higher concentration of MPs was identified in the center-south of the city. The houses located on the highest floors (levels 4 to 13 to ground) displayed higher concentrations. MPs were primarily composed of polyester (PET), polypropylene (PP), and ethylene-vinyl acetate (EVA), among others. The polymers identified suggest that MPs derived from the fragmentation of components frequently found in houses, such as synthetic clothing, food storage containers, toys, carpets, floors, and curtains. The incorporation of MPs from the outside into dwellings is not ruled out. Future studies should evaluate the influence of consumption habits and housing characteristics on the abundance of MPs.

Microplastics research in Nepal: Present scenario and current gaps in knowledge

The topic of microplastics has drawn considerable scholarly interest in recent times. The objective of this study is to provide an overview of the current state of microplastic pollution research in Nepal and to make future research recommendations. To achieve the objective, three popular databases (Web of Science, SCOPUS and Google Scholar) were used. The results showed that the current scenario for microplastic research in Nepal is in its early stage, which commenced in 2020. A total of six papers were recorded over the period from 2020 to 2023. The research conducted in the fields were rivers, lakes, snow, and sediments. Studies have provided evidence of the occurrence of microplastics in diverse aquatic ecosystems. Lakeshore sediments show concentrations of 100.5 ± 58.6 items/kg dry weight, while shoreline sediments of Phewa lake exhibit variability between 55 and 122.5 items/kg. The lake water in winter records 2.96 ± 1.83 Microplastics per Liter (MPs/L), river water indicates 202 ± 100 items/m3, and snow demonstrates 30 MP/L. In freshwater ecosystems, microplastics, specifically fibers, were found to be the prevailing type, while fragments were recorded in road dust. The study conducted in Nepal provided evidence of the presence of a wide range of polymers. The polymers encompassed polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), polyamide, polystyrene (PS), and polyester. Microplastic research in Nepal, initiated in 2020, covered rivers, lakes, snow, and sediments. Diverse aquatic ecosystems reveal microplastic presence, emphasizing the need for continued study and awareness. Although extensive research has been carried out on the subject of microplastic contamination and its effects on various creatures on a global scale, an examination of the implications of microplastics on animals, plants, and humans in Nepal has not been found in any scholarly publications. There exists a noticeable deficit of research investigating the consumption of microplastics by human.