# An Exploratory Review of Microplastic Pollution, Associated Microbiomes and Pathogens in Water
## 3 Results and Discussion
### Type of Microplastic in the Transitional Waters  
**Asia**: In an analysis of the literature in terms of the occurrence of types of MPs in surface waters in Asia, the largest share was represented by MPs from rayon (RA), at 40% on average; Polyethylene (PE), Cellophane (CP), Polypropylene (PP) and Polyester were also frequently reported, alongside terephthalatic acid (PES) (Figure 8a, Supplementary File S1--Asia). In the case of China, a significant share was made up of PE and PP, which on average accounted for 20-30% of the total MP particles. In some places,  
Figure 7: Relationship between the GDP per capita (USD, 2023) and average microplastic (MP) concentration (particles/m\({}^{3}\)) in surface waters, based on 2023–2024 literature data. Scatterplots with linear regression lines illustrate the trends across three aquatic environments: rivers, lakes, and marine coastal areas (Sea/bay). Although no statistically significant correlations were observed (Pearson’s r = 0.10 for rivers, r = 0.28 for lakes, r = 0.20 for sea/bay; all \(p\) > 0.4), the analysis highlights the variability of MP pollution across socioeconomic contexts. RA was also found at the level of 31%, and CP at 29.2% [32; 57; 58; 59; 60; 61]. As in the samples taken from China, in Thailand, a significant share comprised PP and PE, where the percentage for PP ranged from 17 to 60% and for PE ranged from 20 to 73% [62; 63; 64]. The MP samples from Japan, in turn, were characterized by a significant share of PE--the range was from 45 to 80% [65; 66; 67]. The MP particles found in Taiwan surface waters mainly comprised PE, PP, and polystyrene (PS) (respectively: 50, 30, 10%) [68]. The samples from India mainly showed RA, Polyacrylonitrile (PAN), PP and PE, the share of which was up to 50% [69; 37]. **Europe**: The MP samples analyzed in Europe mostly showed the participation of PP and PE (Figure 8b, Supplementary File S2--Europe). In Italy, the share of PE (about 45%) was dominant, followed by PS (18-24%) and PP (15-17%) [70; 71]. In turn, in the Netherlands, PA and Polyvinyl chloride (PVC) were at the level of 30% [72]. In studies on MPs in Germany, the main share comprised PE, from 34 up to 100%. Another type was PP (2.94-68.89%) [73; 74]. MP samples from Spain, France and the UK were characterized by a significant share of PE, ranging from 4 to 67.1%, and PP, from 16.5 to 23%. Additionally, in the MP samples from the UK and France, publications showed a significant share of PS, ranging from 16.1 to 30% [6; 75; 76; 77]. MP tests performed in water reservoirs in Portugal were also characterized by a significant share of PP and PE (ranging from 15 to 29.4% and from 29.4 to 33%, respectively) [78; 79; 80]. **North America**: An analysis of MP types in the literature (Figure 8c, Supplementary File S3--North America) showed that in the USA, the majority was PE (32%) and PP (13%) [36]. Similarly, in Canada, the range was 27-41.2%. Additionally, significant shares comprised PP (5-21.9%) and polyethylene terephthalate (PET) (8-10%). PA was also detected in one of the studies at the level of 16%, and PVC was detected at 1.7% [81; 82; 83]. **South America:** These surface waters (Figure 8d) were characterized by a significant share of PE, PET, and PP (respectively: 11.8-40%, 15-38.3% and 2.9-17%). Additionally, the presence of PS (2.9-8%), PA (6%), Nylon (2%) and PVC (0.03%) was also observed [84; 85]. **Africa:** The most common types of MPs in the waters of Africa were PET, PE, PP and PS (Figure 8e, Supplementary File S5--Africa and Australia). The PET range was 6-72.6%, PE: 0.7-60.5%. PP: 7-38%, PS: 10-56%. In some cases, there was a significant proportion was RA (70.4%) or PA, at 43% [86; 87; 88; 89; 90; 52]. **Australia**: In the case of literature analyzing the type of MPs present in waters in Australia (Figure 8f), PET was the most frequently found, ranging from 35 to 77.7%. Then, the PE ranged from 11.1 to 42%. The presence of PS (4-8%), PA (12.9%), Nylon (7.41%) and RA (8.1%) was also shown.