## 5 Discussion of the Results  
This article addresses the extremely important issue of comparing experimental results from the laboratory to those of organisms living in the environment. Taking into account existing publications, which extensively describe the overestimation of the amount of microplastic in organisms, and the significant differences between internal and external studies, it is worthwhile to analyze the factors affecting these differences in results. An important aspect is the analysis of the factors influencing these discrepancies, which is important for the correct interpretation of the results and their application in assessing the actual impact of microplastics on organisms. [PERSON] et al. [43] emphasized that the toxicity of microplastics may be strongly dependent on the type of polymer and the presence of other contaminants, which further complicates the comparison of results from different environments. In turn, a review of [44] indicates that laboratory conditions may promote increased bioaccumulation of microplastics, because organisms do not have the ability to avoid them, as is the case in natural conditions. Such differences may lead to overestimates of the effects of microplastics on organisms, which have important implications for ecotoxicology. The laboratory conditions in which the primary culture earthworms reproduced were an environment that was devoid of natural predators and rapid temperature changes and with a constant access to food. Placing earthworms in culture containers with microplastic contents that were evenly mixed with soil and food forced the earthworms to ingest particles as a consequence of starvation. In addition, the limited mobility and food selectivity meant that the microplastic exposure was consistently high. For this reason, the authors suggest that the obtained results should not only be interpreted as evidence of the ability of earthworms to accumulate microplastics, but also as a reliable estimate of their actual amount under environmental conditions. The rearing of earthworms in containers significantly affected the results of the study. The increased soil volume and depth of the containers made it possible for individuals to freely choose where to forage, thus contributing to the relocation of the microplastic. In turn, [PERSON] et al. [43] emphasized that differences in food mobility and availability are key factors influencing the degree of exposure of soil organisms to microplastics, which may significantly alter the results of ecotoxicological studies. The identification of microparticles in soil and the determination of their concentration from soil analysis are methods that are subject to constant validation and qualitative  
Figure 18: Determination coefficient for _L. terrestris_ from macro-culture. and quantitative precision testing. Soil is an extremely complex structure, characterized by varying hydrological dynamics and organic contents. As indicated by studies by [PERSON] [45], [PERSON] [46], and [PERSON] [47], there are numerous obstacles to accurate concentration estimation, including the apparatus resolution, particle size, particle aggregation, bonding and adhesion to soil grains, and many others. The research conducted may be an indication of the possibility of using different types of apparatus to identify microplastics based on tissue analysis of earthworms. This method, while certainly requiring more measurements, can provide an open database in which each subsequent study will increase the pools of results that are available for comparison. Each of the aforementioned methods as a single tool is fraught with many possibilities for overestimation or underestimation, but combining them all in the right order offers a chance for effective plastic analysis.