## 4 A Case Study of Glyphosate Transport via Polyethylene Microplastic Fomites  
Shrimp is an economically important aquaculture species, and global Armed shrimp production was estimated to be over 4.5 million tons in 2021, with a growth rate of almost 9% globally [194]. Intensive shrimp production in ponds lined with polyethylene or polyvinyl chloride liners is commonly used in shrimp culture [195]. The use of liners supports the effective removal of settled organics during shrimp grow out, the reduction of pond cleaning and preparation time, and the prevention of acid-sulfate soils contamination [196]. Polyethylene microplastic, a polymer commonly found in surface seawater and sediment [16; 17; 18], may enter shrimp farming and the environment through water runoff, flooding, and winds. The quantification of the release of microplastics into shrimp environments, however, is uncertain, and qualitative assessment assigning relative ratings of high, medium, or low is needed to address the environmentally heterogenous levels [197]. Regardless of the characterization of exposure routes, there is solid evidence that the digestive tracts of commercially harvested shrimp species are contaminated with microplastics, suggesting that shrimp are routinely exposed to microplastics during their production cycle [198]. Routine use of the plastic pond liners in farmed shrimp production and their subsequent degradation into microplastic particles, taken together with environmental microplastics exposure, also suggest a high likelihood of microplastic-shrimp interactions and therefore an increase in the associated risks of a downstream production chain. In addition to microplastics, the likelihood of shrimp exposure to GBHs is also high due to their widespread intensive use and environmental persistence, especially in agricultural areas surrounding shrimp pond farming operations. It has been reported that GBHs can reach aquatic environments through contaminated feed sources, rainfall, leaching, runoff, and intentional introduction [131; 132; 133; 134; 135; 136; 137; 138; 139; 144; 146; 147; 148; 149; 150; 151; 152], and this can include aquaculture establishments. Consequently, the simultaneous exposure of shrimp to both microplastics and GBHs may occur in shrimp aquaculture pond environments and lead to toxicological interactions altering the bioavailability, effects, and bioaccumulation of glyphosate and its metabolites in aquacultured shrimp. Furthermore, shrimp behavior and physiology play an important role in the exposure and intoxication of GBHs-sorbed polyethylene microplastics. The feeding behavior of shrimp as non-selective opportunistic benthic feeders leads to the ingestion of various particles that accumulate at the bottom of their habitats [199; 200] and can contribute to the risk of consuming GBHs-sorbed polyethylene microplastics in ponds with polyethylene liners. Furthermore, the physiological processes of shrimp growth and development, such as the molting cycle, can also be critically linked to GBHs-sorbed polyethylene microplastics toxicity, as only the intact exoskeleton is acting as a defense barrier. As demonstrated during the pathogenesis of a white spot syndrome virus (WSSV), molting can influence the disease susceptibility, and shrimp in the post-molt stages are more susceptible to WSSV infection via immersion than those in the pre-molt stage [201]. Shrimp during the molting process (ecdysis) have the highest mortality rate, followed by the animals in the post-molt and pre-molt stages, respectively [202]. When the concurrent presence of polyethylene microplastics and glyphosate in a shrimp production environment is considered together with the shrimp feeding behavior and molting cycle processes, two potential exposure routes of shrimp to GBHs-polyethylene microplastics (GBHs-PE) fomites emerge: oral and water. Oral exposure to GBHs-PE microplastics from the ingestion of contaminated feed and polluted water is considered an important hazard.