Abstract:

Microplastics are ubiquitous within the environment and their potential toxic effects are not fully understood. Potential physiological changes from the ingestion of microplastics depend on their accumulation within the body, and their ability to translocate from the gut to extraintestinal locations. According to Mehinto et al. 2022, plastic particles less than 83mm in size are at risk of tissue translocation. To test this, soil was spiked to a concentration of 100,000,000 particles/kg (dw) with two sizes of barium-sulfate polyethylene microspheres purchased from CosphericÔ (10-27mm and 45-53mm). 10 earthworms (Eisenia fetida) were introduced to each treatment, as well as a control, and they were allowed to feed for 24 hours. Earthworms were then preserved with formalin and dehydrated using an ethanol dilution series. X-ray microtomography was performed using the BMIT-BM beamline from the Canadian Light Source synchrotron located in Saskatoon, Saskatchewan. Resulting images showcased that there is little evidence for tissue translocation of both the 10-27mm and 45-53mm polyethylene microbeads. Additionally, there was no clear location withing the earthworm gastrointestinal tract that showcased microplastic accumulation for both size fractions. Nevertheless, X-ray microtomography can be seen to be a valuable tool for assessing microplastic deposition and movement within organisms.