Micro- and nano-sized particles of polytetrafluoroethylene (PTFE) were used as model (reference) particles to study the biological effects of plastic pollution. Since the PTFE molecule contains fluorine, considered as an “atomic marker” sharply distinguishing it from other common plastics, micro- and nano-particles of PTFE have a specific crystalline structure and are, therefore, well identified by the methods of polarized light microscopy (POL), Raman microspectroscopy (micro-Raman), and energy-dispersive spectroscopy (EDS). Examples of PTFE particles detection in hemolimph of the cockroach Blatella germanica, in hemolimph of the larva and in faecal pellets of imago of a fly Lucilia sp., in the stomach and hingat of brine shrimp Artemia salina, and in association with cell wall of green unicellular alga Chlorococcus sp. are provided. The presented results strongly suggest that PTFE particles can be detected and identified in the biological medium using the method of “atomic markers”, polarization microscopy and Raman spectroscopy.