Questions regarding EnvO's representation of plastics

[gioUbbiali]

Dear all,
I have some questions concerning EnvO's representation of plastics, particularly regarding the hierarchy classification starting from "piece of plastic". http://purl.obolibrary.org/obo/ENVO_01000776
Does the "piece of plastics" class apply to plastic objects? Do its subclasses refer to just plastic debris, or are they more generally applicable to plastic items as well? I checked the cited literature, and it seems that EnvO classification is intended for litter and debris, but definitions seem to have a broader range of application.
Can you clarify this point to me? Thank you so much!