Am ragor na 70 o flynyddoedd, mae’r rhan fwyaf o leiniau genweirio wedi’u gwneud o PVC (polyvinyl chloride), plastig sy’n naturiol o anystwyth. Mae leiniau PVC yn dechrau dadelfennu’n syth ar ôl eu cynhyrchu.  Gan nad oes ffordd ddiogel o ailgylchu PVC, mae hynny’n arwain at ollwng plastig yn yr amgylchedd, gan effeithio’n arbennig ar fiomas organeddau pridd a’u gallu i oroesi.
For over 70 years, most fly-fishing lines have been made from PVC (polyvinyl chloride), a naturally rigid plastic. However, PVC lines begin to break down immediately after manufacturing. As there is no real way to safely recycle a PVC line, it leads to releasing harmful plasticisers into the environment, particularly affecting the survival and biomass of soil organisms.