Plastics in composting waste

Plastic strands (not unlike a cassette tape) have appeared in the compost, and material submitted for composting,  on our allotment for the whole of the time that I have provided a community composting service. I have mention this before as it  comes from the woven plastic weed suppressant fabric which is sold on the site but news of more microplastics in the Antarctic makes it relevant, 

Today when  turning the first in our row of pallets bins, I found strands of this fabric,   pieces  of pea netting, small bits of plastic sheeting  used for ground cover, plastic "string" and pieces of plastic  flowerpot.

One of the reasons for composting is concern for the environment and I appreciate that the types of waste mentioned above  are insignificant when compared with other plastic waste sources but  should allotment societies, community groups and home composters look again at their use of alternatives to plastic.