According to authors [CheolHong Lim] and [DongSeok Seo], the research covered in this paper was undertaken because of reports of rare cancers among Korean STEM teachers, particularly those who used 3D printers in their curricula. It was thought that only long-term, continued exposure to the particulates generated by 3D printers could potentially be hazardous and that PLA was less likely to be hazardous than ABS. The study was designed to assess the potential carcinogenicity of both ABS and PLA particulates under conditions similar to what could be expected in an educational setting.
So this is just propaganda.
You have a bad understanding of science.
Plastic is a very broad term for materials made from synthetic polymers
…Do you not think corn can be turned into a carcinogen?