Just as BULLWINKLE eluded to, I think the acrylic shavings and dust from pen making it is insignificant compared to the real situation of macroplastic waste. From an environmental perspective, microplastics are more concerning, but the problem is not with cigarette filters or pen turning waste, the real problem is our clothes.
Even though cigarette filters might be getting a lot of blame in the media, the overwhelming problem with plastic microfibers comes from our clothes. For the last 80 years, most of our clothes are made out of plastic. Almost all of us wear all of us wear clothes made from nylon, rayon, or polyester either entirely or as a high percentage. When we wash these clothes, the fractured bits of fabric (plastic) go down the drain and others go into the air from our clothes dryer vent in the form of lint. There were some scientific studies done in Canada a couple of years ago that estimated a single load of laundry will shed over 100,000 microfibers into the environment.
The good news, at least for those hooked up to municipal waste treatment facilities, is that at some point before wastewater is returned to the environment, it goes through LUV-R filters which take out anywhere between 85% to 99.9% of these plastic microfibers. The other good news, I guess, is that this has been going on for the last 80 years and I haven't succumbed to it yet.
Dave