Greenpeace sounds alarm on microplastics ingested by Hong Kong wildlife

The most common types of microplastics detected in the Greenpeace study were polyethylene and polypropylene, commonly found in single-use packaging, takeaway containers and disposable utensils.

This may be Hong Kong or study methodology related. As a hot climate, there may be limited use of synthetic fibers, especially fleeces, which shed lots of microfibers into wastewater. The urbanization of HK will mean limited car use too. Car tyres are a huge source of plastic pollution. These two are bigger sources of plastic pollution worldwide than packaging.

https://www.reddit.com/r/askscience/comments/11i1fox/what_are_the_biggest_sources_of_microplastics/