Well, probably not the nurdles themselves unless they're scooped from the oceans and used as a food additive, but they'll break down into microplastics and enter the food chain that way. The damage of said microplastics is still being researched, at the moment (I believe) it's still fairly vague, not unlike asbestos or smoking. IIRC they have been found to mimic hormones though.
I think they meant "not unlike" as - we didn't think asbestos was bad, then we thought it could be bad, then yes, after studies, this is really awful. Similarly, we might find that ingested plastics cause more damage than we realize now.
