As you wish. However, even a stopped clock tells the right time twice a day. This is something worth putting some research funds into.
Unfortunately it follows the accepted pattern of generate panic, get more funding, generate more panic,...lather rinse repeat, and that's how we got the UN ballyhooing about climate change while people make a very good living off of bad models.
I am all for good research, but pushing the panic button sends up an immediate red flag with me.
If individual organisms ingest so much microplastic debris they die, they become sediment and should have the debris trapped. If scavengers like crabs eat the organisms' remains, it stands to reason the crabs will have high debris levels, too, because they are already concentrated in the scavengers' food source, and those crabs may die, too. If that means that chemicals bound to (adsorbed by) or absorbed by the plastics are buried in sediment, too, those have equally been removed from the food chain. If, somehow, those chemicals are being concentrated in the portion of organisms humans consume, that might be cause for concern.
I doubt humans are eating those small crabs. My concerns would be:
1: are these materials entering the human food chain. (Likely not. We don't eat most shorebirds, we do not eat the viscera of most crabs or fish). Other filter feeders may be of concern (Shellfish).
2: Are these materials so negatively impacting populations of organisms that they are disrupting the food chain, or is this a littoral phenomenon confined to specific areas? I can see where there might be higher concentrations of this type of debris in nearshore areas which get significant human traffic, and even down (longshore) current from them, but is this concentration evenly dispersed or more confined to those high traffic areas?
If the latter, long term disruption of the food chain is less likely, as populations expanding from low traffic areas would move into the high traffic areas, while the microfragmental plastics would be bound in the carcasses of those organisms which had succumbed to excessive ingestion.
The obvious reason for plastics (and metal) containers on beaches is the reduction in injuries due to broken glass container bits in the sand. Both containers are resistant to fracture, although anything can be ground up by abrasion in the surf, which is where I presume most of this debris originates, and why it is so small.
Unfortunately, pack it in/pack it out policies are only as effective as the people who conform to them. There are a lot of litterbugs out there.
I wouldn't panic quite yet, and it seems so many articles are written to induce just that reaction.