> I think people around the world have been ingesting microplastic for 30 years or longer, yet there's no reported case of any direct toxic effects. So I guess microplastic doesn't have immediately effects on health

In this case, 30 years? Or, taken in another light, it doesn't have effects that are visible on the time-scale of known substances such as lead, arsenic, mercury, etc.

In addition, the parent also stated this:

> I won't be surprised if future studies find longterm effects, such as increasing the risk of cancer, damage to the circulatory system or the brain.