As it stands, there are several hypotheses about what effects they might have on the human body.
Some researchers have discovered that microplastic contamination in our reproductive systems may pose a threat to fertility. Cancer rates are skyrocketing in young people, and reasons for that too remain speculative, but microplastics are on the list of suspects. Finally, some limited data shows a correlation between pre- and postnatal microplastics in the brain and a correlation with autism-like traits in mice.