1 in 4 embryos have abnormally small eyes due to nanoplastics

The potential impact of microplastics on early cellular and tissue development that gives rise to organs and bodies is largely unclear. Additionally, most relevant investigations have been conducted on aquatic animals like zebrafish.

In these most recent lab experiments, the 25 nanometer-sized polystyrene nanoplastics appeared to adhere to neural crest stem cells, preventing them from moving into locations where they typically develop critical tissues and organs.

"Neural crest cells are sticky, so nanoparticles can adhere to them and thereby disrupt organs that depend on these cells for their development," said Michael Richardson, a developmental biologist at Leiden University.

Neural crest cells give rise to the heart, arteries, facial features, nervous system, and other organs in all vertebrates.

The researchers found one in four chick embryos had one or two abnormally small eyes. Others had facial malformations, thinning heart muscles, and slow heart rates.

Neural tube abnormalities were also observed, which happens when the neural folds that create the early brain and spinal cord fail to meet and shut properly. The researchers believe this is connected to those neural crest cells.

That said, it's worth noting that the amounts of nanoplastics utilized in this study were artificially injected and much higher than those that humans could have been exposed to.

The researchers contend, however, that even in the case of low-level exposures, the way nanoplastics attach to neural crest cells should be concerning. They also discovered proof that the flaws became widespread as the concentration of nanoplastics rose.

"If society stops now with all plastic pollution, the weathered nanoplastic debris levels from existing plastics in the environment will still increase," the paper stated. 

Wang emphasized that her study is just the first step toward understanding the full impact of nanoplastics on our ecosystem. She thinks we should exercise caution before these severe effects are observed in humans, especially since some people now consider putting them in human medicines.

The research has been published in Environment International and can be found here.

Study abstract:

Nanomaterials are widespread in the human environment as pollutants, and are being actively developed for use in human medicine. We have investigated how the size and dose of polystyrene nanoparticles affects malformations in chicken embryos, and have characterized the mechanisms by which they interfere with normal development. We find that nanoplastics can cross the embryonic gut wall. When injected into the vitelline vein, nanoplastics become distributed in the circulation to multiple organs. We find that the exposure of embryos to polystyrene nanoparticles produces malformations that are far more serious and extensive than has been previously reported. These malformations include major congenital heart defects that impair cardiac function. We show that the mechanism of toxicity is the selective binding of polystyrene nanoplastics nanoparticles to neural crest cells, leading to the death and impaired migration of those cells. Consistent with our new model, most of the malformations seen in this study are in organs that depend for their normal development on neural crest cells. These results are a matter of concern given the large and growing burden of nanoplastics in the environment. Our findings suggest that nanoplastics may pose a health risk to the developing embryo.