A team of researchers, led by toxicologists from UC Santa Cruz, found that all of the seabirds they sampled had ingested microplastics, which are plastic particles that are smaller than five millimeters in length.

The researchers examined the digestive tracts of 19 common murre carcasses collected from Monterey Bay. Although they found a variety of microscopic particles, the most common type of particles that they found were fibers.

These results were consistent with samples they took from the digestive tract of Monterey Bay anchovies, which common murres eat. Taken together, these findings provide evidence that microplastics are moving up coastal food chains, according to the authors of the study.

The researchers suggested that the textile industry could be behind the large number of synthetic fibers that they found. They cited previous studies which showed that a single polyester clothing item can release almost 2000 fibers in one wash cycle in a laundry machine and that wastewater treatment plants commonly discharge into marine waters.

They also found a particle of polystyrene foam, which is used in food packaging.

Subsequent analysis confirmed that the polystyrene could interfere with estrogen receptors, which regulate important functions in the bodies of many animals, including humans.