Just a day after the two universities revealed their research, the Ocean Conservancy and the University of Toronto came out with their own news about ingestion of microplastics.
A new study published in the journal Environmental Pollution found microplastic particles in 88 percent of proteins tested. The research involved 16 types of protein headed for consumers in the United States, including chicken, pork, beef, seafood, tofu and three different plant-based meat products.
The study estimated an American adult will consume, on average, 11,500 microplastics each year. But researchers also said the number could be as high as 3.8 million microplastics per year from protein when considering the "highest levels of microplastics found in each individual protein type and the average reported protein consumption rates."
"This is a startling reminder of just how prolific plastic pollution has become — humans live on land and yet seafood samples are just as likely to be contaminated with plastics as are terrestrial derived proteins," study co-author Britta Baechler, a marine biologist and associate director of plastics science at Ocean Conservancy, said in a statement. "The plastic pollution crisis is impacting all of us, and we need to take action to address its many forms."
As for the bottled water research, Stapleton said more research is needed to determine the impact of ingestion.
"The levels are hard to put into perspective, because at this small size, they don't weigh much. Therefore, it is unlikely to change the estimations of how much plastic we regularly consume. This issue is that we've been aware of microplastics, which are more likely to pass through the GI system and unlikely to be absorbed into the body," the toxicologist said.
"The nanoplastics can breach the biological barriers, including the GI, lung and even placenta and migrate to other tissues in the body, interacting with the cells. Studies are ongoing of what the toxicities may be with this direct contact between the cell and the nanoplastic," Stapleton said.
Yan said further research is necessary to determine if bottled water containing nanoplastics could lead to health problems.
"If people are concerned about nanoplastics in bottled water, it's reasonable to consider alternatives like tap water and reusable bottles. However, it's important to emphasize that staying hydrated is crucial for health. Therefore, we do not advise against drinking bottled water when necessary, as the risk of dehydration may outweigh the potential impacts of nanoplastics exposure," he said.
Researchers in the bottled water work tuned their equipment to look for seven different types of plastics and found that PET was common but not the most common. PET is typically used to make water bottles as well as other beverage and food containers. The most common plastic found was nylon, which likely entered the water through the use of plastic filers used to purify the water. Other plastics found were polystyrene, PVC and acrylic.
Researchers ended up identifying about 10 percent of all nanoparticles found in the water samples. The rest remain unidentified at this point, and researchers indicated there could actually be more nanoplastics in the water than this study initially identified. Or not.
"Previous studies found the major chemical composition to be PET, which is expected since the bottle is made of PET. Therefore, we are not surprised to identify PET nanoparticles. However, we are surprised to see that there are many smaller particles other than PET, such as polyamide [nylon], with a greater particle number. These may leach out from the filter materials during the filtration process," Yan said.
"A small fraction of fine nanoplastics may also come from the source water. Of course, this is just our hypothesis. We need to collaborate with industry to test this hypothesis," he added.