Microplastics and nanoplastics are two types of plastic waste that have become a major concern for environmental and human health. Produced from the degradation of larger plastic items (such as bags, bottles, covers, car tires, fishing nets, packaging material and others), microplastic particles are larger than one micrometer but smaller than five millimeters in size. On the other hand, nanoplastics are very tiny particles that range from one to 100 nanometers in size. Bits of microplastic and nanoplastics accumulate in organisms and contaminate soil and water – causing harm to ecosystems, humans and wildlife. These plastic wastes also act as carriers of chemical pollutants that pose health risks to both animals and humans when ingested or inhaled.
Primary microplastics are intentionally manufactured to be as small as possible (e.g., microbeads in cosmetics and personal care products), or as microfibers in textiles (e.g., polyamide, polyester and polypropylene). Because of their extremely small size, nanoparticles eventually end up inside the body, penetrating cells and tissues and causing more harm to humans and animals compared to bigger-sized microplastics. (Related: MICROPLASTIC INVASION: Researchers find microplastics in human heart tissue.)
According to researchers at the Medical University of Vienna, the micro and nanoplastics (MNPs) absorbed via food sources, water and the air we breathe could act as vectors to transport toxic substances throughout the body, which could damage the digestive tract, have carcinogenic (cancer causing) consequences, and lead to an array of potential adverse health effects.
“Experimental studies indicate that ingested MNPs passing through the gastrointestinal tract lead to changes in the composition of the gut microbiome,” researchers at the university summarized, adding they’ve noted “that such changes are associated with the development of metabolic diseases such as diabetes, obesity or chronic liver disease.”
“In addition to the effects on the gut microbiome, scientists also described specific molecular mechanisms that facilitate the uptake of MNPs into gut tissue. Using specific analyses, it was shown that MNPs in the gastrointestinal tract could increasingly be taken up into tissue under certain physicochemical conditions and activate mechanisms involved in local inflammatory and immune responses,” they wrote, adding, “Nanoplastics in particular are associated with biochemical processes that are crucially involved in carcinogenesis.”
In their research paper, scientists noted numerous ways microplastics enter the body “either directly through the food chain or indirectly via the ingestion of inhaled and regurgitated particles.”
Clothes fibers such as polyester, for example, end up in wastewater after being machine washed; those particles can then re-enter the food chain after being ingested by marine life, or through sea salt, or drinking water.
“Recent studies have also indicated the presence of MPs in some terrestrial food items, such as edible fruit and vegetables and store-bought rice,” researchers warn, adding additional research in that field is still necessary.
Plastics leaching from plastic water bottles are also major contributors to the incidental ingestion of MNPs, with plastics in PET (polyethylene terephthalate) bottles known to have carcinogenic and estrogenic effects, scientists say.
Researchers also made note of the high incidence of microplastics in bottles used to feed babies.
Recently, a dataset was published concerning plastic particle release from infant feeding bottles, demonstrating values ranging from 14,600 to 4,500,000 MPs (> 1 µm) ingested per capita per day. Unfortunately, sterilization of baby milk exacerbates the issue whereby the process of mixing milk powder with hot water at a minimum of 70 °C, shaking and cooling down to feeding temperature, induces thermal and mechanical stress to the bottle material that might further aggravate MNP release (WHO/FAO 2007).
Overall, the microplastics could be a contributing factor to chronic disease and illness, says Center for Biomarker Research scientist Lukas Kenner.
“A healthy gut is more likely to ward off the health risk. But local changes in the gastrointestinal tract, such as those present in chronic disease or even negative stress, could make them susceptible to the harmful effects of MNPs,” Kenner stated.
The study comes as scientists announced they’ve identified microscopic plastic particles in the bloodstreams of test subjects, warning the toxic substances can travel throughout the body and damage human cells, or bio-accumulate in organs and lead to death.
Scientists had previously found endocrine-disrupting chemicals linked to plastics such as Bisphenol A (BPA) in the bloodstreams of 86 percent of teenagers.
The gender-bending chemical BPA “mimics the female sex hormone estrogen, and has been linked to low sperm counts and infertility in men, as well as breast and prostate cancer,” reports the Daily Mail.
Scientists have also warned BPA and other chemicals found in everyday household products and food packaging, including phthalates and parabens, could also be responsible for male infertility problems, causing penises to shrink worldwide, in addition to a host of genital defects.
Nanoplastics linked to Parkinson’s and some types of dementia
According to the Parkinson’s Foundation, nearly a million people in the U.S. are living with Parkinson’s disease, one of the most devastating neurological disorders characterized by the death of a specialist population of nerve cells that control movement.
“Parkinson’s disease has been called the fastest-growing neurological disorder in the world. Numerous studies suggested that environmental factors play a prominent role in increasing the risk of developing the disease but such factors have, for the most part, not been specifically identified,” said Dr. Andrew West, who directs the Duke Center for Neurodegeneration and Neurotherapeutic Research.
As per the Parkinson’s Foundation, almost one million Americans are afflicted with the disease and around 90,000 new cases are being diagnosed each year. Globally, more than 10 million people are suffering from it.
Researchers from the Duke University School of Medicine initially used different types of nanoplastic particles to facilitate biomarker assays for the diagnosis of Parkinson’s disease and dementia. (Related: Study: Microplastics accumulate in the brain and cause behavioral changes associated with dementia.)
Using three models – cultured neurons, a mouse model (genetically engineered to be predisposed to a condition similar to Parkinson’s) and test tube solutions – West and his team found that polystyrene nanoplastics interact with alpha-synuclein, a brain protein that plays an important role in nerve cell communication. Normally, alpha-synuclein is recycled within the nerve cells.
The study, published in the journal Science Advances, reported that the presence of polystyrene nanoplastics attracted unusually large clumps of alpha-synuclein. Of particular interest to the scientists were the tight chemical bonds formed between them.
The researchers also discovered that when the proteins clumped together and formed alpha-synuclein fibrils (aberrant forms of alpha-synuclein), the machinery in the nerve cells that handles waste disposal could not keep up with the waste. This finding suggests that nanoplastics affect the levels of alpha-synuclein in the brain by interfering with the natural cleaning process of neurons.
West and his team emphasized that these were early findings and no tests had been done in humans yet.
“While microplastic and nanoplastic contaminants are being closely evaluated for their potential impact in cancer and autoimmune diseases, the striking nature of the interactions we could observe in our models suggest a need for evaluating [the impact of] increasing nanoplastic contaminants on Parkinson’s disease and dementia risk and progression,” said West.
Plastic pollution a new risk factor for dementia
The authors suggested that increasing micro- and nanoplastic pollution could represent a new risk factor for developing Parkinson’s and dementia. However, more research is needed to better understand how these plastics interact with the human brain and whether different types of plastics have different effects.
The authors also highlighted the importance of monitoring contamination levels with nanoplastics and limiting human exposure.
“If we knew the specific molecular nature of particularly bad nanoplastic actors, we could develop policies and technologies to make sure they don’t end up in our food and water,” said West. “We also need to have a better idea of what lifetime exposures to different types of nanoplastics look like so that our models in the lab are more informative,” he added.
Watch the following video to learn about invisible plastic and Parkinson’s disease – the surprising link.
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