In addition to visible plastic pollution, there is plastic pollution that we cannot see. Three common examples are:
1. Microbeads: tiny plastic pellets used in personal care, cosmetic and household cleaning products (like face and body scrubs, toothpastes and washing powders);
2. Microfibres: released into the drains, then finding their way into waterways and the ocean, every time we wash clothes made from synthetics, like nylon and polyester.
3. Microplastics and nanoplastics: minuscule, indeterminate plastic fragments arising from the weathering and breakdown of larger plastic items.
Microplastics are ubiquitous across ecosystems, yet the exposure risk to humans is unresolved; they have been found in human lungs and blood. Nanoplastics have been found in the remote North and South Poles of the Earth. Marine life is consuming more microplastic every year, passing from zooplankton up the food chain to the largest predators creatures, including humans. Corals around the world are facing 'slow starvation' from ingesting ocean plastic pollution. Microplastics are killing fish before they even reach reproductive age.
Microplastics are plastic fragments less than 5 mm in size (0.1 to 5,000 µm). This definition could apply to anything from microbeads added to beauty products to aid in exfoliation to glitter made from tiny fragments of colored plastic. It could also describe larger plastic items broken down over time by weather or impacts. Artificial textiles like polyester can also shed tiny fibers that qualify as microplastics. Nanoplastics measure 1 to 100 nm (0.001–0.1 µm).
The Australian Government promised in 2018 a ban on microbeads if they are not voluntarily phased out by industry. At 2021, this has not happened.
A 2022 study from the University of Eastern Finland shares how nanoplastics may move upward through the food chain. The researchers used a model food chain consisting of three levels: lettuce, black soldier fly larvae and the insectivorous fish. Nanoplastics from the soil were absorbed through the roots of the lettuce and into the plant leaves. When the insects ate the lettuce, they also consumed the nanoplastics, which remained in their mouths and guts after 24 hours. After the insects were ingested by the fish, the nanoplastics were found in their gills, intestines and primarily in the liver.
Microplastics have been detected in the human body for many years. A 2018 study found microplastics in stool samples taken from people around the globe. In 2020, another study revealed researchers had detected microplastics in every human tissue sample, including in the bloodstream, lung tissue and placentas.
It was estimated in 2018 that a US citizen consumes from 39,000 to 52,000 particles of microplastics per year depending on age and sex. These estimates increase to 74,000 and 121,000 when inhalation is considered. Additionally, individuals who meet their recommended water intake through only bottled sources may be ingesting an additional 90000 microplastics annually, compared to 4000 microplastics for those who consume only tap water.
A 2021 study reported that infants have a higher exposure to microplastics than adults do, possibly due to factors such as child-safe plastic feeding utensils, pacifiers, sippy cups and plastic toys that babies like to chew on while teething. Specifically, PET concentrations were significantly higher in infant faeces than in adult faeces, whereas concentrations of PC microplastics were not significantly different between the two age groups. The microplastics measured in infant and adult faeces were thought to be primarily derived from dietary sources. One-year-old infants are known to frequently mouth plastic products and clothing. Infants often chew and suck cloths and other items derived from plastic. In addition, infant formula prepared in PP bottles can release millions of microplastics, and many processed baby foods are packaged in plastic containers.