Plastic pollution is now pervasive in our environment, contaminating everywhere, from our homes and workplaces to the planet’s deepest recesses. The problem regularly makes headlines, with the spotlight turned toward ocean pollution in particular.
The startling images of plastic pollution may seem far removed from our lives. Still, they should not distract us from a less visible problem, receives far less attention, and affects human beings and ecosystems – microplastic and nanoplastic contamination.
In contrast to macroplastics, which result from the degradation of larger objects (found in the form of paint flakes or fibers, for example), microplastics are usually defined as particles whose size or dimensions do not exceed 5 mm. They have no minimum size.
As for nano plastics, these can be no larger than 0.1 microns, equal to 1/10,000th of a millimeter. Rather instinctively, we were able to predict that the smallest particles could enter organisms, but this had never actually been demonstrated until recently.
Microplastics in our blood
In 2022, a study conducted by several teams in the Netherlands showed for the first time that microplastics were present in the blood of 22 healthy human volunteers at an average concentration of 1.6 mg/L.
The kinds of plastics detected varied greatly, including polyethylene terephthalate (PET), used to make water bottles and other items; polyethylene, used to produce food containers; and polystyrene, whose uses include fresh produce packaging and yogurt pots.
It should be noted that the study focused solely on particles with dimensions of 700 nm and above. As yet, there is no information on the smaller particles categorized among the many forms of nanoplastics.
Microplastics were detected in human blood for the very first time (Down to Earth, 25 Mars 2022).
Adverse health effects in animals
Although no effects on human health were reported in the study, research conducted on animals or using cellular models (some of which modeled human cells) has documented a host of biological impacts from microplastics, including cellular lesions, oxidative stress, and damage to DNA.
In these cases, either the microplastics cause the effects directly, or they act as carriers of other harmful substances. Moreover, some of these substances, such as bisphenols or phthalates, are actually found in the composition of some plastics.
Generally, this contamination may manifest as inflammation or fibrosis, whose effects are already observed in humans via other ways of entry, such as the respiratory tract. The lungs, for instance, have been a reported site of contamination for workers in the plastics industry.
Migration into food and drink
How can we explain this contamination of the healthy volunteers in the study? Simply put, it is linked to the food chain. However, this method of microplastic exposure remains difficult to characterize or measure, with results varying drastically between 0.2 mg per year and 0.1 to 5 g per week.
Nonetheless, a vast number of studies (more than 1,000) clearly indicate that several molecules can migrate into food or drink upon contact. This is the case for reusable plastic sports bottles, which shed a huge quantity of components, and all the more so when cleaned in the dishwasher.