On 12 February 2021, the scientific peer-reviewed journal Science published an article in its Toxicology section, entitled “Microplastics and human health.” Written by scientists Dick Vethaak and Juliette Legler, the publication discusses knowledge gaps regarding the human health impacts of microplastics.
The authors highlight as especially problematic the lack of analytical tools for assessing smaller microplastics (<10 µm) and nanoplastics. They argue that the absence of such tools currently leads to an underestimation of exposure. At the same time, these smaller microplastics are “likely more relevant for toxicity.”
The current knowledge gaps hinder the risk assessment of microplastics for human health, even though humans are ubiquitously exposed to the very diverse class of microplastics via drinking water, food, plastic food packaging, air pollution and other routes. Microplastics are of increasing ubiquity and therefore urgently need to be better understood in terms of long-term, dose-dependent, chronic effects on human’s health.
While there is no disagreement on the issue that humans ingest and inhale microplastics, and they have been found in human placenta (FPF reported), very few studies have attempted to study uptake via the gastrointestinal tract and the subsequent toxicological impacts of microplastics in humans. Current assumptions on human health impacts focus on exposure levels likely being low. However, this cannot be taken as justification for assuming low health risk. As the authors write, this “low proportion of particle uptake is not necessarily unimportant when considering life-long exposure and because of possible accumulation in tissues and organs.”
In addition, most studies neglect the effect of environmental factors on microplastics by using pristine plastic particles in their experiments. Research that reflects real environmental conditions is needed that takes into account, for example, the “Trojan Horse-Effect” – the absorption and transfer of hazardous chemicals to and from plastic particles, as well as, the effects of biofilms on mediating uptake and distribution of microplastics in the human body.
Several ongoing and new research programs that are interdisciplinary in nature, such as in the Netherlands, are now focusing on providing data that will allow closing knowledge gaps on hazard properties of microplastics in humans. This information will ultimately support risk assessments and inform future policy making on plastics in general, and mitigation strategies on microplastics’ impacts in particular.
Dick Vethaak and Juliette Legler (Feburary 12, 2021). “Microplastics and human health.” Science
Tessa Koumoundouros (February 21, 2021). “We Need Urgent Research to Know What Microplastics Are Doing to Us. Here’s Why.”