Research on the abundance of microplastics and their effects on humans and the environment has increased exponentially over the last years. However, little is known about how nano- and micro-sized particles affect early life human health, even though pregnancy and early life are particularly vulnerable periods that affect development and health later in life.

In a commentary published on January 26, 2022, in the peer-reviewed journal Environmental Health Perspectives Kam Sripada from the Norwegian University of Science and Technology (NTNU), Trondheim, Norway, and her eleven co-authors from universities and other institutions worldwide give an overview of the current state of knowledge on the exposure and impacts of nano- and microplastics during pregnancy and the associated impacts on child health.

The authors searched Web of Science and Scopus for literature published between 1991 and April 2021 for primary research articles, reviews, and meta-analyses on the exposure, toxicity, or hazard of nano- and microplastics. They identified 44 articles with relevance for pregnancy or child health, including 37 primary research articles and seven reviews. Nearly half of the research articles (18 studies) focused on the exposure of microplastics. However, estimates on children’s exposure were based on generic assumptions, such as the calculation of particle intake by particle-contaminated seafood (FPF reported). Concerning hazards, 12 experimental studies evaluated toxicokinetic aspects, including ingestion, inhalation, and placental transfer (FPF reported and here), while seven assessed toxicodynamic aspects such as allergy, asthma, embryo development, and reproductive effects (FPF reported). Besides these studies in mammalian models, one study followed an epidemiological approach looking at exposure as well as eye and airways irritation in a school environment.

Based on the reviewed literature, Sripada and co-authors identified large knowledge gaps that make it impossible to fully understand the health risks but they emphasized that the “evidence base around early life exposures to nano-and microplastics provides cause for concern.” Besides the general lack of scientific studies, all but one study used polystyrene beads although humans are exposed to a mixture of particles with a variety of shapes, sizes, and chemical compositions. To advance understanding, the scientists recommend that researchers work across disciplines to better quantify early life exposure, characterize long-term effects, and understand the linking of the two. To policymakers and industry, they advocate implementing precautionary approaches due to the current unknowns of nano- and microplastics associated risks. Although families’ scope of action would be limited, recommended measures to reduce early life exposure to plastic particles include a reduction of foods with plastic contact, a careful choice of personal care products and building materials, as well as a regular wet-cleaning of the house.

Five projects are funded within the EU Research and Innovation program Horizon 2020 to better understand the impacts of microplastic exposure to humans with one of the projects, AURORA, focusing on the effects of micro-and nanoplastics on early life health (FPF reported).

Not only is the risk caused by microplastics to children largely unknown, but also the assessment of microplastics’ risks for human health in general and for the environment needs further advancement. In a review article published on January 21, 2022, in the peer-reviewed journal Nature Reviews Materials, Albert A. Koelmans and co-authors from Wageningen University and Research, Netherlands, summarize microplastic characteristics and effects, as well as risk assessment approaches and propose a new risk assessment framework for microplastic risks on the environment or human health.

The authors outlined the multidimensionality of microplastics regarding sources, polymer and chemical composition, size, and shape, and summarize their interaction with biota regarding uptake, bioaccessibility, and adverse effects. In particular, the scientists compared the characteristics of microplastics with those of natural particles, such as organic matter, and emphasized that natural particles can serve as a proxy for microplastics but still have a distinctive combination of characteristics; “Microplastic particles form a continuum within a broader spectrum of natural and other anthropogenic particles.” Looking at the existing risk assessment frameworks for microplastics, the authors concluded that they simplify the diversity of microplastics, do not take the limited data quality into account, and neither do the assessments account for the impossibility of comparing all available data.

Koelmans et al. further present a generic risk assessment framework for microplastics. The framework is based on three elements: “use of probability density functions to describe toxicologically relevant particle characteristics, so that no simplification with categories is necessary; use of quality assurance and control screening methods to evaluate whether exposure and effect data are fit for purpose; and use of a calculation framework to assess exposure to plastic- associated chemicals through all relevant pathways.” The authors highlighted that their outlined new framework can “consistently account for the multidimensionality of microplastic” and “provide opportunities not only to assess the risks of microplastic particles, but also to unify and align research approaches that have hitherto been fragmented and disparate.”

 

References

Sripada, K. et al. (2022). “A children’s health perspective on nano- and microplastics. Environmental Health Perspectives. DOI: 10.1289/EHP9086

Koelmans, A. K. et al (2022). “Risk assessment of microplastic particles.” Nature Reviews Materials. DOI: 10.1038/ s41578-021-00411- y

 

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