From the Guidelines
The current evidence suggests that while microplastics have been detected in various environments and human tissues, there is not yet conclusive scientific evidence demonstrating significant harm to human health at current exposure levels. The presence of microplastics in drinking water, air, and food has raised concerns about potential health impacts, but the risks are still largely unknown due to the variability of physical and chemical properties, composition, and concentration of the particles 1. Laboratory studies have shown potential cellular damage, inflammation, and oxidative stress in experimental settings, but these findings cannot be directly extrapolated to real-world human health impacts 1. Environmental concerns are better established, with documented impacts on marine organisms including physical harm from ingestion, chemical toxicity from plastic additives, and potential bioaccumulation in food chains.
Some key points to consider include:
- The definition of microplastics is not yet formalized, and the lower size boundary is not well-defined, which can lead to inconsistencies in terminology and communication 1.
- The majority of laboratory studies have used monodispersed polystyrene microspheres (PSMs) to investigate adverse effects, but the applicability of these findings to real-world human health impacts is limited due to the complexity of environmental mixtures of microplastics 1.
- There is a need for multidisciplinary research to better understand the sources, fate, and effects of microplastics in the environment and to develop best practices for generating and characterizing environmentally relevant microplastics 1.
- A holistic strategic framework is envisioned to bring together experts from various fields to address the complexity of microplastic research and to prioritize work on model microplastics that are most relevant to the problem being addressed 1.
Given the current state of knowledge, reasonable precautionary measures are warranted, such as reducing single-use plastics, using natural fiber clothing, filtering drinking water, and avoiding heating food in plastic containers. Scientists are actively investigating potential long-term health effects, particularly regarding chronic exposure and the smallest nanoplastic particles that may cross biological barriers more easily 1.
From the Research
Dangers of Microplastics
- Microplastics are an emerging global environmental contaminant that can affect human health through ingestion, inhalation, and dermal contact 2, 3, 4.
- Exposure to microplastics can cause toxicity through oxidative stress, inflammatory lesions, and increased uptake or translocation 2.
- Several studies have demonstrated the potentiality of metabolic disturbances, neurotoxicity, and increased cancer risk in humans due to microplastic exposure 2, 4, 5.
- Microplastics can release their constituent compounds as well as those that are adsorbed onto their surface, leading to further health risks 2, 6.
Human Exposure to Microplastics
- Humans are estimated to ingest tens of thousands to millions of microplastic particles annually, or on the order of several milligrams daily 5.
- Inhalation of indoor air and ingestion of drinking water bottled in plastic are major sources of microplastic exposure 5.
- Microplastics have been found in human stool, fetus, and placenta, providing direct evidence of microplastic exposure in infants and children 5.
Health Effects of Microplastics
- Microplastic exposure is linked to various forms of inflammation, immunological response, endocrine disruption, alteration of lipid and energy metabolism, and other disorders 5.
- Microplastics can be sources of exposure to plastic additives and other toxicants, leading to adverse effects such as oxidative stress, cytotoxicity, and immunotoxicity 5.
- Maternal transfer of microplastics to the developing fetus has been demonstrated in exposed laboratory animals and through the analysis of human placenta 5.