The scale of micro- and nanoplastic pollution is becoming increasingly clear, yet little is known about how this pollution impacts health. Food packaging can be one exposure source for microplastics (FPF reported) as can synthetic fibers from clothing material or particles from car tires. The Food Packaging Forum works within a large cluster of European organizations quantifying the sources and effects of microplastics in everyday life. Researchers across Europe have recently published work assessing microplastics that end up in human lungs (FPF reported).
In an article published on June 20, 2022, in the Journal of Hazardous Materials, Carlos Baeza-Martínez from Hospital General Universitari d’Elx, Alicante, Spain, and co-authors assessed microplastics in the lower human airways of Europeans. The scientists acquired lower lung samples from 44 living European citizens 35 to 86 years-old using bronchoalveolar lavage fluid collection and analyzed the amount, chemicals composition, and surface characteristics of plastic particles using stereomicroscopy, fourier transform infrared (µFTIR), and scanning electron microscope coupled to energy dispersive X-ray spectrometry (SEM-EDS). They detected microplastics in 30 out of the 44 samples and the average concentration was 9.75 ± 2.49 items/100 mL fluid. With 97% most of the MPs were fibers with an average size of 1.73 ± 0.15 mm, and a maximum length of 9.96 mm. Of all particles detected, more than half (59%) were non-plastics while 41 % were plastics. Most of the plastics were made of polyester or rayon.
Earlier in 2022, Jenner et al. reported a mean of 0.69 ± 0.84 microplastics/g of lung tissue sampled in the United Kingdom (FPF reported). The human placenta and meconium are other tissues in which microplastics have already been detected (FPF reported and here).
As opposed to Jenner et al., Baeza-Martínez et al. also evaluated associations between microplastic presence and the participant’s life habits and physiological parameters. One of the findings here was that fiber concentration and lung function were inversely correlated. Furthermore, microplastics were more frequently detected in smokers and persons with specific occupations. The researchers also reported an association of microfiber concentrations with radiological abnormalities, pathological microbial growth, and decreased lung function which “raises various possibilities regarding what the pathogenic mechanisms could be for microplastics in the lung.” The authors concluded that “although larger studies are necessary to define the role of airborne microplastics in respiratory pathology more effectively, these results alert us that exposure to these microfibers could have important consequences on respiratory health and that it is most likely necessary to implement measurements to reduce human exposure to microplastics.”
Plastic particles, reach human lungs by inhalation, and Tariq Mehmood from Hainan University, China, and co-authors, aimed to define which microplastic type and sources contribute to human microplastic exposure via indoor and outdoor air. In an article published on May 16, 2022, in the journal Environmental Science and Pollution Research, they reported that replacing polyethylene products, “could cut exposure to atmospheric microplastics by up to 50% in some cities worldwide.” For indoor microplastics, they described concentrations to be dependent on indoor sources, such as clothing, furniture, and mattresses, as well as outdoor sources through ventilation.
In a review article published on May 30, 2022, in the journal Frontiers in Public Health, Stephanie Wright and Paul J. A. Borm from Imperial College London, United Kingdom, and Nanoconsult, Meerssen, Netherlands, evaluated whether existing particle paradigms can be applied to microplastics in the lung.
The authors report that for other particles, such as coal mine dust, asbestos, or ambient particulate matter (PM), principles of toxicity have been developed over the past 50 years. One concept that could help to describe the toxicity of an unknown particle is based on the three attributes of the biologically effective dose (BED), (i) surface (including particle area, reactivity, dimension, availability,), (ii) dimension (length, diameter), and (iii) composition (volume, specific volumetric reactivity, availability). The researchers think that “it is logical to assume that the effects of inhaled microplastics in the airway are driven by the same set of particle properties.”
Reviewing existing studies on microplastic inhalation exposure, Wright and Borm, find microplastics only represent a low share of total ambient particulate matter. However, due to challenges in analytics and sampling, they think that exposure to ambient microplastics is probably under or overestimated. To increase knowledge on exposure to ambient microplastics, the small particles could be measured in PM filters. Concerning adverse outcomes of inhaled microplastics, the co-authors assume that they change with the different microplastic types and characteristics but they may all lead to inflammation, aberrant repair, and fibrosis. Wright and Borm consider “bio-persistence, presence of reactive sites and soluble toxicants” as “key properties in microplastic toxicity, but these are not measured in environmental studies and hence are challenging to interpret in exposure.”
The authors summarized that “microplastics likely have similar hazards to other particle domains,” such as engineered nanomaterials and ambient PM, and that paradigms from established particle domains could help to predict microplastic toxicity. To establish if interventions are needed to lower PM < 10 as well as PM < 2.5 µm, and where, it would be necessary to better understand microplastic sources and emissions.
References
Baeza-Martínez, C. et al (2022). “First evidence of microplastics isolated in European citizens’ lower airway.” Journal of Hazardous Materials. DOI: 10.1016/j.jhazmat.2022.129439
Mehmood, T. et al (2022). “Why is inhalation the most discriminative route of microplastics exposure?” Environmental Science and Pollution Research. DOI: 1 0.1007/s11356-022-20653-9
Wright, S. and Borm, P. J. A. (2022). “Applying Existing Particle Paradigms to Inhaled Microplastic Particles.” Frontiers in Publich Health. DOI: 10.3389/fpubh.2022.868822
