Evidence of Microplastics in Bronchoalveolar Lavage Fluid among Never-Smokers: A Prospective Case Series

Abstract

Microplastics (MPs) are abundant in air, but evidence of their deposition in the respiratory tract is limited. We conducted a prospective case series to investigate the deposition of microplastics in bronchoalveolar lavage fluid (BALF) and determine the internal dose of MPs via inhalation. Eighteen never-smokers aged 32−74 years who underwent fiberoptic bronchoscopy with BALF were recruited from Zhuhai, China. Control samples were obtained by performing the same procedure using isotonic saline instead of BALF. Laser direct infrared spectroscopy combined with scanning electron microscopy detected the presence and characteristics of MPs and quantitatively analyzed the microplastic in BALF and control samples. Concentrations of total and specific MPs in BALF and control samples were compared using the Wilcox test. Thirteen types of MPs were observed in 18 BALF samples. Polyethylene (PE, 86.1%) was the most abundant in BALF, followed by poly(ethylene terephthalate) (PET, 7.5%) and polypropylene (PP, 1.9%). Compared with the control samples, BALF had significantly higher concentrations of PE (median [IQR] of BALF: 0.38 [8.05] N/g), PET (0.26 [0.54] N/g), polyurethane (0.16 [0.24] N/g), PP (0.16 [0.11] N/g), and total MPs (0.91 [6.58] N/g). The presence of MPs in BALF provides novel evidence that MPs penetrate deep into the respiratory tract.

New Evidence of Microplastics in the Lower Respiratory Tract: Inhalation through Smoking

“…During the analysis, it was necessary to endeavor in limiting the exposure of samples to air. To confirm the recovery rate of microplastics in the biological specimen, a recovery test was conducted with three known microplastics (polystyrene [PS]; polypropylene [PP], and polyethylene [PE]) in normal saline in our previous study . The average recovery rates of PS, PP, and PE were 92, 89, and 78%, respectively, which indicated the effective performance of the LDIR technique.…”

Application of Infrared and Near-Infrared Microspectroscopy to Microplastic Human Exposure Measurements

“…FT-IR has been used to detect and classify microplastic in all matrices indicative of human exposure, from drinking water [52][53][54][55][56][57][58][59] to the studied food groups, [60][61][62][63][64][65] to air, [66][67][68] dust, 26,28 and human tissues and biofluids. 33,34,37,40,44,[69][70][71] The other vibrational spectroscopy technique that has been applied to microplastic classification, although by less than half as much (based on a PubMed search, "microplastic and FT-IR" resulting in 1102 articles versus "microplastic and Raman" resulting in 494 articles), is Raman spectroscopy. In contrast to the IR spectrum used in FT-IR, Raman spectroscopy irradiates a sample with a monochromatic laser of a defined wavelength, which influences the intensity of the signal and spatial resolution.…”

“…69 In BALF, 0.2 to 141 microplastic particles g −1 of tissue were quantified. 70 In digested semen and testes, 0.23 ± 0.45 microplastic particles mL −1 and 11.60 ± 15.52 microplastic particles g −1 were reported, respectively, 71 whilst for digested placenta, 2.70 ± 2.65 microplastic particles g −1 was found. 33 The distribution of polymer compositions varied in these different biological matrices.…”

“…Investigations on microplastic levels in purified human tissue samples commonly utilize FT-IR (66.6%); 33,34,37,40,44,[69][70][71] and Raman (33.3%). 31,42,72,73 One study combined py-GC-MS with LD-IR analysis.…”

“…40 One study preprocessed the collected spectra, which included spectral smoothing, baseline correction, spectral normalization, and data transformation. 44 With respect to spectral classification, commercial 33,37,40,44,70 and in-house libraries 34,69 were used. The two studies using micro-FT-IR, employ a threshold (HQI) of above 70%.…”