Detection of microplastics in human lung tissue using μFTIR spectroscopy

Airborne microplastics (MPs) have been sampled globally, and their concentration is known to increase in areas of high human population and activity, especially indoors. Respiratory symptoms and disease following exposure to occupational levels of MPs within industry settings have also been reported. It remains to be seen whether MPs from the environment can be inhaled, deposited and accumulated within the human lungs. This study analysed digested human lung tissue samples (n = 13) using mu FTIR spectroscopy (size limitation of 3 mu m) to detect and characterise any MPs present. In total, 39 MPs were identified within 11 of the 13 lung tissue samples with an average of 1.42 +/- 1.50 MP/g of tissue (expressed as 0.69 +/- 0.84 MP/g after background subtraction adjustments). The MP levels within tissue samples were significantly higher than those identified within combined procedural/laboratory blanks (n = 9 MPs, with a mean +/- SD of 0.53 +/- 1.07, p = 0.001). Of the MPs detected, 12 polymer types were identified with polypropylene, PP (23%), polyethylene terephthalate, PET (18%) and resin (15%) the most abundant. MPs (unadjusted) were identified within all regions of the lung categorised as upper (0.80 +/- 0.96 MP/g), middle/lingular (0.41 +/- 0.37 MP/g), and with significantly higher levels detected in the lower (3.12 +/- 1.30 MP/g) region compared with the upper (p = 0.026) and mid (p = 0.038) lung regions. After subtracting blanks, these levels became 0.23 +/- 0.28, 0.33 +/- 0.37 and 1.65 +/- 0.88 MP/g respectively. The study demonstrates the highest level of contamination control and reports unadjusted values alongside different contamination adjustment techniques. These results support inhalation as a route of exposure for environmental MPs, and this characterisation of types and levels can now inform realistic conditions for laboratory exposure experiments, with the aim of determining health impacts.

Automated summary

Airborne microplastics (MPs) have been found to have increased concentrations in areas with high human population and activity, especially indoors. This study analyzed human lung tissue samples and identified 39 MPs in 11 out of 13 samples, with an average concentration of 1.42 +/- 1.50 MP/g of tissue. The most abundant polymer types were polypropylene, polyethylene terephthalate, and resin. The study also found that MPs were present in all regions of the lung, with significantly higher levels in the lower region compared to the upper and middle regions. These findings suggest that inhalation is a route of exposure for environmental MPs.