Researchers have found the presence of microplastics in all regions of the lungs of living people, supporting inhalation as a route of exposure.

The UK study, published in Science of The Total Environment, analysed lung tissue collected from surgical procedures carried out on living patients (n=13) as part of their routine medical care using μFTIR spectroscopy.

They detected 39 different microplastics in 11 of the 13 tissue samples, at a level of 0.69 ± 0.84 MP/g (after adjusting for sample contamination). 12 polymer types were identified, with polypropylene (23%), polyethylene terephthalate (18%) and resin (15%) found to be the most abundant, commonly found in packaging, bottles, clothing, rope, etc.

While their presence was detected in all regions of the lung, significantly more were found in the lower region (21) versus the upper (11) and middle (7) regions, which was an unexpected finding.

Researchers also found a difference in levels of microplastics detected between the sexes, with tissue from male donors containing significantly higher levels of unadjusted microplastics (2.09 ± 1.54 MP/g) compared to females (0.36 ± 0.50 MP/g), and all samples from males containing microplastics versus three out of five from females.

The researchers believe this might be due to female airways being significantly smaller than the airways of males, though they also noted that the relatively small sample size used “dictates that more analyses be conducted to explore such differences further”.

Also of note, and contrary to prior assumption, the team found larger microplastics, with dimensions of greater than 2 mm, in all lung regions, as well as microplastics as small as 4 μm.

“Microplastics have previously been found in human cadaver autopsy samples – this is the first robust study to show microplastics in lungs from live people,” said Dr Laura Sadofsky, Senior Lecturer in Respiratory Medicine at Hull York Medical School and lead author on the paper, commenting on the findings.

“It also shows that they are in the lower parts of the lung. Lung airways are very narrow so no one thought they could possibly get there, but they clearly have. “

“The knowledge that MPs are present in human lung tissues can now direct future cytotoxicity research to investigate any health implications associated with MP inhalation,” the authors added.