Physical Dimension Profiling of Accumulated Nanoplastics in Human Brain, Kidney, and Liver

Details

• Personal Author:
  Erdely, Aaron ; Kodali, Vamsi K. ; Garcia, M. A. ; Bunker, Kristin ; Li, L. ; Marquis, J. ; Levine, A. ; Deible, M. ; Eye, Tracy ; Nihart, A. J. ; Adolphi, N. L. ; Gallego, D. F. ; El Hayek, E. ; Campen, Matthew J.
  More +
• Description:
  Background and Purpose: Recent studies have shown that micro- and nanoplastics have become ubiquitous resulting in inevitable human exposure. To evaluate exposure and link to adverse health outcomes, characterization of internalized plastic particles is necessary. Recent studies provide evidence of plastic particles in various human tissues with reference to accumulated mass, and some provide visual evidence of micron sized particles characteristic of plastic. To date, no study has adequately characterized nanoplastic accumulation in humans. The primary goal of this study was to identify and profile the physical dimensions of nanoplastic fragments in human tissues. Methods: Brain, kidney, and liver were obtained from five decedents by the University of New Mexico (UNM) with approval from the Office of the Medical Investigator and UNM Human Research Protection Office. Tissues (n=15) were digested using potassium hydroxide and ultracentrifuged. The pellet generated by the isolation method was previously shown to contain a mass-based (µg/g) level of plastic measured by pyrolysis gas chromatography mass spectrometry. To understand particle morphology, the pellet was resuspended and visualized by transmission electron microscopy using a modification of previously established methods for generating singlet carbon nanotubes and carbon nanofibers (National Institute for Occupational Safety and Health / RJ Lee Group). Identification and physical dimension profiling of single dispersed nanoplastic fragments was done for each tissue for each individual (n=205-231 individual measurements / tissue) with a total of 3251 measurements performed. Results: When considering all measured plastic fragments from all sampled tissues, the range for the length and width, respectively, were 46-432 nm and 13-107 nm for brain (n=1103), 31-334 nm and 8-83 nm for kidney (n=1075), and 34-654 nm and 10-116 nm for liver (n=1073). The mean ranges for length and width, respectively, of the five individuals were 154.9-181.7 nm and 41.6- 50.2 nm for brain, 110.8-131.8 nm and 30.3-34.3 nm for kidney, and 135.0-172.0 nm and 32.3-40.1 nm for liver. The means of the five separate individuals for length was 171.2 +/- 4.6 for brain, 124.4 +/- 3.6 for kidney, and 147.6 +/- 6.6 for liver. One-way analysis of variance (ANOVA) indicated significance (p<0.0001) with a Tukey's HSD post-hoc test indicating all groups were different from one another for length (p<0.02). The means of the five separate individuals for width was 45.9 +/- 1.5 for brain, 32.3 +/- 0.7 for kidney, and 36.1 +/- 1.3 for liver. One-way ANOVA indicated significance (p<0.0001) with a Tukey's HSD post-hoc test indicating the brain was different from all groups (p<0.001). When examining the aspect ratio, the fragments, 78-83%, consisted of fiber morphology (greater than a 3:1 aspect ratio) as opposed to irregular particle shapes (aspect ratio less than 3:1; 17-22%). Raman spectroscopy, Fourier transform infrared spectroscopy, dissolution experiments using solvents such as chloroform and benzene with and without heating, and energy-dispersive X-ray spectroscopy provided confidence that the fragments were polymer plastic. The isolated and dispersed fragments, washed subsequently in benzene and heated to further remove any potential contaminating lipids, had a Raman spectral profile mirroring polyethylene, the most abundant plastic accumulating in human tissues, albeit with a peak from 1600-1700 cm-1 possibly due to high carbonyl content. A completely different method of tissue digestion using hydrogen peroxide also confirmed the presence of nanoplastic fragments in brain tissue. Procedural tests of 'blank' samples (no tissue) to evaluate for an artifact contributed no discernable pellet after ultracentrifugation and no measurable nanoplastic fragments. Conclusions: The results provide quantification of a size fraction of nanoplastics otherwise not previously characterized in human tissues. From the methods employed, the accumulation of nano-sized plastics comprised of a narrow, but consistent, size range. Interestingly, and quite remarkably, the difference was greater between tissues of a single individual and not across individuals. Consistently, the nano-sized fragments were larger in the brain than kidney or liver. The observations overall suggest some specificity with respect to systemic internalization and subsequent tissue accumulation of nano-sized plastic. Description provided by NIOSH
• Subjects:
  • Brain
  • Kidney
  • Liver
  • Microplastics
  • Occupational Health
  • Safety
• Keywords:
  • Nanoplastics; Tissue distribution; Brain matter; Kidneys; Liver tissue; Humans; Polymers
• Source:
  Toxicologist 2025 Mar; 204(S1):109
• ISSN:
  1096-6080
• Document Type:
  Text
• Genre:
  Abstract or Summary
• Place as Subject:
  Dallas Region OSHA ; New Mexico ; Pennsylvania ; Philadelphia Region OSHA ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  HELD - Health Effects Laboratory Division
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  2 pdf pages
• Volume:
  204
• NIOSHTIC Number:
  nn:20071572
• Federal Fiscal Year:
  2025
• NORA Priority Area:
  Construction
• Peer Reviewed:
  False
• Download URL:
  https://stacks.cdc.gov/view/cdc/259347/cdc_259347_DS1.pdf
• File Type:
  [PDF - 855.14 KB]
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:fb628949f683bf122d8072956cd73516996f5102d83d061c6602a9dea9f28160b482bb7f705afa11b9aac62795958b2522663ad211809a7999406d3a9d8ff83c