Plastics in daily use can be degraded into microplastics which
are smaller than 5 mm and nanoplas-tics which are smaller than
1000 nanometre [1]. These can trigger toxicologic effects in
the human body [2]. Routes of entry of micro and nano
particles (MNPs) into the human body could be by in-gestion,
topical exposure and even by inhalation. Microbeads which are
a type of microplastic are often added as exfoliants to health
and beauty products as well as some cleansers and even
tooth-pastes [3], increasing the chance of human exposure.
Adverse cardiovascular effects of MNPs have come into
limelight with the publication of a paper in NEJM which has
correlated the presence of MNPs in carotid artery atheromas
removed during ca-rotid endarterectomy to increased
cardiovascular events during follow up [4]. Earlier
experimental studies had suggested that MNPs promote oxidative
stress, inflammation and apoptosis in endothe-lial and other
vascular cells which could eventually lead to impairment in
cardiac function, myocar-dial fibrosis and endothelial
dysfunction [5].
The study by Marfella R et al [4] was a prospective,
multicenter observational study of patients undergoing carotid
endarterectomy for asymptomatic carotid artery disease. The
plaques excised from carotid arteries were analyzed using
pyrolysis-gas chromatography-mass spectrometry, stable isotope
analysis, and electron microscopy. Estimation of inflammatory
biomarkers were also carried out. A composite of myocardial
infarction, stroke or death from any cause was the primary
endpoint of the study. Comparison was between those who had
MNPs in carotid artery plaques with those who did not have
them in their carotid plaques.
One hundred and fifty patients had polyethylene in their
carotid artery plaques and 31 patients had polyvinyl chloride
in their carotid plaques. Presence of foreign particles were
noted in plaque mac-rophages and extracellular debris by
electron microscopy. The initial number of patients enrolled
in the study was 304, of which 257 completed the study. Mean
follow up period was 34 months in this study. A hazard ratio
of 4.53 was noted for those who had MNPs in carotid plaques
for the primary endpoint.
An important limitation mentioned in the study was that even
though good care was taken, they could not completely rule out
laboratory contamination as plastics were present in the
laboratory as well! Authors suggested future studies with the
use of clean rooms where there is no plastic in any form
except for the material under study to avoid this confounding
factor [4].
Another group authors who reviewed the cardiovascular effects
of MNPs has even asked whether they are to be considered as a
new cardiovascular risk factor [5]. They have noted direct
cardiac toxicity of MNPs including abnormal heart rate,
cardiac function impairment, pericardial edema and myocardial
fibrosis. Microvascular effects noted were MNP induced
hemolysis, thrombosis, coagu-lation and endothelial damage.
Certainly, more research is needed on these aspects before we
can make definite conclusions about the cardiovascular adverse
effects of MNPs, which would have long lasting implications on
the human community.
References
1. Gigault J, Halle AT, Baudrimont M, Pascal PY, Gauffre F,
Phi TL, El Hadri H, Grassl B, Reynaud S. Current opinion: What
is a nanoplastic? Environ Pollut. 2018 Apr;235:1030-1034. doi:
10.1016/j.envpol.2018.01.024. Epub 2018 Jan 19. PMID:
29370948.
2. Vethaak AD, Legler J. Microplastics and human health.
Science. 2021 Feb 12;371(6530):672-674. doi:
10.1126/science.abe5041. PMID: 33574197.
3. What are microplastics? US National Oceanic and Atmospheric
Administration (NOAA) web page available at:
https://oceanservice.noaa.gov/facts/microplastics.html.
Accessed on 8th March 2024.
4. Marfella R, Prattichizzo F, Sardu C, Fulgenzi G, Graciotti
L, Spadoni T, D'Onofrio N, Scis-ciola L, La Grotta R, Frige C,
Pellegrini V, Municino M, Siniscalchi M, Spinetti F, Vigliotti
G, Vecchione C, Carrizzo A, Accarino G, Squillante A, Spaziano
G, Mirra D, Esposito R, Altieri S, Falco G, Fenti A, Galoppo
S, Canzano S, Sasso FC, Matacchione G, Olivieri F, Ferraraccio
F, Panarese I, Paolisso P, Barbato E, Lubritto C, Balestrieri
ML, Mauro C, Ca-ballero AE, Rajagopalan S, Ceriello A,
D'Agostino B, Iovino P, Paolisso G. Microplastics and
Nanoplastics in Atheromas and Cardiovascular Events. N Engl J
Med. 2024 Mar 7;390(10):900-910. doi: 10.1056/NEJMoa2309822.
PMID: 38446676.
5. Zhu X, Wang C, Duan X, Liang B, Genbo Xu E, Huang Z. Micro-
and nanoplastics: A new cardiovascular risk factor? Environ
Int. 2023 Jan;171:107662. doi: 10.1016/j.envint.2022.107662.
Epub 2022 Nov 26. PMID: 36473237.