A study claims that patients who have suffered a heart attack have higher levels of micro- and nanoplastics in their blood

The article evaluates the presence of micro- and nanoplastics (MNPs) in the coronary and peripheral blood of 61 patients. The results revealed a significantly higher quantity of synthetic polymers in patients suffering from acute myocardial infarction in comparison with patients with normal coronary arteries. The authors observed that higher plastic detection correlates with elevated levels of inflammatory biomarkers, suggesting a direct relationship between MNPs, smoking, and fine particulate matter (PM2.5) pollution as drivers for coronary artery disease

Linking the exposome to cardiovascular health via in vivo detection is a truly pioneering outcome, but the study presents significant methodological weaknesses that compromise its conclusions regarding the relationship between plastics and cardiovascular health. First, the sample size is too small (61 patients, only 31 with detectable MNPs) to reliably support a multivariable regression analysis. The paper omits ingestion as a primary route for MNP internalization, which is contrary to the current scientific consensus. Additionally, relying on monitoring stations near the patients' residences implies that regional outdoor data accurately reflects individual exposure, ignoring indoor air pollution, occupational hazards, and other factors. Finally, the link to smoking is unclear, as cigarette filters are primarily made of cellulose acetate, which is a polymer not found in this study.

Other methodological issues include gender and comorbidity differences across the cohorts, but, more importantly, the use of the Py-GC/MS technique. This methodology is known to give rise to false positives because the thermal degradation of lipids produces volatile compounds identical to those of plastics.

This issue is particularly critical for polyethylene, which accounts for 97% of the findings, as using 1-hexadecene as the sole indicator ignores the fact that this compound is also formed when pyrolyzing biological matrices. The omission of pyrograms and specific ions further undermines the credibility of the quantification. It is important to note that the measured concentrations, reaching up to 2.5 mg/L, are extraordinarily high, falling within the upper range of levels detected in wastewater treatment plant influents. This strongly suggests a potential artifact derived from medical materials and the release of plaque lipids during the aspiration procedure, a possibility the article fails to address.

Finally, while the need to reduce plastic exposure is obvious under the precautionary principle and the approach of in vivo analyses is appealing, the study suffers from major methodological gaps and conclusions that are insufficiently supported by clear evidence.

The key question is whether the study detected plastics or whether it detected molecules that look like plastics. Microplastics are notoriously challenging to measure in human blood, and based on recently published confidence levels, the results presented are presumptive of the presence of plastics at best.

While the authors are to be commended for their efforts to control contamination, the study ignores findings that show that the pyrolysis gas chromatography mass spectrometry method used to quantify "nano- and microplastics (NMPs)" is not suitable for polyethylene and polyvinyl chloride, two of the main plastics detected. It is just as plausible that endogenous lipids in the blood are being misidentified as plastics. The headline could just as well read 'Patients who suffer heart attacks have more lipids in their blood’.

This study provides important new evidence that micro- and nanoplastics can be detected in the coronary circulation of patients experiencing heart attacks and are associated with higher levels of inflammation and environmental exposures such as air pollution and smoking. While the findings do not prove that plastics directly cause heart attacks, they strengthen the growing scientific evidence that plastic pollution is an emerging public health issue deserving serious attention.

Although the authors implemented rigorous contamination controls, measuring micro- and nanoplastics in blood remains technically challenging. There is still no internationally standardised method for sampling, extraction, identification and quantification, making comparisons between studies difficult. In addition, current analytical methods cannot fully characterise the smallest nanoplastics (<1 µm), which may have different biological behaviour. Another limitation is that the study measured the presence of plastic polymers but did not distinguish whether the observed biological effects were caused by the particles themselves, the chemicals they carry, or co-exposure to other environmental pollutants such as air pollution and tobacco smoke. The finding that smoking was the only independent predictor of microplastic detection in multivariable analysis highlights the complexity of separating these environmental exposures.

The study highlights the need for larger, long-term human studies to determine whether reducing exposure to micro- and nanoplastics can lower the risk of cardiovascular disease. Given the widespread presence of plastics in our food, water and air, we need coordinated action to reduce unnecessary plastic pollution, improve human exposure monitoring, and accelerate research into the health impacts of plastics. Protecting people from plastic pollution should become a key component of future environmental and public health policy.

Overall, this study is an important step forward, but much larger prospective studies with harmonised analytical methods and detailed exposure assessment are needed before firm conclusions can be drawn about the causal role of micro- and nanoplastics in cardiovascular disease.

This is an interesting, albeit small, study suggesting a role for micro and nano plastics (MNPs) in ischaemic heart disease. Despite the large increases in MNP exposure observed since it was first reported 20 years ago, few health studies have been conducted. However, evidence from in vitro and animal models show: inflammatory and other immune responses; oxidative stress; endocrine disruption; cyto-, geno-, and neuro-toxicity; metabolic effects; and gut-microbiota disruption. Emerging clinical studies show associations with cardiovascular disease, stroke, neurodegeneration, neurological symptoms, anxiety and depression. This suggests that MNPs may be a significant and emerging health risk, but research on MNPs and health is still in its infancy and more well-designed and larger studies in human populations are urgently needed.

"This study adds to the emerging evidence that MNP exposure may increase the risk of cardiovascular disease. Previous studies have been criticised for using methods that were not specifically designed to eliminate plastic contamination from sample collection and processing, which the current study addressed, adding to the importance of the study.
 
"The paper focuses on airborne MNP exposure, and only in passing refers to MNP exposure through diet, which is another significant exposure route that may be at least as important for cardiovascular risk.

"MNPs originate from items (packaging, car tyres, clothing, toys, household products, etc), or are manufactured for use as additives, e.g., to fertilisers, cleaning agents, and personal-care products, and have become ubiquitous in the environment. As a result, they can be detected in food, drinking water, and air, with exposure occurring through ingestion (e.g., via consumption of highly processed foods, reheated foods in plastic containers, bottled drinks, and teabags), inhalation (associated with synthetic clothing, floor coverings, car-tyre wear, and indoor dust), or skin absorption (via personal-care products and synthetic-fibre clothing). So, other exposure routes may be equally or likely more important.

"Due to their small size, MNPs have the potential to migrate through the body, including, as shown in recent studies, the gut, blood, airways, liver, kidney, cerebrospinal fluid, brain, placenta, breast milk, testicles, etc., so health effects will likely not be limited to the cardiovascular system.
 
"Of interest, in addition to synthetic, mostly oil-derived, polymers, MNPs may contain >16,000 chemical additives, including plasticisers, flame retardants, UV stabilisers, colourants, manganese, other heavy metals, etc, which can leach into surrounding tissue, thus further contributing to health risks, highlighting the need to study the potential health effects that may arise from this new environmental pollutant. This is urgently needed as MNP pollution is rapidly increasing, and currently estimated at 10-40 million tonnes per annum, with an expected doubling of emissions by 2040. If these exposures are, as emerging evidence suggests, causally associated with ill health then we need to start looking at safer options not involving plastics.

Previous studies have shown that micro and nano plastics are present in the human body including blood samples. This study expands on existing studies by looking at coronary blood and looking at these samples and chronic coronary disease and acute myocardial infarction.

The study does not show that micro and nanoplastics cause heart attacks. Instead, this study strengthens the theory or hypothesis that micro and nanoplastics may be harmful to our health but it does not change our current understanding or provide definitive causality.

There are multiple limitations within this study, including a small sample size (61 people), observational cross-sectional design, excluding a lot of potential micro and nanoplastics routes i.e diet, occupational exposure to name a few. Due to the studies design being cross sectional, it looks at exposure and disease at the same time and as a result it cannot say whether micro and nanoplastics caused the disease, increased due to the disease or are just in the blood due to environmental exposure. Another issue is that samples were taken during or after an event so it’s not clear if the presence of microplastic was high before the event.

The high percentage of smokers within the STEMI and CCS both over 70% also raises questions especially as the packs per year is higher in the STEMI group. This confirms what we already know about heart attacks being linked to smoking, but it makes it harder to work out if there is a link between microplastics and heart attacks, microplastics and smoking or if microplastic exposure is from something else.

The study is interesting and whilst it does not prove that micro-nano plastics cause heart attacks it does show the difficulties of moving microplastic studies that investigate impact on the human body from an extremely highly controlled laboratory study to real world human populations where studies become complicated by multiple factors like genetics, lifestyle, exposure and other factors influence disease risk.