Harmful effects of plastics on cardiovascular health

Plastics are synthetic materials made by the petrochemical industry from fossil fuels: oil, gas and coal. Plastics are composed of a matrix of polymers and various chemical additives, which give them various properties such as flexibility, stability, colour, as well as fire and water resistance. Plastic production is increasing exponentially, which is likely to result in higher exposure and more harmful effects for all living organisms. Indeed, global production of plastics has exploded in the 75 years of its existence, from 2 million tonnes in 1950 to 400 million tonnes today. Experts have estimated that this production is expected to double in 2040 and triple in 2060, mainly because the petrochemical industry will turn to the production of these derivatives to compensate for the decreasing demand for fossil fuels as an energy source.

Plastic particles in the human body
Plastic particles were detected in 77% of blood samples from healthy donors. Polyethylene terephthalate (PET) was most commonly present (50% of donors), followed by polystyrene (36%), polyethylene (23%), and polymethyl methacrylate (5%). The maximum concentrations of plastic particles in a donor’s blood were 2.4 µg/mL for PET, 4.8 µg/mL for polystyrene, and 7.1 µg/mL for polyethylene.

Ingested plastic particles can not only cross the intestinal barrier and end up in the blood, but also subsequently in various organs such as the liver, lungs, and placenta, and in bodily fluids such as breast milk and urine.

Plastic particles found in the human body mainly come from the food chain. Based on typical food intake, it has been estimated that each person ingests approximately 39,000 to 52,000 plastic particles each year. The other route is inhalation (35,000 to 62,000 particles/year), which poses risks for the respiratory system.

Plastics from the food chain
Drinking water is a major source of plastics ingested daily. Indeed, high quantities of nano- and microplastics were measured in 92% to 100% of bottled water samples, 24-100% of tap water samples, while few plastics were found in samples of well water (see this review article). PET and polypropylene are the most common plastics since most water bottles are made with PET and the caps are made from polypropylene.

Among the vegetables tested, it appears that broccoli and carrots contain more plastic particles, up to 100,000 particles per g of vegetable. Microplastics are particularly found in the roots of vegetables, which makes root vegetables (carrots, radishes, beets, potatoes) a potentially significant source of plastic particles ingested by consumers.

Fish and seafood contain significant amounts of plastic, but it is mainly found in the digestive system, which is generally not consumed. On the other hand, molluscs, which are consumed in their entirety, are a significant source of plastic particles.

Nanoplastics in atherosclerotic plaques and risk of cardiovascular events
In a prospective study of 257 patients who underwent carotid endarterectomy (surgery to remove atherosclerotic plaque material), those who had plaques containing nano- and microplastics had a higher risk of death or major cardiovascular events than those whose plaques did not contain plastic.

Polyethylene (PE) was detected in the atherosclerotic plaques of 150 patients (58%), while polyvinyl chloride (PVC) was found in the plaques of 31 patients (12%). The average amount of PE in the plaques was 21.7 ± 24.5 µg per mg of plaque and that of PVC was 5.2 ± 2.4 µg per mg of plaque. Analysis of plastic particle size indicates that nanoplastics (1-1000 nm) rather than microplastics (1-1000 microns) are mainly found in the plaques.

During follow-up of an average duration of 34 months after surgery, 8 of the 107 patients (7.5%) whose plaques did not contain plastics suffered an event (non-fatal myocardial infarction, non-fatal stroke, or all-cause mortality) compared to 30 of 150 (20%) patients whose plaques contained microplastics. The researchers estimated that patients who had plastic in their atherosclerotic plaques had a 4.5 times higher risk of experiencing an event than those whose plaques did not contain plastics.

This type of study does not make it possible to establish a causal link. It is in fact possible that the presence of plastic particles in patients’ plaques is linked to their general state of health or poor lifestyle habits, without it being the cause of the increased risk of cardiovascular events. Nevertheless, this study has received a lot of media attention and should prompt the scientific community to further investigate the potentially harmful effects of plastic particles in arteries on cardiovascular health.

Microplastics found in blood clots
In another recent study, researchers assessed and quantified microplastics present in thrombi (blood clots) collected from 30 patients who underwent thrombectomy (removal of a thrombus in a blood vessel) due to myocardial infarction (MI), ischemic stroke (IS), or deep vein thrombosis (DVT). Plastic particles were detected in 80% of thrombi, with average concentrations of 62 µg/g for ISs, 142 µg/g for IMs, and 70 µg/g for DVTs. Among the 10 plastic polymers that were investigated, the presence of polyamide 66 (PA66), polyvinyl chloride (PVC), and polyethylene (PE) was confirmed. Statistical analyses indicate that higher concentrations of microplastics in clots may be associated with increased disease severity. These results do not establish a causal link between the presence of microplastics and the formation of blood clots, but they are concerning and raise the possibility that plastic particles could be harmful to cardiovascular health.

Too much plastic packaging?
In recent decades, more and more foodstuffs have been packaged in plastic, in the form of films, trays and containers. Today, many of the fruits and vegetables sold in supermarkets are packaged in plastic: lettuce, cucumbers, peppers, mushrooms, cabbage, fruits, berries, etc.

A consensus on the need to reduce the use of plastic packaging is emerging globally. In Europe, countries such as France and Spain have imposed limits or taxes on the use of plastics in an effort to reduce their use. The European Union, Canada and the United States are developing plans to significantly reduce the use of plastic in packaging.

Not that easy. . .
This represents a challenge because plastic packaging is very useful in protecting fruits and vegetables and therefore very effective in reducing food waste and its impacts on the environment. Wasted food ultimately ends up in landfills where it is responsible for nearly 60% of methane emissions. A study carried out in Switzerland showed that every cucumber (imported from Spain) thrown in the trash has an environmental impact equivalent to 93 plastic cucumber packages. How did the researchers arrive at this estimate, which may seem surprising at first? They analyzed two scenarios and estimated the climate change impact of producing and transporting a metric tonne of cucumber:
1) without the use of plastic packaging, and 2) with the use of low-density polyethylene film. They took into account greenhouse cultivation, transport in refrigerated trucks (1200 km), production and incineration of plastic, etc. For comparison, the estimated environmental cost of producing and transporting a single cucumber was 0.992 kg CO₂-eq, while that of producing and disposing of plastic packaging was only 0.0106 kg CO₂-eq (i.e., 93 times less). Researchers estimated that using plastic to package cucumbers would reduce waste by 4.8%. The environmental benefits of cucumber packaging would be 4.9 times greater than the negative environmental impact caused by the plastic packaging itself.

Alternatives to plastic packaging

New packaging has recently been created to replace plastic. Here are some examples:

• Biodegradable cellulose mesh bags.

• Films made from orange peels, shrimp shells, and other natural waste that can be used like cellophane or made into bags.

• Containers (trays, boxes) made from plants: rice straw, sugar cane stalks, food waste.

However, this new compostable or recyclable packaging is still a long way from replacing plastic packaging. If we were to eliminate all plastic packaging tomorrow by replacing it with fibre packaging, the shelf life of fruits and vegetables would be considerably reduced. It would then become impossible to buy certain fruits and vegetables out of season, and the price of the grocery basket would increase accordingly, which is probably not what most consumers accustomed to abundance want.