22
Mar
Plastics in Agriculture and Packaging Clog Arteries Raising Rate of Cardiovascular Disease and Stroke
(Beyond Pesticides, March 22, 2024) With long-running efforts to keep organic land management in the forefront of public health and environmental measures to eliminate petrochemical synthetic substances, including pesticides and fertilizers, plastic again emerges as an increasing threat in a study linking microplastics to cardiovascular disease. The study by Italian researchers, published in the March 7 issue of the New England Journal of Medicine, finds an elevated risk factor for heart attack and stroke associated with plastics found in the plaque of the majority of patients’ carotid arteries. A holistic approach to agriculture that embraces principles and values to enhance biodiversity and protect health, the organic system requires that synthetic substances are compatible with that system. In this context, the environmental and public health effects of plastics are increasingly subject to scrutiny as they permeate nearly every aspect of food production, including fields, crops, foods, and food packaging.
Plastics also migrate from other sectors into agriculture via wind and water and are now ubiquitous in every environment. Removing plastics from any ecosystem is extremely problematic, so getting them out of agriculture will be difficult – but necessary, given the accumulating evidence of their toxicity.
Beyond Pesticides continues to push for eliminating plastic use in organic agriculture. The organization is urging the U.S. Department of Agriculture’s National Organic Standards Board (NOSB) to increase its research into ways to accomplish this. The NOSB is accepting online public comments on its policy goals until April 3 this year. In a recent comment to the NOSB, Beyond Pesticides notes that major sources of plastic inputs to agriculture include plastic mulches, compost, and leachate that migrate from landfills into ground and surface water. Beyond Pesticides has identified key issues, available here, and urges the board to take important actions regarding microplastics and compostable materials.
Beyond Pesticides’ comment states that in addition to their direct harm to health, microplastics “also act as carriers of toxic chemicals that are adsorbed to their surface.” For example, many plastics contain additives such as bisphenol A, organotins and phthalates, all known endocrine disrupters, and these can hitch a ride on the plastic particles. The letter continues, “Some studies on fish have shown that microplastics and their associated toxic chemicals bioaccumulate, resulting in intestinal damage and changes in metabolism. Microplastics can increase the spread of antibiotic resistance genes in the environment.” Studies have shown that microplastics migrate into many human tissues, including the lungs, liver, breast milk, urine, blood, and the placenta.
The universal distribution of plastics ensures that they cannot be avoided. Humans and other organisms take up plastics in the form of micro- and nano-particles by inhalation, ingestion, and skin contact every day. Micro-plastics are about the width of a human hair; nano-plastics are much smaller, about twice the width of a DNA strand. Larger pieces of plastic are ground down to these tiny sizes by weathering, temperature, biological processes, and chemical conditions.
Emerging evidence shows that plastics affect many organs and physiological processes. They can influence cellular metabolism, cell signaling, iron transport, and other vital cellular processes. As scientists find closer connections among various systems previously considered separate, such as gut health, mental health, and immune responses, plastics’ effects on cardiovascular health are attracting more scrutiny. Plastics can impair heart function. They can induce several markers of oxidative stress and associated inflammation. Pregnant mice fed microplastics developed disturbed gut microbes and changes in lipid metabolism, including cholesterol levels, which are factors in cardiovascular disease.
The Italian researchers studied a group of 257 hospital patients who had been diagnosed with plaque in their carotid arteries, a major risk factor for heart attack and stroke. Plaque is a sticky goo of cholesterol and fats that narrows arteries. The researchers examined each patient’s plaque for the presence of microplastics. (They added micro- and nano-scale sizes together in their analysis.) They found two types of plastic out of the 11 they looked for: polyethylene (PE) and polyvinyl chloride (PVC), two chemically related compounds used globally in massive quantities. At 36 percent of the global plastics market, PE is the highest-production non-fiber plastic in the world; PVC is third at 12 percent.
More than half of the full group of patients had PE in their plaque; 12 percent had PVC. The team divided their subjects into those with microplastics and those without microplastics and followed both groups for 34 months, tracking their incidence of cardiovascular events. At the end of the study period, the scientists found that the group with microplastics was at “a higher risk of a composite of myocardial infarction, stroke, or death from any cause” than the group without microplastics. The team tested a set of inflammation markers in the plaques, finding sharply higher levels in the group having microplastics in their plaque. They also checked collagen levels in the plaque as an indicator of activity by lymphocytes and macrophages, immune cells with a role in cardiovascular disease development, finding higher levels associated with the microplastics group.
The study results were adjusted to account for age, sex, body mass index, total cholesterol, diabetes, hypertension, and other conditions. The patients with microplastic-laden plaques were younger, more likely to be male, less likely to have hypertension, more likely to be diabetic, and to have heart disease and high cholesterol. They were also more likely to smoke. Thirty of 150 patients with microplastics in their plaque died or had non-fatal cardiovascular events, while only eight out of the 107 patients without microplastics experienced such events.
Size matters at the scale of these plastic particles. The smaller the particle, the farther it can travel and the more types of tissues it can enter. Nanoplastics are in the size range of viruses, which means they may enter individual cells. The present study’s authors suggest that nanoplastics likely account for the bulk of the plastics in the plaques. In addition, the smaller a particle, the larger its surface area in proportion to its mass. This makes micro- and nanoplastics able to carry relatively high amounts of absorbed chemicals like pesticides, increasing their effects. And more surface area increases the likelihood of chemical reactions with other substances in the environment, so that the microplastics themselves may be more reactive with biochemistry than their larger versions. Nanoscale particles can also cross the blood-brain barrier. These properties have not been comprehensively assessed for their role in health risks, but they are of increasing concern regarding the smallest particle sizes.
It is also dawning on researchers that plastics’ full chemical interactions with biology are only dimly comprehended and not confined to any compound’s disclosed ingredients. Beyond Pesticides’ letter to NOSB cites a Norwegian study finding that “the components of 50 items in common use—plastic bags, disposable cups, dishwashing gloves, car tire granules, children’s toys and balloons…could not be identified because they were not listed in the major chemical substance databases. Only 30 percent of the chemical compounds identified in the study were present in two or more products. This suggests that most plastics contain many unidentified chemicals, far beyond the known impurities, metabolites and degradation products. Further, it suggests that in the environment plastics are chemically reactive and forming new compounds no one has anticipated and whose toxicity is unknown.” This problem applies to micro- and nano-plastics to an even greater degree, partly because of the abovementioned property of increased chemical reactivity with increased surface area at small scales.
A 2017 Science Magazine review titled “Production, use and fate of all plastics ever made” observed that “without a well-designed and tailor-made management strategy for end-of-life plastics, humans are conducting a singular uncontrolled experiment on a global scale, in which billions of metric tons of material will accumulate across all major terrestrial and aquatic ecosystems on the planet.”
As widely recognized, plastics are a form of fossil fuel, and it is not just its contribution to the climate crisis that is of concern. Their intractable ubiquity makes the urgency of removing plastics to the greatest extent possible from food production systems all the more dire. Plastic production must be cut drastically back, and a way to recover and sequester even the smallest particle sizes must be developed and implemented without delay. Fossil fuels must, from now on, be left in the ground rather than extracted, extruded, and distributed as micro- and nano-scale invaders of the biosphere.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Sources:
Microplastics and Nanoplastics in Atheromas and Cardiovascular Events, N Engl J Med 2024;390:900-10, DOI: 10.1056/NEJMoa2309822, https://www.nejm.org/doi/full/10.1056/NEJMoa2309822; PVC, other microplastics found in clogged arteries: Medical News Today, March 12, 2024, https://www.medicalnewstoday.com/articles/pvc-other-microplastics-found-in-clogged-arteries; Production, use, and fate of all plastics ever made, Roland Geyer, Jenna R. Jambeck, Kara Lavender Law, Science Magazine, July 2017, https://www.science.org/doi/epdf/10.1126/sciadv.1700782; The need for environmentally realistic studies on the health effects of terrestrial microplastics, Lauren Mills, Joy Savanagouder, Marcia de Almeida Monteiro Melo Ferraz and Michael J. Noonan, Microplastics and Nanoplastics, https://doi.org/10.1186/s43591-023-00059-1, https://microplastics.springeropen.com/articles/10.1186/s43591-023-00059-1; Farm animals as a critical link between environmental and human health impacts of micro-and nanoplastics, Hilde Aardema, A. Dick Vethaak, Jorke H. Kamstra & Juliette Legler, Microplastics and Nanoplastics, volume 4, Article number: 5 (2024), https://microplastics.springeropen.com/articles/10.1186/s43591-024-00082-w; Interactions of Microplastics with Pesticides in Soils and Their Ecotoxicological Implications, Aránzazu Peña, José Antonio Rodríguez-Liébana and Laura Delgado-Moreno, Agronomy (2023) 13(3), https://doi.org/10.3390/agronomy13030701, https://www.mdpi.com/2073-4395/13/3/701; Nanoplastics and Human Health: Hazard Identification and Biointerface, Hanpeng Lai, Xing Liu, and Man Qu, Nanomaterials, April 2022, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9026096/, Genotoxic and neurotoxic potential of intracellular nanoplastics: A review, Claudio Casella and Santiago J Ballaz, Journal of Applied Toxicology, 24 February 2024, https://analyticalsciencejournals.onlinelibrary.wiley.com/doi/epdf/10.1002/jat.4598; Microplastics derived from plastic mulch films and their carrier function effect on the environmental risk of pesticides, Xin Bao, Yuntong Gu, Long Chen, Zijian Wang, Hui Pan, Shiran Huang, Zhiyuan Meng, Xiaojun Chen, Science of the Total Environment, 10 May 2024, https://www.sciencedirect.com/science/article/pii/S0048969724016139?via%3Dihub
