Potential Health Risks of Nano and Microplastics

By Paul E. Lemanski, MD, MS, FACP

[Editor’s Note…]

Medicines are a mainstay of American life and the healthcare system not only because they are perceived to work by the individuals taking them, but also because their benefit may be shown by the objective assessment of scientific study. Clinical research trials have shown that some of the medicines of Western science may reduce the risk of Type 2 diabetes, heart attacks, strokes, cardiovascular death and even some cancers.

In the first 120 installments of the Non-Medicated Life, a healthy diet and lifestyle have been shown to accomplish naturally for the majority of individuals most of the benefits of medications in the prevention of the chronic medical conditions mentioned above. The definition of a healthy diet described in this column, previously, can be summed up as a predominately plant-based diet, emphasizing unrefined foods with minimal processing. The Mediterranean diet would be an example. A further refinement of a healthy diet would include marinating animal protein, cooking it at lower temperature to avoid carcinogen production and the consumption, when possible, of organic produce to minimize pesticide residues. 

In this article I want to shed light on the potential health risks of nano and microplastics which have become all pervasive in the environment and the food supply with the advent of plastic manufacturing since the 1960s. Emerging research suggests cause for concern. Until definite risks to human health are better established, simple precautions may significantly reduce exposure and risk.

First, it is important to define what we mean by plastic and then nanoplastics and microplastics. Plastic is a synthetic material made from petroleum products consisting of chains of molecules called polymers which may have side chains contributing different properties. Examples include polyethylene terephthalate (PET), high density polyethylene (HDPE), polyvinyl chloride (PVC), low density polyethylene (LDPE), polypropylene (PP), and polystyrene (PS). Nanoplastics are plastic particles with a size between one nanometer and one micrometer. Microplastics are plastic particles with a size between one micrometer and five millimeters.

In reviewing the available research multiple studies suggest an association between plastic exposure and certain health concerns including an increased incidence of certain cancers (most notably pancreatic cancer, colon cancer, and bladder cancer), hypersensitivity pneumonitis (a type of allergic lung disease), asthma, and inflammatory bowel disease. Most of these studies involve significant occupational exposure to plastics in manufacturing. Other studies document the presence of nano and microplastics in human organs such as lung, liver, spleen, colon, blood and placenta. Nano and microplastics are also found in breast milk, blood, sputum, saliva, and semen.

What concentration of nano and microplastics that will possibly produce disease in humans is unclear and an area of ongoing research. However, in vitro (cell culture) studies and animal studies do suggest a more direct possibly causative connection with disease. For example, cell culture studies document cytotoxicity and apoptosis (programmed cell death) with microplastics as well as inflammation, and oxidative stress. In mice, PVC microplastics lead to gut barrier dysfunction (leaky gut syndrome), endocrine disruption and metabolic disorders, and changes in the gut microbiome.

Nano and microplastics gain access to the human body though respiratory inhalation, skin absorption, and digestive tract absorption, with the latter constituting the greatest risk. Minimizing exposure through these three routes of entry can minimize total nano and microplastics exposure. Respiratory inhalation can be minimized in the occupational setting with proper respirator use. However, clothes with synthetic fabrics can also offer exposure and thus choosing natural fiber clothing may minimize risk. Skin absorption of many cosmetics and skin products employ a high concentration of nanoplastics to encourage skin absorption. Unfortunately, such absorption may not be confined to skin alone and may enter the blood stream and thus be systematically absorbed and distributed.

Digestive tract absorption is by far the largest source of nano and microplastics exposure and presents a leveraged opportunity to minimize absorption by identification and avoidance of food and drink with the greatest concentrations. While all animal derived foods as well as plant based foods contain microplastics eating low on the food chain and avoiding petroleum based fertilizers may be helpful. Because much of the plastic pollution of the planet is in Earth’s oceans and because the oceans are exposed to sunlight and wind agitation which can break down plastic, microplastic concentrations are high in seawater and consequently in marine life. 

Making matters worse, marine life exhibits bioconcentration of microplastics in much the same way as there is bioconcentration of heavy metals. In the marine food chain, smaller fish are eaten by larger fish with the largest fish not only absorbing microplastics from seawater through their gills, but also absorbing all the microplastics contained in the flesh of the fish they eat. As a consequence, large fish such as tuna and swordfish contain very large amounts of microplastics, and the frequency of consumption as well as the portion size should probably be minimized.

Water consumption, especially from plastic bottles, is also a significant source of microplastics with longer storage times increasing MP particle number. Disturbingly, even 81% of tap water contains microplastics Moreover, all plastic bottles are implicated as well as food in metal cans – the Bisphenol A (BPA) free lining used in such cans is better but still contains microplastics. Choosing products in glass containers rather than in metal cans can help reduce exposure. Fresh fruits and vegetables, especially organically grown can further reduce digestive tract exposure. Drinking water that has been filtered through a reverse osmosis membrane and stored in a glass or stainless steel lined water bottle will also help to minimize microplastics exposure. 

Never storing food in plastic containers in favor or glass or silicone will further reduce exposure. Never heating foods in plastic containers in favor of glass, porcelain or stainless steel is also prudent. Changing a plastic cutting board to a wooden or titanium cutting board can also reduce exposure.

In summary, nano and microplastics have been implicated in a range of health concerns. Although studies to determine the exact level of risk and which diseases are definitely causally related to plastic exposure through nano and microplastics remains to be determined. Nevertheless, enough evidence has been gathered to institute prudent and practical precautions in the meantime. Avoiding unnecessary respiratory inhalation thorough the use of a proper respirator and the wearing and use of natural fibers in clothing and bedding may be helpful. Avoiding the use of cosmetics and skin products containing nano and microplastics may be helpful. 

Minimizing the consumption of seafood, especially larger fish, choosing products in glass containers rather than metal cans, drinking reverse osmosis filtered water stored in glass lined or culinary grade stainless steel lined bottles, storing food in glass or silicone containers and cooking food only in glass, porcelain or stainless steel are practical simple practices to minimize exposure and risk. In this way, you may avoid excess nano and microplastics and the possible diseases they may cause, and be more likely to lead a non-medicated life.

Paul E. Lemanski, MD, MS, FACP (plemanski3@gmail.com) is a board-certified internist practicing internal medicine and lifestyle medicine in Albany. Paul has a master’s degree in human nutrition, he’s an assistant clinical professor of medicine at Albany Medical College, and a fellow of the American College of Physicians.