Can plastic harm the brain?

Plastic has become a ubiquitous feature of modern life. As a non-biodegradable material, it ends up accumulating in the environment, such that from the highest mountain peak to the deepest ocean trench, there is no place on Earth that is untouched by plastic waste [1]. Over time, plastic sheds tiny particles into the environment, which can be ingested or inhaled, leading to the accumulation of these plastic particles within our bodies. Researchers are beginning to characterize the potential health risks associated with the increasing load of plastic particles in our environment and bodies.

Plastic particles, called microplastics, have been found throughout the bodies of animals, including in the brain, following deliberate plastic exposure in laboratory settings, as well as in the context of unintentional exposure from environmental contamination [2]. Microplastics have also been detected in human tissues and biofluids. Inside bodily tissues, the plastic particles can induce an immune response, such that the inability to effectively clear the plastic can lead to a state of chronic inflammation. Extremely small particles, referred to as nanoplastics, can get inside of cells and damage cellular machinery, leading to oxidative stress. Because the plastic particles are not biodegradable, efforts by the cells to degrade the plastic internally can clog up the cell’s waste disposal systems, leading to the accumulation of other toxic substances in the cells [3].

In order for plastic starting materials to be transformed into usable objects, they are treated with thousands of chemicals [1]. Many of the chemicals have been shown to pose health risks, such as the disruption of hormones, while the safety risks for the vast majority of these chemicals have not yet been fully characterized. The risks posed by these chemicals are minimized when they are bound up in the plastics, however, the bonds between them weaken over time, resulting in the eventual leaching of these chemicals into the environment. These shed plastic particles can act as vectors to bring these chemicals into the body and promote their accumulation to potentially toxic levels. The plastic particles can also act as substrates for other toxic substances in the environment, such as pesticides, heavy metals, and pathogens, which then get carried into the body following the ingestion or inhalation of these particles.

Bioplastic, which is derived from renewable carbon sources, such as plants, has been touted as a more environmentally friendly form of plastic [4]. However, bioplastics tend to require a higher degree of chemical treatment to obtain the same structural properties as conventional plastics. They can be somewhat biodegradable, but the partially broken-down bioplastics may lead to a greater transfer of chemicals to the environment. While some forms of bioplastic appear to be largely nontoxic, other forms may have similar or worse toxicology profiles relative to conventional plastic [5].

MAJOR SOURCES OF PLASTIC PARTICLE EXPOSURE

The ingestion of plastic particles from food and drinks serves as the major source of microplastic exposure for most people [2]. The wear and tear of plastic is accelerated under conditions of stress, such as high heat [1]. As a result, the shedding of plastic particles is dramatically increased when plastic is exposed to high temperatures, such as during cooking. Some tea bags are made with plastic materials and can transfer millions of microplastic particles into a cup of hot water.

While many people turn to bottled water to avoid potential contaminants in tap water, beverages that are stored in plastic bottles can serve as sources of microplastic and chemical exposure, especially if kept at high temperatures. Water filters can potentially reduce exposure to microplastics in drinking water. However, not all water filters are designed to remove plastics, as they are generally rated for their ability to remove chemicals and heavy metals. One study found that multiple methods of filtration, such as granular activated charcoal, ion exchange, and microfiltration are required to effectively remove microplastic, and that smaller filter pore sizes allow for greater plastic removal capacity [6].

WHAT YOU CAN DO

Due to the ubiquity of plastic, it is not possible to avoid it in everyday life, however, there are ways to mitigate exposure to microplastic particles.

1. Avoid heating/cooking food or drinks using plastic containers.
2. Store food and beverages in non-plastic containers.
3. Do not store plastic water bottles in hot locations, such as outdoors or in a car.
4. Look for brands which state that their tea bags do not contain plastic.
5. Use a water filter with the capacity to remove microplastics.
6. Take caution when removing dryer lint to avoid inhaling microfibers shed from synthetic clothing.

While exposure to plastic particles cannot be eliminated completely, taking these steps can help reduce some of the health risks associated with microplastics.

 

1. Landrigan PJ, Raps H, Cropper M et al. (2023) The Minderoo-Monaco Commission on Plastics and Human Health. Annals of global health 89, 23.
2. Barceló D, Picó Y, Alfarhan AH (2023) Microplastics: Detection in human samples, cell line studies, and health impacts. Environmental toxicology and pharmacology 101, 104204.
3. Yang Q, Dai H, Cheng Y et al. (2023) Oral feeding of nanoplastics affects brain function of mice by inducing macrophage IL-1 signal in the intestine. Cell reports 42, 112346.
4. Venâncio C, Lopes I, Oliveira M (2022) Bioplastics: known effects and potential consequences to marine and estuarine ecosystem services. Chemosphere 309, 136810.
5. Zimmermann L, Dombrowski A, Völker C et al. (2020) Are bioplastics and plant-based materials safer than conventional plastics? In vitro toxicity and chemical composition. Environment international 145, 106066.
6. Cherian AG, Liu Z, McKie MJ et al. (2023) Microplastic Removal from Drinking Water Using Point-of-Use Devices. Polymers 15.

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