Microplastic Inhalation and Potential Risk To Respiratory Health

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By Rachel Jordan

The impacts of microplastic inhalation on our health are becoming a significant concern due to the mounting evidence that people living in urban areas may be inhaling microplastics throughout their daily lives. Previous studies have indicated a potential link between microplastics and respiratory illness, but there is a lack of research exploring the specific health effects of microplastic inhalation or what the major sources of microplastics are outside of occupational exposures. Comparisons can be drawn between asbestos particle exposure and microplastic exposure, although significantly more research has been pursued on the link between respiratory disease and asbestos. Until further research is conducted, prevention measures cannot effectively be employed to avoid the development of microplastic caused respiratory illness among urban populations. 

Microplastics are robust, small particles with diameters of less than 5 millimeters that occur in a wide range of shapes and chemical compositions formed through the degradation of macroplastic waste (Vethaak and Legler, 2021). By 2050, due to the high concentration of global plastic consumption, if unchecked, 12 billion metric tons of plastic will be deposited in landfills or the natural environment compared to 4.9 billion metric tons in 2015. 

High levels of plastic waste could pose a significant threat to human health, because the diameter of most microplastics are small enough to move into the human respiratory system, potentially causing respiratory issues (Cox, et al., 2019). According to Greenpeace, microplastics are small enough to travel through the wind or water cycles and enter the atmosphere. The water and wind cycles circulate the microplastics through the stratosphere and the oceans, not only becoming capable of being inhaled by humans but also placing the health of marine life at risk. Scientists speculate that due to the robust nature of microplastics, the deposited particles could remain in the respiratory system for extended periods. The microplastic deposits inside the lungs could cause serious respiratory illnesses, but scientists are unsure as to how long it takes for the plastics to degrade inside the respiratory tract or what the specific health effects could be. Compared to asbestos particles, which have been known to cause significant health effects such as lung cancer when inhaled, the effects of microplastic exposure are unknown.

Historically, textile workers who handle microplastics have reported symptoms of respiratory illness such as coughing and shortness of breath, indicating a possible relationship between the inhalation of plastic particles and respiratory illness (Plastic Soup Foundation, 2019), but until 2022 there was not enough evidence to confirm the relationship. According to the 2022 study of lung tissue samples, microplastics were found in 11 of the 13 lung samples. Because the research was not performed at an occupational level like, in past studies, the microplastics found in the lung tissue samples may not have all been work-related and could have been the result of other environmental exposures throughout the participants’ daily lives (Jenner, et al., 2022). The results of the study expanded the risk of microplastic inhalation from an isolated occupational hazard to an issue involving the general population, increasing concern about its health effects, and placing the global population at risk. In a study conducted in 2019, microplastic fibers were discovered in London’s atmospheric deposits with the number of microfibers in the deposits 20 times greater than in more remote areas. The results of the study identified a potential source of the plastic found in the 2022 lung tissue samples: urban atmospheric deposits. Due to the size of microplastics and the microplastic fibers discovered in the urban atmospheric deposits, there is mounting evidence that civilians living in cities, which constitute 56% of the world’s population, are potentially inhaling microplastics daily. By identifying a potential risk factor, living in a major city, a large portion of the population would be considered at risk for microplastic inhalation, increasing the importance of further research (Wright, et al., 2019). 

A more recent study conducted on the lungs of rats points toward a similar result. Scientists found that because of the small size of microplastic particles, direct tracheal exposure to microplastics caused disruption of the alveolar structure and disorganized arrangement of bronchial epithelium. The results of the study indicated that respiratory exposure to microplastic particles could cause injury to the lungs and could potentially lead to the development of lung disease (Lu, et al., 2022). Although the study was not conducted on humans, it can be inferred that similar effects could occur in humans who are regularly exposed to microplastic particles. 

Comparisons have been made between environmental asbestos exposure and potential environmental microplastic exposure. Asbestos exposure has been a known carcinogen and cause of certain cancers such as lung and ovarian cancer. It has also been linked to chronic lung disease asbestosis, and according to the Mayo Clinic, can cause symptoms that range from mild to severe, occurring years after exposure (Mayo Clinic, 2023). 

According to experts, no amount of asbestos exposure is safe, despite the majority of asbestos sources being microscopic asbestos in old buildings and industrial materials. Much like current known microplastic exposures, most cases of asbestos exposure occur due to occupational hazards where workers are exposed to other pollutants, such as in industrial plants. Asbestos fibers can be inhaled, or become degraded down to mineral dust which can settle in the air for up to 72 hours. Asbestos fibers can be quantified in fibers per cubic centimeter of air, and air can be tested for asbestos fiber contaminants through specific sampling methods (Minnesota Department of Health, 2022). Although research has linked asbestos and certain cancers, definitive research linking asbestos exposure and asthma has not been conducted. Some research has noted a connection between the development of bronchial asthma and asbestos particle exposure alone, however much of the research done on respiratory illness induced by asbestos has included exposure to other particle pollutants (Toyoshima, 2022).   

Similar to microplastics, if operating near industrial plants water supplies can become contaminated with asbestos and ingested. Both microplastics and asbestos particles are incredibly robust and difficult to eradicate, although  asbestos exposure has a multitude of research supporting its detrimental effects on human health, and numerous health and safety codes protecting workers and civilians from asbestos exposure. For example, protective equipment is provided for workers occupationally exposed to asbestos, as the law requires employers to protect their workers from such job-related risks (Whitmer, 2022). Unlike asbestos, due to the lack of research on microplastic exposure and inhalation, no safety regulations similar to asbestos have been advocated for. Additionally, microplastic exposure has not yet been definitively linked to respiratory illness or cancer development like asbestos has despite the increasing evidence of detrimental health impacts of environmental exposure. 

Other than research differences, asbestos fibers, and microplastics have physical differences as well. Too small to see with the naked eye, asbestos fibers can naturally occur in the form of deposits and are easily detectable due to existing asbestos detection measures. Microplastics have a much larger range of diameter, and some can be seen with the naked eye while others require a microscope. Microplastics are not naturally occurring, although they are commonly found in everyday products. 

Despite the mounting evidence that microplastic inhalation, particularly when compared to asbestos exposure, could be causing respiratory illness, little research has been done to study the health effects of microplastics. Although it is difficult to eliminate microplastic use, microplastic consumption should be decreased until additional research is conducted on its major sources and specific health effects  so that those who may already be suffering from its effects can be treated. Many major companies rely on microplastics to manufacture products used in everyday life, but when looking toward the future, renewable alternatives to plastic could be explored to avoid the degradation of plastics into microplastics. 

In addition to identifying the sources of microplastics and the specific health effects of inhalation, the population most at risk of such health effects must be identified to reduce the scope of prevention. Ideally, once more is known about the potential health impacts of microplastic inhalation, primary and secondary prevention can be effectively pursued, and preventative action can occur. 

 

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