Severity of health impact was proportional to the concentration and particle shape of microplastics
Microplastics and nanoplastics considerably impact human and animal gut microbiomes as well as the environment, noted a report by the Food and Agriculture Organization (FAO).
Though the effects of its exposure to other plastic chemicals in the gut microbiome are still unexplored, instances of alteration in the intestinal structure and the functioning of the gastrointestinal tract have been observed, FAO noted in its report Impact of Microplastics and Nanoplastics on Human Health.
After examining various literature on the topic, researchers found that exposure to plastic has led to intestinal inflammation and gut dysbiosis — changes in the gut microbiome and microbiota. The findings stood true for aquatic species and rodents as well.
Also read: Microplastics time-bomb: Why we should not reuse plastic water bottles
The findings of the study are crucial as microplastics and nano plastics are known to affect larger soil microorganisms and penetrate the entire food web.
Evidence suggests that microplastics found in water bottles and food items such as sugar, honey, sea salt, tea and others have eventually deposited in human lung tissue, placenta, stool, blood and meconium.
Microplastics (0.1 to 5 000 μm) and nanoplastics (0.001 to 0.1 μm) are ubiquitous contaminants of emerging interest due to their potential effects on the environment, animals and human health.
Their capacity to release plastic additives or adsorb, transport and release environmental contaminants (e.g. heavy metals and organic pollutants) and modify the exposure and toxicity of these contaminants have not been well studied.
Further research is required to understand how microplastic exposure or co-exposure with other chemicals affects the host and the gut microbiome.
When plastic spreads in the environment, they undergo ageing, weathering and deterioration. Such changes cause mechanical abrasion, breakage, fragmentation and photo-oxidation, which involves chemical release or adsorption, the report stated.
Plastics eventually break into different sizes and shapes and undergo changes during interactions with microorganisms and other substances in their surroundings.
Watch video: 74 tonnes of microplastics fell from the air on Auckland in 2020
Another point to note is how the plastic’s surface properties interact with the environment, whether they release chemicals or bind to other particles.
Plastics of hydrophobic nature, for instance, can adsorb hydrophobic chemicals or persistent organic pollutants from the environment (for example, polychlorinated biphenyls, polycyclic aromatic hydrocarbons and dichloro diphenyl trichloroethane), the document noted.
“The interactions between environmental contaminants and microplastics and their transfer from the environment to living organisms are complex and challenging to understand, as many factors (microorganisms, sediments, pH, etc) will influence these processes,” it added.
After examining 146 articles, the report’s authors observed that most studies depicted limited evaluations of the effect of microplastics on the gastrointestinal tract and gut microbiota.
The authors considered parameters such as accumulation of microplastic in the gut, changes in the mucus layer and gut permeability, alterations of the mucosal structure, oxidative stress and immune response.
Every study showed some level of alteration in the host to the microplastic exposure. In some instances, alterations of gene markings and biochemical markers were also observed.
Physical abrasion of microplastic and its accumulation in the gut can lead to satiety in the organism and even reduce food consumption. It may eventually lead to weight loss and metabolic changes. A few studies indicated the impact of microplastics on liver function and metabolism.
The analysis highlighted that the severity of the impact was proportional to the concentration and particle shape of microplastics. Microplastics act as stressors and cause inflammatory responses in the host, affecting certain microorganisms and resulting in microbial dysbiosis.
However, despite increasing interest in the topic, many knowledge gaps regarding micro and nano plastic consumption and its effects on gut microbiome and human health remain unfilled.
“There are questions concerning the gut microbiome’s sensitivity to chronic exposure to microplastics and low concentrations of chemical residues, and whether microbial disturbances lead to short and long-term effects on human health,” it said.
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