PET bottle nanoplastics may harm gut bacteria and human cells: New study
Lab-made PET bottle nanoplastics were found to weaken probiotic bacteria and trigger stress and inflammation markers in human and blood cells, raising fresh safety questions
 "PET bottle nanoplastics may harm gut bacteria and human cells: New study")
Researchers in India have found that nanoplastics released from everyday PET (polyethylene terephthalate) water bottles can harm beneficial gut bacteria and even damage human cells.
Published in Nanoscale Advances, the research titled Nanoplastics from single-use polyethylene terephthalate bottles impair the functionality of human gut-dwelling Lactobacillus rhamnosus and induce toxicity in human cells recreated these tiny plastic particles in the lab and tested them on gut microbes, red blood cells and human epithelial cells. The results showed reduced probiotic function, signs of cellular stress, inflammation and even DNA damage.
According to the research team at the Institute of Nano Science and Technology (INST), Mohali, these particles were between 50 and 850 nanometres, closely resembling the fragments now found in food, water and even human tissues.
How do these nanoplastics affect good gut bacteria?
According to the study, after 16 days of exposure, the researchers found:
- Reduced growth and survival of gut microbes (Lactobacillus rhamnosus)
- Damage to bacterial membranes, seen through microscopy
- Disturbed metabolism, including altered energy use and amino acid balance
- Weakened antioxidant capacity
- Lower ability to adhere to colon cells, crucial for colonisation
- Reduced ability to fight harmful bacteria like Pseudomonas aeruginosa
- Increased sensitivity to antibiotics, meaning the probiotics became easier to kill
According to doctors, gut microbes regulate everything from immunity and metabolism to mood and inflammation. When beneficial bacteria are weakened, especially in their ability to colonise the gut, resist stress and fight pathogens, the internal ecosystem becomes more vulnerable.
Can nanoplastics affect blood cells too?
When red blood cells were exposed to higher concentrations of nanoplastics, the study observed:
- Membrane disruption
- Shape deformities
- Signs of haemolysis (rupturing of red blood cells)
Even though effects were mild at lower doses, the findings highlight that once nanoplastics enter the bloodstream, they can mechanically and chemically disturb red blood cells, compromising oxygen transport and blood stability
What happens when human cells encounter nanoplastics?
Human epithelial cells that help protect organs showed significant changes during long-term exposure:
- DNA damage, especially at higher concentrations
- Activation of stress and apoptosis (cell death) pathways
- Surges in inflammatory markers like TNF-α and IL-6
- Oxidative stress, reflected in elevated NRF-2 and HO-1 expression
- Shifts in energy and nutrient metabolism, including glucose pathways and amino acid utilisation
- Collectively, these signals point to a cell under distress, fighting oxidative imbalance, DNA injury and inflammation.
Where do these nanoplastics come from in everyday life?
PET bottles are constantly subjected to:
- Sunlight
- Heat
- Repeated opening and closing
- Reuse beyond intended limits
All these can accelerate fragmentation. Environmental samples already show nanoplastics in drinking water, bottled beverages, marine foods, cooking salt, fruits, vegetables and even human blood and placenta.
The new study highlights that once inside the body, these particles are biologically active, not inert. They can interact with biological systems in subtle yet significant ways.
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