A significant study from the University of Cambridge finds that everyday pesticides and industrial chemicals can kill beneficial gut bacteria, potentially harming digestion, immunity, and overall health
A new lab study has revealed that many pesticides and common industrial chemicals widely used in farming and consumer products are toxic to the “good” bacteria essential for a healthy human gut. Testing over 1,000 chemicals on 22 species of gut microbes, researchers identified 168 that hamper bacterial growth, with some even triggering antibiotic resistance.
The findings raise serious concerns about how routine exposure to environmental and food-based chemicals may affect digestion, immune function, and long-term health worldwide.
Identifying 168 chemicals toxic to the gut
The researchers tested the effect of 1076 chemical contaminants on 22 species of gut bacteria in the lab. These chemicals include pesticides and insecticides sprayed on food crops, as well as industrial chemicals used in flame retardants and plastics.
The researchers identified 168 chemicals that are toxic to healthy human gut bacteria. Most of these chemicals likely enter the body through water, food, and environmental exposure and were previously not suspected of affecting gut health.
As gut bacteria adapt to resist chemicals, this can also lead to antibiotic resistance to certain medications. This makes infections more challenging to treat.
Limited knowledge on environmental chemicals affects our gut microbiome
The human gut microbiome comprises around 4,500 distinct bacterial species. When it is knocked out of balance, it can have wide-ranging effects on our health, including obesity and digestive problems.
Currently, standard chemical safety assessments do not consider the human gut microbiome because chemicals are formulated to act on specific targets.
The researchers used this data to create a machine learning model that accurately predicts whether industrial chemicals, already in use or in development, will harm human gut bacteria. This tool could inform regulatory assessments and guide safer chemical development, making it highly relevant for policymakers and scientists aiming to prevent adverse health outcomes.
There is limited information on how environmental chemicals affect our gut microbiome, and although our gut is likely exposed to these chemicals, the exact concentrations that reach it remain unknown. This uncertainty underscores the need for further research to better understand exposure levels and potential health risks, which is important for health professionals and policymakers working on safety standards.
Dr Indra Roux, a researcher at the University of Cambridge’s MRC Toxicology Unit and first author of the study, said: “We’ve found that many chemicals designed to act only on one type of target, say insects or fungi, also affect gut bacteria. We were surprised that some of these chemicals had such strong effects. For example, many industrial chemicals like flame retardants and plasticisers – that we are regularly in contact with – weren’t thought to affect living organisms at all, but they do.”
Professor Kiran Patil, in the University of Cambridge’s MRC Toxicology Unit and senior author of the study, said: “The real power of this large-scale study is that we now have the data to predict the effects of new chemicals, with the aim of moving to a future where new chemicals are safe by design.”
Dr Stephan Kamrad at the University of Cambridge’s MRC Toxicology Unit, who was also involved in the study, said: “Safety assessments of new chemicals for human use must ensure they are also safe for our gut bacteria, which could be exposed to the chemicals through our food and water.”
