Researchers find link between household chemicals and gut microbiome

A team of researchers has for the first time found a correlation between the levels of bacteria and fungi in the gastrointestinal tract of children and the amount of common chemicals found in their home environment.

The work, published this month in Environmental science and technology letters, could provide a better understanding of how these semi-volatile organic compounds can affect human health.

Courtney Gardner, assistant professor in the Department of Civil and Environmental Engineering at Washington State University, is the lead author of the article, which she completed as a postdoctoral researcher in collaboration with Duke University .

The gut microbiome, the community of microbes that live in our intestinal tract, has attracted increasing interest in researchers in recent years. The microbes in our gut, which include a wide variety of bacteria and fungi, are thought to affect many processes, from nutrient absorption to our immunity, and an unhealthy microbiome has been implicated in diseases ranging from obesity asthma and dementia.

In the study, researchers measured the levels of semi-organic compounds ubiquitous in the blood and urine of 69 toddlers and preschoolers, then, using fecal samples, studied the gut microbiomes of children. The semi-volatile organic compounds they measured included phthalates used in detergents, plastic clothing such as raincoats, shower curtains, and personal care products, such as soap, shampoo, and hairspray. hair, as well as per- and polyfluoroalkyl substances (PFAS), which are used in stain-resistant and water-repellent fabrics, carpet and furniture coatings, non-stick baking products, varnishes, paints and cleaning products. People are exposed to such chemicals in the air and dust in their homes on a daily basis, especially young children who might ingest them by crawling on rugs or frequently putting objects in their mouths.

When the researchers looked at the levels of fungi and bacteria in the gut, they found that children who had higher levels of chemicals in their bloodstream had differences in their gut microbiome.

Children with higher levels of PFAS in their blood had a reduction in the amount and diversity of bacteria, while increased levels of phthalates were associated with reduced populations of fungi.

The correlation between chemicals and less abundant bacterial organisms was particularly pronounced and potentially of most concern, Gardner said.

“These microbes may not be the primary drivers and may have more subtle roles in our biology, but it may be that one of these microbes has a unique function and that lowering its levels could have significant impacts. on health, ”she said.

The researchers also found, surprisingly, that children who had high levels of chemical compounds in their blood also had several types of bacteria in their gut that were used to clean up toxic chemicals. Dehalogenating bacteria have been used for the bioremediation to degrade persistent halogenated chemicals such as environmental dry cleaning solvents. These bacteria are usually not found in the human intestine.

“Finding the increased levels of this type of bacteria in the gut means that, potentially, the gut microbiome is trying to correct itself,” Gardner said.

Gardner hopes to use the information gathered from the study to develop a diagnostic tool for people and possibly future probiotic interventions to improve health outcomes.

“While these data do not indicate causation, they do offer an indication of the types of organisms that may be affected by exposure to these compounds and provide a springboard for future research,” she said. “Gaining a more holistic understanding of the interactions between man-made chemicals, the gut microbiome, and human health is a critical step in advancing public health.”