The study finds the link between children’s gut microbiomes and household chemicals

Reviewed by Emily Henderson, B.Sc.November 12, 2020

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 present in their home environment.

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

Courtney Gardner, assistant professor in Washington State University’s Department of Civil and Environmental Engineering, is the lead author of the paper, 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 become of growing interest to researchers in recent years.

Microbes in our gut, which include a wide variety of bacteria and fungi, are believed to influence many processes, from nutrient absorption to our immunity, and an unhealthy microbiome has been implicated in diseases ranging from obesity to asthma and to dementia.

In the study, the researchers measured the levels of ubiquitous semi-organic compounds in the blood and urine of 69 young and preschool children and then, using fecal samples, studied the children’s gut microbiomes.

The semivolatile organic compounds they measured included phthalates used in detergents, plastic garments such as raincoats, shower curtains and personal care products, such as soap, shampoo and hairspray, as well as per- and polyfluoroalkyl substances (PFAS), which are used in stain and water repellent fabrics, carpet and furniture coverings, non-stick kitchen products, polishes, paints and cleaning products.

People are exposed to these chemicals on a daily basis in the air and dust in their homes, especially young children who may ingest them by crawling on carpets 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 showed differences in their gut microbiome.

Children with higher levels of PFAS in their blood had a reduction in the quantity and diversity of bacteria, while an increase in phthalate levels was associated with a reduction in mushroom populations.

The correlation between the chemicals and less abundant bacterial organisms was particularly pronounced and potentially more concerning, Gardner said.

These microbes are perhaps not the main drivers and may have more subtle roles in our biology, but it may be the case that one of these microbes has a unique function and decreasing its levels could have significant health impacts.. “

Courtney Gardner, Assistant Professor, Department of Civil and Environmental Engineering, Washington State University

The researchers also found, surprisingly, that children who had high levels of chemicals in their blood also had different types of bacteria in their intestines that were used to clean up toxic chemicals.

Dishalogenated bacteria have been used for bioremediation to degrade persistent halogenated chemicals such as dry cleaning solvents from the environment. These bacteria are not typically found in the human intestine.

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

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

“While these data do not denote a causal link, 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,” he said. “Gaining a more holistic understanding of the interactions between human-made chemicals, the gut microbiome and human health is a critical step in advancing public health.”