Household cleaners and their effect on the intestinal microbiome

Detergents and other common household chemicals greatly impact the number and type of bacteria and fungi in children's gastrointestinal tract.

Detergents and other chemical substances used daily in the household have a major impact on the number and type of bacteria and fungi in children's gastrointestinal tract. This was discovered by a research team from the Washington State University.

The microbes in the intestines, which include a variety of bacteria and fungi, affect many processes in the human body, from nutrient absorption to immunity. An unhealthy microbiome can cause diseases like obesity, asthma and dementia.

The team led by Courtney Gardner, assistant professor at the Faculty of Civil and Environmental Engineering (Washington State University, USA), measured the levels of ubiquitous semi-organic compounds in the blood and urine of 69 toddlers and pre-school children and used faecal samples to examine the children's intestinal microbiomes. They found semivolatile organic compounds such as phthalates used in detergents, plastic clothing such as mackintoshes, shower curtains and personal care products such as soap, shampoo and hairspray, as well as per- and polyfluoroalkyl substances (PFAS) used in stain and water repellents, coatings for carpets and furniture, non-stick cooking products, polishes, paints, and cleaning products. People are exposed to such chemicals in the air and dust in their homes every day, especially young children who absorb these chemicals by crawling on carpets or putting objects in their mouths.

Fewer fungi and bacteria

The children with higher blood levels of PFAS had fewer and less diverse bacteria in their bowel, and with higher phthalate levels there were fewer fungal populations. The correlation between the chemicals and less common bacterial organisms is particularly strong and potentially of particular concern, says Gardner. "These microbes may not be the main drivers and may have more subtle roles in our biology, but it could be the case that one of these microbes has a unique function, and a reduction in their numbers can have significant health effects," Gardner added.

Children who had high levels of chemical compounds in their blood also had several types of bacteria in their intestines that were used to cleanse toxic chemicals. Dehalogenating bacteria were used for bioremediation to remove persistent halogenated chemicals such as solvents for dry cleaning from the environment. These bacteria are not typically found in the human gut. "Finding elevated concentrations of this type of bacteria in the gut means that the gut microbiome may be trying to correct itself," Gardner explained.

Gardner hopes to use the information gained from the study to develop a diagnostic tool for humans and perhaps future probiotic interventions to improve health outcomes. "Although these data do not show causal links, they do provide an indication of the types of organisms that can be affected by exposure to these compounds and provide a springboard for future research," she said, "Achieving a more holistic understanding of the interactions between man-made chemicals, the intestinal microbiome and human health is a crucial step in promoting public health".