In the last week, my son fell down the steps and broke his foot and my hot water tank failed, flooding my basement and ruining the floor of my professional offices. This, as you can imagine, has put me into a pretty bad mood and since misery loves company, I figured I’d write depressing posts this week so you can all commiserate. So on Tuesday I told you all about how bad food is correlated with specific species of inflammatory bacteria and inflammatory metabolic pathways. Today I’ll tell you all about the relationship between household chemicals and adverse changes to the biomes of children.[i]
The research was conducted by scientists at Washington State University. They measured the levels of ubiquitous chemicals in the blood and urine of 69 toddlers and preschool-aged children, as well as analyzed the fungi and bacteria in their stools. The chemicals they specifically looked at were called semivolatile organic compounds (SVOCs), which includes phthalates – which are found in detergents, plastic clothing (like raincoats), shower curtains, shampoos, soaps, hair sprays. They also looked at polyfluoroalkyl substances (PFASs), which are used in stain- and water-repellent fabrics, carpets, furniture, non-stick cooking products, paints and cleaning products. In other words – these chemicals are everywhere and we are all exposed to them in the air and dust of our homes: “…SVOCs and their metabolites have been consistently measured in biological samples at concentrations spanning several orders of magnitude, and research suggests that the indoor environment is a significant source of human exposure to SVOCs.” Children are especially vulnerable to exposure because they spend much more time on the floor, crawling and playing, as well as putting things into their mouths. There is no real research on the long-term exposure to these chemicals.
Their results are not hugely surprising really. The higher the levels of chemicals in the bloodstreams of the children, the greater the differences in their microbiomes. High levels of PFASs was associated with reduced diversity and overall amount of bacteria. Increased levels of phthalates reduced the mycobiome (fungi) population. These changes were highly statistically significant and, as the lead researchers says, extremely concerning. The main bacteria and yeasts of the gut were not affected; the changes were seen more in the less abundant species: “Less abundant taxa like Thermogemmatisporales, Stigonematales, and Legionellales, which play critical and beneficial roles in the assimilation of nutrients in omnivores were strongly linked to PFASs. Thus, alterations to gut microbiome structure and function may be felt most by taxa that play more subtle roles rather than those thought to be large drivers of host health…”
Another finding: the children with the high levels of chemicals in their blood also had high levels of different kinds of bacteria that are used to clean up toxic chemicals. For example, the children had measurable levels of a bacteria used to clean dry cleaning solvents from the environment, which are not typically found in humans. The scientists believe that the presence of these kinds of bacteria is a sign that the gut biome is trying to correct itself.
Their conclusion: “Gaining a more holistic understanding of the interactions among anthropogenic chemicals, the gut microbiome, and human health is a critical step in advancing public health.” Yeah, I’d say so.
________________________ [i] Gardner, CM, Hoffman, K, Stapleton, HM, and Gunsch, CK. Exposures to Semivolatile Organic Compounds in Indoor Environments and Associations with the Gut Microbiomes of Children. Environmental Science & Technology Letters 2021 8 (1), 73-79. DOI: 10.1021/acs.estlett.0c00776