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 July 13, 2017
Could house dust make us fat?

 A new study indicates that exposure to endocrine-disrupting chemicals present in house dust may disrupt metabolic health and trigger an increase in body fat, particularly for children.

Researchers from Duke University in Durham, NC, exposed mouse-derived precursor fat cells to small amounts of house dust containing endocrine-disrupting chemicals (EDCs). This caused the fat cells to mature and acquire more fat, or triglycerides.

Study co-author Heather M. Stapleton, of the Nicholas School of the Environment at Duke University, and colleagues reported their findings today in the journal Environmental Science & Technology.

EDCs are man-made or naturally occurring chemicals that can interfere with hormone production and functioning. They are found in an array of products that we come across every day, including pesticides, cosmetics, food packaging, and household cleaning products.

Bisphenol A, phthalates, and flame retardants are among the most common EDCs that we are exposed to.

Studies have shown that exposure to EDCs can raise the risk of serious health conditions, including cancer, infertility, and neurodevelopmental disorders.

Exposure to EDCs in utero has also been linked to an increased risk of weight gain and obesity in childhood.

With this in association in mind, Stapleton and colleagues sought to investigate whether exposure to house dust - which is known to harbor EDCs - affects the growth of fat cells, or adipocytes.

House dust spurred triglyceride buildup

To reach their findings, the researchers visited 11 homes in North Carolina and collected samples of indoor dust. The house dust samples were analyzed for levels of EDCs, and the team identified a total of 44 contaminants.

Next, the researchers tested extracts of each dust sample on 3T3-L1 cells, which are precursor adipocyte cells derived from mice.

These cells are commonly used in scientific research to assess how specific compounds influence the buildup of triglycerides, a type of fat that the body stores for energy. Having too much of this fat, however, can lead to weight gain and related health complications.

The researchers found that extracts from seven of the house dust samples caused the 3T3-L1 cells to mature into adipocytes and accrue triglycerides, while extracts from nine of the house dust samples triggered cell proliferation, increasing the number of precursor fat cells.

"Only one of 11 dust samples appeared completely inactive, suggesting that the causative chemical(s) are nearly ubiquitous in the indoor environment," say the authors.

'A novel potential health threat'

The team identified three EDCs that had the greatest effects on triglyceride accumulation and 3T3-L1 cell proliferation: the pesticide pyraclostrobin, the flame retardant TBPDP, and the plasticizer DBP.

The researchers note that as little as 3 micrograms of house dust triggered fat-producing effects, which is well below the 50 milligrams of house dust the United States Environmental Protection Agency (EPA) say that children ingest, inhale, or absorb through their skin every day.

While further studies are needed to gain a better understanding of how house dust might interfere with metabolic health, the researchers believe that their findings are a cause for concern.

"The adipogenic activity in house dust occurred at concentrations below EPA estimated child exposure levels, and raises concerns for human health impacts, particularly in children," the team says, adding:

"While studies often highlight individual contaminants and classes of contaminants of concern for potential metabolic disruption, there is a critical need to more thoroughly assess realistic environmental mixtures that may be contributing to this and other adverse human health trends," the researchers conclude.