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Image result for household dust Ten chemicals suspected or known to harm human health are present in more than 90% of U.S. household dust samples, according to a new study. The research adds to a growing body of evidence showing the dangers posed by exposure to chemicals we are exposed to on a daily basis. The chemicals come from a variety of household goods, including toys, cosmetics, personal care products, furniture, electronics, nonstick cookware, food packaging, floor coverings, some clothing (e.g., stain resistant), building materials, and cleaning products. How do the chemicals get into the dust? The chemicals can leach, migrate, abrade, or off-gas from the products, which winds up in the dust and  results in human exposure. (That's right:  vacuum a lot and wash your hands a lot, and try to avoid or cut  back use of products with these chemicals,)

What was found in the dust? The main chemicals were: phthalates — a group of chemicals that includes DEP, DEHP, DNBP and DIBP (these were present in the highest concentrations),  highly fluorinated chemicals (HFCs), flame retardants (both old and newer replacement ones), synthetic fragrances, and phenols. These chemicals are known to have various adverse health effects, including endocrine disruption, cancer, neurological, immune, and developmental effects. (See posts on endocrine disruptors and flame retardants) Studies typically study one chemical at a time, but household dust contains MIXTURES of these chemicals with effects unknown. How does it get into us? Inhalation, ingestion, and through skin contact. And while the levels we are exposed to may be low, research is showing that even low level exposure can have adverse health effects. From Medical Xpress:

Potentially harmful chemicals widespread in household dust

Household dust exposes people to a wide range of toxic chemicals from everyday products, according to a study led by researchers at Milken Institute School of Public Health at the George Washington University. The multi-institutional team conducted a first-of-a-kind meta-analysis, compiling data from dust samples collected throughout the United States to identify the top ten toxic chemicals commonly found in dust. They found that DEHP, a chemical belonging to a hazardous class called phthalates, was number one on that list. In addition, the researchers found that phthalates overall were found at the highest levels in dust followed by phenols and flame retardant chemicals....."The findings suggest that people, and especially children, are exposed on a daily basis to multiple chemicals in dust that are linked to serious health problems."

Chemicals from consumer products are released into the air and get into dust, which can settle on household items or on the floor. People can inhale or ingest small particles of dust or even absorb them through the skin. Infants and young children are particularly at risk for exposure to the chemicals found in dust because they crawl, play on dusty floors, and put their hands in their mouths, the authors say.

Zota and colleagues pooled data from 26 peer-reviewed papers and one unpublished dataset that analyzed dust samples taken from homes in 14 states. They found 45 potentially toxic chemicals that are used in many consumer and household products such as vinyl flooring, personal care and cleaning products, building materials and home furnishings. The meta-analysis combines information from smaller dust studies and thus offers solid conclusions with greater statistical power, the authors say. The team found that:

  • Ten harmful chemicals are found in ninety percent of the dust samples across multiple studies, including a known cancer-causing agent called TDCIPP. This flame retardant is frequently found in furniture, baby products and other household items.
  • Indoor dust consistently contains four classes of harmful chemicals in high amounts. Phthalates, substances that are used to make cosmetics, toys, vinyl flooring, and other products, were found in the highest concentration with a mean of 7,682 nanograms per gram of dust-an amount that was several orders of magnitude above the others. Phenols, chemicals used in cleaning products and other household items, were the number two highest chemical class followed by flame retardants and highly fluorinated chemicals used to make non-stick cookware.
  • Chemicals from dust are likely to get into young children's bodies. A flame retardant added to couches, baby products, electronics and other products, TCEP, had the highest estimated intake followed by four phthalates—DEP, DEHP, BBzP and DnBP. The intake numbers in this study probably underestimate the true exposure to such chemicals, which are also found in products on the drug store shelf and even in fast food the authors say.
  • Phthalates such as DEP, DEHP, DNBP, and DIBP, are not only found at the highest concentrations in dust but are associated with many serious health hazards. Phthalates are thought to interfere with hormones in the body and are linked to a wide range of health issues including declines in IQ and respiratory problems in children.
  • Highly fluorinated chemicals such as PFOA and PFOS are also high on the potential harm scale. These types of chemicals, which are found in cell phones, pizza boxes, and many non-stick, waterproof and stain-resistant products have been linked to numerous health problems of the immune, digestive, developmental and endocrine systems.
  • Small amounts can add up. Many of the chemicals in dust are linked to the same health hazards, such as cancer or developmental and reproductive toxicity, and may be acting together. Exposure to even small amounts of chemicals in combination can lead to an amplified health risk, especially for developing infants or young children, the authors say.

In the meantime, consumers who want to reduce their exposure to chemicals in household dust and the environment around them can take a few simple steps such as keeping dust levels low by using a strong vacuum with a HEPA filter; washing hands frequently; and avoiding personal care and household products that contain potentially dangerous chemicals.

From the original study in Environmental Science and Technology: Consumer Product Chemicals in Indoor Dust: A Quantitative Meta-analysis of U.S. Studies

Indoor dust is a reservoir for commercial consumer product chemicals, including many compounds with known or suspected health effects. However, most dust exposure studies measure few chemicals in small samples. We systematically searched the U.S. indoor dust literature on phthalates, replacement flame retardants (RFRs), perfluoroalkyl substances (PFASs), synthetic fragrances, and environmental phenols and estimated pooled geometric means (GMs) and 95% confidence intervals for 45 chemicals measured in ≥3 data sets. In order to rank and contextualize these results, we used the pooled GMs to calculate residential intake from dust ingestion, inhalation, and dermal uptake from air, and then identified hazard traits from the Safer Consumer Products Candidate Chemical List. Our results indicate that U.S. indoor dust consistently contains chemicals from multiple classes. Phthalates occurred in the highest concentrations, followed by phenols, RFRs, fragrance, and PFASs. Several phthalates and RFRs had the highest residential intakes. We also found that many chemicals in dust share hazard traits such as reproductive and endocrine toxicity

People in developed countries spend more than 90% of their time in indoor environments, creating an important link between indoor environmental quality and public health. Consumer products and building materials including furniture, electronics, personal care and cleaning products, and floor and wall coverings contain chemicals that can leach, migrate, abrade, or off-gas from products resulting in human exposure. Consequently, chemicals such as phthalates, phenols, flame retardants, and polyfluorinated alkyl substances (PFASs) are widely detected in the U.S. general population, including vulnerable populations such as pregnant women and children. Exposure to one or more of these chemical classes has been associated with adverse health effects including reproductive toxicity, endocrine disruption, cognitive and behavioral impairment in children, cancer, asthma, immune dysfunction, and chronic disease.

Nice update from a large crowd sourced study I posted about September 1, 2015. Main finding: all our homes are teaming with microorganisms, which vary according to sex of occupants, pets, geographical location and humidity. In total, the indoor dust contained more than sixty-three thousand species of fungi and a hundred and sixteen thousand species of bacteria. The scientists have posted it all online and members of the public can download the complete data set and hunt for new correlations and patterns. Just remember that all these microbes in our lives is completely normal, and many species are important partners in maintaining our health. From New Yorker:

Our Dust, Ourselves

Dust talks. That clump of gray fuzz hiding under the couch may look dull, but it contains multitudes: tiny errant crumbs of toast, microscopic fibres from a winter coat, fragments of dead leaves, dog dander, sidewalk grit, sloughed-off skin cells, grime-loving bacteria. “Each bit of dust is a microhistory of your life,” Rob Dunn, a biologist at North Carolina State University, told me recently. For the past four years, Dunn and two of his colleagues—Noah Fierer, a microbial ecologist at the University of Colorado Boulder, and Holly Menninger, the director of public science at N.C. State—have been deciphering these histories, investigating the microorganisms in our dust and how their lives are intertwined with our own.

The scientists began with a small pilot study, recruiting forty families in the Raleigh-Durham area to swab nine locations in their homes. When the researchers analyzed these cotton swabs and sequenced the fragments of bacterial DNA that they contained, they found that even the most sparkling houses were teeming with microbial squatters—more than two thousand distinct types, on average. Different rooms formed distinct ecological niches: kitchens were popular among the bacteria that grow on produce, whereas bedroom and bathroom surfaces were colonized by those that typically dwell on the skin. (In a troubling discovery, Dunn and his colleagues learned that, from a microbiological perspective, toilet seats and pillowcases look strikingly similar.)

In many ways, these findings were predictable. What the researchers had some difficulty making sense of was the variation that they observed between homes. “What, really, is determining what lives in your house versus my house?” Dunn asked. To answer that question, they expanded the study to a larger, more diverse set of homes—about eleven hundred in total, from across the continental United States—and asked volunteers to swab the trim around their interior doorways. “We focussed on that because nobody ever cleans it,” Fierer told me. “Or we don’t clean it very often—maybe you’re an exception.” (I am not.) To provide a point of comparison, each volunteer also collected dust from an exterior door and then mailed the samples to Fierer’s Colorado lab.

Fierer and his team isolated, amplified, and sequenced the DNA that was present in each sample, listing the types of bacteria and fungi that they found. The list soon grew long. “The diversity was just crazy,” Dunn said. In total, the indoor dust contained more than sixty-three thousand species of fungi and a hundred and sixteen thousand species of bacteria. For the fungi, location was king. Houses in eastern states had different fungal communities than those in western ones. Ditto homes in humid climates compared with those in dry ones. In fact, the geographic correlation was so strong that Dunn and Fierer have since shown, in a separate paper, that they can use fungal DNA to determine, to within about a hundred and fifty miles, where in the United States a dust sample originated. 

Bacterial communities, on the other hand, were shaped less by a home’s location than by its occupants. “We’re really the dominant sources—us and our pets are the dominant sources—of bacteria inside homes,” Fierer said. The fur factor loomed especially large. Dogs introduced unique drool and fecal microbes into a home and tracked in soil dwellers from outside. Cats also changed a home’s microbial makeup, but more modestly, perhaps because they are smaller and venture outside less often. By analyzing the bacterial DNA in dust, the researchers were able to predict whether a home contained a dog with ninety-two-per-cent accuracy and a cat with eighty-three-per-cent accuracy.

The sex of a home’s human occupants also played a role in shaping the indoor ecosystem. Lactobacillus bacteria, which are a major component of the vaginal microbiome, were most abundant in homes in which women outnumbered men. When men were in the majority, however, different bacteria thrived: Roseburia, which normally lives in the gut, and Corynebacterium and Dermabacter, which both inhabit the skin. Corynebacterium is known to occupy the armpit and contribute to body odor. 

Most of our microscopic roommates are unlikely to present a real threat; many species of bacteria, scientists now know, are crucial partners in maintaining our health. “We’re surrounded by microbes all the time, and that’s not a bad thing,” Fierer said.

 Another article from results of the crowdsourced study in which household dust samples were sent to researchers at the University of Colorado from approximately 1200 homes across the United States. Some findings after the dust was analyzed: differences were found in the dust of households that were occupied by more males than females and vice versa, indoor fungi mainly comes from the outside and varies with the geographical location of the house, bacteria is determined by the house's inhabitants (people, pets, and insects), clothes do not prevent the spread of bacteria from our bodies, and dogs and cats had a dramatic influence on bacteria in the home. In other words: where you live determines the fungi in the house and who you live with determines the bacteria in the house. From Discovery News:

Household Dust Packed With Thousands of Microbes

Household dust is full of living organisms that are determined, in large part, by where the home is located and who is living in it, finds a new study that includes some surprising revelations. Homes with a greater ratio of male occupants, for example, were found to contain large amounts of skin and fecal-associated bacteria, while women-dominated households contained an abundance of vaginally shed bacteria that somehow wound up in dust.

He and his colleagues used DNA sequencing and high tech imaging to analyze dust samples from approximately 1,200 homes across the United States. They used volunteers to help collect the material. They discovered that indoor fungi mostly originates outside of the home, such that the geographical location of any home strongly predicts the types of fungi existing within dust.“If you want to change the types of fungi you are exposed to in your home, then it is best to move to a different home, preferably one far away,” Fierer and his team said.

Bacteria, on the other hand, were largely predicted by the home’s possible inhabitants, including humans, pets and even insects. Fierer said, “Our bodies are clearly the source for many bacteria that end up in our homes.” The researchers suspect that body size, relative abundance, and hygiene practices are why men tend to shed more Corynebacterium and Dermabacter (the skin-associated species), as well as the poop-associated Roseburia.

The vaginal-linked bacteria Lactobacillus, discovered in homes with a larger ratio of women, provides evidence that clothes do not fully contain the spread of microorganisms produced by our bodies. Members of this genus are actually thought to protect against allergies and asthma, based on earlier research, but further studies are needed to confirm how this, and other bacteria found in dust, impact human health.

Dogs and cats had such a dramatic effect on dust bacterial communities that the researchers could predict, with around 92 percent accuracy, whether or not such animals were in the home, just based on bacteria alone....So far, the news is good for dog lovers, as he pointed out that “previous work conducted by other groups has shown that living with a dog at a young age can actually reduce allergies.”