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Household dust carries many toxins, a groundbreaking new study discovers

The exposure risk is highest for children; they play on the floor, and their developing brains and bodies are especially vulnerable.

Raise your hand if you see a source of chemical poisoning in that dust that has collected behind the sofa, under the piano strings, atop the bedside pile of magazines. …

That’s what I thought. But we all ought to think again given the findings of what is claimed to be the first comprehensive assessment of how toxins shed by consumer products — plasticizers, solvents, preservatives — might make their way into our bodies via household dust.

The study, undertaken by scientists at the George Washington University, Harvard and the University of California at San Francisco, was published this morning in the journal Environmental Science & Technology. Some of its key findings:

  • Indoor dust is “a reservoir for commercial consumer product chemicals, including many compounds with known or suspected health effect”; odds are about 90 percent that any household dust sample will contain one or more of 10 known to be harmful.
  • High amounts of four harmful chemical groups — phthalates, phenols, flame retardants and highly flourinated components of nonstick coatings — are found consistently in household dust.
  • The dust presents a special, double-edged threat to small children because they play on the floor and put their dusty fingers in their mouths, and because the chemicals are thought to be especially potent in their effects on developing bodies and brains.

Much of this may seem sort of obvious, when you stop to look at it, but thus far the looking has been on the light side. As the paper notes,

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[F]ew indoor dust studies report on a broad range of consumer product chemicals. Most studies measure only one or two chemical classes, and a number emphasize legacy chemicals like PBDEs [which have been taken off the market]. Further, the small sample sizes and convenience populations used in most studies make it difficult to assess generalizability to a broader population.

Therefore, the research team undertook a meta-analysis of some 27 studies, all employing relatively current sampling (since 1999) and methods that made their findings reliable and tailored to the same research objective: measuring the chemical taint of dust gathered by vacuum cleaners from U.S. residential environments.

(Another 19 studies were considered and rejected because they aligned poorly with the main set — some measured different chemicals, some included dust from aircraft and other international sources, some did not report their data in usable ways.)

45 chemicals prove common

The team then focused on 45 chemical compounds that turned up in three or more samples across the studies to produce what lead author Ami Zota of GWU’s Milken Institute School of Public Health calls “the first comprehensive analysis of consumer product chemicals found in household dust.”

These are products most of us would never think of putting in our mouths, or letting our children put in theirs — including vinyl flooring, cleaning compounds, personal care products, building materials, electric cables and electronic equipment, upholstery and carpet.

And that caution is a good thing, too, because chemicals used to make them have been associated with such health risks as cancer, endocrine disruption and reproductive damage. Nevertheless, we’re ingesting them every day via dust in the air, in our food, on our fingers.

The National Resources Defense Council, which funded the work along with the National Institute of Environmental Health Sciences and the U.S. Department of Housing and Urban Development, noted that the phthalate compounds used in plastics manufacturing were the most ubiquitous of all the chemicals assessed and said:

This is concerning because these chemicals are associated with multiple health hazards, are linked to reproductive and developmental problems in human studies, and came out on the top of the list when we estimated kids chemical intakes.

The chemical classes found at the next highest levels in dust were environmental phenols, flame retardants and fragrances. Fluorinated chemicals were found at the lowest levels.

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A call for further research

It was beyond the reach of this paper to attempt to quantify how the levels of chemical taint in household dust might raise the incidence of this illness or that one; much work remains to be done to assess such impacts — not only of individual chemicals but of our typical exposure to many of them in combination.

There were other limits to the study as well, none of which tend to make its findings less worrisome:

  • Although the average American now spends 90 percent of his or her time indoors (!!), the study addressed dust exposure only in residential environments; the authors think it would be worthwhile to examine dust exposure in workplaces and automobiles as well.
  • The 45 chemicals considered comprise only a small portion of dust-borne chemicals, which have been shown to include “legacy chemicals, combustion byproducts, pharmaceuticals, pesticides, and metals.”
  • The studies judged amenable to this meta-analysis were taken mostly in urban areas in the east or west coastal regions of the U.S., and nobody really knows how that might have influenced the findings.

The paper ends with a call for serious investment in rigorous research to better quantify chemical exposure via dust across all indoor environments, as well as deeper inquiry into the likely health impacts.

But most of the chemicals of concern aren’t regulated to limit such exposure and aren’t likely to be controlled for that purpose anytime soon.

Which means that we’re on our own for dealing with this form of nearly unseen chemical pollution, and about the only responses available are to clean more often, maybe upgrade the filters in the vacuum cleaner and heating/cooling systems … oh, yes, and wash those hands.

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The full paper, “Consumer Product Chemicals in Indoor Dust: A Quantitative Meta-analysis of U.S. Studies,” has been made available along with other materials on the NRDC website.