How Dangerous Is Dust?

Household dust is teeming with hidden nasties

The Guardian reports on a major new study on pesticides in household dust.

Almost 200 different pesticides—chemicals used primarily in agriculture to kill or control anything considered threatening to crops, like insects, weeds, or rodents—were detected in household dust samples in 10 European countries.

More than 40% of the pesticides identified are considered highly toxic and linked to cancer and endocrine disruption.

Especially concerning was the presence of DDT—an insecticide widely used in the mid-20th century that was later discovered to cause significant harm to human and environmental health—even in samples taken in countries that banned it decades ago. This speaks to the often under-appreciated persistence of toxic chemical substances that regulators and the public presume are no longer with us in any meaningful sense.

The research also raises another crucial point: in some homes, as many as 121 different pesticides were detected. It’s possible, in theory, that many or all of these substances don’t represent a major threat to our health, especially at the low concentrations in which they’re generally present in our homes.

However, we know alarmingly little about the interactions between these compounds—or how harmful the chemical cocktails that result from their combination might be. And we can’t know, given that, as we saw in the case of DDT, we don’t even have a firm handle on what these cocktails actually consist of.

A pesticide could be approved for use as safe—because it is when assessed in isolation—while the harmful effects it might produce when mixing with other substances present in the environment go unnoticed.

And this applies to all hidden hazards, of course. It’s not just pesticides mingling with other pesticides that may be of concern; they’re also teaming up with PFAS, volatile organic compounds, mycotoxins, and whatever else coalesces to form the household dust we know and love.

Indeed—surprise, surprise—there’s actually a lot of research on how dust in our homes is a primary source of everyday microplastic exposure, too.

This study from a few years back found that, above offices, hotels, and other indoor environments, the dust tested in residential settings contained the highest concentration of microplastics.

Microplastics find their way into the dust that pervades our homes by shedding from clothing, furniture, paint, and carpets. We also carry them in on our shoes—the great outdoors being a carnival of microplastic contamination, exposing us via everything from car tyres and road paint to synthetic turf and plastic waste.

The good news? Uncharacteristically, this problem is a fairly easy one to keep on top of: if it wasn’t already obvious, another paper found that, unsurprisingly, the most effective way to keep microplastic-laden dust out of our systems is to frequently vacuum it up. It’s also a good idea to keep things that spend a lot of time outside (like shoes) out of the indoor spaces we use most.

Microplastics impair blood flow to the brain in mice

A new study of the effects of microplastics in mice found that plastic particles can move through blood vessels in their brains and cause build-ups and blockages.

Researchers gave the mice water containing fluorescent polystyrene and used advanced imaging techniques to watch the plastic reach their brains in real time.

They think that, essentially, the mice’s immune cells absorbed the plastic particles, causing the cells to become irregularly shaped and subsequently lodge in narrow cerebral vessels.

When a blockage occurred, cells would begin piling on top of each other like cars in a road traffic accident.

This reduction in blood circulation led to noticeable cognitive problems, with the mice exposed to the microplastic-laden water performing worse on tests of memory, movement, and coordination than unexposed mice.

Importantly, the microplastic particles didn’t have to actually enter brain tissue itself; the damage was done solely as a result of blood vessels being blocked and blood flow being impaired.

While mice aren’t people, the research could offer a clue as to how exactly microplastics cause neurological harm (adding colour to the many correlations previously made): by restricting blood supply to the brain (though this likely isn’t the only way).

PFAS in the real world: Jersey residents told to blood-let to reduce PFAS levels

A bit of backstory: in the early 1990s, firefighting foam containing PFAS chemicals was used heavily at Jersey Airport’s training ground. The PFAS leaked into private boreholes, contaminating crops and drinking water without residents knowing.

The contamination was discovered in 1993, but those living in the affected area had by that point already been using the water for years. Some of them began reporting unusually high rates of cancer, autoimmune diseases, and other health issues.

In 2005, Jersey’s government reached a secret settlement with 3M, the company that manufactured the PFAS, for £2.6 million, agreeing not to sue in exchange for clean-up money. This was only made public after a series of documents leaked a few years back.

It wasn’t until 2006—over a decade after the contamination was first discovered—that residents in the known affected area were moved onto the mains water supply.

Tests were carried out in 2022 and found that most local residents had very high levels of PFAS in their blood, with some exhibiting extremely high levels—one resident had levels 16 times higher than normal.

Fast forward to today, and an advisory panel was set up to figure out how to help residents. It recommended that, as well as taking cholesterol-lowering drugs (because PFAS exposure can raise cholesterol), those affected should undergo blood-letting—that is, repeatedly draw blood, slowly and safely, to lower the amount of PFAS-containing blood pumping through them and have their stocks of fresh blood replenished.

What’s more, this is far from an isolated incident. Just last week, it was reported that the UK Ministry of Defence was investigating three military bases in England over concerns that they may be leaching PFAS into nearby drinking-water sources and ecologically sensitive areas—for the same reason, the use of PFAS-laden firefighting foam.

The UK government is actually moving to ban PFAS in firefighting foam, but the problem won’t end there. As we know, PFAS are called ‘forever chemicals’ for a reason. A ban would only stem the tide of pollution; PFAS in the environment may persist for hundreds or even thousands of years, barring a Herculean clean-up operation.

Findings from a 20-year research project on the effects of toxic chemical exposure in children

A fascinating and arresting paper from Japan was recently published on what widespread environmental toxicity might mean for future generations of humans.

It launched in 2001 and tracked participants from birth up to age 20, looking at the prenatal and early-life impacts of environmental chemical exposure, focusing on a wide array of hidden hazards.

There’s a lot to the study, but some comments, insights, and findings that jumped out at me were:

• There are 275 million substances registered with the American Chemical Society, and thousands more are registered or updated every day.

• Exposure to dioxins (persistent toxic by-products of industrial processes), PFAS, and DEHP (a phthalate used to make plastics more flexible, found in products like medical devices, vinyl flooring, and food packaging—and historically in cosmetics and children’s toys) was associated with lower birth weight in infants.

• In boys, tests done on umbilical cord blood showed that higher levels of PFOS (a type of PFAS) or DEHP were correlated with lower markers of testosterone production—and the effect was dose-dependent, meaning that the higher the PFOS levels, the greater the effect.

• Being exposed to dioxins was also associated with poorer early years cognitive and motor development, but the effects faded a little as the kids got older. Additionally, the researchers found an association between PFAS exposure and poorer mental development (but specifically only in girls at six months).

• Weirdly, the study found that children exhibiting higher PFAS levels before birth actually went on to develop lower rates of ADHD, though this could be a fluke finding.

• The authors note that the recent development of new and more precise instruments of measurement allowed them to detect pollutants in subjects’ blood and other samples that they wouldn’t have spotted using previously available technology. This raises an interesting point: the tools we have today for detecting and measuring the presence of toxic chemicals in our bodies are as bad as they’ll ever be and will only continue becoming more refined and sensitive—so however serious the data tells us the problem is, it’s almost certainly worse than we currently believe. We just don’t yet have tools sophisticated enough to enlighten us about the full extent of the issue—but eventually, we will.

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