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Nanopollutants Harm Vessel Health

Thinking of going for a training ride when the air pollution is high? Slathering on titanium dioxide sunscreen for your skin health?

Science News (March 11-15, page 18) reports that nanoparticles can impair small blood vessel function. See also Nano Hazards: Exposure to minute particles harms lungs, circulatory system and Exhaust fumes might threaten people's hearts, and more.

These finding are directly relevant to cyclists, or any athlete, and to your health in general. Perhaps these findings dovetail with the increased incidence of asthma near polluted roads and seaports.

One could easily infer that training, especially intensive training, is a Bad Idea in polluted air. My understanding is that diesel exhaust produces particles in the 10 nm range, definitely a nano particle size. I am rarely in favor of government regulation, but I would love to see diesel engines lacking particle traps banned completely.

I’ve long been both suspicious of and disliked sunscreens with titanium dioxide; it permanently stains my leather car seats or anything similar, and generally makes a mess on anything it touches (e.g., a camera). Titanium dioxide is a nanoparticle.

Excerpts:

Vessels called arterioles don’t dilate or constrict appropriately after recent nanoparticle exposure. The changes are small “but equate to a level of impairment that would preclude affected tissues from functioning normally,” says microvascular physiologist Timothy Nurkiewicz of West Virginia University in Morgantown.

...

In one set of tests, physiologist Travis Knuckles of West Virginia University exposed rats to airborne titanium dioxide nanoparticles — spheres 100 billionths of a meter across — for four hours on two consecutive days. The common material appears in a range of materials, including sunscreen and cosmetics.

Twenty-four hours after the second day’s exposure, Knuckles stimulated the animals’ muscles to contract. This triggers arteriole dilation, increasing blood flow. But compared to changes witnessed in rats that had breathed only clean air, vessel dilation in those that had inhaled nanoparticles was impaired.

This diminished vessel relaxation is similar to what elicits a muscle cramp, chest pain in the heart or transient stroke in the brain...

Moreover, the findings showed that vessel impairments did not require lung exposures: In these experiments, ingested nanotubes produced the most dramatic change in arteriole reactivity.

...

toxic immune responses to other nanoparticles.

DIGLLOYD: seems like a good plan to avoid air pollution, exhaust (especially diesel) and titanium dioxide sunscreens. And to be deeply suspicious of any new medicines delivered with nanoparticle carriers; as far as I know nanoparticles are not recognized as something worthy of being tested for health risks.

“Four hours on two consecutive days”— how about 2-3 hours every day for many months, as in a human riding a bike in polluted air?

It would not surprise me if the negative health effects extended well beyond simple impairment of blood vessel function; subtle side effects could also be at play, perhaps mostly short-term, but perhaps also long term and accumulative degradation, a slow downhill slope from which there is no ascent.

Good clean air in the Sierra makes for wonderful riding
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