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Paul D. Blanc M.D., M.S.P.H.
Paul D. Blanc M.D., M.S.P.H.
Environment

At Home in Your Vehicle

Toxic Hazards Take a Ride

The “house” in “household hazards” depends on where you spend your time. And, as the venue changes, so too can its potential hazards.

Many folks spend so much time commuting that their vehicle is tantamount to a second home. And for the marginally housed, a car or van may be the only home they have. Despite these realities, there is very little written about the toxicants that can be present inside an automobile or in the cab of a truck.

One vehicular hazard that commonly does get attention is the carbon monoxide in automobile exhaust. The dominant scenario for severe automobile carbon monoxide poisoning is deliberate exposure as a means of suicide. Nonetheless, serious and even fatal exposures can occur unintentionally, such as was described a number of years ago in “A curious autopsy case of accidental carbon monoxide poisoning in a motor vehicle.” That report described an unfortunate young man who was killed when the deadly gas leaked into his car. It came out of a rusted away exhaust pipe and then went up through holes in the floor of the car.

Although less widely appreciated, windshield wiper fluid is another potential source of toxicity inside a motor vehicle. The primary chemical hazard of concern is methanol, commonly known as wood alcohol. When ingested, typically as an ethanol substitute, methanol is very effectively lethal, first causing blindness along the way. Breathing in methanol fumes can also be hazardous, even though not as efficiently poisonous as drinking the stuff. Moreover, methanol in windshield wiping fluid can track into the passenger compartment, seeping in while as slappin’ time. The most recent scientific study on this subject that I could find was published a decade ago. Remarkably, it found levels as high as a 1000 parts per million (which is five times higher than the legal OSHA limit for workers). There are other common chemical components of windshield fluid as well, including antifreeze (ethylene glycol) and rubbing alcohol (isopropyl). We do not know if or how much of that is coming in.

A study just released earlier this year examined all cases of poisoning from windshield washer fluid reported over four years to poison control centers in the United Kingdom. Over there, they call it “screenwash,” which may sound more genteel but doesn’t mitigate the problem. Granted, most of the 255 odd cases tallied were not too serious and most were from ingestions (one in four among children – methanol-laced windshield washer fluid being one of the most common accidental sources of access to this poison). Nonetheless, there were cases of inhalation in which “the patients had been exposed to screenwash as it had leaked out of the container whilst in the vehicle boot-space or on the car back seat.”

One fix for the windshield wiper fluid problem would be to eliminate methanol in the mix, something that the European Community is doing (the UK will have to refigure that one out on its own, post-Brexit). The California Air Resources Board (known as CARB) has partially restricted such formulations on air pollution grounds (its still ok to use in California snow country and, anyway, the limitation only applies to premixed solutions not concentrates you mix on your own). Still and all, CARB does take windshield wiper fluid seriously. Back in 2014, it levied a hefty fine against a trucking company that deliberately violated the rules, inflaming the trucking community. As one irate follower of The Truckers Report website posted in response to the story, “And Global Warming is a big pile of crap too, look at the winter we had and all the snow in the Arctic. Then look up geo engineering and the effect it will have on the earth, again the government passing the buck blaming emissions for destroying the planet. Only to waste the tax payers money, because global warming dosnt (sic) exist.”

Using plain water in the windshield reservoir, however, may have its own drawbacks. Another study out of the UK found that those who had ridden in automobiles that did not have added chemical screenwash had nearly 50 times greater odds of contacting Legionnaires’ disease. Seems the stuff is good at poisoning bacteria, whatever it does to humans.

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About the Author
Paul D. Blanc M.D., M.S.P.H.

Paul D. Blanc, M.D., M.S.P.H., is a professor of medicine and the endowed chair in Occupational and Environmental Medicine at the University of California San Francisco.

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