There's no great mystery as to why lead and arsenic have been found in such great abundance amongst the ashes spread by California wildfires. Until just a few years ago, pressure treated wood sold for use in decks, railings, fences, wooden playground structures, and foundation sills was highly impregnated with "CCA" - the common term for a wicked brew of Chrome, Copper, and Arsenic salts. If large volumes of CCA-treated wood burned up, it easily accounts for much of the culturally introduced arsenic amongst the ashes.
Ash from wildfires in Southern California's residential neighborhoods poses a serious threat to people and ecosystems because it is extremely caustic and contains high levels of arsenic, lead and other toxic metals, according to a study by federal geologists released Tuesday.
U.S. Geological Survey scientists warned that rainstorms, which are forecast for the region beginning Friday, are likely to wash the dangerous substances into waterways, polluting streams and threatening wildlife.
Some ash collected in residential areas after the October fires registered a pH of 12.7, a level more caustic than ammonia and nearly as caustic as lye.
Metals, particularly arsenic, were found in such high concentrations in the ash that they would violate federal standards for cleaning up hazardous waste sites. Metals could have come from treated wood in decks, old lead-based paint, plumbing solder and other household substances.
What about the lead you ask? Vinyl products spec'd to perform in electrical applications like junction boxes may contain large amounts of lead stabilizer.
More importantly, you have your vinyl garden hoses, the nice Chinese-made toys we've all been hearing about from the budget deprived Consumer Products Safety Commission, and miles of plastic fencing, all of which may potentially have included large amounts of lead compound as a "stabilizer." These too went up in flames. And then, as the LA Times points out, there is the matter of lead-based paint on older structures.
Odd, though, that no media stories we've seen or heard got at the fact the lead is commonly added to plastic in China. It's one thing to test the surface of an object to decide if its safe for kids to play with. Quite another to think of the consequences of fire with such products.
Regardless of the lead's origin, is the ash fall a significant source of exposure for children? Is waiting for the rain really a way to mitigate that exposure? This is sounding more ground-zero like than it should. Does Cal EPA have an opinion about whether the heavy metal exposure is a serious concern or not?
Next in line: marine filter feeders. Abalone anyone?
As a matter of public safety, we wonder of contemplated revisions to building codes will take this after-effect into consideration?
Points of clarification: Chinese vinyl products commonly have lead added, whereas vinyl products made elsewhere tend not to have it, with the possible exception of electrical fixtures.
We don't know where all that ghastly looking white vinyl fencing and decking one now sees in the suburbs was made, or what the stabilizers generally are.
Finally, vinyl siding generally uses titanium dioxide as a stabilizer - not lead.
Via::Los Angeles Times, "Wildfires leave caustic ash, study finds" Image credit::Ken Hively / Los Angeles Times