Caoimhín P. Connell is a Forensic Industrial Hygienist here in Colorado with extensive credentials. He has posted on the NACHI board a number of times over the last year and a half or so, usually in threads related to mould, but his expertise cuts a wide swath.
Here’s what he has to say about aresenic…
Many toxic elements occur naturally in soils surrounding houses including copper, lead, cadmium, mercury and arsenic. Several of these elements are the so-called “heavy metals” (lead, cadmium, mercury, etc). Some of the toxic metals are not what most people would consider to be a problem (such as silver) and yet, silver is what is known as a “D-Listed” waste (indicating that it appears on the “D List” for RCRA wastes). As such, a Department of Health, such as the Mass. Department of Health will express concern for these elements in the surrounding soils.
We definitely have elevated levels of many toxic elements in many, many places in Colorado. Indeed, in Jefferson, Boulder, Park, Teller and Lake Counties in Colorado we can find native mercury and a mineral called “Coloradoite” (which is a Hg/Te amalgam). Pause for a moment and think of the California State Rock: It’s serpentine! (an asbestiform mineral - i.e. asbestos!). We also can find arsenic in homes that have been placed there on purpose such as in old yellow and red wallpapers, and wood treatments.
I was the Industrial Hygienist on a mercury clean-up project in Golden, Colo, wherein the State mandated that the remediator was required to clean-up a mercury spill to a specified level. However, the level they specific was lower than the naturally occurring mercury concentrations for the soils in the area, and I successfully challenged the Colo Dept of Health and told them we were going to ignore their clean-up level and require them to sue my client if they wanted to enforce their clean-up level. The CDOPHE backed off.
As a geochemist, we used to use a variety of indicators to look for gold- one of those indicators was the presence of arsenic-tolerant plants which would indicate the presence of high levels of arsenic in the soils; which in turn would indicate the presence of gold! In some cases, one may find extremely elevated concentrations of naturally occurring arsenic in surrounding soils. I was one of the researchers on the famous “Globeville” site in Denver - my job was to calculate the toxicity and human risk to arsenic due to the concentrations of arsenic in the soil and in local vegetables that the residents of Globeville grew in their gardens and consumed. What I found was that significant bioaccumulation of arsenic can certainly occur, and can certainly result in toxic levels in the vegetables (and soils), but can be well below those found in nature anyway.
Should an homeowner be concerned? Ever hear of Love Canal? For the most part, today’s large commercial residential communities have been required to perform environmental impact studies, which usually identify many of the potential problems. However, we have seen in Colorado entire communities that were built on massive radium and uranium deposits. Is it the Home Inspector’s responsibility to find these things? I would not want to make it so!
As far as testing goes, all the mumbo-jumbo about data quality objective and uncertainty and error, that I spew out regarding sampling for indoor moulds applies equally to testing the soils for arsenic. Sampling theory doesn’t change just because the item of interest changes; and the exact same sampling errors and decision DQOs apply to sampling a soil for arsenic as for sampling the air for moulds (of surfaces for PCBs, or pesticides, or anything else). Additionally, with regard to naturally occuring toxic elements, we get into the discussion of “total” vs. “bioavailable” (i.e., just because it is present at high concentrations (total) doesn’t mean it is in a form that the human body will adversely respond (bioavailable)).
Arsenic, like mould, occurs EVERYWHERE in virtually EVERY cubic foot of soil and in virtually EVERY cubic meter of air on the planet. So unless an Homer Inspector is willing and technically able to take the stand during litigation and make a statement such as: “My samples indicate that, within reasonable professional limits, there is less than a 3% probability that toxicologically significant arsenic exists in the native overburden, and less than a 5% chance it exists in toxicologically significant concentrations in the artificial fill; but only less than a 25% chance of toxicologically significant concentrations greater than the EPA MCL in vadose zone water….etc….” and then go one to explain what they mean by “toxicologically significant”… and how deep the vadose zone is…they probably don’t want to get into environmental sampling. (But that’s just me).
Sorry I haven’t been posting to the board for a while… I’ve been slammed. However, feel free to share this info with the board, and let me know if there are any questions, and I promise I will respond directly.
Caoimhín P. Connell
Forensic Industrial Hygienist