Arsenic, in particular, creates the most problem for establishing a "safe" level at which to leave the soil in OU-4. Because OU-4 is the area where exposure can take place.
The problem with arsenic is not the poison part we all associate it with, but instead our knowledge that it may cause cancer at low concentrations.
The problem with contaminants that are suspected to cause cancer is that we are told:
The underlying presumption for carcinogens is that the introduction of even one molecule of the contaminant can cause cancer in an individual even if the probability is very low. This conservative, “non-threshold” concept is used because it is presumed that there is no level of exposure to a carcinogen that does not pose a certain level of risk.That's from Illinois' TACO's Fact Sheet. That statement is one of the presumptions we hold as true when we look at risk of exposure to a chemical.
You can see the bind that puts us in. If we say exposure to "even one molecule of the contaminant can cause cancer in an individual" setting a "safe" concentration is, well, not possible. Instead we draw a line in the sand and say:
You see how they put us risk calculating types between a rock and a hard place? For exposure to a contaminant in soil, I have to come up with a concentration that theoretically will show no more than one excess cancer per 1,000,000. That number, based on what we know today, is calculated to be no more than 0.39 mg of arsenic in a kg of soil (0.39 mg/kg).
Now there is no way on God's green earth that you will ever find soil at less than 0,39 mg/kg of arsenic. Arsenic is a naturally occurring element. It is everywhere. Because it is everywhere, we are constantly exposed to it. In this case, we cannot reasonably ask that soil be cleaned up to a standard lower than what good ol/ mother nature has exposed us to. So we settle on a background concentration as our cleanup objective.
According to the regulations in Illinois (742.Appendix A, Table G) the background for arsenic in soil at 11.3 in non-metropolitan areas. Therefore, we are now going to live with this:
But this creates a sense of foreboding when the levels exceed background. What is the probability of added risk?
In OU-4 there are 98 samples out of 125 that are at or above the background concentration of 11.3 mg/kg arsenic. The spreadsheet provided by Cleanup DePue shows the average amount of arsenic in OU-4 to be 19.6 mg/kg of arsenic.
Now anyone can see that 19.6 is higher than 11.3. Does that constitute a "way-above-normal concentrations?"
As I discussed in my last post, what we need to look at is the amount of exposure above normal. In this case, on average, the soil in OU-4 is 8.3 mg/kg higher in arsenic than the regulatory background limit.
If, and this is a big if, a citizen of DePue is exposed to that soil for 350 days a year for 70 years, by my estimate, that would bring about a probability of 1.8 excess cancers in 10,000.
Now anyone can see that a probability of 1.8 in 10,000 is much higher than 1.0 in 1,000,000. But that probability of 1.8 in 10,000 is based on coming in direct contact with the soil and having the arsenic in that soil enter into the body. You must also have that happen each day for 350 days a year for 70 years. It is also based on a theoretical slope factor that we guestimate will show cancer at a particular concentration.
So how close is that added probability of 1.8 excess cancers in 10,000 to what might actually happen? Possible? Maybe. Probable? Not even close.
That puts me between a rock and hard place. One one hand I accept the "even one molecule of the contaminant can cause cancer" presumption and on the other I can soundly state that ya' got nothin' to worry about in OU-4.
And here is where it get's all ethical on us...or at least for me.
- If I accept the "even one molecule of the contaminant can cause cancer" presumption then exposure to any molecule above zero presents a risk.
- If I accept one in one million as being an acceptable level of risk, then I accept as "safe" a concentration that will not present a risk of no more than one excess cancer in one million as my threshold.
- If I accept the premise that arsenic - like chromium, cadmium, and lead - are naturally occurring in the soil, then I must accept the fact that I will always be exposed to some concentration of those contaminants when I come in contact with soil.
- If I accept that there is a concentration of contaminant in the soil that is low enough to be considered "safe" then my responsibility to cleanup my mess will end when that threshold is met.
That side is determined by doing a risk assessment. Apparently, Nancy Loeb, the director of the Environmental Advocacy Clinic at Northwestern University School of Law’s Bluhm Legal Clinic, has told the folks in DePue that this risk assessment is flawed:
“The companies spent millions of dollars on consultants in an attempt to show that this SuperFund site poses no significant risks, and they delivered a superficial plan that barely touches many of the contaminated areas, leaves the slag pile and other waste in place, does nothing to stop contamination from seeping into the groundwater, and leaves backyards, playgrounds and Lake DePue without real remediation.”Ms. Loeb claims that the "safe" line is not set low enough. She offers no calculations or explanation to support that claim, but, nonetheless, that's her contention.
I am going to look for this plan that she speaks of to see what those cleanup levels and remediation methodologies are to see if they are indeed lacking.
Right now, all I have is a bunch of data that shows an average concentration of arsenic in the soil in OU-4 to be 8.3 mg higher than the legal background concentration established by Illinois in 742.Appendix A, Table G.
Regardless of what I think the true risk is. Regardless of whether or not 8.3 is to be considered "way-above-normal," the one fact that remains is this. If I am going to draw a line in the sand that says "clean" then I must do something about the soil that has a concentration above that threshold.
I need to see what is proposed for OU-4. In particular, I need to see how they are addressing arsenic above background.
Ethically, if I use a concentration to make the statement of clean soil, then I have a responsibility to do something about soil that falls above that level designated as "safe." I have an obligation regardless as to whether or not the soil above that line presents a risk or not.
This is the double-edged sword we live by. If I draw a line in the sand to say "safe" and therefore my responsibility is ended, then I have an ethical responsibility to rectify those areas that are above that threshold.
Since Illinois has stated that background may be used as a cleanup objective, anything above background must be remediated. This is the ethical contract we must adhere to if we are to use the benefit it provides in establishing a level of "safe." If my responsibility can be terminated at a particular concentration, then ethically I need to be responsible for areas above that. I cannot accept background when it suits me and discount it when it does not.
Ms. Loeb seems to indicate that the bar of what is "safe" has been moved to allow for exposure to higher concentrations then she thinks is "safe." What I need to see is how the soil screening levels are being calculated and what constitutes a "safe" concentration.
At this point, 98 samples are above background concentrations for arsenic in OU-4. The Illinois regulators have drawn a line in the sand and said that background is an appropriate cleanup objective.
Is that legal background concentration in 742.Appendix A, Table sacrosanct?
If we have an ethical duty to reduce the risk for the people living, working, and playing in OU-4, then establishing what a "safe" level of exposure is becomes critical. This, if I had to guess, is the main sticking point with Ms Loeb.
Not sure if I can get a hold of that information, but I am going to start looking.
Next post: The Village of DePue: What's in store for OU-4 - Part 12
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