The Village of DePue: The ethics of drawing a line - Part 11

Looking at the 125 samples collected in OU-4, I found that a number of them exceed the level of concern.

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 last one is the premise of "how clean is clean?"  Since we are concerned about a risk of acute and chronic health problems because of our exposure to the soil in OU-4, we must draw a line in the sand and say on this side it is clean.

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

The Village of DePue: Theoretical Cancer Risk at Background - Part 10

The theoretical cancer slope factor (CSF) that has been set for Arsenic is 1.5 (mg/kg)/day.

So...theoretically:

• The soil screen level that will achieve a risk of one additional cancer in one million for arsenic is 0.39.
• A person exposed for 350 days a year, for 70 years, to 0.39 mg/kg of arsenic in soil would have a 33.3334 percent chance of getting cancer in their lifetime
• A person not exposed to 0,39 mg/kg of arsenic in soil will have a 33.3333 percent chance of developing cancer in their lifetime.
• The difference is 0.0001 percent or a probability of 0.000001 (1 in a million)

This is how we look at chemicals suspected to cause cancer.  There is no "safe" dose, so we calculate the risk based on a chronic exposure to a set amount.

We feel that one in one million is an acceptable risk and the amount of arsenic in soil that would be expected to produce the chronic daily intake (CDI) necessary to show a one in one million risk is 0.39 mg of arsenic per kg of soil.

All of this is theoretical.  But for purposes of setting a cleanup standard, it is the best we have so we will make the assumption that 0.39 mg/kg is the "safe" limit.

That, as we discussed in a previous post, is a value that is unable to be obtained in nature.  That is, there is a natural amount of arsenic that we are exposed to.  We call that "background" and it is set based on what we "normally" see in places where we live.

Illinois has set the background for arsenic in soil at 11.3 in 742.Appendix A, Table G.

11.3 is quite a bit higher than the theoretical "safe" value we want which is 0.39 mg/kg.

There is nothing we can do about background, so we ignore the theoretical what we want, and accept the background as "safe."

So...11.3 mg/kg is "safe."

In OU-4 we have 102 samples that exceed the background concentration that Illinois has said is acceptable.

What do those exceedances  mean in terms of additional risk?

Let's look at this from EPA's Integrated Risk Information System (IRIS) perspective:

IRIS

IRIS shows that the concentration of 0.02 μg of arsenic per liter of drinking water is the "safe" amount that will increase the risk of cancer from 33.3333 to 33.3334 percent.

If you increased the concentration 100 fold, from 0.02 μg to 2.0 μg per liter of water, the risk would move from 33.3333 to 33.3433 percent.

100 times more arsenic consumed increases the risk from 33.3334 percent to 33.34 percent.

Okay, so what does this mean for the people who live in DePue?  It depends on how one wants to look at it.

First off, the slope factor used to calculate the risk is very conservative which means it most likely over-estimates the risk.  Second, the amount of arsenic that enters into the body from soil fluctuates wildly.  Our calculations of how much are based on a consistent amount of arsenic entering into the body 350 days a year for 70 years.  Third, we are looking at excess cancer above and beyond the one in three chance of getting cancer in a 70 year lifetime.

But let's ignore all of that and focus solely on establishing a threshold where on one side it is "safe" and on the other side there is "risk."

The Illinois background level for arsenic has been set at 11.3 mg/kg.  This level is a cleanup objective that Illinois assumes presents a "safe" environment if the arsenic is at or below that amount.

For all intents and purposes, we will assume 11.3 or less to present no excess cancers above the norm of a 33.3333 percent chance of getting cancer in a 70 year lifetime.

That assumption means, theoretically, that exceeding the value of 11.3 presents an additional risk.  So...how much are we talking about?

The average exceedance of the background threshold of 11.3 mg/kg was 1.7 times the background for an average amount of arsenic in the soil in OU-4 (where the people live) of  19.6 mg/kg.

19.6 mg/kg exceeds the threshold of 11.3 mg/kg by 8.3 mg of arsenic.  So...8.3 mg of additional arsenic exposure is what we will estimate the additional cancer risk on.

Here is where it gets fun.

The EPA's soil screening level (SSL) for arsenic is 0.39 mg/kg.  0.39 mg of arsenic in the soil is assumed to present a risk of no more than one additional cancer in one million cancers for a person exposed 350 days a year for 70 years.

EPA's IRIS has calculated the chronic daily intake (CDI) for arsenic to be 0.02 μg of arsenic per liter of drinking water for a risk of one additional cancer in one million cancers  .

Since the average person is assumed to consume 2 liters of water per day, the amount of arsenic that will theoretically bring about a risk of one additional cancer in one million is 0.04 μg per day for 70 years.

So...we can assume that exposure to 0.39 mg/kg of arsenic in soil, for 350 days a year, for 70 years, will equate to a CDI of 0.04 μg of arsenic.

0.04 μg of arsenic.consumed each day for 70 years will theoretically result in no more than one additional cancer in one million.

0.39 mg/kg exposure = 0.04 μg of arsenic consumed.  That's our line in the sand.

On average, in OU-4, the soil exceeds background by 8.3 mg of arsenic per kg of soil.

Okay...take a break and relax.  Here is a picture of a kitten and a puppy to help...before we do more math and take on more assumptions.

Source

Feeling better?  Okay, let's continue.

8.3 mg is 21 times higher than 0.39.  Therefore, the CDI at 8.3 mg of arsenic exposure would - theoretically - be 21 x 0.04 = 0.84 μg of arsenic consumed.  That's based on the SSL calculations the EPA used.

So what is the risk of consuming 0.84 μg of arsenic per day for 70 years?

In my previous post I showed this calculation:

Source

Here is what we know:

• The NSRL is the uptake - 0.84 μg which is equal to 0.00084 mg
• The the slope factor (qhuman) is 1.5 (mg/kg-day)-1
• The body weight we use is 70 kg.

Basic algebra here with the math.  We need to solve for the risk "R"

(0.00084 x 1.5) / 70 = 0.00018 or 1.8 excess cancers in 10,000.

Here is what the TACO's fact sheet says about that:

The risk of cancer due to exposure to a contaminant is commonly expressed in exponential terms, e.g., 10-6 and 10-4. These terms equate to a risk of 1 in 1,000,000 and 1 in 10,000 respectively. Adding a 10-6 risk would increase the probability of an individual getting cancer to 0.333334. With the addition of a 10-4 risk, the probability of an individual getting cancer would be 0.333433.

On average, in OU-4, the probability of an individual getting cancer would be 0.333453.

What that means is one's normal probability of cancer in a life-time of 0.333333 becomes 0.333453 if exposed to that soil for 350 days a year for 70 years.  This is based on contact with the soil so that the soil enters into the body.

Although it is possible, it is highly improbable that any one in DePue would have an uptake of soil over a lifetime that would equate to a risk of 1.8 excess cancers in 10,000.

Based on how conservative these formulas are, and how theoretical the slope factor is, I do not see any reason to be concerned about the amount of arsenic in the soil in OU-4.

But that raises and ethical question.

Should the citizens of DePue be exposed to any risk above one in one million?

Next Post: The Village of DePue:  The ethics of drawing a line - Part 11

.

The Village of DePue: By how much and how many - Part 9

Tis the day after Christmas, and Excel sorting I will go....

Okay, it took me a few more days to get through all this....

In my last post I looked at the Illinois requirement for residential use which told me to meet Appendix B, Table A objectives.

Based on the data in the Excel files I downloaded from the Cleanup DePue website, six contaminants were found in OU-4 - the area where people have access to, that were above the Illinois cleanup objective concentrations in Appendix B, Table A.

I now need to sort the data to see by how many of them are over the objectives.  This, along with how much the exceedance is, will give me a good indication of risk.  I am only concerned with OU-4 because that is where exposure can take place.

Right now, I have a ton of data from soil samples collected in OU-4.  What I don't know is what the plan addresses.  What I do know is that the plan is much more complicated  in evaluating risk than what I am doing here.  What I am trying to do in these posts is make an assessment as to the claim of  "way-above-normal concentrations of pollutants at hundreds of contaminated sites" so don't go telling people "Bowman says you only need to clean it up to this level."

With that in mind, lets do some sorting...

Ahh, but first we need to get some things out of the way first.

1. csv_post_date is 1996 and 2009
2. Thallium is identified as less then "<" a value.  Therefore less than 10 will mean it is below TACO Appendix B, Table A objectives.  I am removing thallium from the CoC list.
3. Other values identified with "<" will be assumed to be the number below it.
4. Only one sample exceeded the mercury objective of 23 mg/kg.  Since the analytical value is only 24.4 I am going to remove it from the CoC list.

Now that I have it sorted, of the 125 soil samples:

• 102 exceed the objective for one of the chemicals, arsenic, barium, cadmium, or lead. 
• Of these 102 OU-4 samples, all but five exceed the objective for arsenic, which is set at background.
• Only two samples show exceedance for all four of the CoCs.

How, then, do I make sense out of this data?  That's what's missing from the Cleanup DePue's web site.  Tons of data and no context.  This is where I need to be careful in how I describe what I see.  I don't have access to the plan so I cannot speak on the validity of the risk calculations.  I also do not know what the remediation plan is for OU-4.  If they are going to leave the soil in place, well maybe these folks in DePue have something to beef about.  If these "hot spots" are going to be removed, then what I say from this point on is moot.

Oh how I wish I knew what Cleanup DePue and Nancy Loeb, director of the Environmental Advocacy Clinic at Northwestern University School of Law’s Bluhm Legal Clinic and pro-bono counsel for the Village of DePue want.  All I know is they think the plan insufficient to protect them.

The other thing missing from their site is what cleanup levels do they think are health protective and what areas do they want these levels met?  I have been writing these previous posts trying to answer my own curiosity about "way-above-normal concentrations of pollutants at hundreds of contaminated sites"

My problem is that I don't know what they construe as "way-above-normal concentrations."  I am missing some important pieces here.  Since I don't now how the remediation plan is addressing the soil in OU-4, I can only look at what I see from the sample data that I have.

Right now, arsenic is where my focus is because of the number of OU-4 samples where it exceeds the threshold - or cleanup objective in Section 742 Appendix A, Table G.

What I see when I sort the OU-4 soil sample concentrations is that arsenic shows up like this:

• 27 of the samples are more than twice background
• Two samples are three times background (3.0 and 3.3)
• One sample is 4.2 times above back ground
• The average exceedance is 1.7 times background with a median exceedance of 1.6.

Depending on how one looks at it, twice the amount could be seen as "way-above-normal concentrations of pollutants at hundreds of contaminated sites."  Unfortunately, that's not how it works out in this case with arsenic.

Arsenic is set at background because natural background concentrations of arsenic are often well above the health-based, direct-exposure goals in soil.  That's a bit confusing.  On one hand you tell me the "safe" concentration in soil for arsenic is 0.39 mg/kg and then you tell me you only need to clean it up to background.

Yeah...that's what we are telling you.  Our health-based cleanup goals (objectives) are theoretical erring on the conservative side.  Because we suspect arsenic to be a human carcinogen, we set the acceptable risk for an adverse health affect to no more than one additional cancer out of one million cancers.

I'll let TACO's explain that:

For carcinogens, risks are estimated as the probability of an individual developing cancer over a lifetime as a result of exposure to a contaminant.

What we are looking at is a probability of cancer, in the case of soil, we set that probability of a "safe" level at a concentration that we expect to see no more than one additional cancer out of one million cancers over a 70 year lifetime.  We do this with a calculation involving our good friend the slope factor:

This value is known as a slope factor (SF), and it converts daily intakes of a carcinogen averaged over a lifetime directly to the upper bound risk of an individual developing cancer.  That is, risk is equal to chronic daily intake (CDI) averaged over 70 years (lifetime) multiplied by the SF. (page 4 of TACOs)

Figuring out the dose that will give you no more than one additional cancer in one million is quite simple:

Source

Calculating how low a concentration of a contaminant needs to be in soil to bring about that dose is a bit more complicated.  For risk, we are assuming that ingestion, dermal contact, and inhalation of dust for getting the chemical into to human receptor.  We know that as little Suzy grows from a toddler to an adult she will come in contact with that contaminated soil.  We assume that little Suzy will be in contact with that soil for some period of time each year for 70 years (default is 350 days/year).  We know, through a bunch of different studies, that people like little Suzy and adult Suzy will ingest a certain amount of soil in a day.  The question becomes how much contaminant in that ingested soil needs to be there to bring about a probability of one additional cancer in a million.

Remember this bad boy calculation?

Source

That's how it is calculated.  When you see "IFS" it is "age-adjusted soil ingestion factor." DFS is the "age-adjusted soil dermal factor."  These formulas take into account the differences in body weight and uptake as little Suzy goes from a toddler to an adult.  They are very, very conservative and very, very protective.

So for arsenic, the amount in soil that will bring about no more than a one in one million probability of an additional cancer is 0.39 mg of arsenic per one kilogram of soil.  Why show y'all this?  Because that's how we come up with a "safe" threshold for a contaminant we suspect to be a carcinogen.  You need to see that in order to understand the next part of the calculation.

If little Suzy is exposed to 0.39 mg of arsenic in one kilogram of soil for 350 days a year for 70 years, we expect her to have a one in one million chance of developing cancer.  This is a probability based on assumptions which are all worst case.  The biggest assumption is the Slope Factor (SF or CSF):

The SF is derived through the plotting of a curve that compares dose to response. Statistical procedures usually calculate the SF as the upper 95th percent confidence limit of the slope of the dose-response curve (i.e., there is only a 5% chance that the cancer risk could be greater). Because this is the upper bound risk, the actual risk is between that value and zero. The SF is roughly equivalent to the risk per unit dose, expressed as (mg/kg/d)-1. As with the RfD, the SF is provided by the U.S. EPA. (page 4 of TACOs)

And what is the SF provided by the EPA for arsenic?  1.5 as it stands today.  With that, we can calculate the chronic daily intake (CDI) for arsenic to get us a one in one million risk probability.  We can use the method described in the California equation above:

• We know the risk (R) we want is one in one million or 1.0 x 10-6 or 0.000001.
• We know the slope factor (qhuman) is 1.5 (mg/kg-day)-1
• We know the average weight of the human is 70 kg

So, a little math...and we can calculate the intake level (I) or CDI

I = (0.000001 x 70 kg) / 1.5 mg/kg-day = 0.000047 mg/day or 0.05 μg/day.

0.05 μg of arsenic consumed for 365 days a year for 70 years should see no more than one additional cancer per one million cancers.  What does that mean?  Here is how Illinois describes it in the TACO's Fact Sheet:

The risk of cancer due to exposure to a contaminant is commonly expressed in exponential terms, e.g., 10-6 and 10-4. These terms equate to a risk of 1 in 1,000,000 and 1 in 10,000 respectively. In the benzene example, the risk estimate of 1.5 x 10-5 means that 1.5 additional cases of cancer above background might occur among 100,000 exposed persons (or 15 cases in 1,000,000 persons) as a result of benzene exposure. The background cancer rate is 1 in 3, meaning that over a lifetime, an American’s probability of getting cancer is 0.333333. Adding a 10-6 risk would increase the probability of an individual getting cancer to 0.333334. With the addition of a 10-4 risk, the probability of an individual getting cancer would be 0.333433.

Confused?  Focus on the numbers here:

The slope factor is a value that is a very conservative number.  It is very, very protective of public health in and by itself.

• The probability of cancer risk is based on a CDI of that concentration of arsenic each day for 70 years.
• The probability of consuming that amount over 70 years and getting cancer is one in one million.
• The chance of getting cancer in your lifetime is one in three - 33.3333%.
• If we expose you to soil with 0.39 mg/arsenic per kg of soil for 350 days a year for 70 years, the chance of getting cancer increases to 33.3334%

Now if you have stayed with me to this point, you might be asking "what is the risk of cancer at the background concentration of arsenic?"

Good question.

Next post: The Village of DePue:  Theoretical Cancer Risk at Background  - Part 10

The Village of DePue: Mmm....TACOs - Part 8

I'm still trying to support Cleanup DePue's Press Release claim that:

Contaminated debris blows onto public and private property throughout the village and surrounding natural areas, exposing residents -- more than a quarter of whom are children under the age of 16 -- and local wildlife to arsenic and heavy metals such as lead, mercury and cadmium. Visit www.CleanUpDePue.org to see an interactive map that details the way-above-normal concentrations of pollutants at hundreds of contaminated sites.

I did visit their site and I have been looking at the data to see where these "way-above-normal concentrations of pollutants at hundreds of contaminated sites."

I thought possibly that it might be arsenic and chromium leading this charge since every single one of the samples in OU-4 - where the people of DePue live, work, and play, were above the screening levels for these two compounds.

Then I remembered that Chemicals of Concern (CoCs) that are carcinogens are calculated differently and calculate considerably lower levels than background concentrations making them impracticable to use for remediation goals.

On the Cleanup DePue's website they write about background concentrations:

"For each parameter whose sampling results demonstrate concentrations above those , the [responsible party] shall develop appropriate soil remediation objectives in accordance with this Part." The Illinois EPA considers these background standards an appropriate measure by which to compare soil samples.

Yes that is true.  But background levels are not the sole remediation goal, and I believe that may be where the confusion lies and why Nancy Loeb, director of the Environmental Advocacy Clinic at Northwestern University School of Law’s Bluhm Legal Clinic states in the Press Release:

“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.” 

The issue, as I think I am now coming to understand, is twofold.

1. They are leaving the contaminated areas in place and moving contaminated media to these areas.
2. They are not remediating the area, specifically OU-4, to background levels in Section 742 Appendix A, Table G of Title 35 of the Illinois Administrative Code or groundwater down to MCL/MCLG levels.

Loeb also criticized CBS and ExxonMobil for their totally unrealistic methods for looking at risk:

“In determining whether a person is exposed to potentially harmful levels of toxic pollutants, CBS and ExxonMobil are counting each exposure as if it were an isolated incident, and pretending that residents are exposed only to a single contaminant and only in one area of the town. The reality is that children are growing up here, eating from home gardens, playing in parks and ball fields, boating in the lake, and later working and living as adults in DePue. Any realistic assessment of health risks has to take these multiple, constant and long-term exposures into account.”

I do not have access to the plan, but I am pretty sure that the Illinois EPA is making CBS and ExxonMobil cleanup to a level consistent with the "Tiered Approach to Corrective Action Objectives":

Source

...or more affectionately called "TACOs"

I know nothin' about this thing called TACOs.  All I know is what any other person reading up on this topic and trying to understand it gets to look at on the interwebs.  What I do know about my industry, including the regulators that oversee it, is that they overkill everything when you attach the words "Superfund" and "Town" together.

I am pretty sure that the remediation plan CBS and ExxonMobil put together meets TACOs.  If Cleanup DePue thinks it does not, I will need to see their reasoning.  All I have is a Press Release stating that the plan is not a "realistic assessment of health risks," and a bunch of analytical data.

So let's get back to the question of are there "way-above-normal concentrations of pollutants at hundreds of contaminated sites?"  And, are the levels found high enough to present a concern?

TACOs tells us this:

The purpose of these procedures is to provide for the adequate protection of human health and the environment based on the risks to human health posed by environmental conditions while incorporating site related information.

With that in mind, we must assume that meeting TACOs meets adequate protection of human health and the environment.  If one wants to make an argument that it does not, let me know why in the comments.  For the most part, TACOs gets you to the same place that EPA's soil screening level calculations do.  They will spit out basically the same remediation goals.

Here is how TACO is designed to work:

Source

You can read more about TACOs by going here.

OU-4 will be samples collected in residential areas so that's the path we will go down.  This requires Appendix B Table A and Table E objectives.  Based on the values in Table A, the new CoC list looks like this:

I still show that some of the OU-4 CoCs exceed the Table A objectives (the one's in purple).  Also note how Illinois goals match closely in some cases with EPA's SSLs.

So, based on the data in the Excel files I downloaded from the Cleanup DePue website, six contaminants were found in OU-4 - the area where people have access to - that were above the Illinois cleanup objective concentrations in Appendix B, Table A.

My next quest will be to see by how much over the objectives as well as how many sample points are elevated.


Next post: he Village of DePue:  By how much and how many  - Part 9


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The Village of DePue: "A" is for Arsenic - Part 7

T'was the day before Christmas...
And I'm looking at sample data.

Last post I looked at all the 125 samples collected in OU-4.  These samples I surmised, represented the potential exposure for the people who live in DePue.

Yellow = Chemicals of Concern for public health.  Red indicates the highest concentration found that exceeds the soil screening level for residence chronic health.  If the highest value is not in red, there were no samples that exceeded the SSL and those sites do not pose a human health risk for that chemical at that concentration.

I found that seven of the contaminants exceeded the screening level threshold.  That being the case, I need to look to see how many samples exceeded it and if that exceedance elevates my concern for a risk to public health.

The one that caught my eye was arsenic.  If you are going to make a statement of "way-above-normal concentrations" that one might fit the bill.  What's important here is to see how many of the 125 soil samples from OU-4 exceed the Soil Screening Level (SSL).

So I go back to the Excel file, sort on arsenic, and...they all do!

Well that can't be right.  No where have I read that arsenic was a chemical of concern for this site.  Yet all 125 samples are above the screening level establish for inorganic arsenic!

In 1992 - before any cleanup had begun, the Illinois EPA said this about the site:

All residential soil samples showed elevated levels of cadmium when compared to samples taken in Tiskilwa. All but two samples showed elevated levels of zinc. Thirteen samples showed elevated levels of barium. Other samples showed elevated levels of arsenic, lead, copper, mercury, and selenium.

Okay, so arsenic is identified there.  But they go on to say:

Many of the contaminants are naturally occurring in soil at lower concentrations. Based on this first round of sampling, cadmium appears to be the main contaminant of concern.

Wait...cadmium is the main CoC, not arsenic?  Okay...so if cadmium is elevated and it is being dispersed in dust, then one would expect the other metals to follow along with it.  But we have only 26 that are elevated for cadmium, with the average concentration at 91 mg/kg - which is very close to the cadmium SSL of 70 mg/kg.

Something isn't right here.  I would think the Illinois EPA would be making much more of a concern over arsenic and chromium since the SSL is exceed considerably for both those compounds.  Why focus on cadmium?

Oh..."many of the contaminants are naturally occurring in soil."

What are the screening levels for arsenic and chromium based on?  Cancer (ca).

Oh yeah...carcinogens are calculated differently.  If you will recall from previous posts, cancer risk is based on the number of excess cancers we are willing to accept.  In the case of soil screening levels, the cancer risk plugged into the formula that spits out that number uses a value of one additional cancer in one million cancers (1.0E-6).

Source

This creates a problem for us.  Our formula that calculates a SSL does so based on the parameters and values we assign.  If we tell it to spit out a SSL for a contaminant we classify as a carcinogen, it will use the slope factor and the target cancer risk of 0.000001.  Here is what those calculations look like:

Source

Aren't you glad the computer does those calculations for you?  Trust me on that one.  I had to do these by Excel which is way easier than the poor chaps who had to do them with a paper and a calculator.

Don't get bogged down on those formulas.  What I want you to see is that these calculations use the cancer slope factor (CFO) and the target cancer risk (TR) of one in one million in their calculation of the soil screening level.  If you want to know more about the cancer slope factor see my previous posts.

So...based on these two parameters, CFO and TR, we get SSLs that are very...very...very low for suspected carcinogens.  They are that low because our margin of safety is less than one additional cancer in one million over a 70 year lifetime - based on a theoretical dose from the cancer slope factor.

The point is, our SSL for aresenic is lower than what our background exposure to that compound will be.  Arsenic and chromium are natural elements (yes, I know chrome VI is not, I used the most toxic form and assume that all of the chromium they detected is chrome VI).  In other words, what we theoretically want to see is not the reality of the world we live in.  In this case, we can ignore the calculated SSL and set the SSL to background.

That's what California does:

Source

And that's how the Illinois EPA does it as well:

IL EPA Soil Background Level: The standards used to compare soil samples are the Illinois EPA's background concentrations of inorganic chemicals in counties outside metropolitan statistical areas, as published in Section 742 Appendix A, Table G of Title 35 of the Illinois Administrative Code (starting on page 89 of this document). The standard states that "For each parameter whose sampling results demonstrate concentrations above those in Appendix A, Table G, the [responsible party] shall develop appropriate soil remediation objectives in accordance with this Part." The Illinois EPA considers these background standards an appropriate measure by which to compare soil samples.

That came from the Cleanup DePue's website.  Table G looks like this:

Source

...and with that table, as well a MCLs, we get a whole bunch of confusion as to what level is "safe."  The Cleanup DePue webpage writes:

The standard states that "For each parameter whose sampling results demonstrate concentrations above those in Appendix A, Table G, the [responsible party] shall develop appropriate soil remediation objectives in accordance with this Part." The Illinois EPA considers these background standards an appropriate measure by which to compare soil samples.

I'll need to look into that statement.  If that is what it states, then it is looking at risk incorrectly when requiring a cleanup plan be developed.  And since this is a Superfund site, there's this thing we call ARARs that are taken into consideration.  Oh goody.  Looks like I will be posting into the double digits before I get through with this series.


Next post: The Village of DePue:  Mmm....TACOs  - Part 8

The Village of DePue: Looking at red dots - Part 6

In the Chicago Tribune news article that started this series of posts, my eyes sent a signal to my brain when I read this:

But many say the involvement of Northwestern University's Environmental Advocacy Center — which is providing DePue with free legal representation — has given them some much-needed clout and could help the town finally realize its goal of eliminating or containing the contamination.

My brain told me that something must be happening there in DePue if Northwester University's Environmental Advocacy Center has gotten involved.

Now I know nothing about Northwestern University or their advocacy center.  My interest was piqued because they - a university - had gotten involved, and, that involvement was with a center that had the term "environment" in its name.

"University" plus "environment" equals "you got my interest."

So when I then read this:

"All the complaining we've done, we've learned that there's good reason for us to be worried about the type of cleanup we get here."

...I'm wondering what the heck is going on in DePue?

I work in the environmental field and I have worked for a plethora of private companies and governmental organization that deal with remediation and site cleanup.  I also have worked for hundreds of companies that are guilty of past behavior - the ones who get tagged as Potentially Responsible Parties (PRPs).  I know how my industry - including the regulators - behave in this type of situation where contamination from previous activities - legacy property - has initiated a cleanup order.

I know how it works.  I know the sampling that must be done.  I know the qualifications of the guys who collect and analyze and interpret the results.  They are not perfect, and they get it wrong, but the overall methodology does not leave too many stones unturned.  There is tons of data from these sites and everything is made available for public feedback.

So with that in mind, my curiosity piqued, and reading "we've learned that there's good reason for us to be worried about the type of cleanup we get here,"  I set out to see for myself.

I don't see anything to be worried about...yet.

According to the Press Release that appears on the Cleanup DePue organizations website, these folks contend:

The slag and waste left behind continue to leach heavy metals and carcinogens into ground water that runs off into Lake DePue, which flows directly into the Illinois River. Contaminated debris blows onto public and private property throughout the village and surrounding natural areas, exposing residents -- more than a quarter of whom are children under the age of 16 -- and local wildlife to arsenic and heavy metals such as lead, mercury and cadmium. Visit www.CleanUpDePue.org to see an interactive map that details the way-above-normal concentrations of pollutants at hundreds of contaminated sites.

I went looking for these "way-above-normal concentrations of pollutants at hundreds of contaminated sites."

I am giving the Cleanup DePue folks the benefit of the doubt by not dismissing their claims.  I don't automatically think their  "just a bunch of hicks out here crying about our town being contaminated."  With Northwest University involved, and being told in the Press Release:

The map shows the location for 1,976 samples taken by the companies over the past several years, exactly which contaminants were found in each sample, and the health risks of residents’ prolonged exposure to these contaminants. The website and map were built under grants from the Initiative for Sustainability and Energy at Northwestern (ISEN) and the Environmental Chemical Sciences Program of the  National Science Foundation's Division of Chemistry, Northwestern University Chemistry student interns worked over six month to analyze, interpret, and enter the data that you see on the map." 

...I'm thinking I hit the goldmine in being able to use viable data to support a claim of risk.

The Press Release tells me there is an  "interactive map that details the way-above-normal concentrations of pollutants at hundreds of contaminated sites," and that map was put together with funds provided by the University and the National Science Foundation, and "Northwestern University Chemistry student interns worked over six month to analyze, interpret, and enter the data that you see on the map," I'm looking a good, sound, peer reviewed, scientifically valid information.

I started writing Post Number 1 because of what I know about the industry - my industry - and the claim that "we've learned that there's good reason for us to be worried about the type of cleanup we get here."

What did they learn?  What are they being told?  Does that data Northwestern University "worked over six month to analyze, interpret, and enter" into the interactive map detail "the way-above-normal concentrations of pollutants at hundreds of contaminated sites."

My last two posts dealt with Mr. Garcia, a science teacher at DePue High School "who had his class sample soil and water to document unsafe concentrations of pollutants."  I looked at this data.  Nothing that even comes close to "way-above-normal concentrations."

Now it's time to look at the rest of the data.  I have looked at a few of the red dots on the map already:

 Now I would love to spend my two days before Christmas looking at all those red dots.  Even I'm not that nerdy to do that.  Instead, I'm going to bias my chance of finding a "way-above-normal concentration" somewhere close to where the contaminated sites are.

Once again.  I do not care about what is on the contaminated site.  I only care about what comes off that site and the exposure level the folks in DePue are forced to live with.  If you tell me that there is "way-above-normal concentrations" present then I expect to see them.  "Way-above-normal concentrations" would be an indication of exposure and we could estimate the risk of a health affect from the contaminants these folks are exposed to.

That's how we do it.  We are looking to estimate the dose that is being received by the people who live in DePue.  "Way-above-normal concentrations" would indicate a dose that could be "jeopardizing the health and well-being of the children, families and wildlife in DePue.”

So where should I start looking...

Here is what we know about where the contaminated property is located and its proximity to where people live.:

Source

OU-1: South Ditch Contaminated Sediments
OU-2: Phosphogypsum Stack
OU-3: Former Plant Site Area (FPSA)
OU-4: Off-site Soils
OU-5: DePue Lake Sediments and the Flood Plain

From the map above, it looks like samples from OU-4 represent the concentrations for contaminants that DePue folks would be exposed to.  What I find there - where people live, work, and play - would support the claim:

"Contaminated debris blows onto public and private property throughout the village and surrounding natural areas, exposing residents -- more than a quarter of whom are children under the age of 16 -- and local wildlife to arsenic and heavy metals such as lead, mercury and cadmium."

Mr. Garcia's samples did not support that claim.  So what did they find in the soil samples collected where people live?  I expect the contamination in OU-2 and OU-3 to be "way-above-normal concentrations."  I need the concentrations to be below soil screening levels in the areas where people live.

Wait a minute!  The website allows me to download an Excel file that has all the soil sampling data that has been collected!  I can look at it all.  Less bias on my part, less randomness, less leaving something out.  Cool!

I can then look at all the samples for OS-4 and find out which samples have the highest concentrations of the 12 contaminants Mr. Garcia looked at.  I don't care about potassium, sodium, manganese, pH, or anything else.  I want to look at the metals we normally consider toxic - the RCRA 8 and copper, nickel, and zinc, but I'll list the others simply because they are there.

I am also going to assume that the values entered into this spreadsheet are in mg/kg - ppm concentrations.  Looking at OU-4 data, I have 125 individual sample results.

So here is what I found:

Yellow = Chemicals of Concern for public health.  Red indicates the highest concentration found that exceeds the soil screening level for residence chronic health.  If the highest value is not in red, there were no samples that exceeded the SSL and those sites do not pose a human health risk for that chemical at that concentration.

So...life would have been a heck of a lot easier for me if they were all less than the screening level.  I could have ended this series of posts with a brief statement of no concern.  But some of the OU-4 samples did come show a concentration above the screening level.  How much higher will determine my concern.

Source

Before we get into this, a little reminder about the generic soil screening levels I am using:

The generic SSLs [are] calculated from the same equations used in the simple site-specific methodology, but are based on a number of default assumptions chosen to be protective of human health for most site conditions.  Generic SSLs can be used in place of site-specific screening levels; however, they are expected to be generally more conservative than site-specific levels. (Page 3)

Because I am doing this research in real time, I am writing about what I see and what I find out.  It would be easy for me to ignore things, such as the Thallium, but I want my work to stand scrutiny.  If it cannot be explained then more work will need to be done.  I am trying to provide information as well as support the claim that there are "way-above-normal concentrations of pollutants at hundreds of contaminated sites."

So far we have levels for some chemicals of concern (in red) that exceed the generic SSL.  I need to pause here and change my initial assumption that there is nothing to worry about based on Mr. Garcia's samples.  There are sample sites where the townsfolk of DePue have access to that appear to exceed the level that is accepted to be protective of public health.

The question I need to ask now is; "do any of the seven chemicals in red that exceed the SSL pose a health risk at that concentration?"  If yes, how many locations are at an unsafe level and where are they located?

Dang...two day to Christmas and I am going to be looking at an Excel file.  Maybe there is something there that they see...maybe...


Next post: The Village of DePue: "A" is for Arsenic - Part 7

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The Village of DePue: Where are they way-above-normal? - Part 5

Here is what the DePue Press Release states:

Contaminated debris blows onto public and private property throughout the village and surrounding natural areas, exposing residents -- more than a quarter of whom are children under the age of 16 -- and local wildlife to arsenic and heavy metals such as lead, mercury and cadmium. Visit www.CleanUpDePue.org to see an interactive map that details the way-above-normal concentrations of pollutants at hundreds of contaminated sites.

The folks who support the claims of the Cleanup DePue website believe that:

• “The companies spent millions of dollars on consultants in an attempt to show that this SuperFund site poses no significant risks."
• The companies "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.”
• "Any realistic assessment of health risks has to take these multiple, constant and long-term exposures into account.”
• The remediation plan the companies submitted is "not even close to what’s needed.”
• The companies are "jeopardizing the health and well-being of the children, families and wildlife in DePue,”

I look at those claims and I ask, how are they substantiated?  That is, on what basis is the contention made that the current situation in DePue is "jeopardizing the health and well-being of the children, families and wildlife?"  How is that determination of jeopardizing being made?

My last four posts have been setting the groundwork to answer that question.  I have no dog in this hunt.  I am solely interested in ascertaining the contention of harm because of a Superfund site in the near vicinity.  It is easy for me to look at this objectively because I don't live there.  But even if I did, the same methodology would still be used to determine if the site is indeed "jeopardizing the health and well-being of the children, families and wildlife in DePue."

When I read that the city is now being represented by a university, I assume that the university is giving them unbiased and sound risk assessment advice on how to properly gauge the effectiveness of the plan that the responsible companies have submitted to the Illinois EPA.

When I read that Northwestern University is assisting them and has developed their website - Cleanup DePue.org - I assume that the information provided on that site is accurate.  I also assume that the Northwestern University's Environmental Advocacy Center - which is providing DePue with free legal representation - is aware of what has been stated in the Press Release that is available on the website.

When I read in the Press Release that Nancy Loeb, director of the Environmental Advocacy Clinic at Northwestern University School of Law’s Bluhm Legal Clinic makes the following statement:

“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.”

I assume that there is real data supporting that statement.  As is stands now, Cleanup DePue and the folks representing Northwestern University, are telling the citizens and the world that there is a real risk to human health and the environment because of this Superfund site.

They tell me, and the world, to "visit www.CleanUpDePue.org to see an interactive map that details the way-above-normal concentrations of pollutants at hundreds of contaminated sites."  Well I did.  And right now, at least for the baseball field, there is no reason for concern.  That is, the amount of contaminants present in the soil and in the groundwater are below the levels necessary to present a real risk for short term or long term - chronic - health concerns.

I guess we need to look at Mr. Garcia's samples for the other four stops on the virtual tour.  If the baseball field does not have concentrations "way-above-normal", maybe somewhere else in DePue these way-above-normal concentrations have been found.

Here are all the five sites on the virtual tour and the concentrations detected in the five samples Mr. Garcia's students collected:

The Lake DePue sample results are in question since they are identified in mg/kg.  The "Virtual Tour Stop #5: Lake DePue" identifies this as a water sample and should be in mg/L.  I am going to assume that the cadmium listed at "79.05 mg/kg" is actually 79.05 mg/L.  That being the case, only the cadmium in the lake throws up a red flag.  All the other concentrations are far below health based screening levels.

All these additional sites, similar to the baseball field, do not show concentrations "way-above-normal."   In fact, these levels are normal and will pose no health or environmental concerns requiring remediation or other measures.

So what about the cadmium that Mr. Garcia's class found in the lake?  One sample does not a determination make.  Based on what I have seen on the Cleanup DePue website, there have been other samples collected from Lake DePue that can be looked at for cadmium:

Source

Notice at the top it says "Download water & groundwater samples only?"  Well I did.  Here is what the excel spreadsheet shows (cleaned up and sorted - no modification to the data too place)

Surface Water Samples

Shoreline Seep

Based on these samples, sampled in 2006 and 2007, cadmium does not seem to be elevated detected at a high of  0.0006 mg/L.  Based on this, I would now have to question the cadmium results shown for Mr. Garcia's water sample from the lake.

We cannot, however, ignore cadmium as it is a chemical of concern (CoC) for this site:

The sediment samples from the ditch leading to Lake DePue, when compared to sediment samples from Turner lake, showed elevated levels of cobalt, cadmium, copper, mercury, selenium and zinc. These same metals, with the exception of cobalt, were also found at elevated levels in sediment samples taken from Lake DePue. Surface water samples from Lake DePue and the ditch leading to the lake, when compared to Turner Lake water, had elevated levels of cadmium, copper, zinc and ammonia. (Fact Sheet #1 1992)

So we know cadmium is present in 1992.  Samples of the lake in 2006 and 2007 show very low concentrations of cadmium.  Mr. Garcia reports 79.05 mg/kg for his sample.  This needs to be rectified with additional samples - more than one to statistically show what we can assume is the "true" concentration for cadmium in the lake at this time.

If I am going to assume Mr. Garcia's sample results are valid and make a statement that the amount of contaminates he found were below EPA's screening levels, then I must also assume that he found 79.05 mg/kg of cadmium in the lake.  I suspect he did not based on other samples collected.  Until I have conformation telling me otherwise, I will have to assume that it is 79.05 mg/kg.

Based on this assumption - that Mr. Garcia's data is representative of the conditions at the five locations sampled - none of these results were "way-above-normal."  That statement is not backed up by his sample results or the sample results collected by other parties.  Looking at what data is available, my conclusion would be that there is no elevated chronic health risk "jeopardizing the health and well-being of the children, families and wildlife in DePue.”

Unless I am missing some other data, I am unsure why Nancy Loeb, director of the Environmental Advocacy Clinic at Northwestern University School of Law’s Bluhm Legal Clinic is telling DePue that the potential responsible parties (PRP), Mobile and CBS, have:

"...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.”

I am not seeing it, based on the data that they have presented on their website, CleanupDePue.org.

Okay, so maybe there are other backyards, playgrounds, and living areas that have contamination "way-above-normal."   They are telling me to go to their webpage and look.  I have.  I do not see it.  Maybe it is in one of those red dots on that interactive map...what am I missing...??


Next Post.  The Village of DePue: Looking at red dots - Part 6

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The Village of DePue: I'll take information for $200, Alex - Part 4

According to the "Contamination Map" on the "Clean Up DePue" web page, the two samples collected at the baseball field show:

Contaminants above MCL for drinking water : Iron, Manganese, Sulfate, pH

Clicking on the little red question mark tells the reader that an MCL stands for Maximum Contaminant Level and is the EPA's "level of a contaminant in drinking water below which there is no known or expected risk to health."  The reader is then told that "EPA standards for human health risk in soil are relatively close to those set for drinking water."

No...no they are not.  Why they state that is...well..perplexing, because at the end of the paragraph they write:

Please note: There are no known soil "standards" on a state or federal level; there are only objectives or screening criteria and those vary with the source. EPA drinking water MCLs exist, however they may not be compared directly to the soil concentrations listed on this website.

So what is the reason for posting the data in the first place?  What is the information that the reader - particularly a DePue resident - supposed to think when they read:

• "Contaminants above MCL for drinking water : Iron, Manganese, Sulfate, pH"
• "EPA standards for human health risk in soil are relatively close to those set for drinking water.

C'mon, they - Northwestern University's Environmental Advocacy Center - know exactly what message they want the reader - particularly a DePue resident - to come away with.  And if they - Northwestern University's Environmental Advocacy Center - do not understand how data can be misinterpreted then perhaps they should not be the ones to be relied on for their expertise on evaluating the remediation plan.

I know, I know, "they put a note there at the bottom," you might be thinking.  That's the giveaway for me.  They do understand that the secondary MCL has nothing to do with evaluating the risk at the baseball park.  They needed to show something above a threshold, so they choose Iron, Manganese, Sulfate, and pH

And therein lies the problem, it distorts the thinking of the folks who live in DePue:

ExxonMobil and CBS are continuing to minimize the risks to human health and the environment and to set the groundwork for leaving the contaminated waste where it is,” said Nancy Loeb, director of the Environmental Advocacy Clinic at Northwestern University School of Law’s Bluhm Legal Clinic and pro-bono counsel for the Village of DePue. 

With Northwestern University School of Law’s Bluhm Legal Clinic telling the the village of 1,800 residents that the actual risk has been minimized, you can see how easy it is for those citizens to tell the Chicago Tribune:

"All the complaining we've done, we've learned that there's good reason for us to be worried about the type of cleanup we get here."

..and be quoted in the Press Release stating:

“The consent order required the responsible parties to come up with the plan, supervised by the Illinois EPA. I don’t know how to respond to that plan. It’s not even close to what’s needed.” 

What they are being told may - or may not - be a factual/sound representation of risk.  So how can we go about evaluating that risk with the information we do have?  If all we have is groundwater samples and we are told that "EPA drinking water MCLs exist, however they may not be compared directly to the soil concentrations listed on this website," what can we look at to give us an idea if, as per the Press Release:

Contaminated debris blows onto public and private property throughout the village and surrounding natural areas, exposing residents -- more than a quarter of whom are children under the age of 16 -- and local wildlife to arsenic and heavy metals such as lead, mercury and cadmium. 

Let's focus on that concern.  That the contaminants are blowing onto public and private property.  If that statement is true, then we would expect to see these contaminants outside of the fence line.  And, if they are outside of the fence line, they must be in a concentration high enough to cause a health effect.

We can assume that any amount outside of the fence line that falls below a health/environmental threshold is not a concern.  This is how the EPA looks at contaminated property.  This graphic comes from the EPA from the data that the Cleanup DePue website cites:

Source

So you see from the graphic that somewhere between "zero" concentration and this thing called a "screening level" no further study is necessary.  In other words, below the screening level for that contaminant we will consider the site to not present a health concern for the activity that will commence on it.  For the citizens of DePue we will consider the activity to be "residential" use.

So what the heck is a "screening level" and can it be used to determine if the conditions found today are "jeopardizing the health and well-being of the children, families and wildlife in DePue?”

when the reader is incorrectly told by Cleanup DePue that  "EPA standards for human health risk in soil are relatively close to those set for drinking water," that statement is attributed to a document cited as "[2, PDF]."  That EPA publication is called the "Soil Screening Guidance: Technical Background Document."  Now where in that EPA document - I checked - does it imply or state that risk in soil are relatively close to an MCL.

What it does say, in relationship to an MCL, is this:

SSLs are backcalculated for migration to ground water pathways using ground water concentration limits [nonzero maximum contaminant level goals (MCLGs), maximum contaminant levels (MCLs), or health-based limits (HBLs) (10-6 cancer risk or a HQ of 1) where MCLs are not available]. (Page 5)

What that means is the contribution to groundwater contamination through leaching - which is the primary health concern if the groundwater is used for drinking - is considered when establish the Soil Screening Level (SSL).  Even if little Sally will not come in contact with that soil through contact and/or ingestion, the impact on the drinking water that little Sally will drink is considered in setting that SSL.

So once more, what the heck is a soil "screening level?"

SSLs are risk-based concentrations derived from standardized equations combining exposure information assumptions with EPA toxicity data. (1)

So...there is an equation that is used to make this determination of risk.  Cool.  And I know that Mr. "Keith Garcia, a science teacher at DePue High School [had] his class sample soil and water to document unsafe concentrations of pollutants."  And those soil sample results are available on the Cleanup DePue website:

Source

Now that I know the contaminants of concern, I can look to see what the Soil Screening Levels are for those compounds that have been calculated based on residential use of the property.

You know what really cool about being a researcher in the 21st century.  The internet, google and the availability of mathematical formulas to calculate just about anything.  you provide the data and they provide the calculation.  How cool is that!

The EPA just so happens to have a really cool calculator for doing this.  This is based on the methodology put forth in the "Soil Screening Guidance: Technical Background Document" the Cleanup DePue's website cites.

Source

So...I asked it to calculate the Soil Screening Levels (SSLs) for the 12 metals that Mr. Garcia, a science teacher at DePue High School had his class sample for at the baseball field.  Here is what the calculations look like:

Wow, that's a lot of numbers.  A lot of scientifically looking stuff.  A lot of data.  Yeppers, that's what we have here.  A lot of data and no information.  So if you are still reading this...let's get to understanding what it all means.

First, if you recall the definition of a SSL:

SSLs are risk-based concentrations derived from standardized equations combining exposure information assumptions with EPA toxicity data. (1)

...then we need to accept those calculations as sound.  If you have a better way of calculating the concentration that is of concern, then you need to support that method and tell me why it is better than this one.  I am going to assume - warts and all - that the value and parameters used in these calculations is conservative enough to be an indicator of the risk if those levels are exceeded.

That's how we do it.  We public health scientists have agreed to these formulas and parameters.  So the number it spits out; "Screening Level (mg/kg)," is how we will make a determination of potential risk to a resident at this site.  And yes, they take into account exposure of children in these calculations.

With that in place, if the quantity of any of these 12 compounds Mr. Garcia' class sampled at the baseball field exceed the Screening Level, we can assume that a value below that is protective of human health.

At this point - I am writing this as I do the research - I do not know if the 12 compounds at the baseball field exceed the SSLs establish for a resident.  Lets put this data in a more user friendly format to find out:

In looking at the Screening Levels that were calculated for chronic exposure to these 12 contaminants, none of the concentrations found by Mr. Garcia's class in the soil at the baseball field are exceeded.  That's just as I suspected when I looked at them on the website.

This means, that based on one sample collected, assuming that it is representative of the baseball field where children play, the level of contaminants found are low enough to be protective of public health.  Magnesium and Manganese are not public health concerns in soil which is why they are not calculated.

This soil sample, along with the two groundwater samples that were collected, does not support the conclusion of the press release:

Contaminated debris blows onto public and private property throughout the village and surrounding natural areas, exposing residents -- more than a quarter of whom are children under the age of 16 -- and local wildlife to arsenic and heavy metals such as lead, mercury and cadmium. Visit www.CleanUpDePue.org to see an interactive map that details the way-above-normal concentrations of pollutants at hundreds of contaminated sites.

...at least for the baseball field.  I guess we need to look at Mr. Garcia's samples for the other stops on the virtual tour.  If the baseball field does not have concentrations "way-above-normal", maybe somewhere else does.

Next Post: The Village of DePue: Where are they way-above-normal? - Part 5

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