Arsenic in Rice: Part 8 - How Low Can You Go?

Consumer Reports implies that rice above a 5 ppb standard poses a "troubling," "worrisome," "cause for concern," or "potentially harmful"situation for those who eat it.

Using the 5-ppb standard in our study, we found that a single serving of some rices could give an average adult almost one and a half times the inorganic arsenic he or she would get from a whole day’s consumption of water, about 1 liter.

That threshold of "5-ppb" came from New Jersey:

[t]he 5 μg/l arsenic MCL [was selected] after consideration of the findings and recommendation of the New Jersey Drinking Water Quality Institute (Institute). The Institute reviewed the reports issued by the National Academy of Sciences (NAS) on the health effects of arsenic in drinking water in 1999, as well as an update of this report released in 2001 (Arsenic in Drinking Water: 2001 Update, NAS Press, 2001).  Based on the current NAS analysis, the Institute determined that the drinking water concentration that results in a one-in-one-million excess lifetime risk of lung and bladder cancer for United States populations was an estimated 0.003 μg/l (or three nanograms per liter or three parts per trillion).

Therefore, in view of its concerns regarding reliable removal technology, the [New Jersey Department of Environmental Protection] determined to promulgate the arsenic MCL at 5 μg/l. This determination comports with the NJSDWA mandate to establish the MCL at the most protective level within the constraints of medical, scientific and technological feasibility.

Even at that, some folks, like Jeffrey H. Tittle with the Sierra Club were not happy:

Source

How New Jersey got to "5-ppb" is important because it is what Consumer Reports uses to inform their readers that rice samples found with inorganic arsenic over that threshold of "5-ppb" is "troubling," "worrisome," "cause for concern," or "potentially harmful."  If 5-ppb is okay for Consumer Reports and is implied to be "safe," they are telling the Sierra Club that 3-ppb is too low.  But I digress....

5-ppb, which is 5 μg/l, was the amount settled on because a water system cannot effectively treat water to get the arsenic down below 5 ppb.  If you cannot treat it to less than 5 ppb, then all water systems with arsenic above 3 ppb would be in violation.  Even though the Sierra Club and the NJ Institute believe 3 ppb should be the standard, that unfortunate little devil called "reality" steps in and tells them that you can't always get what you want.

The point here is this:  5 ppb or 3 ppb is not the number that will get you to what New Jersey's law wants - which is an excess cancer risk of one in one million.  To get to that risk level, 1 in 1,000,000 the water must have an inorganic arsenic concentration of  "0.003 μg/l (or three nanograms per liter or three parts per trillion)."

My point is that none of these numbers, 5 μg/l, 3 μg/l, or 0.003 μg/l, are thresholds to which exceeding them by up to 5 ppb would be "troubling," "worrisome," "cause for concern," or "potentially harmful," as Consumer Reports tells its readers.

So lets look at just how conclusive that number of 0.003 μg/l (or three nanograms per liter or three parts per trillion) is.  That number presents an acceptable risk on one excess bladder/lung cancer per 1,000,000.  Basically anything above 0.003 μg/l increases the risk.  When, I will ask, does that increase start to meet the Consumer Reports designation of "troubling," "worrisome," "cause for concern," or "potentially harmful?"

New Jersey came up with the Slope Factor that produced 0.003 μg/l,using the research performed by the National Academy of Sciences (NAS) who put forth the NRC report,  In the NRC report we learn:

Because the EPA did not present theoretical lifetime excess bladder and lung cancer risk estimates [in 2000], the [NAS] used linear extrapolation from the EDs [1% Effective Dose's] presented in Morales et al. (2000) to estimate these risks at 3, 5, 10. and 20 μg/l .

So here we are in 2012.  New Jersey settled on 5 μg/l, they proposed 3 μg/l which would have made the Sierra Club happy, but REALLY wanted 0.003 μg/l.  The EPA, on the other hand, came up with an MCL of 10 μg/l and an MCLG of zero.

So many numbers, so many choices of "safe."

And when you look at how those numbers were derived, one thing starts to pop out at you (well at me anyway).  That is, there is a connection that binds them all:

After the publication of the proposed rule, Morales et al. (2000) published a study in which a risk assessment for mortality from several internal cancers was presented.  The risk assessment was based on reanalyses of the data from southwestern Taiwan.  Risk estimates were calculated for mortality from lung, bladder, and liver cancers, as well as combined cancer deaths, using 10 different statistical models, calculated with and without a Taiwanese comparison population.  [NRC]

Which then tells us this:

EPA was considering those analysis in the final rule making [that established the current 10] and, therefore, published a Notice of Data Availability in the Federal Register summarizing and further analyzing the information from Morales et al. [NRC]

Which leads to the EPA producing a draft document in 2010 called the "IRIS Toxicological Review of Inorganic Arsenic (Cancer)" where we learn this:

In the course of this analysis, EPA has investigated the impact of alternative model forms on the cancer risks estimated for the Taiwanese and U.S. populations for individual endpoints (lung and bladder cancer). Based on the past experience of Morales et al. (2000) and modeling results presented by NRC (2001), this effort was limited to exploring alternative forms for the dose dependence of risks.

These MCLs, these thresholds for what is "safe," are the result of a Slope Factor that is used to estimate excess cancer risk from inorganic arsenic that was derived this way:

EPA investigated a range of model forms for use in the risk assessment, building on previous efforts, including U.S. EPA (2001) and Morales et al. (2000).  The model used in the derivation of the preferred risk assessments employs:

• Poisson regression (of cancer mortality against age and dose) fit by maximum likelihood estimation (MLE).
• A quadratic age model.
• A linear multiplicative dose term.
• Confidence limits on the dose term estimated by profile likelihood.
• Estimates derived for the data set that includes the southwest Taiwan reference population.

That's complicated toxicologist talk.  What I want to focus on is that all of these numbers are based on a Slope Factor that comes from data provided by some guy named "Morales" and his friends "et al."

Morales...Morales...Morales...

Next Post: Arsenic in Rice:  Part 9 - The Broad Shoulders of Morales et al.

.

Arsenic in Rice: Part 7 - EPA and IRIS

So what do we know so far...

• Consumer Reports compares the amount of arsenic found in rice to the New Jersey threshold for arsenic in drinking water.
• New Jersey set its arsenic level based on the "limits of medical, scientific and technological feasibility."
• The New Jersey limit is based on data presented in the National Academy of Sciences (NAS) report titled Arsenic in Drinking Water: 2001 Update
• The NAS report is based on a health risk assessment performed by the EPA in 1996.
• The EPA had proposed an arsenic standard for drinking water of 5 μg/l
• The EPA set an MCL standard of 10 μg/L on January 22. 2001 based on dose-response models and extrapolation from a cancer study of Taiwanese population exposed to high concentrations of arsenic in its drinking water.

We went from a proposed threshold of 5 μg/L to a threshold of 10 μg/L.  New Jersey, in 2004 takes that information and ends up back at 5 μg/L. Interesting...

Which brings us to present time.  February 19, 2010 EPA places in the Federal Register a notice for public comment the "2010 draft document titled, Toxicological Review of Inorganic Arsenic: In Support of the Summary Information on the Integrated Risk Information System (IRIS)":

The purpose of this Toxicological Review is to provide scientific support and rationale for the hazard and dose-response assessment in IRIS pertaining to chronic exposure to inorganic arsenic.

In the document, the EPA states:

Quantitative risk estimates may be derived from the application of a low-dose extrapolation procedure. If derived, the oral cancer CSF (CSF) is a plausible upper bound on the estimate of risk per mg/kg-day of oral exposure.

 Heading on down to page 151, I read, in bold print, this:

In keeping with EPA policy, the combined oral CSF for women (25.7 per mg/kg-day) is appropriate for use in establishing health criteria, since, based on the available data, women appear to be the more sensitive group.

Wow, that's a significant difference in the Slope Factor New Jersey used which was 11.6 mg/kg-day.  At that Slope Factor, New Jersey determined that the drinking water concentration that results in a one-in-one-million excess lifetime risk of lung and bladder cancer for United States populations was an estimated 0.003 μg/L (or three nanograms per liter or three parts per trillion).

With a Slope Factor of 25.7 per mg/kg-day that estimated μg/L will be even lower.  So lets look at estimating what exactly that risk would be.  I'll use the IRIS calculation for that:

IRIS - Draft

With that formula in Equation 5-4, we can calculate the excess risk for one μg/L of arsenic at a Slope Factor of 25.7 per mg/kg-day.

25.7 x 0.001 x (1 / 70) = 3.67 excess cancers in 10,000 per μg/L of arsenic.

Let's put this into play.  If Consumer Reports believes that exceeding 5 ppb of arsenic is "troubling," "worrisome," "cause for concern," or "potentially harmful," then the risk they are assuming what is "safe" will present a risk of  8 excess bladder and lung cancers per 10,000 if the Slope Factor is 11.6 mg/kg-day as New Jersey used.

If the 2010 EPA IRIS Slope Factor of 25.7 mg/kg-day is used, 5 ppb would present a risk of  2 excess bladder cancers per 1,000.

You should start to see the problem we produce when we draw a line in the sand and claim "safe" on this side and "troubling," "worrisome," "cause for concern," or "potentially harmful," on the other.  It is only safe if the starting point for where "safe" begins is agreed upon.

Because Consumer Reports is using 5 ppb based on the New Jersey standard, it is claiming that "safe" means no more than 8 excess bladder and lung cancers per 10,000.  If New Jersey was wrong, and the EPA is correct, what Consumer Reports considers "safe" is now 2 excess bladder cancers per 1,000.

If you think about it, that number "5" does not really mean "safe" anyway - nor does it mean "troubling," "worrisome," "cause for concern," or "potentially harmful."  It is a theoretical number based on a model that spits out a value we say defines the risk.  The question becomes is how close to reality is that theoretical number?

To use "5" - as Consumer Reports does - is to say definitively that 5 is "safe."  "5," however, is just a threshold established by the EPA and New Jersey based on a theoretical calculation of a cancers potency (the Slope Factor).  That calculation, along with our technological ability to remove arsenic down to that level, is what sets the level which, for New Jersey, becomes known as "most protective."

If arsenic is a carcinogen, then less is better.  Period.  But with that in mind, exceeding a threshold based on a theoretical calculation does not make the product "troubling," "worrisome," "cause for concern," or "potentially harmful."

What does it make it then?  Good question.  Thanks for painting me into a corner.

All I can tell you is that exceeding 5 ppb does not make it "troubling," "worrisome," "cause for concern," or "potentially harmful."  Does that clear things up?  Now you see my problem with reports such as these.  They elude to something dangerous, when all that happened is that in some samples the threshold was exceeded.

That number detected - that concentration - would need to be significantly higher than 5 ppb before it got anywhere close to being "troubling," "worrisome," "cause for concern," or "potentially harmful"  So what would be considered significantly higher to warrant those concerns?  Good question, at least, in my opinion, rice that result in an 70 kg adult uptake of 56 μg of inorganic arsenic per day.  That would make me concerned (0.8 x 70 = 56 IRIS).  That would be at least six (6) servings of the highest concentration (9.4 μg/L) of inorganic arsenic Consumer Reports found in the rice.

But let's say the real hazard for arsenic is cancer, and that 10 ppb is not protective enough based on the Slope Factor's calculated.  In this case, we will need to look deeper into at how that Slope Factor was determined.  Is 5 ppb a good threshold?  Too restrictive?  Not protective enough?  We'll need to look at how they came up with it to make that call.


Next post: Arsenic in Rice:  Part 8 - How Low Can You Go?


.

Arsenic in Rice: Part 6 - In the beginning there was a model

The issue I have with Consumer Reports looking into the amount of arsenic in rice is not that they report it, but that they and their experts do not honestly explain what the data means.  Yeah, they found arsenic, but they also sounded an alarm telling their readers that the concentration of arsenic they found was "troubling," "worrisome," "cause for concern," or "potentially harmful."

Consumer Reports, aided by public health experts they consulted with, drew a line in the sand stating that on this side it was "safe" and on the other side...well...:

We found significant levels of inorganic arsenic, which is a carcinogen, in almost every product category, along with organic arsenic, which is less toxic but still of concern. Moreover, the foods we checked are popular staples, eaten by adults and children alike. 

Once again, they drew a line in the sand using the New Jersey value for arsenic in drinking water as the threshold.

Using the 5-ppb standard in our study, we found that a single serving of some rices could give an average adult almost one and a half times the inorganic arsenic he or she would get from a whole day’s consumption of water, about 1 liter. 

What this implies is this:

By assuming that 5 ppb is safe, they imply that anything above that value is unsafe.  Make no mistake about that implication, that is exactly the message they want projected.  Arsenic is a carcinogen, therefore any amount of carcinogen cannot be anything but "troubling," "worrisome," "cause for concern," or "potentially harmful."

True statement that.  Can't argue against it, if that's true.  So I wont.

What I will argue against is accepting that 5 ppb is "safe" and anything above 5 ppb is unsafe.  Why argue this?  Because it assumes that 5 ppb is safe in the first place.  It assumes that 5 ppb is an acceptable threshold because New Jersey established it.  It assumes that 5 ppb actually represents a value that below which is protective of public health and above which presents risk.  Consumer Reports uses 5 ppb as a threshold for safe.  And by doing that, by drawing a line in the sand, they imply that rice with more than that amount is cause for concern.

What is troubling here is this.  5 ppb is not the value that represents safe, 0.003 ppb is.  If, and that is a huge if, the potency for arsenic is correct (the Slope Factor) then 0.003 ppb is the threshold not 5 ppb.  Therefore, exceeding 5 ppb does not fundamentally change the risk until that risk becomes significant.

Calling the arsenic concentrations they detected in rice "troubling," "worrisome," "cause for concern," or "potentially harmful," implies that the exceedance presented a significant risk.  Consumer Reports, however, does not address that, only stating that "we found that a single serving of some rices could give an average adult almost one and a half times the inorganic arsenic he or she would get from a whole day’s consumption of water, about 1 liter."

So I'll ask this question;  Does an adult consuming almost one and a half times the inorganic arsenic he or she would get from 1 liter of water increase their risk significantly enough to be "troubling," "worrisome," "cause for concern," or "potentially harmful."

Consumer Reports does not answer that question in their report.  They are very crafty on how it is written.  They do not answer it because they cannot.  This is the corner we paint ourselves into.  If there is zero threshold for carcinogens, and arsenic is a carcinogen, then any amount of arsenic presents a risk.  If we assume that 5 ppb is what we can get it down to, then we will set 5 ppb as the new "zero" and anything above 5 ppb will be "troubling," "worrisome," "cause for concern," or "potentially harmful."

Now I'll ask another question; Is 5 ppb a reasonable - or sound - number to use as the threshold?  After all, we know from reading the New Jersey justification that they chose 5 ppb, instead of 0.003 ppb, because it would not be technologically possible to treat the water to a level below 5 ppb.  In other words, New Jersey took the lowest possible concentration of arsenic that could be obtained.  They did this because the actual number they wanted is lower than that.  The assumption here is that 5 ppb is where we can get to, and going that low is necessary because the one in one million mandated risk concentration is calculated to be 0.003 ppb at that Slope Factor.

What if, however, that number - 0.003 ppb - is not a realistic - or sound - number?  What if the Slope Factor that was used to determine that risk of one in one million excess cancers is off?  What if the excess bladder and lung cancers actually seen in the United States is no where near the two in 1000 or one in 100 the scientists estimated in their modeling?  Would that change things?

Let's start here:

Arsenic in Drinking Water 2001 Update

When New Jersey set out to protect it citizens, it was faced with this little bit of the toxicological nightmare.  In order to protect public health we need to draw a line in the sand by establishing a threshold.  At one time the threshold for arsenic in drinking water was 50 μg/L

How did we get to 5 ppb?  Well it all starts here...

In 1988, EPA conducted a risk assessment for arsenic in drinking water and, in 1996 requested that the National Research Council (NRC), the operating arm of the National Academy of Sciences and the National Academy of Engineering, independently review the scientific database and evaluate the scientific validity of the risk assessment.  In response to that request, the NRC published Arsenic in Drinking Water in 1999.  following that report, EPA proposed an arsenic standard of 5 μg/L in the Federal Register.

That's from a document called Arsenic in Drinking Water 2001 Update produced by the National Research Council (NRC),  There are two things you should notice, one is that this is from the NRC and the second is the proposed arsenic standard of 5 μg/L.

To answer that question of how did we get to 5 ppb, it started here.  In fact everything involving the risk associated with arsenic in drinking water, the threshold Consumer Reports is using, started from this risk assessment.  That's what New Jersey used to justify their "most protective" limit of 5 μg/L.

[t]he New Jersey Drinking Water Quality Institute (Institute) reviewed the reports issued by the National Academy of Sciences (NAS) on the health effects of arsenic in drinking water in 1999, as well as an update of this report released in 2001 (Arsenic in Drinking Water: 2001 Update, NAS Press, 2001). Based on the current NAS analysis, the Institute determined that the drinking water concentration that results in a one-in-one-million excess lifetime risk of lung and bladder cancer for United States populations was an estimated 0.003 μg/l (or three nanograms per liter or three parts per trillion).

Hmmm.  So this is where the Slope Factor used to calculate the 0.003 ppb came from.  Interesting, I bet there will be something else of interest we can find other than a boring ol' history lesson.  Speaking of history, here is what we find out by reading the NAS report:

After review by EPA's Science Advisery Board (SAB) and a period of public comment, EPA issued a pending standard of 10 μg/L on January 22. 2001.  That pending standard was based on dose-response models and extrapolation from a cancer study of Taiwanese population exposed to high concentrations of arsenic in its drinking water.   

So, the EPA proposed standard was 5 μg/l and what we ended up with was 10 μg/L.  That threshold of 10 μg/L was based on a dose-response model, which means it was based on a non-cancer risk.  Interesting...they also extrapolated for cancer, but still did not find it necessary to drop it down to the proposed 5 μg/L.  Off course that was in January 2001, the New Jersey assessment was made in 2004.  So something happened to move the EPA away from a non-cancer dose response that supported 10 μg/L and to a cancer slope factor that would justify 5 μg/L?

Hold on to your hats, its going to get a bit bumpy from this point on.

Next post: Arsenic in Rice:  Part 7 - EPA and IRIS

.

Arsenic in Rice: Part 5 - What Does "Most Protective" mean in New Jersey?

There is a reason for all these posts on one topic.  If you have read any of my other post, you will see that some 'splainen has to be done to support my conclusion.  I am pretty sure I know what my conclusion will be about Consumer Reports' research on inorganic arsenic found in rice.

It's not that they went looking for the arsenic that bothers me, it is how they describe what they found to their readers:

• "troubling" 
• "worrisome" 
• "cause for concern"
• "potentially harmful"

Those words mean something.  They mean exactly what they sound like.

So the question I am posing at this point in time, before I run through all the numbers, is; Is this terminology appropriate for the concentration of arsenic that Consumer Reports detected in the samples of rice they tested?

I like Consumer Reports.  I think they do good science.  However, as with their report on apple juice, they are not able to properly and/or adequately explain what the data they gathered actually means.  Like their report on arsenic in apple juice, this one regarding arsenic in rice uses expertise that support and conclude an incorrect conclusions on the risk.

I am starting to see a pattern here with these two reports and the experts they rely on.  These claims of  "troubling," "worrisome," "cause for concern," or "potentially harmful," are not supported by the data nor reality.  The experts Consumer Reports consults with must - or should - be aware of this.

It appears to me that the agenda of Consumer Reports is to protect public health by supporting a move towards lower and lower exposure levels.  In principle, this is a noble goal, but it is not necessary.  The EPA seems to be following this same philosophy, which is why I posted this quote from TCEQ's Dr. Honeycutt on my second post and also used it in my presentation at the AHMP conference two weeks ago.

So onward...

With a Slope Factor of 11.6  (mg/kg-day)-1, New Jersey estimates no more than one excess bladder/lung cancer out of a million over a 70 year lifespan for a concentration of arsenic in the drinking water of up to 0.003 μg/L

0.003 μg/L = 1 in 1,000,000 excess cancer risk over a lifetime based on drinking 2 liters/day.

The regulatory limit that New Jersey sets for arsenic in the drinking water is 5 μg/L.  New Jersey claims that this level is "most protective." (NJ)

So if 0.003 μg/L = 1 in 1,000,000 excess cancer risk over a lifetime, what is the excess cancer risk we will see at the "most protective" concentration of 5 μg/L.

Fun Time with Math!

....substitute 0.003 for 5, and we get a risk of 2 excess cancers per 1,000 (2.E-03)

5.0 μg/L = 2 in 1,000 excess cancer risk over a lifetime based on drinking 2 liters/day

You can calculate those numbers yourself, but that's what you get - and - they are consistent with the risk reported in supporting documents used by New Jersey (more on that in a later post):

Arsenic in Drinking Water 2001 Update

So if two excess cancers in 1000 is considered "most protective," would increasing that risk to three excess cancers in 1000 be considered  "troubling," "worrisome," "cause for concern," or "potentially harmful,"

If we are "most protective" at a concentration that theoretically will bring about 2 excess cancers in 1000, are we that more worse off at a concentration that increases that risk by one or two?

We need to stick some reality in here.  If 10 μg of arsenic consumed when drinking 2 liters of water brings forth 2 excess cancers in 1000, does New Jersey see that rate of cancer in their population?

Think about that for a moment.  Do we see that many bladder and lung cancers in the United States?  Remember, that's the estimated excess cancers from drinking 2 liters of water.  For those folks in New Jersey that drink two liters of water AND eat rice at 10 μg of arsenic, their rate of excess bladder/lung cancer doubles.  Do we see that many cases of bladder cancer?  I'll look at that in a few posts from now.

If Consumer Reports believes that the level of arsenic in rice should be at the "most protective" level set by New Jersey, then "troubling," "worrisome," "cause for concern," or "potentially harmful," is based on exceeding that level.  They are reporting that we are safe at a concentration that results 2 excess cancers per 1000 and harmful at anything above that.  Are we?

Did anyone at Consumer Reports ask this question; What is the actual rate of bladder and lung cancer in the United States?  If we know the concentration in rice is that high, are we seeing that much bladder and lung cancer in our population?


Next post: Arsenic in Rice:  Part 6 -  In the beginning there was a model

.

Arsenic in Rice: Part 4 - Slope Factor...one more time!

I have written about the good ol' Slope Factor a number of times.  It is how we look at the risk from exposure to chemicals we view as carcinogens.  Carcinogens are where we have painted ourselves in the corner by claiming:

In contrast, the Federal SDWA sets an MCL goal of “zero” for carcinogens. (NJ)

You cannot have zero, so why even bring it up?  All it does is sets the stage for lower and lower exposure limits because zero becomes the goal.

If the cornerstone of the science of toxicology is accepting the premise that there is a "range of exposures from zero to some finite value can be tolerated by the organism with essentially no chance of expression of the toxic effect," then zero is just as relevant to protecting public health as some other number.  The quest is to find that number and set that as the threshold.

New Jersey has set the threshold at 5 ppb which it claims is "the most protective level within the constraints of medical, scientific and technological feasibility" for protecting public health from and "excess lifetime risk of lung and bladder cancer"

From my last post, we learned that 5 ppb is a threshold that was derived because of technological feasibility. In other words, ain't no way to treat water for arsenic to get it below that concentration.

The real number they wanted to see was 0.003 ppb which would give them an excess risk of one in one million excess cancers in a 70 year lifetime.

Now that we know those two values, 0.003 and 0.000001 (one in one million) we can calculate the slope factor they used in their calculation.

To do this we will use the method developed by California's EPA (CalEPA) for determining the "no significant risk level" (NSRL) for Proposition 65 "Known to the State of California to Cause Cancer" notifications.

Source

California uses a lifetime cancer risk at or below one in one hundred thousand (10-5 or 0.00001).  New Jersey sets the risk at or below one in one million (10-6 or 0.000001).  New Jersey law in this case aims to be more protective since zero is a non-attainable number.

What we need to do now is find the Cancer Slope, which CalEPA calls the qhuman.  The qhuman is a value described in terms of  (mg/kg-day)-1.

To get this value, we will need to convert our 0.003 ppb (which is in μg/L) to the amount in milligrams (mg).

So...if there are 1000 μg in a mg, the μg is 1000 times smaller than a mg.  Which makes 0.003 μg equivalent to 0.000003 mg.

Here is where it gets a bit confusing.  That number that New Jersey came up with, that's for a safe level of arsenic in drinking water for a life time excess cancer risk of one in one million.  A lifetime is 70 years and the amount of drinking water we consume is calculated on 2 liters a day.  So, the total amount of arsenic that would be consumed over a lifetime is 0.006 μg.

In other words, if a 70 kg person drank two liters of water a day, they would consume a total of 0.006 μg of arsenic from that water.  At that total amount, the drinking water would pose no more than one additional bladder or lung cancer in one million folks drinking the same water.

The key then is to keep the total arsenic from drinking water to at or below 0.006 μg or 0.000006 mg.

That total concentration is based on the potency of the carcinogen we are looking at.  That potency is called the slope factor and is a "theoretical estimate for humans" which CalEPA calls the qhuman which is in (mg/kg-day)-1.

Math time!

Using the CalEPA formula, I calculated the qhuman (Slope Factor) that was used by New Jersey to come up with the 0.003 μg/L for drinking water to give a lifetime cancer risk of one in one million excess bladder/lung cancers.

By my calculation, the qhuman (Slope Factor) = 11.6  (mg/kg-day)-1

That Slope Factor is consistent with the one the one the EPA uses for their male bladder cancer lifetime incidence estimate:

Table 5-3 Male Bladder Cancer Lifetime Incidence Estimate.xls

So now that we have the Slope Factor, we can look at the theoretical risk at different concentrations, such as 5 ppb and 10 ppb.

Next Post: Arsenic in Rice:  Part 5 - What Does "Most Protective" mean in New Jersey?

.

Arsenic in Rice: Part 3 - Why is 5 ppb the "safe" threshold for arsenic?

According to Consumer Reports:

No federal limit exists for arsenic in most foods, but the standard for drinking water is 10 parts per billion (ppb). Keep in mind: That level is twice the 5 ppb that the EPA originally proposed and that New Jersey actually established. Using the 5-ppb standard in our study, we found that a single serving of some rices could give an average adult almost one and a half times the inorganic arsenic he or she would get from a whole day’s consumption of water, about 1 liter. (CR)

In their earlier report on arsenic and apple juice they write:

The Environmental Protection Agency periodically revises its assessment of the toxicity of various chemicals to offer guidance on drinking-water standards. Based on such a review, the agency changed the water standard for arsenic to 10 ppb, effective in 2006, from the 50-ppb limit it set in 1975. The EPA had proposed a 5-ppb limit in 2000, so the current limit is a compromise that came only after years of haggling over the costs of removing arsenic. Since 2006, New Jersey has had a 5-ppb threshold, advising residents that water with arsenic levels above that shouldn't be used for drinking or cooking. (CR)

According to Consumer Reports, the New Jersey "5-ppb threshold" is the standard to which arsenic concentrations in the items we consume should be compared to.  This assumes that we are all on board with the idea of a threshold concentration below which we would consider the foodstuff to be "safe."

Why 5 ppb?  What does New Jersey know about the risk of arsenic in drinking water that the EPA does not know?  The EPA has a enforceable limit, a threshold, they call the maximum contaminant level (MCL) and has set the concentration at 10 ppb.

As Consumer Reports reminds its readers to "Keep in mind: That level is twice the 5 ppb that the EPA originally proposed and that New Jersey actually established" one must assume that 5 ppb is therefore "safe" and 10 ppb is, well, err..."troubling", "worrisome," or "potentially harmful?"

Where did that number "5-ppb" come from?  How did they end up with 5 and not 6, or 3, or 10?  One of the cool things about the government is that before it makes a regulation it has to put it out there for public comment.  The other cool thing is the internet and Google!

Here is what New Jersey says is their justification for a threshold of 5 ppb and not 10 ppb like the EPA uses for its MCL.

The NJSDWA differs from the Federal SDWA regarding the process for establishing MCLs.  For carcinogens, the NJSDWA mandates a cancer risk level of one-in-one-million additional cancer cases over a lifetime of exposure. (NJ)

What does the New Jersey say about arsenic as a carcinogen?

Arsenic is one of a relatively small number of chemicals that has been classified by the USEPA as a known human carcinogen, based on human epidemiological studies. Exposure to high concentrations of arsenic through drinking water has been linked to several types of cancer, including skin, lung, and bladder cancer.  (NJ)

So New Jersey sees arsenic as a carcinogen therefore they mandate "a cancer risk level of one-in-one-million additional cancer cases over a lifetime of exposure."

Which means that 5 ppb must be the maximum level of arsenic in a liter of water that will meet the threshold of "one-in-one-million additional cancer cases over a lifetime of exposure."  That's correct isn't it?  5 ppb is the threshold for the mandated cancer risk level of "one-in-one-million additional cancer cases over a lifetime of exposure?"

Yeah, I'm beating to hell that dead horse but this is important and it gets to the heart of the matter when looking at concentrations above a threshold.  If New Jersey law mandates a one in a million cancer risk, then 5 ppb must be the maximum concentration so that at or below we would see no more than "one-in-one-million additional cancer cases over a lifetime [70 years] of exposure."

That 5 ppb is what Consumer Reports uses as the threshold for rice.  And when their analysis showed levels above that, they printed them in red and used terms such as "troubling", "worrisome," "cause for concern." or "potentially harmful."

If the arsenic threshold is set by New Jersey at the concentration that will bring a cancer risk level of one-in-one-million additional cancer cases over a lifetime of exposure, is 5ppb, then any concentration above 5 ppb will increase that risk to more than one.  How much above one would we consider too much risk?

Now New Jersey had to do some toxicology and risk calculations to get to this number.  And good ol' government transparency makes that information public knowledge.  Since they were "mandated" to derive a cancer risk level of one-in-one-million additional cancer cases over a lifetime of exposure, they did the calculation and found:

Based on the current National Academy of Sciences (NAS) analysis, the New Jersey Drinking Water Quality Institute (Institute) determined that the drinking water concentration that results in a one-in-one-million excess lifetime risk of lung and bladder cancer for United States populations was an estimated 0.003 μg/l (or three nanograms per liter or three parts per trillion). (NJ)

Wait...does that say 3 parts per TRILLION?  Huh?  The threshold New Jersey uses to say the water is "safe" - and the threshold that Consumer Reports uses to claim rice that exceeds that threshold to be "troubling", "worrisome," "cause for concern." or "potentially harmful" - is 1666 times higher than the concentration that "results in a one-in-one-million excess lifetime risk of lung and bladder cancer."

Lucy!  You got some 'splainen to do!

According to New Jersey:

Therefore, in view of its concerns regarding reliable removal technology, the Department determined to promulgate the arsenic MCL at 5 μg/l [ppb]. This determination comports with the NJSDWA mandate to establish the MCL at the most protective level within the constraints of medical, scientific and technological feasibility. (NJ)

So it is 5 ppb instead of 0.003 ppb because arsenic in water cannot currently be treated to a level below 5 ppb.  Well then why is the EPA at 10, if 5 ppb is "most protective?"  Well you see...

USEPA conducts a cost-benefit analysis that considers the implementation costs of an MCL for water systems and their customers, which in some cases results in adjusting the MCL to a different level than might be the case if such costs were not considered. Because the MCL-setting process under the NJSDWA does not include a costbenefit analysis, the State MCLs for certain contaminants, such as arsenic, are more stringent than the Federal MCLs. (NJ)

Well now, isn't that nice, reality and costs come into play when trying to figure out a threshold.  So if 0.003 ppb is what we really need to be protective, how much more lung and bladder cancer above one-in-one-million additional cancer cases over a lifetime of exposure are we expected to see?

And, based on those numbers of additional cancer, how many more would we see at 10 ppb?  And then, in looking at those numbers, if we assume, as New Jersey does, that 5 ppb is the "most protective level within the constraints of medical, scientific and technological feasibility," how much less protective would 10 ppb of arsenic in the drinking water be.  If 0.003 ppb spits out a number of one-in-one-million, 5 ppb and 10 ppb will spit out a number as well.

So, once we know the x-in-one-million number for 5 ppb, we can compare the y-in-one-million number for 10 ppb to see if that number, y - x, is so high that we would consider it to be "troubling", "worrisome," "cause for concern." or "potentially harmful."

Remember, the number we will get for 5 ppb is considered "most protective" so how much above that x-in-one-million number can be considered "troubling", "worrisome," "cause for concern." or "potentially harmful?"

Cool, we get to use the slope factor.

Next post: Arsenic in Rice:  Part 4 - Slope Factor...one more time!

.

Arsenic in Rice: Part 2 - Let's Agree to This...

In my presentation on "Arsenic, Apple Juice, and Risk" at the Anchorage, Alaska AHMP conference last week, I started out with this slide:

My presentation was not directed at the EPA, although the EPA played a big part in it.  It was geared toward the concept of how we look at risk from exposure to a chemical.  Basically, I have come to accept a few tenants with regard to toxicity.  The first being that there is a dose-response which brings about an acceptance that there is, therefore, a level that is safe.

If that is true, and it must be if we are to come up with a safe level, for example, the "safe" level of arsenic in apple juice or rice, we must accept this philosophy as truth.  I do, and I was trying to get my audience to accept it as well.  With that in mind, I put up this slide:

I thought the "line in the sand" was a good way to illustrate this concept.  With that line, I could visually show what was meant by a threshold and how that threshold signifies the idea of "safe."

The problem is, once we establish a threshold, what does it mean when we fall on the other side of the "safe" line?  What does being on that side mean?

This, in my opinion, is the $64,000.00 question.  We have painted ourselves in a corner that is becoming increasingly difficult to get out of.  Simply put, if it is "safe" over here, what is it over there?  C'mon...you know what it is, and so does the general public.  If it is "safe" over here it is "unsafe" over there.  And unsafe requires actions to get us to the safe area.  

But that's not risk of chemical exposure works.  The "safe" area - the threshold - means:

"daily exposure to the human population (including sensitive subgroups) [to that dose is] likely to be without an appreciable risk of deleterious effects during a lifetime [70 years]. (EPA)

If the cornerstone of the science of toxicology is based on the individual threshold hypothesis that:

"a range of exposures from zero to some finite value can be tolerated by the organism with essentially no chance of expression of the toxic effect.” (EPA)

Then we must agree that there is an amount of arsenic in apple juice and rice that is "likely to be without an appreciable risk of deleterious effects during a [70 year] lifetime.  Most importantly, we must move away from the philosophy that there is no safe level of exposure, as Dr. Honeycutt with the Texas Commission on Environmental Quality (TCEQ) is accusing the EPA of adapting

If we cannot agree that there is a "safe" level, then you might as well stop reading at this second post.  If you can accept that, then we can move on.

So what is the "safe" amount of arsenic that can be in rice so that it is likely to be without an appreciable risk of deleterious effects during a [70 year] lifetime?

Consumer Reports indicates that the "safe" level is less than 5 µg/L or 5 ppb:

No federal limit exists for arsenic in most foods, but the standard for drinking water is 10 parts per billion (ppb). Keep in mind: That level is twice the 5 ppb that the EPA originally proposed and that New Jersey actually established. Using the 5-ppb standard in our study, we found that a single serving of some rices could give an average adult almost one and a half times the inorganic arsenic he or she would get from a whole day’s consumption of water, about 1 liter. (CR)

The EPA established a threshold of 10 ppb as "safe", New Jersy established a threshold of 5 ppb as "safe."

Does this mean that 5 ppb is "safe" and  6 ppb is "unsafe"?  How can it be "unsafe" if the EPA says 10 ppb is "safe."  And why did Consumer Reports choose the New Jersey threshold to compare the concentration of arsenic found in a serving of rice?  Why 5 ppb?  Is 5 ppb "safe" because it is lower than 10 ppb or is it actually - really - safe?

This is what Consumer Reports is telling their readers:

The question I'm asking - and as I write this, I don't know the answer - is 5 ppb safe making anything above that concentration "troubling", "worrisome", or "potentially harmful?"

Why 5 ppb?  Why not zero?

For known human carcinogens such as inorganic arsenic, the EPA assumes there's actually no "safe" level of exposure. (CR)

If there is "no safe level" why is 5 ppb the threshold that indicates "safe."  Why 5 ppb, and, if that number is acceptable, why not 10 ppb?  If zero is the actual safe threshold, then 5 must pose some risk, correct?  Why is that risk okay, but the risk above 5 ppb "troubling", worrisome, or potentially harmful?

Next post: Arsenic in Rice:  Part 3 - Why is 5 ppb the "safe" threshold for arsenic?

.

Arsenic in Rice: Part 1 - We Meet Again

Bam!  Bam!  Bam!  Bam! Bam!  That's me banging my head on my desk after one of my fellow CHMMs sent me a link to this:

"Elevated Levels of Arsenic Found in rice Products."  Sept 19: "A new study from Consumer Reports found an increased amount of arsenic in some of the most popular brands of rice products.  TODAY's national investigative correspondent Jeff Rossen reports." (MSNBC)

Bam!  Bam!  Bam!  Bam! Bam! That's me beating this dead horse one more time.

Do you know what I did last week?  I presented my paper "Apple Juice, Arsenic, and Risk" at the 2012 AHMP Conference in Anchorage Alaska.  My paper was on Dr. Oz and Consumer Reports findings regarding arsenic detected in apple juice.  I wrote kind of extensively - ad nauseum some might argue - on this topic in bunch of previous posts.

So what new insight can I add to this new enlightenment coming from Consumer Reports?  At this point in time, I have not dived into it too deeply.  I do know that they have determined the range of inorganic arsenic in rice and published that range indicating, in red, where the concentration of arsenic exceeded the New Jersey standard for arsenic in drinking water.

Bam!  Bam!  Bam!  Bam! Bam!  If I have said it once, I will say it a million more times (see photo of Lego storm troopers beating a dead horse above to illustrate my point).  Do not - I repeat - DO NOT compare a value found in one thing with a regulatory limit set for another thing.  To pardon the pun, compare apple juice with apple juice, not apple juice with drinking water (read my previous posts if you want to know why).

Dear Consumer Reports; Stop.  Please stop reporting on what you find without having a full and complete understanding of what the numbers mean.  The experts you are consulting, with their highfalutin degrees and university connections are not giving you the full monty.  I am unsure as to what makes highly educated scientists lose sight of how their numbers stack up against reality.  You see, in assigning risk to an exposure, we are only as good as the data we can gather and the certainty we have in how accurate that data reflects our reality.  If the glove don't fit, you must acquit!

Which brings us to this:  Does the amount of arsenic that Consumer Reports found in the rice that they found reflect a risk of a health harm, in this case cancer, for those that consume it?

At this point in time, I don't know.  I remain skeptical of the findings because of how Consumer Reports looked at apple juice.  I am also skeptical because they lowered the threshold to the number New Jersey uses for arsenic in drinking water instead of the MCL that they compared apple juice to.  Why?  I suspect it was to get more red numbers in their table (red means it exceeded the threshold).  But that's speculation on my part.  Consumer Reports would not stoop that low, would they?

Next Post: Arsenic in Rice:  Part 2 - Let's Agree to This...


.