Arsenic in Rice: Part 13 - It's There, You Just Can't See It.

Wow, 12 posts already, my, I do like to ramble.

And ramble on I will!  There is a reason for this rambling I do, and that is one of soundness.  I am calling Consumer Reports out on their recent report on arsenic they found in samples of rice they tested.  I am making a case that the amount of arsenic they found and printed in red does not warrant the use of the terms "troubling," "worrisome," "cause for concern," or "potentially harmful."

I could just stop at one post and call them a bunch of cotton-headed ninny muggins and be done with it.  And even though I would be right that there is not cause for concern, without supporting my contention, I would be no better then them.

Consumer Reports bases "troubling," "worrisome," "cause for concern," or "potentially harmful," because some rice exceeded a threshold:



For me to say there is no health concern at the maximum concentration of inorganic arsenic found, 9.6 ppb, means I have to show why Consumer Reports concern is not warranted.  The previous 12 posts have focused on what that threshold of 5 micrograms actually means in terms of risk as well as tried to show how exceeding it up to 9.6 ppb does not pose a health concern.  I tried to do this by  by showing how New Jersey came up with the number "5" and how it is dependent on a Slope Factor that most likely does not represent the true risk it theoretically calculates.

If exceeding 5 micrograms per serving is "troubling," "worrisome," "cause for concern," or "potentially harmful," then rice below that amount is not.  And if 5 micrograms is safe, then we assume a certain number of excess bladder and lung cancers is therefor acceptable.  But we can only accept those excess cancers at 5 micrograms if the Slope Factor they used actually reflects the real risk.  And when we look at the actual risk at low levels of arsenic in drinking water, the researchers find:

Since the NRC reports, a number of studies have been published that did not find an increase of internal cancers at low level arsenic exposure. These include Guo (2000), Steinmaus (2003), Lamm (2003, 2004), and Bates (2004), all of which found no evidence of an increase in bladder cancer rate at low-level arsenic exposure levels. Both Guo (2004) and Chen CL (2004) found no increase in lung cancer rate at low-level arsenic exposure levels.

Which means when Dr. Lamm reports:

• An ecologic analysis of the white male bladder cancer risk in the United States found no increase over an arsenic exposure range of 3–59 μg/L (ppb).
• Case–control bladder cancer studies found no increased risk in the United States for exposures less than 80 μg/day (ppb).

...and we take those numbers, a maximum of 59 ppb and 80 ppb, finding 9.6 micrograms in one rice serving sample will show no increased risk for bladder or lung cancer.

Dr. Lamm, Dr Honeycutt, and the National Rural Water Association lead me to conclude that the Slope Factor - used by New Jersey and the EPA in the draft IRIS document - from data presented by Morales - is incorrect and does not represent the true risk of lung and bladder cancer seen at low levels.

Not so fast, say the NRC researchers:

NRC 2001 Arsenic in Drinking Water

Which leads them to write this:

NRC 2001 Arsenic in Drinking Water

So you mean to tell me that you can calculate the risk from data collected for "Liver, lung, and bladder cancer mortality data [that was] collected from death certificates of residents in 42 villages during 1973 through 1986"....

....And you can make a Slope Factor based on arsenic concentrations in the drinking water wells "collected from wells in the 42 villages between 1964 and 1966" (1)....

...And then you tell me that you cannot calculate the low level risk from the current data available in the US because of "unknown distribution of other risk factors?"

Really?  Tell them what I think about that Col Potter:















Here is what Dr. Lamm points out:

If an ecological study in the range of interest is desired, then the data are available for analysis from US government sources. These data would obviate the need to make speculative assumptions of differences in body weight, fluid consumption, nutritional status, etc. between the study population and the US population.

And here is what the EPA is concluding should be the Slope Factor and risk for arsenic

EPA IRIS

At that Slope Factor, we would expect to see 7.3 excess cancers in 1000 (7.3E-03).

Dr. Honeycutt with the TCEQ says "horse hockey" as well:

For bladder cancer alone, the incidence risk calculated by USEPA based on final draft values for males/females is 3.1E-04 per μg/L. Therefore, based on 2 μg/L as an average drinking water concentration, the estimated bladder cancer risk for the US population would be 6.2 per 10,000 or 62 per 100,000. However, the actual occurrence of bladder cancer in the US is about 23 cases per 100,000 (males/females combined). It would take 3 times the actual bladder cancer incidence for US males/females combined to even make possible the 62 cases per 100,000 estimated due to arsenic exposure from drinking water alone. Thus, the incidence risk calculated by USEPA final draft values for bladder cancer appears to be inaccurate and overly conservative.

Okay, so I have beat the hell out of this dead horse on Slope Factor.

If I have not supported by argument that the Slope Factor is incorrect, and, therefore the 5 ppb is incorrect, there is not more evidence I can offer.  I can say, based on what I have shown in these previous 13 posts, that rice that may go as high as 9.6 μg per serving is not "troubling," "worrisome," "cause for concern," or "potentially harmful."  It is just rice.

I have also concluded this as well about how a Slope Factor for cancer risk is calculated:

The ability to fit a line through data points does not necessarily mean that the underlying data adequately define the shape of the dose-response curve, including the critical low dose region.
(Honeycutt TCEQ)

Next Post: Arsenic in Rice:  Part 14 - Give me a "P"...Arsenic in the Urine

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Arsenic in Rice: Part 12 - Look No Closer Than Your Own Backyard

The real problem with Consumer Reports articles on arsenic in apple juice and rice is that it shows concentrations of arsenic that are not "troubling," "worrisome," "cause for concern," or "potentially harmful."

The rice report, specifically, conveys to the public that there is a risk by showing rice samples with arsenic concentrations printed in red.  This table of inorganic arsenic they found in the rice they samples is explained like this::

What message does Consumer Reports want their readers to leave with?  Should they stop consuming rice? Buy only brands without out the "red" numbers?  Throw out the rice they have in their pantries?  What should be done?

What, other than "troubling," "worrisome," "cause for concern," or "potentially harmful," will the average reader conclude when looking at those results?

This is the problem with a threshold.  Safe on one side, unsafe on the other.  What Consumer Reports and their experts are either woefully ignorant of, or are be purposely misleading, is that the New Jersey threshold of 5 ppb does not in itself mean "safe" nor does exceeding it by twice the amount, in this case 9.6 ppb (the maximum inorganic arsenic Consumer Reports detected) mean "unsafe."

That 5 ppb "limit" is nothing more than a number New Jersey wants based on the Slope Factor that shows a one in one million excess bladder/lung cancer risk of 0.003 ppb.

My point - and maybe i made it long ago - is that 5 ppb is just a number that can be obtained, it is not a number that exceeding it is "troubling," "worrisome," "cause for concern," or "potentially harmful."  It came about from a Slope Factor based on data from an ecological study from a high exposure population in Taiwan.

The Taiwanese dataset [data underlying the study Wu et al. (1989) study and the analyses in Morales et al. (2000)] has been analyzed by the NRC (1999; 2001) and the EPA]. It has served as their analytic database for estimating the risk of internal cancers from the ingestion of water containing inorganic arsenic. NRC considered that the reason for modeling with the SW-Taiwan data was that at that time there was insufficient information to assess the risk from low-level exposure and only the SW-Taiwan study had a sufficient quantity of data over a wide range of arsenic exposures that could be used for risk analysis and extrapolation. (Lamm 2005)

That same dataset is also being used EPA to lower the MCL of arsenic to 3 ppb, and it is based on the Slope Factor derived from that data.  That Slope Factor, the one that leads Consumer Reports to 5 ppb "limit" and is sending the EPA towards a 3 ppb limit, is being questioned as to its validity and the potential damage it will cause if it is adopted if it is indeed incorrect.  As Dr. Honeycutt with the TCEQ tells the EPA:

Proceeding with this SFo will unnecessarily alarm the public by giving a greater perception of harm and risk than is actually taking place.

Dr. Honeycut is not the only one who takes issue with the draft IRIS report and the Slope Factor derived from the Taiwanese dataset.  Here is what the National Rural Water Association wrote about this draft IRIS report:

High quality data from the US and elsewhere indicate much lower risks from iAs ingestion at the levels of exposure relevant for the past and current MCL, yet these studies are not used at all in the Agency’s new quantitative risk assessment because EPA focuses exclusively on the Taiwanese data.  

I know what you may be thinking: Well of course those two are opposed to a lower standard!  It's going to cost them money and effort!  Yeah, that could be the driver, but in the end, is what they are saying, their "point" sound?  Heck, even though I have no dog in this hunt, I have used 12 posts to support my point, and I got a lot more support I am going to throw out there.

Okay, so I'll give you the bias angle, is there anyone else that takes issue with the EPA and the dataset used to determine the Slope Factor?

Well I found something written by this guy named Steven H. Lamm.  He is an MD and an MPH (like me) and bills himself as a "Consultants in Epidemiology & Occupational Health, LLC. with Johns Hopkins University-Bloomberg School of Public Health Georgetown University School of Medicine."

I found a letter from him to the EPA Science Advisory Board (SAB), dated September 5, 2005.  He writes:

There are many questions regarding data quality that are raised by the above analysis. Are the diagnoses correct? Is the case count correct? Is the population ascertainment and subsequent person-year distributions correct? Is the well inventory complete and accurate? Are the arsenic measurements correct? Did the residents only drink from their village wells? Was the arsenic level constant over decades? Were the risks independent of subsequent switch to piped water both quantitatively and temporally?

What becomes troubling about the Slope Factor the EPA wants to use is that they seem to be ignoring this:

As the data to examine these questions is limited or absent, we have to accept various assumptions. We are struck with the observation that in multiple ways when the data is bifurcated, the dose-relationship differs in the two sections. We conclude that there exists within the data some additional unobserved factor(s) that influences the outcome, but has not been adequately identified or characterized. Lamm

And now the plot thickens.  Remember how the Rural Water guys said "High quality data from the US and elsewhere indicate much lower risks from iAs ingestion at the levels of exposure relevant for the past and current MCL?"  Well here is what Lamm reports to the EPA - using the same data used by the EPA:

We noted that the lower level exposure villages showed a negative slope with R2 = 0.25, which appears to be inconsistent with the general expectation of a dose-response model, though p=0.10.

The SW-Taiwan dataset reflects significant inherent geographically-based risk factor(s) which, when disentangled, reveal no significant arsenic-dependent risk for bladder and lung cancers for the low-level exposure villages.

"Disentangled,"  hehe, MPH's use funny words.

Well now...where does all this lead us?  Dr. Honeycutt complains about the noise, Dr. Lamm says the lower dose-level exposed Taiwan villagers reveal "no significant arsenic-dependent risk for bladder and lung cancers," and The National Rural Water folks wonder why the EPA is not looking at "data from the US and elsewhere indicate much lower risks from iAs ingestion at the levels of exposure relevant for the past and current MCL."

That's a good question, that last one.  Why don't we look at US exposure to arsenic and compare bladder & lung cancer incidence based on exposure?  I mean, to me, that would show if these low levels of arsenic actually do present the same degree of risk the EPA's new Slope Factor is predicting.

I mean, wouldn't current data using American's with American habits and American data on cancer make a much better study group?  Has that been looked at?  Why yes, yes it has.  According to Dr. Lamm in Environmental Health Perspectives 2006 July; 114(7): 1077–1082:

• An ecologic analysis of the white male bladder cancer risk in the United States found no increase over an arsenic exposure range of 3–59 μg/L (Lamm et al. 2004). 
• Case–control bladder cancer studies found no increased risk in the United States for exposures < 80 μg/day (Steinmaus et al. 2003)

Interesting...

Dr. Lamm finds:

• A threshold-like model indicating that the bladder cancer mortality risk does not increase with exposure levels < 150 μg/L is consistent with other epidemiologic data.
•  Cigarette smoking still remains a risk factor for bladder cancer.

So here is my take on this.  We have really, really good data on the arsenic concentration in water that is consumed.  For example:

Evaluation of Arsenic Contamination in Texas

...and we have really, really, good data on cancer

Source

So putting the two together, me thinks we would see elevated incidence of bladder and lung cancer in areas where the arsenic is highest and less in areas where the arsenic is low.  At least that data would be newer and more complete and any confounders present would be relatively the same as in Taiwan.

Makes sense to me to look here as well as there.


Arsenic in Rice: Part 13 - It's There, You Just Can't See It.

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