Apples, Arsenic, and Risk - Part 16: The Great and Powerful Oz

Dorothy: Oh, apple juice! Oh - look! Oh!

Scarecrow: Come along, Dorothy - you don't want any of that apple juice. Hmm!

Apple Tree: Are you hinting my apple juice aren't what they ought to be?

Scarecrow: Oh, no! It's just that she doesn't like arsenic in her apple juice!

Apple Tree: Oh, you!  Have you been listening to Dr. Oz and Chuck Norris?

Scarecrow: Yeah.  But I also read about it in Consumer Reports...

Apple Tree: Sigh...Them too?  What did they have to say about my apple juice?

Scarecrow: Stuff like "mounting scientific evidence suggests that chronic exposure to arsenic and lead even at levels below water standards can result in serious health problems."

Apple Tree:  Really, and how much arsenic did they find in my apple juice?

Scarecrow: 3 ug/L...4 if you want to high-side it.

Apple Tree:  And Consumer Reports told you that at that level it could result in serious health problems.

Scarecrow:  Yeah.  And Dr. Oz said the same thing on his web site...that "the findings raise significant health concerns for us and for our children, and have generated incredulousness that this could happen in our country."

Dr. Oz: I am the great and powerful Oz!

Apple Tree: Yeah, so I've been told.

Scarecrow: Chuck Norris said "Poisonous apples are definitely not just being offered in fictional Snow White adventures."
 
Apple Tree:  So my apple juice is poisonous?

Dorothy:  Oh my goodness!  And I've been drinking it.  And Toto too!

Scarecrow:  Consumer Reports says that "arsenic has been notoriously used as a poison since ancient times. A fatal poisoning would require a single dose of inorganic arsenic about the weight of a postage stamp."  A postage stamp!  Do you know how small a postage stamp is!?!

Dorothy: Oh my!

Apple Tree: And how much did they find in my apple juice?

Scarecrow: 4 ug/L.

Apple Tree. How much do you weigh scarecrow?

Scarecrow:  About 70 kilograms

Apple Tree:  Do you know how much Arsenic in a liter of water it would take to kill you or Dorothy?

Doroethy: Oh my, leave me out of this...

Apple Tree:  Well I looked up on the Google and found the weight of a postage stamp.  0.0533 grams.  Do you know how much that is in micrograms?

Scarecrow:  Nope (points to head).  Haven't got a brain, remember?

Apple Tree:  Okay, work with me here.  There are 1000 milligrams in a gram and 1000 micrograms in a milligram.

Dorothy:  This is why Barbie hated math too!

Apple Tree:  Yeah, but this is important.  Everyone is sayin' my apple juice aren't what they ought to be because of arsenic.  They are trying to compare what 0.0533 grams of arsenic will do to you with the 4 micrograms found in my juice.  0.0533 grams is 53,300 micrograms.  The amount needed to kill you is 13,325 times higher than what one liter of my apple juice contains.

Dorothy: Lions, and Tigers, and inorganic arsenic, oh my!

Scarecrow:  Well on the Dr. Oz web page, it does have a Clinical Assistant Professor of Medicine, some guy by the name of Russell H. Greenfield, MD, that tells us:

Arsenic is naturally abundant in our environment in such places as rock formations, minerals and soil, and is also a byproduct of human agricultural and industrial pursuits. Keep this in mind, because it’s important to understand we are all exposed to small, background amounts of arsenic on a regular basis from the food we eat, the water we drink, and the air we breathe. Concerns only arise when considering the type of arsenic (organic or inorganic) we are exposed to, and especially the degree of exposure.

Apple Tree:  Precisely!  Now you're catching on.  Look at the NHAMES study Consumer Reports reviewed.  The average total urinary arsenic is about 8 ug/L.  Now some of that is organic and some inorganic, but that fact is, Americans are exposed to arsenic without drinking apple juice.  It's the dose that's important.  My apple juice has about 4 ug/L of arsenic.  A juice box holds about 8 ounces - or about 0.25 Liters...so that's about 1 ug of arsenic consumed.

Scarecrow: So what your really telling us is that if arsenic exposure is so bad, why don’t you see more people sick or dying from it?’

Apple Tree:  No.  What I'm saying is to consider the dose...the amount of arsenic being consumed from my apple juice in comparison to the total.  The reason you don't see more people getting sick or dying is that the dose we take in is small.

Scarecrow:  Yeah, I thought that would be your argument.  So did Consumer Reports.  They say "many diseases likely to be increased by exposure even at relatively low levels are so common already that its effects are overlooked simply because no one has looked carefully for the connection.”

Apple Tree: So if no one has looked for a connection, does that mean a connection is there?

Scarecrow: Yer' givin' me a headache Apple Tree!  Consumer Reports says that when they did look, "the connections they've found underscore the need to protect public health by reducing Americans’ exposure to this potent toxin."

Apple Tree:  Once again with the potent toxin....

Scarecrow:  Well it is...a postage stamp amount can kill you.

Apple Tree:  We're not dealing with anything near that amount in my apple juice.  Why bring up a potential harm that's not present?  Let's stick to the arsenic in my apple juice, not what's found elsewhere.

Scarecrow: Well...still, they found connections....

Apple Tree:  You mean the type 2 diabetes study and the study showing poorer scores in global cognition, processing speed and immediate memory?

Scarecrow:  Yeah...and Sharyn Duffy's hyperkeratosis...

Apple Tree:  Okay, and even if there was a connection, was that connection based on 4 ug/L in one juice box...or even two juice boxes a day?

Scarecrow: Ahhh...well, even without a brain, consuming more arsenic can't be good.  Isn't it additive?

Apple Tree:  Yes it is.  But were talking 1.4 ug/L more arsenic in apple juice drinkers.  Does 1.4 ug/L create any additional risk for these apple juice drinkers?  Not based on any of the studies Consumer Reports or Dr. Oz presented.

Dorothy: But what if I don't want to consume any more arsenic than I have to?  What if I want to limit Toto's exposure just in case?  If it is a carcinogen there is some risk right?

Apple Tree:  Yes.  And it is perfectly fine for you to choose not to drink my apple juice.  There is no such thing as zero risk, so if reducing the amount of arsenic you take in is something you think prudent, then by all means stop drinking my apple juice.

Dorothy:  And you won't be mad at me?  You won't throw apples at me?

Apple Tree:  Nope.  All I ask is that you don't tell folks that my apple juice aren't what they ought to be.

Dr. Oz: I am the great and powerful Oz.  Pay not attention to that apple tree!

Chuck Norris:  He's part of a government cover-up, chop him down and buy local!

Apple Tree:  I am local you ignorant munchkin!

Dorothy: Oh my!

Apple Tree: Un-tether that balloon and get those two fear-mongers out of here.

Dorothy:  Well I better be going, but which way is the correct way forward?

Apple Tree:  Follow the path the data leads you down, not where the hype sends you.

Dorothy:  But it's all so confusing and scary!  How will I know when there really is a connection?

Apple Tree:  Be objective.  And when you read something that says there is a correlation, click your heals three times and repeat:

Correlation does not imply causation...

Correlation does not imply causation...

Correlation does not imply causation...

Next Post: Apples, Arsenic, and Risk - Part 17: Generated Incredulousness


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Apples, Arsenic, and Risk - Part 12: Correlation does not imply causation

In my last post I asked the question:

What about Consumer Reports telling its readers about a 2011study in the International Journal of Environmental Research and Public Health that examined the long-term effects of low-level exposure on more than 300 rural Texans whose groundwater?

Consumer Reports claims in their January 2012 article on arsenic in apple juice that these Texans were estimated to have exposure to arsenic at median levels below the MCL and when tested showed poor scores in language, memory, and other brain functions.

That brings me to asking this question: will "low-levels" of arsenic, as was found in the apple juice samples tested by Consumer Reports lead adversely affect those that consume apple juice?  Here is what they state at the beginning of their report:

Mounting scientific evidence suggests that chronic exposure to arsenic...even at levels below water standards can result in serious health problems.

I've looked at cancer, hyperkeratosis, and type 2 diabetes, that leaves this one last study on chronic exposure to look at.  Will this support their claim that levels below the MCL can result is serious health problems?

Here is what Consumer Reports tells their readers about this 2011 study:

It found that exposure was related to poor scores in language, memory, and other brain functions.

Here is what that paper concludes:

The results of the study showed that GIS-based groundwater arsenic exposure (current and long-term) was significantly related to poorer scores in language, visuospatial skills, and executive functioning. Additionally, long-term low-level exposure to arsenic was significantly correlated to poorer scores in global cognition, processing speed and immediate memory.

"Significantly related" and "significantly correlated."

Two things to keep in mind here:

1. The term "significantly" is in reference to statistics.  That is, it is unlikely to have occurred by chance.  Not significant as in "sufficiently great or important to be worthy of attention."
2. The term "correlated" means a statistical measurement of the relationship between two variables.

So "significantly correlated" means a relationship between two variables that is unlikely to have occurred by chance.

Rule number one about correlations:  They do not imply causation!!!

Source

...and so it goes with low-levels of arsenic in our our apple juice and water.

Let's look at the table of results:

Source

I am by no means a statistician, nor am I really that versed to expertly explain "unstandardized regression coefficient" as it is derived from a "linear regression" model.  For more info on this see 1, 2, 3, or 4.

What I do understand about this table is this:

Linear regression models were created using raw neuropsychological test scores as outcome variables and either current or long-term arsenic exposure estimates as predictor variables.

So....

Simple linear regression is when you want to predict values of one variable, given values of another variable.

The purpose of regression analysis is to come up with an equation of a line that fits through that cluster of points with the minimal amount of deviations from the line. The deviation of the points from the line is called "error."

Once you have this regression equation, if you knew a person's Long-term or current arsenic level of exposure, you could then predict their score on one of the  neuropsychological tests administered.

The data in Table 3 is reported for:

B = unstandardized regression coefficient.

So...

B coefficients are interpreted as the amount of change in the dependent variable (Y) that is associated with a change in one unit of the independent variable (X).

All B coefficients are unstandardized, which means that the magnitude of their values is relative to the means and standard deviations of the independent and dependent variables in the equation.

It represents the slope of the regression line--the amount of change in Y due to a change of 1 unit of X.

The unstandardized coefficients are used for actually making a prediction, using the independent variables as they were measured.  For example, if a variable is in dollars, the unstandardized coefficient is in dollars, if a variable is in inches, it is in inches.

What Table 3 tells us is this:

If "RBANS Language scores" is the dependent variable, and "current arsenic level" is one of the independent variables, and the unstandardized regression coefficient (B) for  "RBANS Language scores"  is −0.458 (p = 0.008), then this would mean that for every additional ug/L of arsenic exposed to, there would be a decrease of 0.458 in the RBANS Language scores  (controlling for the other independent variables in the equation).

Remember, correlation does not imply causation.  In other words, it may not be the arsenic that drops the score but something else going on.  For example, there was an increase in polio cases correlated to the amount of ice cream sold.  Ice cream was not the cause of polio, polio cases increased in the summer as did sales of ice cream.

But let's say that this model is predictive, as the authors claim:

Groundwater arsenic exposure (current and long-term) was significantly related to poorer scores in language, visuospatial skills, and executive functioning.

What "serious health problems" - or in this case - how much "poorer" would the scores be for children who drink apple juice?

Next post: Apples, Arsenic, and Risk - Part 13: How much is "19 percent higher levels?"


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