Friday, October 7, 2011
By Deborah Blum
Let me get this out of the way first: I don’t watch Dr. Mehmet Oz on television.
I did see a show the year before last while I was keeping an older relative company. I can’t tell you what it was about, though, because we weren’t that long into it before my relative suggested that that I take myself, my twitches, and my sarcastic mumbling to another part of the house.
Consider this a full disclosure of attitude toward Dr. Oz. Consider it also an explanation of why I didn’t see his show last week on the (alleged) dangers of arsenic in apple juice. It was impossible to miss, of course, the backwash of the critical reaction that followed, my favorite being Steve Salzberg’s wickedly smart take, “Dr. Oz Tries to be A Scientist” in Forbes. I also enjoyed Pharyngula’s tale of the FDA’s unsuccessful efforts to educate Dr. Oz about arsenic prior to his show. The theme of the news coverage throughout was, let’s say, unsympathetic.
The primary criticism was that for a man with a medical degree, Dr. Oz didn’t seem to know very much about arsenic. The FDA – rather testily, actually – had pointed out to him that he was testing for total arsenic load. Their objective was that this overstates risk by combining levels of both inorganic (bad, bad) and organic (not so very bad) arsenical compounds.
On average, inorganic arsenic is considered about 500 times more poisonous that organic arsenic. So a high test number that combined the two but was mostly organic would actually indicate less risk than a lower number that involved more inorganic arsenic. Unfortunately – for Dr. Oz and his viewers – he either didn’t get this or considered it too complicated for the audience.
As Salzberg pointed out, those combined totals weren’t necessarily reliable anyway. Dr. Oz didn’t follow the standard test practice of sending his samples to multiple labs. Instead he relied on one testing facility. When the FDA sent juice samples from the same lots to other laboratories, the arsenic levels were a fraction of what Dr. Oz reported. All of which leads us to the essential criticism here, that Dr. Oz sensationalized a non-problem and by doing so irresponsibly frightened consumers of apple juice.
In a cranky, reluctant way, if you’re me, you have to kind of admire the way Dr. Oz responded to this concerted hiss of dismay. He continued to maintain that arsenic exposure should always be considered a big, bad thing. And he managed to suggest that this big picture was more important than nitpicking whining about things like test accuracy and arsenic classification. He did this well enough that, for instance, U.S. Sen. Charles Schumer, D-NY, asked the FDA to take another look at arsenic levels in apple juice.
So I’m not going to dwell further on the problems with his broadcast; I’m hardly going to mention the issues with shoddy science and the sensationalism. Hardly at all. What I would like to mention, whine about, nitpick, however, is Dr. Oz’s lost opportunity to r illuminate the actual risks. This is arsenic, after all, one of the world’s most important – and fascinating – poisons.
He could have sifted out those organic and inorganic test results, for instance, and helped his viewers to understand what they meant. Arsenic (As) is, after all, a naturally occurring metallic element (sometimes called a metalloid). It’s also one of those elements that likes to partner up, either with organic (carbon-based) compounds or with inorganic (which for these purposes pretty much means no carbon involved).
Fortunately for us, our bodies tend to break down and metabolize away most organic arsenic compounds fairly efficiently. In fact, many of these organic arsenic compounds (such as arsenobentaine, in case you wondered) form naturally in fish and shellfish. Fish-lovers thus receive get a steady low level exposure to organic arsenic, as far as we know, without reported health effects. A few years ago, there was a suggestion that kelp-based health supplements might contain an arsenic problem, but it foundered – just as Dr. Oz’s apple juice case did – on the type-of-arsenic issue.
We humans – and, in fact, most living creatures, don’t handle inorganic arsenic nearly as well. Arsenic trioxide (AsO3) or white arsenic is one of history’s most famous homicidal poisons – so much so, that back in the 19th century, it was often referred to as the inheritance powder. By some estimates, inorganic arsenic can be fatal in the amount of 60,000 micrograms (about 1/50th the weight of a penny).
Why is it so dangerous? And don’t we wish that Dr. Oz had used his moment to ask this very question? As it turns out, the answer lies in actually being nitpicky about the question. Inorganic arsenic toxicity has a lot to do with the number of valence bonds the compound possesses. Valence bonds are created when atoms cling to each other because of an interaction between electrons in their outer shells.
In other words, the higher the valence bond number, the grabbier the compound, the greater its ability to insinuate itself into a living system. The two grabbiest forms of inorganic arsenic are trivalent (three bonds) and pentavalent (five). Pentavalent arsenic can, in fact, do a perfectly lethal job of disrupting cellular metabolism. But toxicologists tend to worry more about trivalent arsenic forms, which are also nasty poisons, more persistent, and much harder to remove from drinking water supplies.
And naturally occurring, inorganic arsenic in drinking water around the world does real and physical harm. I’ve written about this myself regarding the poisoning of water supplies in countries like Bangladesh. But there’s health risks to go around even in countries like the United States.
In other words, Dr. Oz could have used this arsenic moment to have picked out a real health risk, educated people about it, maybe even saved a few lives and there. And that’s what I hold against him – the careless waste of opportunity - and that’s why he makes me twitch. Even at this safe distance from a sofa in front of the television set.
Posted by Rachel Davis at 12:30 AM