Saturday, January 28, 2012

Orange Juice: Full of Vitamin C, Fiber, and....Carbendazim?

NPR reports that the US FDA recently detained several shipments of orange juice imported from Brazil. The agency received a December 2011 tip-off from a juice company (Minute Maid, via parent company Coca-Cola) that the imports contained low concentrations of the fungicide carbendazim. While this amount is unlikely to harm anyone, FDA indicated in its letter that the EPA hasn’t established safe levels for the compound in juice, and thus considers it an unlawful additive.

Carbendazim, a benzimidazole (a two-ringed aromatic structure with two nitrogens) metabolite of benomyl, was first prepared as a discrete compound by DuPont in the early 1960’s. It’s approved in several other countries to treat black spot, Dutch elm disease, powdery mildew, and a host of other fungal diseases. The fantastic NIH resource Toxnet tells us that carbendazim is a “Group C Possible Human Carcinogen,” but given how many different standards exist for this metric, what does that mean?

Diving deeper into the data, carbendazim appears to be both a teratogen (meaning it impairs fertility or embryonic development), and causes chromosomal aberrations; both effects appear at relatively high doses that you wouldn’t drink in a single glass of OJ.

The unspoken fear here may be long-term exposure. Consider other recent reports on the ability of PFC’s (perfluorinated compounds, like the long-chain PFOS found in Scotchgard) to decrease vaccine response. Or, read the never-ending list of maladies brought on by exposure to phthalates, omnipresent plasticizers known to cause endocrine disruption. Health risks from accumulated compound may prompt the FDA’s proactive stance towards even tiny amounts of this fungicide in imported juice.

Surly Chemist Soapbox Moment – Both NPR reports refer to their subjects as “chemicals” sometimes as early on as the article’s title! The connotation for this word is overwhelmingly negative, which should be apparent from the “chemical-free” movement and the interchangeable use of “chemical” with toxin, poison, or contaminant. Doesn’t chemistry already have image problems?

Here are a few chemical synonyms for the next go-around: compound, moiety, substance, entity, additive, species, or moleculeNone of these are perfect for every situation, but any would be preferable over the catch-all, “chemical.”

9 comments:

  1. I think the issue with the word "chemical" is that it is used to represent "man-made chemicals that we don't really understand yet" rather than the actual definition. Maybe chemists (and the word chemist connotes to me smart people in glasses and white lab coats pouring things from beaker to beaker) need to find another term to use. It's very, very hard to change a cultural connotation like that. "Synthesized molecular compounds" is wordy, but sounds cool.

    Don't chemists have a lobbying firm in Washington? Or a trade group that could pull this together?

    But I don't think I know anyone who is anti-science, at least.

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  2. While I accept your definition, I still contend that the overuse (and negative lean) of the term makes it more difficult when we chemists want to use the word to present our work, or advance a concept.

    RE: Lobbyists - Most of the DC groups represent exactly the big industrial concerns you've just mentioned. We chemists must therefore be active promoters of the benefits and "Gee, wow!" moments of our discipline as best we can.

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  3. Agreed that "chemical" is used so often and in such a way it has overwhelmingly negative connotations -- hence advertising campaigns with "chemical-free products". What really drives me nuts, though, is the way people use the word "Natural" to mean "pure, wholesome, good for you", etc -- a blatant misuse that has become ubiquitous in modern advertising.

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  4. Hey, mutantdragon, welcome! I completely agree, ditto the word "organic" to mean derived from natural "chemical-free" sources. When I think of organic, I think of carbon chemistry....

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  5. If they had focused on the lack of fungi in the OJ perhaps it would have gone over better. People really don't like mystery fungi in their foods! (Except edibles of course.)

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  6. Carbendazim is extremely unlikely to accumulate; with a reactive carbamate it should degrade quite rapidly.

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  7. @gippgig: The World Health Organization released a major carbendazim tox study back in 1993. As you pointed out, the main breakdown product involves carbamate hydrolysis; the parent imidazole has been detected in microbes. The fungicide itself actually has a half-life (water, aerobic conditions) of 2 months.

    The LD50? Ridiculously high (2-15 GRAMS / kg) in most organisms tested. The panel here seemed pretty far-ranging: rats, mallard ducks, earthworms, bobwhite quail (?!). Pity the poor channel catfish, whose 96-h LD50 was a mere 7 ug / L of tank water.

    Potential take-home lesson: don't pour tainted orange juice into nearby streams!

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    1. I'm surprised it lasts that long; do you have any idea what the typical lifetime of a carbamate in the environment is (or know of a good source for that kind of information)?

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    2. @gippgig - I used http://toxnet.nlm.nih.gov/ to get relevant info. I've also used pubmed.gov, the Merck index, and sometimes the MSDS for the individual compounds for background (not that those are 100% reliable, anyway!).

      My feeling is that carbamates are quickly metabolized by hydrolases in vivo, but have higher non-enzymatic stability.

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