Some Carcinogens Are More Equal Than Others (sigh)

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Following up on the glyphosate as carcinogen story, I couldn’t help notice some coverage that shows how political orientation informs the way different people cover different issues.

In response to news about acrylamide’s carcinogenicity, Marion Nestle, the head of the nutrition department at NYU and a trained molecular biologist mustered a sigh, literally:
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In a later post, she refers to the “fuss”, notes that this is a familiar ingredient that is yummy and then provides readers with context to put the risk into perspective:

The fuss about acrylamide continues. This, you may recall is a carcinogen formed when foods containing sugars and the amino acid asparagine are cooked at high temperatures. Acrylamide is formed during the Maillard reaction, which causes baked, fried, and toasted foods to turn attractively brown and taste yummy.

Obviously, acrylamide has been around in foods for a long time. But now that everyone knows how bad it is, what should be done about it?

A new toxicology study provides estimates for an upper level of intake that can be considered safe: 2.6 micrograms per kilogram of body weight. This would be equivalent to 182 micrograms for a 70 kg human to prevent cancer. Much higher levels are required to cause neurological problems: 40 micrograms per kg per day, or 2,800 micrograms per day for a 70 kg human. But since you have no idea how much is in the foods you are eating, these figures don’t help much.

But maybe you don’t need to worry? Even the lower of the toxic levels is much higher than intake levels estimated by health agencies. The average exposure of adults to acrylamide in food has been estimated to be below 0.5 micrograms per kilogram of bodyweight, which is five times lower than the upper limit considered safe.

So a compound that is universally recognized as a powerful carcinogen but is also a familiar part of our morning coffee gets a shrug. What happens when the compound at hand isn’t an old, naturally occurring friend, but possibly a ‘probable carcinogen’ sold by a much maligned ag input giant?

The shrug turns into a smear. Instead of laying out the evidence and providing context, she keeps changing subject.

Nestle quotes the IARC statement on glyphosate, switches the topic to organophosphates – which are truly a cause for concern, and then trails off with a bunch of unrelated, out of context, and misleading statements about superweeds, glyphosate and biotech crops; rather than trying to provide any useful context to her readers about what the relative risks suggested by the IARC report actually are.

So actual carcinogens get a sigh, while probable (probably not) carcinogens get a smear job. No wonder Dan Kahan stays so busy.

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6 Comments

  1. IARC wrongly refers to glyphosate as an organophosphate.

    In March, 2015, 17 experts from 11 countries met at the International Agency for Research on Cancer (IARC; Lyon, France) to assess the carcinogenicity of the organophosphate pesticides tetrachlorvinphos, parathion, malathion, diazinon, and glyphosate.

    via http://www.thelancet.com/journals/lanonc/article/PIIS1470-2045%2815%2970134-8/

    Glyphosate is usually formulated as an isopropylamine salt. While it can be described as an organophosphorus compound, glyphosate is not an organophosphate ester but a phosphanoglycine, and it does not inhibit cholinesterase activity.

    via http://pmep.cce.cornell.edu/profiles/extoxnet/dienochlor-glyphosate/glyphosate-ext.html

    And Wikipedia’s entry for organophosphate opens with the warning “Not to be confused with organophosphorus”

    So in this case some blame for organophospate subject switch falls back on IARC (and really casts some doubt on credibility of the report in my mind).

    • Is that an incorrect attribution? Or just poor grammatical construction?

      “to assess the carcinogenicity of the organophosphate pesticides tetrachlorvinphos, parathion, malathion, diazinon; and glyphosate.”

      Either way, it’s sloppy to lump the assessment of glyphosate in with a raft of organophosphates. It should have been two separate reviews.

      • I don’t think it’s just a problem with sentence construction. On their news release page at iarc.fr they put it under the heading IARC Monographs Volume 112: evaluation of five organophosphate insecticides and herbicides. Then in the descriptive text they switch up the location of glyphosate:

        A Working Group of 17 experts from 11 countries met at the International Agency for Research on Cancer (IARC) on 3–10 March 2015 to review the available published scientific evidence and evaluate the carcinogenicity of five organophosphate insecticides and herbicides: diazinon, glyphosate, malathion, parathion, and tetrachlorvinphos.

    • Marion Nestle should know that glyphosate is not an organophosphate. It’s her damn job to know the difference.

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