Terra Sigillata

Melamine and cyanuric acid revisited

This morning’s post from Molecule of the Day reminds me to ask “cyanuric acid question.”

With the recent adulterations with melamine of Chinese milk and milk products (like White Rabbit chocolates) and foods with other milk-derived ingredients, we wonder if we will ultimately hear that a compound from fertilizer, cyanuric acid, is part of the mix.

Melamine is a cheap chemical that gives a false positive in typical protein assays; therefore, it can be used to make food appear to contain more protein than it actually does. You’ll often hear of cyanuric acid being referred to as a pool chemical as it helps stabilize chlorine donors in the sun, but it is often used as a nitrogen source in fertilizers. It tends to concentration in wheat gluten and that’s how it may end up together with melamine in some food products.

What is not mentioned too often in the press is that melamine alone is remarkably safe – an FDA report notes that the oral dose required to kill 50% of test rats, or LD50, is 3161 mg/kg body weight – an astronomical dose. Cyanuric acid is even less toxic, with a reported LD50 of 7700 mg/kg. While the LD50 is a single-dose, acute toxicity test, even prolonged daily dosing of either compound is relatively safe with a no-observed-adverse-effect-level (known as NOAEL) of 63 mg/kg daily for 13 weeks in rats.

So, while you don’t want to ingest either compound unnecessarily, they become much more problematic when combined. Melamine and cyanuric acid polymerize and precipitate out in the kidney, causing renal failure and death. In May 2007, I posted on one of the best journalism stories on the topic, by David Brown at the Washington Post, who wrote on the pet food contamination episodes then.

Molecule of the Day is a great resource for learning more about the chemistry of these compounds, complete with chemical structures – in general, MoTD is a great, quick, content-rich and enjoyable read every single post.

See “Melamine and Cyanuric Acid Chemistry Lesson” for our more detailed discussion of melamine and cyanuric acid.

Comments

  1. #1 Orac
    September 30, 2008

    But wasn’t of the reason melamine led to children’s death was malnutrition? Children were not getting as much protein as was thought based on the amount of milk being consumed, and over months their nutritional status deteriorated.

  2. #2 Orac
    September 30, 2008

    Let’s rephrase that, as my rapid typing and too-rapid hitting of the “Post” button led me to sound incoherent:

    Wasn’t one of the reasons melamine led to children’s deaths malnutrition? Children were not getting as much protein as was thought based on the amount of milk being consumed, and over months their nutritional status deteriorated.

  3. #3 Julie Stahlhut
    September 30, 2008

    I haven’t seen any references to malnutrition as the cause of the children’s deaths, although it would be a no-brainer that living on diluted milk laced heavily with fake protein would result in malnutrition even if the adulterant wasn’t actually toxic. In 2004, there was a counterfeit infant formula scandal in China that resulted in many starvation deaths and a huge number of malnutrition cases, but that one didn’t involve melamine.

  4. #4 ifan
    September 30, 2008

    “In 2004, more than 200 Chinese infants suffered malnutrition and at least 12 died after being fed phony formula that contained no nutrients.” (quoted from: http://www.baltimoresun.com/news/world/bal-te.china20sep20,0,1800503.story)

  5. #5 Abel Pharmboy
    October 1, 2008

    Orac, Julie, and ifan: News reports to date suggest that malnutrition was the cause of some infant deaths but that many of the thousands of hospitalizations have been due to kidney stones (which do not normally occur in people aged 0 to 3 years). So the answer is really a little bit of both. The US FDA also noted in their 12 September release that some Chinese infant formula-related sicknesses have been associated with kidney stone formation.

    Interestingly, when I opened some of your comments in my Gmail account yesterday, one associated ad was for a Chinese company that sold melamine, not for any infant formula scam, of course, but rather for industrial production of foams and “Magic Erasers.”

    Today, your comments are accompanied by an ad for a company that makes an ELISA to detect melamine in milk-based products. Hail capitalism.

  6. #6 HN
    October 7, 2008

    In many places in China (and I believe probably in many cultures that have rice as the major carbohydrate source), diets of babies of 5mth or older are supplemented with “watery rice soup”, which is a sensible practice passed down by grandmothers. First you make congee by , say, boiling 100g of rice in say 500ml of water for 30min . Then you filter the rice out and the remaining cloudy liquid is quite nutritional. Some people actually use this liquid, instead of plain water, to make milk drinks from infant formula for their babies for extra nutritions.

    So, unless the children come from very poor regions (where most of the 2004 victims were), malnutrition may not play a major role in the recent widespread, nation-wide health problem with milk-derived products.

    By the way, in recent years, there seem to be more and more people in China who believe artificially enhanced infant formulae and “nutritional drinks” are better than the mothers’ milk and other baby diets their grandmothers swear by. It’s probably time to question this religion in chemistry.

  7. #7 Hank Roberts
    October 28, 2008

    I’ve been looking for any clear info on bioaccumulation of either chemical — anyone know of references?

    On the interaction, I recall early (cat and dog food episodes) mention of cyanuric acid plus melamine making crystals — I think out of U.C Davis Veterinary. Among these:
    http://www.google.com/search?q=veterinary+melamine+cyanuric+cat+dog+kidney+crystal

    Same interaction discussed in Chinese kids now:
    http://uk.reuters.com/article/healthNews/idUKTRE49R3CJ20081028
    —-excerpt——
    By Tan Ee Lyn

    HONG KONG (Reuters) – Some children who have fallen ill in China after being fed milk formula that had been contaminated with melamine have developed “crystals” in their kidneys, a WHO food safety expert said on Tuesday.

    “Our understanding is that these are not normal kidney stones because they are not being detected via all of the tools that one uses to detect kidney stones, so some are not showing up on x-rays,” said Anthony Hazzard, regional advisor for food safety at the World Health Organization.

    “We believe at this stage that it’s really the complex of melamine and cyanuric acid forming what you call crystals … they can form in the small tubules (in the kidneys) and they get bigger and can block the tubules,” he said in a telephone interview from Manila.
    —————

    Melamine in chicken eggs in China is in today’s news.

    Earlier in animal feed:
    doi:10.1016/j.aca.2008.08.037 How to Cite or Link Using DOI (Opens New Window)
    Published by Elsevier B.V.

    Determination of cyanuric acid residues in catfish, trout, tilapia, salmon and shrimp by liquid chromatography�tandem mass spectrometry

    Christine M. Karbiwnyka, Corresponding Author Contact Information, E-mail The Corresponding Author, Wendy C. Andersena, Sherri B. Turnipseeda, Joseph M. Storeyb, Mark R. Madsonb, Keith E. Millerd, Charles M. Giesekerc, Ron A. Millerc, Nathan G. Rummelc and Renate Reimschuesselc
    aAnimal Drugs Research Center, U.S. Food and Drug Administration, P.O. Box 25087, Denver, CO 80225-0087, USA bDenver District Laboratory, U.S. Food and Drug Administration, P.O. Box 25087, Denver, CO 80225-0087, USA cUniversity of Denver, Department of Chemistry and Biochemistry, Denver, CO 80208, USA dCenter for Veterinary Medicine, U.S. Food and Drug Administration, 8401 Muirkirk Road, Laurel, MD 20708, USA

    Received 18 June 2008;
    revised 22 August 2008;
    accepted 26 August 2008.
    Available online 3 September 2008.

    Purchase the full-text article

    References and further reading may be available for this article. To view references and further reading you must purchase this article.

    Abstract

    In May 2007, investigators discovered that waste material from the pet food manufacturing process contaminated with melamine (MEL) and/or cyanuric acid (CYA) had been added to hog and chicken feeds. At this time, investigators also learned that adulterated wheat gluten had been used in the manufacture of aquaculture feeds…..
    —————

    Kind of makes you wonder, with the total number of artificial chemicals known in small amounts to bioaccumulate, if there might not possibly be another interaction or two yet to be discovered out there somewhere. Hmmm.

    Too bad the precautionary principle has been defeated as public policy for so long in the USA.

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