ET
Mar 7, 2004, 6:28 PM
Post #14 of 16
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This probably has wider applicability and belongs in the "Living and Working" forum, but I'll leave it up to a moderator to move it.
TomG writes:
Isn't there a safer product than Microdyn avail in Mexico?
The real problem is that (a) there's multiple products which have some variation of the "microdyn" (microdyne, microdine) product name, (b) each of these products have very different active ingredients, and (c) few people have any idea what active ingredient might have any effect, they're simply grabbing for bottles with the "microdyn" (microdyne, microdine) name. Active ingredients-wise your choices include metallic or inorganic silver compounds, quaternary ammonium chloride compounds, and iodine or an iodophor. Each will have its own bacteriological as well as toxicological profile. Here's some quick thoughts, I'd suggest anybody who's interested should spend some time doing their own homework (note - research does not include any website where a product is being sold).
silver - high (percentage-range) concentrations of metallic silver, inorganic silver compounds such as silver nitrate, and organic silver compounds such as silver sulfadiazine are used medically as topical (direct contact treatment) antimicrobial treatments. At one time activated charcoal used to strip organic compounds from water were treated with silver compounds to inhibit bacterial and algal growth, but this application appears to died out, at least in the US. Similarly, a colloidal silver and copper compound ("Microdyn", in the US, EPA-registered by a Movidyn Corporation) was once sold to suppress bacterial and fungal build-up in recirculated industrial water such as used in the pulp and paper industry; Movidyn cancelled its registration for Microdyn in the mid-80's. I can find no legitimate references to the use of metallic, inorganic, or organic silver compounds as a sanitizer, disinfectant, or sterilizing agent.
quaternary ammonium chloride compounds - Mixtures of compounds such as alkyl dimethyl benzyl ammonium chloride, didecyl dimethyl ammonium chloride, dioctyl dimethyl ammonium chloride, and octyl decyl dimethyl ammonium chloride are very commonly used as surface sanitizer; if you look at your household cleaners that claim disinfecting properties, there's a high percentage chance that you'll find a "quat". Eurochem International has what's in the US an EPA-registered product under the Microdyne Extra tradename for use as an industrial and institutional sanitizer. Although the quats are commonly used as food-service sanitizing agents, in my limited poking around I can find no reference to their use disinfecting foodstuffs like produce (my initial reaction is yuck....).
iodine - Iodine solutions such as tincture of iodine (2% iodine, 2.4% sodium iodide in ethanol) and povidone-iodine are commonly used medically as topical antimicrobial treatments; in this application there's a considerably greater breadth of use than with silver compounds. Falling into the same chemical class as chlorine, iodine also has uses as a disinfectant, albeit a lesser one, possibly because of its lower reactivity (the halogens function as disinfectants through the simple means of oxidizing whatever they come into contact with), as well as an poorly-characterized concern about excess iodine-induced thyroid disorders. Although more commonly recognized in the US as "Betadine", povidone-iodine solutions (typically 10%, which would yield about 1% available iodine) are sold worldwide under the name "Microdine". Targeted to the food services industry Rochester-Midland Corporation also sells what's in the US an EPA-registered germicide/sanitizer under the "Microdyne" tradename which contains 3.5% available iodine and phosphoric acid.
It should be noted that there's also a food and institutional deodorizing product sold by Misco International under the Microdyne name which contains "enzymatic odor eliminators".
Now my overall take on the subject is that the "microdyn" that people originally suggested for use on produce was an iodine compound. Iodine compounds have been one of the traditional compounds used for purifying water while camping or traveling, and by extension for sanitizing washable foods and utensils. In at least the early (1988) edition of Carl Franz's classic The People's Guide to Mexico I've got kicking around, Franz recommended purchasing Yodo para lavar veduras in drugstores, and using 1-2 drops per quart of water to sanitize vegetables. According to a poster a few months ago, in some later edition of the People's Guide the term "microdyn" started to be used for the same solution. Somewhere along the line, the substitution for a colloidal silver product was made in at least some locations, possibly because colloidal silver is one of those fad miracle "health" products, or simply because of product name confusion.
Please note that none of the above should be taken to be me advocating or refuting the need for the disinfection of produce, which could be the subject of an entirely separate discussion, which I'm not particularly interested in taking on for the time being.
Additional Notes:
1. Quantities of iodine required for disinfection will vary depending on the actual product used. The 1-2 drops/quart of water does, however appear to be somewhat low, noting that 0.25-0.5 mL of a standard tincture of iodine is recommended for treating water for drinking, while 0.35-0.7 mL of a 10% povidone-iodine solution is normally used. If this sounds low, calculate how much of a colloidal silver compound would be needed to achieve the 5-10 ppm concentration recommended by Movidyn for bacteriostatic use in what's a markedly non-critical application.
2. With regards to the recommendation for the use of Grapefruit Seed Extract (GSE), there's at least two articles (a, b) published in peer-reviewed journals indicating that commercial GSEs tested contained all contained significant concentrations of synthetic anti-microbial agents including benzethonium chloride, methyl-p-hydroxybenzoate and 2,4,4'-trichloro-2'-hydroxydiphenylether (triclosan). A third publication (c) went further to identify that 5 of 6 tested commercial GSE products contained measurable anti-microbial agents, and neither the 6th compound, nor several in-house prepared GSEs exhibited any kind of anti-microbial activities. Try:
a. Sakamoto, S.; Sato, K.; Maitani, T.; Yamada, T. Analysis of components in natural food additive 'grapefruit seed extract' by HPLC and LCIMS. Bull. Nat. Inst. Health Sci. 1996, 114,38-42.
b.Takeoka, G.; Dao, L.; Wong, R.; Lundin, R.; Mahoney, N.; Identification of Benzethonium Chloride in Commercial Grapefruit Seed Extracts. J. Agric. Food Chem. 2001, 49, 3316-3320.
c. Von WoedTke, T.; Schluter, B.; Pfiegel, P.: Lindequist, U.; Jiilich, W. -D. Aspects of the anti-microbial efficacy of grapefruit seed extract and its relation to preservative substances contained. Pharmazie 1999, 54.452-456.
(This post was edited by ET on Mar 8, 2004, 9:38 AM)
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