Methylisothiazolinone in food?

Is there methylisothiazolinone in food?

This synthetic preservative has not been approved for food preservation, and neither have any of its relatives, such as methylchloroisothiazolinone. There should not be, nor should there ever have been, any MI in any products for human oral consumption.

But could this status quo be at risk?

No, one would hope. Food industry has plenty of food-grade preservatives — including traditional ones such as plain salt, and vinegar — at its disposal.

Not processed using MI …. yet.

But what about its use in food processing? A paper published in July in the International Journal of Food Microbiology suggested that the MI / MCI blend could be “a plausible alternative to chlorine” as a anti-microbial agent in the fruit and vegetable processing industry.

I have to wonder whether the food microbiologists who I presume were responsible for this paper have ever looked into the allergic potential of MI / MCI or whether any dermatologists or allergists were consulted ahead of publication …

Whether isothiazolinone use for fresh produce processing might ever get approved is anyone’s guess, but I would hope it never would, as traces could well remain on food items such as lettuce leaves and apples, which aren’t always washed by consumers. Quite what kind of reaction the immune system would mount to orally consumed isothiazolinone in a consumer sensitised to these anti-microbials is uncertain, given exposure is typically through skin, though also through lungs / nasal membranes in the case of paint. Small consolation it may be, but even if their use was to be passed and authorised, that approval would come in many years’ time, and with the isothiazolinone community now strong, and awareness among allergists high, protests and dissent would surely get in the way of the unthinkable ever happening.


So does that mean eating is safe for now?

As many with long established MI allergy will tell you, eating out and being served food on plates which has been washed in MI-containing detergent and insufficiently rinsed, or tabletops which have been cleaned with MI-preserved surface wipes, can lead to a possible reaction.

It’s entirely plausible that jars and bottles and other food and drink containers are sterilised in the food industry with isothiazolinone-containing detergents or agents. One would assume these are thoroughly rinsed, but who knows how often mistakes happen? It’s the same for food machinery in processing plants, where it’s safe to assume vast quantities of (possibly) MI-containing industrial cleaners are deployed.

Food labels too are likely to be printed with inks and on paper which both may be processed using isothiazolinone-containing materials — and we all may touch such products or containers dozens of times daily.

Do any readers have a story of a possible food-related reaction? Please leave a comment if so, as it could inspire a future post or research into the issue. 


Oral exposure

Although we normally associate MI allergy with skin exposure — mainly through cosmetics — and aerosolised exposure via recently-applied paint, there is also a potential risk through products we use to maintain oral hygiene.

Long standing readers may remember my post several years ago about methylisothiazolinone in Colgate Cavity Protection mouthwash

Although I’ve yet to see an isothiazolinone in toothpaste, we must bear in mind that both toothpaste and mouthwash are classed as (rinse-off) cosmetics, so could in theory contain MI and perhaps MCI too. You can imagine exposure via oral membranes might be particularly unpleasant. 

Stay safe, people … 



Over on Facebook, reader Bellè Pytlinskí has told us an interesting story of her experience with Californian almonds, on which isothiazolinone-based pesticides are used:

“For a while I was eating almonds in products and couldn’t figure out why I always had an upset stomach, rash, felt itchy, etc. Then I found this article on one of the MI pages and stopped eating almonds and almond products. Those issues got better. One of my favorite cookies was Emmys cookies.. but they contain almond flour. I figured I would try it out. Everytime I ate a pack I had GI issues for several days. While I can’t prove the link between MI and food causing issues, I do think it’s a likely cause/effect based on my personal experience.”


  1. chris

    Does organic food have the possibility to be sprayed with this at all? I also have a latex allergy and there is a list a mile long of foods related to latex including almonds Pretty soon it will get that I cannot eat anything.

    1. MI Free (Post author)

      I would imagine the risk is very low for non-organic, and lower still for organic, but I don’t know for sure. There is a long list of potential cross-reactions to latex but did your immunologist not advise you to only avoid the ones you react to? Or can you have tests to discover which foods you can tolerate? Push to see a dietitian if you are on a very restricted diet.


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