Reader Melody dropped me a line recently to share her experience with regard to exposure from food:
I seem to react more strongly and obviously to MI on my insides rather than my ‘outsides’, though I still do react on my skin. How much does it get into our food products? Because for me that is as large an issue as soaps etc. I found eliminating isothiazolinone-containing parchment paper improved my gastric symptoms tremendously. I can’t eat certain peanut butters because the manufacturers clean their facilities with MI-containing detergents. I can’t eat eggs that have been packaged in paper cartons.
Can anyone else relate to this?
Melody added that “No one talks about this aspect of MI” and I agreed — why aren’t we considering possible contamination of our food or food packaging much more, once we’ve successfully eliminated sources from cosmetics and household products, our usual main sources of exposure?
In September 2025, I shared on this site’s Facebook page some concerning news. A Chinese paper was published arguing that benziothiazolinone was a promising agrochemical for the management of blight in pears and perhaps apples, and that the Ministry of Agriculture and Rural Affairs of China had approved BIT’s registration for this purpose.
In fact, this wasn’t the first time such a suggestion had been made. Back in 2018, the need for alternatives to chlorine in fruit and vegetable processing was highlighted in a paper from the International Journal of Food Microbiology, with the MI/MCI blend a strong candidate in combination with others.
Another Chinese paper, from 2021, supported the use of all common isothiazolinones in pest control.
I imagine the use of isothiazolinone-containing formulations is now more widespread in the food security and farming industry than we might imagine.
Systemic Contact Dermatitis (SCD) and Methylisothiazolinone
SCD occurs when we experience symptoms to our contact allergens when exposed to a source other than through the skin.
We know this already happens with isothiazolionones off-gasing from paint, and absorbed into the system via the lungs, and the humidifier disinfectant scandal of South Korea highlighted how serious such exposures can be.
And we also know that SCD from dietary sources is real — with respect to some other allergens, it’s potentially quite common.
As I learned when researching The Metal Allergy Guide, incidental dietary intake of nickel (and sometimes cobalt and chromium) can have a severely detrimental effect on health in those who are particularly sensitive. Gut disorders, IBS and gluten hypersensitivity may all be interlinked in some people with ACD, and unpicking the problem in struggling patients can be particularly challenging for allergists, dieticians and gastroenterologists. Low-nickel diets are tough, especially for vegans and the gluten-free.
And it’s not only nickel. People with Balsam of Peru contact allergy may well also need to avoid certain foods which contain chemicals related to components in BoP, such as cinnamon, cloves, cola drinks, vanilla, chocolate and more.
Could consumers be consuming isothiazolinones in food too, and could it be having symptomatic impact?
Isothiazolinones in food packaging
We know paper processing uses solutions, preservatives and detergents which contain isothiazolionone preservatives.
We know such exposures through toilet paper can cause symptoms in the anal and genital regions.
We know too, from this study back in 2010, that isothiazolinones are present in paper used in food packaging, and from this paper from 2019, in the adhesives used in packaging too.
So can trace isothiazolinones migrate from paper or adhesives to food in sufficient quantities to cause a reaction? If Melody’s parchment paper experience is anything to go by, the answer might be yes, but has it been looked at scientifically?
I’ve been unable to find any published research, but I suspect the answer would indeed be yes, and I suspect that it may be more prevalent when the foods are moister, or kept in a more humid or lit environment, or packaged when warm — such as freshly baked bread in a paper bag — or when stored for a lengthy period of time.
Isothiazolinone Detergents in Food Processing
As we all know, detergents are commonly preserved with the isothiazolinones, and such detergents are likely to be used widely in food processing factories to wash down equipment.
Manufacturers obviously do rinse, but can we be sure it is sufficient? With anecdotal reports of reactions to rinsed plates and rinsed laundry, it’s fair that we question exposure via trace detergent residue.
Melody mentioned peanut butter, which I think is interesting, because allergen control is particularly difficult for sticky and fatty food. Chocolate is the usual prime example — it is extremely challenging to avoid cross-contamination with nuts, for example, in nut-free chocolate bars produced on lines where nuts are used for nutty chocolate. Could similar be happening with the isothiazolinones?
What can be done?
I don’t want to alarm the isothiazolinone-allergy community. If you’re on top of symptoms and have management under control, you shouldn’t have to worry about rogue exposure through means you’ve never previously suspected. And it’s important to recognise that gastrointestinal symptoms are generally much more likely to be caused by foods or other conditions, which you should explore with your doctors and specialists.
But I agree with Melody — I do think it’s time for researchers to look seriously at this issue, and undertake some mass spectroscopy analysis of foods which are potentially vulnerable to isothiazolinone contamination through detergents, pesticides or packaging.
Meanwhile, I guess I can only advise you to choose organic if possible (not that that is any absolute guarantee of isothiazolinone-free process), or peel and scrub your vegetables.
Or alternatively, wash them! Isothiazolinone-free brand Attitude offer a Fruit & Vegetable Wash.
Your experiences …
Please comment below if you have any thoughts or experiences to share, or know of studies that I have missed. I would like to revisit this subject in future, and I know Melody will be addressing it too.
Hi,
Thank you for this post. I can use this when advocating against these products by the Dutch Gouvernement.
@webmaster. If Melody is Dutch, can you ask her to contact me. Maybe we can coöperate. I have loads of research on aquatic live and pets.
Hi Vanessa. Melody is in Canada, but I am sure she will read this post and the comments.
I think Netherlands is bound by EU regulations on isothiazolinones, which are more strict than in most other places in the world.
Good luck, Alex.
Thank you for your article. We are careful to avoid MI in the dishwasher. The only Rinse Aid I have found that does not contain products in the MI family is Ecover. Others can cause coughing when the dishwasher is opened after use for those who react to MI in the air – so definitely want to avoid it as residue on our dishes which could transfer to our food.
Similarly we are careful with dishwashing tablets and also washing up liquid – both Ecover and Blue Fairy washing up liquids do not trigger symptoms here.
We switched clothes washing liquids due to MI family of products in the previous clothes washing liquid which caused coughing near the drying clothes, even after the clothes had been thoroughly rinsed. Therefore agree that rinsing is not enough to get rid of MI residue.
The odd thing with laundry is that this *has* been researched and rinsing was found to be effective – but the experience of many with MI allergy says otherwise. (See https://mi-free.com/mi-in-laundry-detergent/)
I have to wonder about what laundry machines were used in this research, and how they would compare to the reality of those who don’t maintain them to manufacturer standards. Or if they have tested now that scented bead products are so popular.
For example. I was renting in a building with a laundry room shared with two other tenants. Fortunately they agreed to use my detergent, but even still, there was residual water in the machine when I would go to use it – clearly not draining properly.
I now rent in a complex with a large shared laundry room with multiple machines. The machines are so gummed up with detergent that even running an empty wash still has the previous user’s detergent in the dispenser.
And the use/overuse of scented beads (which are wax based) have lead to a number of dryer fires because the residual builds up.
(I am hand washing in my unit).
If Methylisothiazolinone can cause horrible skin rashes that are visible on the outside of our body, I’m sure isothiazolinone-containing formulations can be having a detrimental effect on us internally, too.
When I had a patch test in May 2017 the head of the Contact Dermatitis Investigation Unit told me my contact dermatitis was not caused by anything I ate. But some of the symptoms I am having lately regarding my gut make me think otherwise.
I’ll keep on the look out for any relevant studies.
You’d think so, wouldn’t you, but I wish we had more data and evidence … I really hope it’s looked at soon.
Having been much more severely afflicted by MI/MCI and many others post Covid. I’ve discovered that different allergens present themselves on different parts of my body. After multiple presentations I’ve been able to differentiate the allergens by where they present. Very strange, I know. MI/MCI are the worst, yet easier to avoid. Balsam of Peru is particularly difficult to avoid, due the lack of common name or just “natural flavor ” as described in ingredients. BoP comes in so many ways and is often ingested. I was always told I had contact dermatitis by allergists, yet BoP is ingested and difficult to avoid.
BoP allergy is very troublesome. I’ve been looking into it a little lately. From what I can gather BoP itself is mainly used in cosmetics and medicinal products, but chemicals found in it are also found in lots of foods, fragrances and other natural components, which is where the difficulty arises – ‘natural flavor’ being a perfect example. I think more precise declarations should be required for foods. Too many problematic ingredients can ‘hide’ behind vague expressions.
Me too. I was recently in A&E for 10 hours while they checked why I had a bad bout of diarrhoea and was losing blood. All the various specimens they took from me to test for bacteria, parasites, C Diff etc., even for cancer, were completely normal. When I mentioned my allergy to Methylisothiazolinone they just brushed it aside. Not interested. No investigation. So how will we ever know?
What a grim experience, Sally. I would hope MI could not cause such a bad bout of symptoms in the quantities we’re discussing here, but without research into what is going on with dietary exposure, there is very little for us to go on. In fairness to medical and healthcare workers, they are only trained in what we know – it’s the gap in knowledge that’s the problem. I don’t know how we can resolve it, other than sharing experiences and hoping some allergists or allergist researchers pick up on it. I know that many of them subscribe to this site. Here’s hoping ….