Cleaning Tips, Sustainable Living | Feb 19, 2020 11:54:00 PM

Why Methylisothiazolinone-Free Cleaning Products Matter

Methylisothiazolinone (MI) is a synthetic ingredient that is commonly found in many household cleaners, including “healthier” alternatives despite numerous studies proving that it causes harm to human health and the environment. Read on to find out more about Methylisothiazolinone and why it should be avoided.

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What is Methylisothiazolinone?

Methylisothiazolinone is a synthetic chemical used in consumer products for its antimicrobial properties. It is most often applied to cleaning products as a synthetic preservative. This chemical is used to extend a product’s shelf life and protect consumers against exposure to bacteria and mould by inhibiting the growth of those organisms.

Methylisothiazolinone can be found on product labels under the following names:

  • MI
  • MIT
  • 2-methyl-4-isothiazoline-3-one
  • Neolone 950 preservative
  • OriStar MIT
  • Microcare MT

This chemical poses various health concerns linked to allergies and potential neurotoxicity.

Is Methylisothiazolinone harmful?

Methylisothiazolinone in household cleaners may cause respiratory irritation, skin sensitivities (including dermatitis), skin burns and eye damage according to peer-reviewed research and data from the European Chemicals Agency (ECHA) reported as part of the Environmental Working Group’s ‘Guide to Healthy Cleaning’.




The American Contact Dermatitis Society named Methylisothiazolinone “allergen of the year” in 2013 due to growing concern and reports of Methylisothiazolinone sensitivity, but like many other harmful chemicals use in consumer products continues.

The Canadian government has actually banned it for use in leave-on cosmetics but it is still allowed in rinse-off products at the maximum allowed concentration of 0.0015%. Unfortunately regulation of household cleaners is weak in North America so similar guidelines for Methylisothiazolinone use in cleaning products do not exist.

Adverse effects of Methylisothiazolinone also extend to the natural environment. The Environmental Protection Agency (EPA) states that Methylisothiazolinone is highly toxic to freshwater and marine organisms.

What is worse is that only one of the two compounds that make up Methylisothiazolinone is susceptible to degradation in water - and only in specific conditions. This means that it has the potential to persist in our natural environment, the effect of which is yet to be assessed.

Can Methylisothiazolinone Cause Allergies?

Yes. Methylisothiazolinone (MI) can cause allergic reactions. In fact, this preservative was dubbed “Contact Allergen of the Year” in 2013 by the American Contact Dermatitis Society.

The North American Contact Dermatitis Group found that methylisothiazolinone “...caused 10.9% positive reactions, being the third most common contact allergen” in patch test results which surveyed close to 5000 Contact Dermatitis patients. 

In more recent years, a study that was conducted in Western Canada and published in 2017, found an increasing prevalence of methylisothiazolinone allergy between 2008 and 2015.

The following symptoms may occur and worsen with each use of products containing combinations of MI.

  • Red rash or bumps
  • Itching
  • Swelling, burning, or sore skin
  • Dry, cracked or scaly skin
  • Fluid-filled blisters

Health Canada says that consumers with an MI allergy or sensitivity should avoid the use of products containing this preservative.

Methylisothiazolinone Free Cleaning Products

Methylisothiazolinone is found in a wide range of consumer products from cosmetics to home cleaning products, even “healthier” alternatives. If a product has it’s ingredients listed, look for Methylisothiazolinone (MI/MIT) or Methylchlorisothiazolinone (MCI/MCIT).

It is also used in manufacturing to control the growth of bacteria in the industrial process.  

The list below includes a list of brands that offer MI-free household cleaning products in Canada and the US. Other MI-free brands and products can be found on

  • AspenClean (Canada / US)
  • Attitude (Canada / US)
  • Bio-D (US)
  • Biofactor (Canada)
  • Branch Basics (US)
  • Charlie’s Soap (US)
  • Earthview (US)
  • Eco-Max (Canada)
  • Eco Me (US)
  • Eco Nuts Soap
  • Fit Organic (US)
  • Greenshield Organic (US)
  • Logic Products (US)
  • Meliora Cleaning Products (US)
  • Molly’s Suds (US)
  • Pure Haven Essentials (US)
  • Sun & Earth (US)
  • Vitacost (US)

conventional cleaning products

What can be done?

Methylisothiazolinone is one of many chemicals that compound to chemical pollution of the natural environment, and according to the UN Environment Programme, producers and manufacturers are part of the solution.

The second Global Chemicals Outlook presented during the UN Environment Assembly in Nairobi found that the current chemical production capacity is projected to double by 2030. This means that the goals set in the original Global Chemicals Outlook will not be achieved by the set date of 2020.  

But the report maintains that positive solutions from companies that practice sustainable supply chain management, full material disclosure, and risk reduction beyond compliance can help mitigate the issue.

In the case of Methylisothiazolinone, solutions are seen in the many cosmetics brands that abide by the ingredient ban.

The reason why cleaning companies don’t use natural alternatives is that these ingredients are more expensive – and also because it puts more demand on the production process. This is because natural preservatives are more vulnerable to pathogens, bacteria and yeast so more care and cleanliness must be observed during manufacture.


Methylisothiazolinone free natural laundry spray and dishwasher packs


But the fact is that it is possible! AspenClean uses Aspen Bark as a natural product preservative for example and produces products in entirely chemical-free environments.

As a consumer, it is difficult to keep track of every chemical that you encounter. The best thing you can do to limit your exposure to Methylisothiazolinone is to avoid it by reading product labels and using resources like the EWG’s Guide to Healthy Cleaning to ensure your cleaning products are Methylisothiazolinone free.


Buy Methylisothiazolinone-free Cleaning Products

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