What scary ingredients are hiding in your favorite products?


What scary ingredients are hiding in your favorite products?

Hey everyone! Welcome back for Part 2 of the blog series where we get to discover, or rather uncover, what scary ingredients are hiding in some of our go-to products. We’re looking into ingredients that are widely used in everything from shampoos, to creams, facemasks, nail polishes, perfumes, laundry detergents… you get the idea.

Last week, we went over the term “fragrance” – what it means and what types of products it can be found in (spoiler alert, it’s in everything!) and what health and environmental impacts it can have. This week, we will be taking a closer look at one of those long scientific-type words that lives on ingredient labels. This ingredient is widely used in shampoo, conditioner, laundry detergent, liquid soap, hair dye, body wash, lotion, mascara, as well as baby shampoo and lotion to name a few. We’ll take a look at what this ingredient is (and how to properly pronounce it!), the health impacts, as well as the associated environmental impacts. So, without further ado, onto the good stuff!

Methylisothiazolinone – say that ten times fast!

Methylisothiazolinone, also known as MI or MIT, is used as a preservative in personal care products and cosmetics to prevent the growth of different fungi and bacteria. MIT is a potent biocide, which is a broad-spectrum term used to describe various chemical substances with the ability to kill living organisms in a selective way. The term biocide also covers antibiotics, antifungals, antimicrobials, and germicides.

This preservative is commonly found in various moisturizers, shampoos, conditioners, and other personal care products and household cleaners. MIT is also used in industrial settings to slow the formation of mildew, mold, and sap stain in wood products, as well as to control the population of slime-forming organisms in fuel storage containers, water systems in pulp and paper mills, and oil extraction systems. But yes, let’s lather it onto our scalp? I think not.

Methylisothiazolinone falls under a family of isothiazolinone preservatives, which can appear on a product label under many different names. The two most common names that will appear on personal care products are methylisothiazolinone (MI/MIT) and methylchloroisothiazolinone (MCI/MCIT). Other common names, more so  found in household cleaners are benzisothiazolinone (BIT), chloromethylisothiazolinone (CMIT), and octylisothiazolinone (OIT). 

It can be a challenge when attempting to avoid MI in the products we choose to purchase.  Although normally listed on its own, MI is one of the many chemicals that can be disguised on a label when in a blend with other permitted chemicals and hidden under the term “fragrance” or “parfum”.  

Health Impacts

The health impacts of methylisothiazolinone are quite serious; so much so that it was found unsafe for use in cosmetics and therefore banned in Europe. It is a known human immune toxicant, a skin toxicant, and a human sensitizer toxicant. A study was also done on the brain cells of mammals which indicated that MI may be a neurotoxin. 

In 2015, a study was done to determine whether or not the current allowed levels of MI in rinse-off cosmetic products were causing allergic contact dermatitis. The study was carried out on thirty-eight individuals, with equal parts of MI-allergic subjects and a control group of non-allergic subjects. 

Each subject applied two liquid hand soaps five times per day to an area on each forearm. Ten allergic individuals and the entire control group used one soap containing the allowed concentration of MI in cosmetics, which is 100 ppm (parts per million). Another soap containing 50 ppm MI was used by the other nine allergic subjects. The last soap, used by all subjects as a negative control, was a soap containing 0 ppm MI. The study ran the duration of 21 days, or until a positive reaction occurred. 

The study showed that no reaction occurred to the soap without any MI, while all ten allergic individuals had reactions to the 100 ppm MI hand soap. Seven out of the nine subjects also reacted to the 50 ppm MI hand soap, and no reaction was seen among those without allergies. The study concluded with a statement saying, “Rinse-off products preserved with 50 ppm MI or more are not safe for consumers. A “safe level” has yet be identified.

In Australia, MI was reported as an important cause of facial and hand dermatitis in caregivers and children due to the presence in baby wipes and facial wipes. Various patch test studies conducted between 2011 and 2013 showed a significant rise in contact dermatitis from MI; jumping from 3.5% in 2011 to 11.3% in 2013. It was concluded that the continued use of the chemical in baby wipes and facial wipes will lead to increased rates of allergy to these preservatives in adults.

Environmental Impacts

Methylisothiazolinone has many environmental impacts on aquatic life. The chemical is moderately to highly toxic to freshwater, estuarine, and marine organisms. Although these risks are known, it is hard to know exactly how harmful they are to aquatic life forms as no formal assessment has not yet been performed. However, not being able to prove the extent of the damage we know MI is causing does not mean we should continue to use it.

So, will you be paying more attention to product labels?

These chemicals can be easy to avoid in products once you know what to look for! There are plenty of resources available for the consumer that can make shopping for new, safe products a breeze and not a daunting task! Stay tuned next week as we look into resources that you can use to help avoid these ingredients, as well as many more!


Written by: Quinn Ponton, Holistic Nutritionist CNP

Questions for Quinn?

Reach her via email at quinn.ponton@gmail.com