You may have noticed some hard-to-pronounce ingredients in your home and personal care products.
Methylisothiazolinone (MIT) and Methylchloroisothiazolinone (CMIT) are preservatives used to inhibit microbial growth in liquid personal and home care products. They're very effective and inexpensive and if that sounds too good to be true, it is.
These preservatives have two big problems:
1. They are known allergens and commonly cause contact dermatitis. In 2013, The American Contact Dermatitis Society named Methylisothiazolinone (MIT) its Allergen of the Year. Sensitivity is especially likely when MIT and CMIT are used together, as they often are. This group of chemicals are suspected neurotoxins but there isn't enough testing data yet, which is also a red flag.
2. Isothiazolinones are highly toxic to aquatic organisms. The EPA states that Methylisothiazolinone is moderately to highly toxic to freshwater and estuarine/marine organisms.
In the U.S.A, these preservatives are widely used in shampoo, conditioner, lotion, liquid soaps like hand soap and dish soap, and many other products. That's no surprise; only a tiny percentage of chemicals are regulated in the U.S. Other developed nations have either banned or are moving towards strict regulation of these same chemicals. The EU is banning the use of isothiazolinones in leave-on products, the U.K. said: "Methylisothiazolinone can no longer be considered safe at current levels", and South Korea has banned their use in air fresheners and cleaning products.
Preservatives are a necessary ingredient in many products - especially those with water as their base. We can use pH to control bacterial growth in some products. Others need a neutral pH to be gentle on skin. In those cases, we have to use a chemical preservative to make sure they don't spoil. Look for products with better-known and tested preservatives like sodium benzoate and phenoxyethanol. They're also not suspected to be environmental toxins and are much less likely to cause adverse reactions.
Want more information? Here are some places to start:
https://www3.epa.gov/pesticides/chem_search/reg_actions/reregistration/fs_G-58_1-Oct-98.pdf
https://www.ewg.org/skindeep/ingredients/703935-METHYLISOTHIAZOLINONE/
https://www.ewg.org/skindeep/ingredients/703924-METHYLCHLOROISOTHIAZOLINONE/