Benzisothiazolinone. Methylchloroisothiazolinone. Methylisothiazolinone. Complicated names but this post is going to break it down. These are preservatives, and you may have seen them in their shortened forms, BIT and MI/MCI, on a label. They're a common source of questions, so here's a simple explanation of what they are, why we use them, and how we think about them.
Why do cleaning products need preservatives?
Anything water-based is a welcoming home for bacteria and mould. Without protection, a dishwashing liquid or surface cleaner could spoil, change smell or colour, or grow things you definitely don't want in your kitchen. Preservatives keep the product clean and effective from the day it's made to the last dose.
What are these three?
BIT, MI and MCI belong to the same family of preservatives, which have been used in household products for many years. Each one is better at some jobs than others, so using them together gives us a synergy: we can use less of each and still get better protection than we would from a single ingredient at a higher level.
Why do they have a bad reputation?
It's a fair question. These preservatives can cause allergic reactions in some people, particularly with repeated skin contact. That's exactly why their levels are limited, and why we keep ours as low as we effectively can.
Why dose matters
The safety of an ingredient depends on its dose. We keep these preservatives to very low levels: BIT below 400 parts per million (ppm), and MI/MCI below 15 ppm. These are the legal limits, what can be added without serious warnings. You could always use more but have to put warnings on the label.
To put that in perspective, 15 ppm is about 15 grams in every tonne of product. Picture 4,000 coconuts, which is about 1,000 liters of coconut water. Now add a single level tablespoon of preservative to all of it. That’s 15 ppm: a tiny amount, and it’s only there to do a specific job.
We aim to use the lowest effective level, because we know these ingredients can cause reactions in some people.
What if I'd rather avoid them?
That's completely reasonable, and we make it easy. Our Sensitive Dishwashing Liquid contains no BIT, no MI/MCI, no fragrances and no dyes. It's available at Chemist Warehouse and independent supermarkets.
The bottom line
At the very low levels we use, these preservatives are safe for most people, and they're what keeps water-based products clean and effective. But they can cause allergic reactions in some people, so we use the minimum needed and offer a gentler alternative, made without them, for anyone who prefers to skip them.
Have a question about a specific product or ingredient? Our customer service team is happy to help at enq@naturesorganics.com.au.