As a step towards improving safety and reducing potential health risks associated with the use of biocides, the European Commission has now decided to lower the specific concentration limit for the biocide BIT (1,2-Benzisotiazol-3(2H)-one) from 500 ppm to 360 ppm. This means that products containing BIT at or above 360 ppm are now considered harmful if in contact with the skin, eyes or lungs and will need to be labelled with a hazard symbol.
The new regulation, which will come into effect on September 1st 2025, has been published in ATP21 - the 21st technical adaptation of the CLP Regulation "Adaptation to Technical Progress".
What is BIT and why is it used in process fluids?
BIT is a bactericide, due to its effective antimicrobial properties, and is widely used in many process fluids. BIT belongs to the group of isothiazolinones, which also includes the bactericide MIT, the fungicides BBIT and OIT, and the mixture of CMIT/MIT, which is a broad-spectrum biocide that prevents growth of both bacteria and fungi. These are all organic compounds that can cause allergic reactions.
An increasingly better working environment
The biocides MIT, OIT and CMIT/MIT had their specific concentration limits reviewed and lowered to 15 ppm in 2020 and 2022 respectively, and now BIT has also been given a lowered specific concentration limit. It is very likely that BBIT, which currently has a concentration limit of 10,000 ppm, will also have its limit reviewed shortly (*).
This adjustment is part of a broader trend towards stricter controls on chemical substances, driven by ongoing research and a better understanding of their impacts on health and the environment. As industries adapt to these changes, the goal remains to provide safer products for users and reduce the ecological footprint of chemical use.
| Active substance | Identifier | Concentration limit | Applies from |
| 1,2-Benzisotiazol-3(2H)-one | BIT | 360 ppm | Sep 1st 2025 |
| 2-methyl-2H-isothiazol-3-one | MIT | 15 ppm | May 1st 2020 |
| 2-n-butyl-benzo[d]isothiazol-3-one | BBIT | 10 000 ppm* | Dec 1st 2010* |
| 2-octyl-2H-isothiazol-3-one | OIT | 15 ppm | March 1st 2022 |
| Mix of 5-chloro-2-methyl-2H-isothiazol-3-one och 2-methyl-2H-isothiazol-3-one |
CMIT/MIT | 15 ppm | May 1st 2020 |
Amines replace biocides
Alternatives to biocides that are harmful to health and environment are becoming increasingly relevant as the consequences of stricter legislation result in deterioration of the bio-protection of the process fluids.
To continue to maintain a strong bio-protection in process fluids, the chemical industry has instead sought to raise the pH of the fluids, sometimes up to pH 9.5 or higher, to prevent microbial growth. The pH increase is made with amines, which are basic organic compounds, but a strong alkaline (> pH 7) fluid contributes to an increased risk of skin irritation and other health problems.
It has become more important today, as the pH is critical, to ensure that the concentration of the process fluid remains at the correct and stable level to avoid a low pH that quickly invites to increased activity of microorganisms.
Technology helps the fluid
To protect and further improve both our environment and the working environment, industrial process fluids will be further limited by protective and increasingly strict regulation.
Modern technical solutions play an important role in making process fluids, and industrial processes, meet the high productivity and quality requirements. In 2010, the first FluidWorker units based on UV technology were introduced to the market and have now been developed into a product range expanded with automatic control of the cutting fluid concentration and tank level. Results from customers who have implemented FluidWorker show reduced fluid consumption, fewer production stops and a better working environment with low bacteria levels and no biocidal use. Read more about FluidWorker installed at GKN in Köping, Sweden.
Image: unsplash.com
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