When the carcinogenic formaldehyde releaser is being phased out of metal cutting fluids, another group of biocides re-enters the market: isothiazolinones. They are now being examined by the EU, and so far the classification is always stricter after investigation.
Isothiazolinones is a group of biocides used for example in cosmetics, hygiene products, water-based adhesives and paints. These biocides were also common in coolants 10-20 years ago. After reports of increased frequency of contact allergy to isothiazolinones, especially the combination chloromethylisotiazolinone/methylisothiazolinone (also known as CMI/MI or Kathon CG), they were banned from many industries. It was also phased out in the other areas, and CMI/MI is not allowed in cosmetics which are left on the skin. The phasing out of CMI/MI in coolants have been of benefit to other types of biocides, especially formaldehyde releaser has increased in use.
Rated as carcinogenic
In recent years, also formaldehyde releaser is deprecated. This is mainly due to that the substance released during use, formaldehyde, is classified as a carcinogen since April 2015. When European Chemicals Agency, ECHA, in the autumn of 2015 evaluated three of the most common formaldehyde releasers, it was concluded that these should be classified as a carcinogen.
Challenge for suppliers
Most companies have therefore stopped using these substances and have been putting pressure on the process fluid suppliers to formulate fluids without these chemicals. Formaldehyde releasers has been around a long time in the industry and many formulations based its biostability entirely on these types of biocides. It is obviously a challenge for suppliers to formulate bio-stable process fluids without these biocides. A worrying trend is that isothiazolinones makes a re-entry into the process fluid market. Usually do not CMI/MI that caused so much trouble in the 90s, but other combinations. Is there reason to worry?
New combinations as dangerous
When CMI/MI were phased out of the cosmetics products, the use of methylisothiazolinone (MI) increased in these products. As a result, the number of documented cases of MI-allergy increased exponentially. When ECHA's Risk Assessment Committee in the spring of 2016 also assessed this substance, it was concluded that it is as allergenic as CMI/MI. The next isothiazolinone to be evaluated is oktylisotiazolinon. The proposal is to lower the concentration limit to 1/10 of the current limit. The judgement on this and other isothiazolinones remains to be seen. Only a few of the biocides used in metal cutting fluids have been through evaluation and in most cases, the classification has been much stricter after the evaluation.
So - when a biocide is to be phased out, make sure that you don’t get another one with unknown properties. There is a great risk that you will make the situation worse rather than improve it.
Chemicals legislation in the EU
Changes within the chemicals legislation are affecting the metalworking industry a lot right now. With our e-book, you can keep up to date. (CS)
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