Cooling lubricants in use must be stable against bacteria in order to achieve a long service life. So-called formaldehyde depot substances (FAD) are used for this purpose. The biocidal active ingredient is present in a chemically bound form and is initially only present in very small quantities in the concentrate and the ready-to-use emulsion or solution.
The Risk Assessment Committee (RAC) has classified formaldehyde 1) as a Class 1B carcinogen and Category 2 mutagen. Rhenus Lub does not use pure formaldehyde in its cooling lubricants. However, some Rhenus cooling lubricants contain the above-mentioned formaldehyde depots 2).
1) Formaldehyde = proportions in free form
2) Formaldehyde deposits = proportions in bound form
Rhenus Lub’s cooling lubricants do not and will not reach the limit value of 0.1%. Therefore, rhenus products containing formaldehyde deposits can be used without hesitation.
At present, the following therefore applies:
- rhenus metalworking fluids are not labelled with information regarding formaldehyde and formaldehyde releasers.
- Handling by users remains the same.
- There are no changes to labelling.
Measurement and labelling
In the Rhenus Lub laboratory, formaldehyde concentration has been a standard test parameter for years. An automatic laboratory analysis system is used to determine the separable formaldehyde. This method determines the maximum possible separable amount from the formaldehyde deposit. Since only a small fraction of this amount is actually separated in practical application, this measurement method offers maximum safety for the user. Measurements of rhenus cooling lubricants used in accordance with instructions have consistently shown values below the limit values.
Air limit values and inhalation of formaldehyde
The previous MAK value (maximum workplace concentration) as a workplace limit value of 0.62 mg/m³ is no longer valid. Instead, the legally binding long-term value of 0.37 mg/m³ and the short-term value of 0.74 mg/m³ of TRGS 900 now apply.
This means that, based on current knowledge, the use of Rhenus Lub cooling lubricants containing FAD is safe and permissible under normal working conditions. Furthermore, there is no obligation to measure formaldehyde in indoor air. An evaluation of formaldehyde measurements in the air in mechanical production work areas for the period from 1999 to 2009 showed that 95% of all measurements were well below the recommended limit value of the MAK Commission (0.37 mg/m³). In addition, compliance with the SCOEL (Scientific Committee for Occupational Exposure Limits) limit value of 0.2 ppm = 0.25 mg/m³ discussed at the time was also ensured in over 95% of all measurements carried out. This information takes into account the current legal guidelines (as of October 2025). Should any further changes occur, Rhenus Lub customers will be automatically informed.
Despite new guidelines for the classification of formaldehyde, metalworking fluid users and producers will not encounter
- any change in labelling
- any obligation to take measurements
- It’s up to you!
As a customer of Rhenus Lub, you have the same two possibilities as have previously been available: metalworking fluids with or without formaldehyde releasers.
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