2014.10.22 Bacteria and endotoxines

Microorganisms in process fluids

Microorganisms are present everywhere, and live on and in everything from sea beds to tree tops. So why don't you want them in your metalworking fluid?

Metalworking fluid systems often constitute very suitable environments for microbial growth due to the excellent access to nutrients, water and heat. Microorganisms will consequently always be present in metalworking fluid systems, and the real challenge is primarily to restrict their numbers over time.

The problems that arise with microbial attacks on metalworking fluids are both related to health and safety and productivity.

Work environment

Microorganisms can constitute a health hazard, but far from all bacteria and fungi are harmful. Both harmless and harmful microorganisms have been found in metalworking fluids.

Infections, poisoning or development of allergies are typical health problems that can be linked to contact with microorganisms. With metalworking fluids, it is most common for staff to have symptoms such as eczema, respiratory problems and general respiratory tract disorders such as a runny nose.

By-products from microbes, as well as the substances that are secreted in conjunction with killing bacteria, convey increased health risks. Acids and endotoxins are often released in connection with decomposition of bacteria, which has known negative health effects on contact and inhalation.

Besides microorganisms, contact with biocides also entails a similar health risk. The attempt is often made today to balance the content of biocides with the content of bacteria in systems, and it is not unusual that a pendulum effect quickly arises with high bacterial content and high biocide content succeeding each other. None of the states are particularly desirable and they increase the health risk for the staff.


The organisms that are present in metalworking fluid systems live on the nutrients available in the form of ingredients in the concentrate, the water and that which potentially ends up in the fluid via, for example, the components that are machined. The fact that microorganisms eat nutrients is also called decomposition, in this case of the metalworking fluid.

Typical components in the metalworking fluid, such as rust protection and emulsifying agents, as well as salts of phosphorus and nitrogen have important properties for the satisfactory functioning of the metalworking fluid, but unfortunately they are simultaneously fertilizers for many microorganisms.

The more microorganisms that live in the metalworking fluid system, the greater and faster the decomposition of these components in the metalworking fluid will be. Maintaining the contents of bacteria and mould at a low level in systems is therefore important in reducing the consumption of concentrate and ensuring good quality in the metalworking fluid over a longer period.

The problems associated with productivity that can arise in connection with impaired metalworking fluid quality include corrosion, impaired lubricity, foaming, mess on components and machine parts, clogged filters and a bad smell in the workshop.

Caroline Sterneryd
Caroline Sterneryd

Som applikationsspecialist sysslar Caroline dagligen med frågor som rör skärvätskor, bakterier och UV. Hon är medlem i Processvätskecentrums Arbetsmiljö- och Hälsagrupp där hon ser till att hålla sig uppdaterad på biociders hälsoeffekter och den allt striktare EU-lagstiftningen. As an application specialist, Caroline is involved on a daily basis with questions that concern metalworking fluids, bacteria and UV. She is member of the Swedish Process Fluid Centre's work environment and health unit, where she makes sure to keep herself updated on biocides' health effects and the more strict EU legislation. Als Anwendungsspezialistin befasst sich Caroline täglich mit Fragen über KSS, Bakterien und UV. Sie ist Mitglied des schwedischen Zentrums für Prozessmedien in der Arbeitsumwelt. Ihre Aufgabe ist, sich über Biozidprodukte auf dem Laufenden zu halten. Sie aktualisiert die Erkenntnisse über deren Auswirkungen auf die Gesundheit und die Informationen über die aktuelle EU-Gesetzgebung.


Follow the blog