Skin irritation prevention has always been an important objective for Cimcool, and substantial tests have been conducted to exclude Cimcool metalworking fluids as a contributing irritant.

With many years of tribological experience, using tests that are state-of-the-art, Cimcool has developed metalworking fluids that are heading toward being completely skin compatible, thereby removing irritation issues. One of the aims of REACh (Registration, Evaluation, Authorisation restriction of Chemicals) is to improve the flow of health, safety and environmental communications from the manufacturers of chemicals to their end users.

The product safety data sheet (SDS) is a tool for achieving this. One aspect for consideration when producing an SDS is the skin and eye irritating properties of the product. The information on the SDS for the irritating properties of mixtures, such as metalworking fluids, are determined according to the EU’s calculation procedure. Animal tests are used, but are less acceptable due to unnecessary animal suffering.

"Cimcool performed eye irritation tests on 34 products, and skin irritation tests on 27"

Several new non-animal tests are now being officially accepted and consequently Cimcool has undertaken large scale skin and eye irritation tests using these methods. This fulfils the company’s obligations to REACh, as well as the future GHS (global harmonised system) requirements.

European Union directive 1999/45/EC is referred to as the Dangerous Preparation Directive (DPD) in which, amongst others issues, skin and eye sensitivity is considered. The principle for establishing irritation according to the EU DPD is straight forward, at first sight: it is based on the raw material information and the concentration. Take two ingredients of a metalworking fluid, monoethanolamine (8%) and biocide (3%); both can be considered as corrosive to the skin/eye (R34).

Using the EU’s calculation method, this metalworking fluid would be classified as corrosive since the combined concentration is above 10%, the point above which the DPD states the product is corrosive. This calculation, however, does not take neutralization into account. The corrosive effects of the alkaline monoethanolamine are decreased with acidic materials such as boric and fatty acids. In order to investigate the true irritation properties of metalworking fluid concentrates, Cimcool performed independent irritation tests.

Samples were examined for acute eye irritating/corrosive properties in an ex vivo screen using the chicken enucleated eye test. The purpose of this study was to provide data on the irritancy of the substance after a single application to isolated eyes of slaughtered chickens.

In their latest updates of the guidelines on Eye Irritancy Testing, both the EC and the OECD (Organisation for Economic Co-operation and Development) allow for the use of alternative ex vivo/in vitro test systems for pre-screening or identification of severe eye irritants, in order to reduce animal use and suffering. Moreover, the CEET test is one of two organotypic in vitro assays accepted by ECVAM (European Centre for the Validation of Alternative Methods).

A 3D skin model is a viable reconstituted human epidermis retrieved from human keratinocytes, which themselves are retrieved from cosmetic surgery or circumcisions. The human origin of the test system itself therefore holds another considerable advantage compared to other animal models: in August 2007, ESAC (European Scientific Advisory Committee) recommended the use of in vitro reconstructed human skin models for in vitro skin irritation testing.

Since then, a prediction model based on a set of two parameters (viability and IL-1 alpha release) is considered to be state-of-the-art. The test is exclusively used for the prediction of irritating (I) or non irritating (NI). The multiple endpoint analysis (MEA) on Cimcool products includes histological examination and, additionally, determination of LDH release refines the prediction model tremendously.

"The total influence of metalworking fluids on skin irritation is not fully understood"

In total, Cimcool performed CEET eye irritation tests on 34 products, and 3D skin irritation tests on 27 products, all at 100% concentration. Nearly all products are considered non-irritating and do not require specific labelling. Exceptions include a mineral oil containing product that is considered to be an eye irritant. Skin compatibility, however, is good.

The chemistry used to give this type of product the required performance (including phenoxy propanol) contributes to the eye irritation properties. The other four products considered skin/eye irritants include true synthetic, alkanolamine borate free products.

These products are highly concentrated and are consequently used at a mix of 2.5 per cent to 5 per cent. Therefore, although the product concentrate is irritating, these products are considered acceptable in use.

Within the metalworking industry, skin irritation is a generally occurring problem. Although the total influence of metalworking fluids is not fully understood, it is now commonly accepted that wet working contributes significantly to skin irritation.

Optimum working conditions, including a skin protection plan, will limit these levels. For more than 40 years, Cimcool has performed skin irritation tests to exclude metalworking fluids from being a significant contributor to skin irritation, always using the latest available technology.

With the recently completed 3D skin and CEET eye irritation tests, Cimcool not only has information on the irritating properties of the products in use, but also has the correct information on its safety data sheet about skin/eye irritation – thereby fulfilling REACh and GHS requirements.

In addition, because of the large scale investigations, Cimcool can extrapolate the data to other products. Last, but not least, it continues to provide information to the Engineering and Development (E+D) department to aid its goal of making completely skin compatible metalworking fluids.

www.cimcool.net