Acetic aldehyde and formaldehyde in cutting fluids and their relation to irritant symptoms

The objective was to study the formation of acetic aldehyde in cutting fluids and its relation to irritation of mucous membranes and the skin. Acetic aldehyde and formaldehyde were analysed in two large cutting fluid systems in an engineering industry. Samples were taken 1-5 times a week during a year. Concentration of the cutting fluid, leakage oils, pH, bacteria, yeast and fungi were analysed weekly. The occurrence of mucous membrane irritation was registered through questionnaires to the exposed workers. About 50 persons were exposed to each of the cutting fluids. The concentration of the aldehydes varied with time and between the cutting fluids. None of the analysed parameters could explain the variable concentration of aldehydes. Mucous membrane irritation was much more common in one of the systems, e.g. the prevalence of irritation in the nose was about 30-40% in workers exposed to a cutting fluid, while the corresponding prevalence was less than 10% in workers exposed to another fluid. The occurrence of symptoms was slightly associated with the concentration of aldehydes and pH of the fluid varied more in the fluid that caused most symptoms. A few measurements of ammonia indicated a higher concentration of ammonia in the fluid that caused most symptoms. It is concluded that irritation of mucous membranes and the skin may vary considerably between different cutting fluids of similar composition and use but the causal factor could not be determined in this study, but a variable pH and an increased concentration of ammonia may be indicators in this context. The concentration of acetic aldehyde vary with time and between cutting fluids with similar composition. A high variability may be an indicator of less stable cutting fluids. Better markers for the surveillance of cutting fluids needs to be developed as well as a health control programme.