The irritant effect of different metalworking fluids.

The irritant effect of different water-based cutting fluids (CFs) on the skin was investigated in healthy subjects (n = 10) using 2 non-invasive bioengineering methods. Transepidermal water loss (TEWL) was measured by an evaporimeter EP1 (Servo Med), skin blood flow (SBF) was recorded with a laser Doppler flowmeter (MBF 3D, Moor Instruments England). Additionally all test sites were evaluated by visual scoring before measurement. 3 cutting fluids A, B and C from different manufacturers were tested at use concentrations of 4% or 5%. Single 24-h patch tests and repeated patch tests were performed on the volar side of the right forearm. Measurements were carried out before and after exposure to assess basal values and the skin response to CF. Tests with CFs A and C resulted in significant increase in TEWL after 24 h and after cumulative treatment, compared with controls (p < 0.01). The TEWL values for CF B did not differ from the water probe. An increase in SBF was found only for CFs A and C after cumulative patch testing (p < 0.01). In spite of their similar alkalinity, the 3 CFs showed different irritant skin reactions, due to their chemical components. This was verified particularly by measurement of TEWL.