Determination of occupational exposure to alkanolamines in metal-working fluids

Overall exposure to alkanolamines in metal-working fluids (MWFs) in machine shops was studied by determining alkanolamines in air samples and in rinse-off samples from the hands of machinists. Methods for collecting airborne alkanolamines and alkanolamines absorbed to the skin of the hands were developed and tested. The exposure measurements were carried out in nine machine shops. After a 2 h working period the dominant hand of 37 machinists was rinsed with 200 ml of 20% isopropanol for 1 min in a plastic bag. Personal air samples were also collected during the 2 h working period onto acid-treated glass fibre filters. The filter samples were desorbed with methanol and analysed by liquid chromatography with mass spectrometric detection (LC-MS). The rinse-off samples were also analysed for alkanolamines by LC-MS. The median air concentration of monoethanolamine (EA) was 57 microg m-3, diethanolamine (DEA) 64 microg m-3 and triethanolamine (TEA) 6 microg m-3. The workers' overall exposure to alkanolamines was estimated by calculating the amount in inhaled air and the amount on the skin. The median amount of EA on the skin of the dominant hand was 9-43 times the median amount in inhaled air during 2 h exposure. The corresponding ratio for DEA was 100 and for TEA 170. According to this study the exposure to alkanolamines occurs mainly through the skin. EA was the only alkanolamine with a noticeable inhalation uptake compared to the skin uptake. Total exposure to MWFs may be reduced by reducing skin exposure. The hand rinsing method can be used to assess the efficiency of protective gloves.