AN ASSESSMENT OF EXPOSURE TO CYCLOHEXYLAMINE ARISING FROM STEAM HUMIDIFICATION OF INDOOR AIR

The United States uses two to three million kilograms of cyclohexylami ne (CHA) each year as a corrosion inhibitor in steam lines and boilers . Many existing boiler heating systems vent CHA treated steam into occ upied space to humidify indoor air. As a result, CHA has been implicat ed in acute toxic events arising from steam humidification. A study wa s undertaken at the East Carolina University School of Medicine to acc urately assess exposure to CHA, predict conditions or circumstances wh ich could lead to a toxic event, and make recommendations based on fin dings. Within the study areas, CHA levels averaged 6.6 parts per billi on (ppb), well below the present OSHA Permissible Exposure Level of 10 parts per million (ppm). A material balance helped identify the addit ive feed mechanism as the control point most likely to influence the o ccurrence of a toxic event arising from humidification with steam cont aining volatizing amine corrosion inhibitors. The automatic feed devic e should be carefully maintained and manual dosing of the boiler shoul d never be emitted within the Medical School Complex.