Health hazard evaluation report: HETA-2004-0399-3007, NTN-Bower Corporation, Hamilton, Alabama.
On September 15, 2004, the National Institute for Occupational Safety and Health (NIOSH) received a health hazard evaluation (HHE) request from the United Auto Workers Local 1990 to evaluate dermal exposures to metal working fluid (MWF) at the NTN Bower Corporation facility in Hamilton, Alabama. The request also alleged that management was not allowing employees sufficient time for washing their hands after exposure to MWFs. During the initial site visit to NTN Bower on December 7-8, 2004, NIOSH medical officers interviewed 46 employees regarding their work history, potential dermal exposures, use of personal protective equipment, frequency of hand washing, and history of atopy and skin rashes. Four employees were identified with skin conditions that could be work related. In a questionnaire administered to NTN Bower employees, 36 of the 46 employees responded that they wash their hands five or more times per day. Bulk samples of MWF from the three systems used at the facility were analyzed for metals, bacteria, endotoxins, and polynuclear aromatic hydrocarbons (PAHs). During this initial site visit NIOSH investigators noted MWF mist throughout the production area. NIOSH investigators returned to NTN Bower on June 20, 2005, and collected personal and area air samples for MWFs, carbon monoxide (CO), ethanolamines, PAHs, and formaldehyde. Fifteen of 18 personal breathing zone (PBZ) air samples for MWFs exceeded the NIOSH Recommended Exposure Limit (REL) of 0.40 milligrams per cubic meter (mg/m3) of air for thoracic particulate mass. Instantaneous readings of CO in the Heat Treating area ranged from 34 to 86 parts per million (ppm), suggesting that the NIOSH Recommended Exposure Limit-Time Weighted Average (REL-TWA) of 35 ppm could be exceeded. An evaluation of the ventilation systems used to control MWF mists revealed that many of the systems were not in operation. In addition, machines were not properly enclosed, flexible exhaust hoses were disconnected or torn, and the exhaust systems needed maintenance. Airborne levels of ethanolamines, PAHs, and formaldehyde were below applicable occupational exposure limits. NIOSH investigators concluded that a health hazard existed at the time of this evaluation due to employee's exposures to MWFs above the NIOSH REL. In addition, employees in the Heat Treating area were potentially overexposed to CO, and the ventilation systems used to control MWF mists were ineffective and needed maintenance. Four of 46 employees interviewed by NIOSH Medical Officers had skin conditions that could be work related. Recommendations include the use of respiratory protection until concentrations of MWF mist can be reduced below the NIOSH REL.