Hazard evaluation and technical assistance report: HETA-98-0263-2817, General Electric Evendale, Cincinnati, Ohio.
In July 1998, the National Institute for Occupational Safety and Health (NIOSH) received a health hazard evaluation (HHE) request from the International Association of Machinists (IAM), Local Lodge 912 concerning the Special Product Operations (SPO) at General Electric (GE) plant in Evendale, Ohio. The request concerned the lay-up of uncured PMR-15, a graphite composite material used to make jet engine parts. Potential exposures included methanol and 4,4-methylenedianiline (4,4'-MDA), a component in the PMR-15 composite material. The union suspected higher 4,4'-MDA exposures in the "case room." Prior air monitoring by GE industrial hygienists had measured very low concentrations of 4,4'-MDA, but occasional high concentrations of methanol (ranging from 160 to 180 parts per million [ppm]). In March 1999, personal breathing-zone (PBZ) air samples for 4,4'-MDA and methanol were collected by a NIOSH industrial hygienist and a NIOSH medical officer conducted confidential interviews with SPO employees. The Occupational Safety and Health Administration (OSHA) Log and Summary of Occupational Injuries and Illnesses, Form 200 (OSHA 200 log), and company injury reports from the preceeding three years were reviewed. The company medical records of 19 SPO employees, including 12 of the 14 employees listed as currently working in the lay-up area, were reviewed. All interviewed employees were included in the medical record review. The concentration of 4,4'-MDA ranged from trace amounts (defined as between 0.015 and 0.062 parts per billion [ppb] for this sample set) to 0.42 ppb, as time-weighted averages (TWA). All of these results were well below the OSHA Permissible Exposure Limit (PEL) of 10 ppb and the American Conference of Governmental Industrial Hygienists (ACGIH ) Threshold Limit Value (TLV) of 100 ppb, TWA over an 8- hour work day. NIOSH recommends that exposures be kept a low as feasible. Methanol concentrations ranged from 4.4 to 22 ppm, all of which were well below the NIOSH recommended exposure limit (REL), OSHA PEL, and ACGIH TLV of 200 ppm, TWA over an 8- to 10-hour work day. Six of 14 SPO current lay-up employees and one former lay-up employee were interviewed. The remaining SPO lay-up employees were unavailable or declined the interview. Five of the seven employees reported musculoskeletal disorders, two reported fatigue, and two reported sore throat with methanol and/or a decontamination solution use. Concerns of the interviewed employees included: lack of solvent handling and ergonomic training, ventilation in the SPO lay-up area, adequacy of personal protective equipment (PPE), and lack of representative air sampling due to the daily variability of work activities. Additional concerns included exposure to 4,4'-MDA (both airborne and dermal) in the lay-up area, and the lack of biological monitoring (urine testing) for 4,4'-MDA in the company medical surveillance program. Company medical records of 19 employees working in SPO were reviewed, including the seven workers who had been interviewed. Not all of the 19 were working with 4,4'-MDA at the time of the review. Of the 19, three had a history of abnormal liver function tests, two had a history of hematuria (blood in the urine), and two had a worsening of dermatitis that began prior to their working with 4,4'-MDA. Fourteen of the 19 charts indicated visits for musculoskeletal complaints. The liver and renal problems appeared to be due to non-occupational causes. The OSHA 200 logs from 1996 through October 1998 were also reviewed. Of 22 injuries and/or illnesses recorded for SPO workers during this time period, one involved a heart arrhythmia potentially aggravated by methanol exposure and 10 involved cumulative trauma disorders (CTD's) of the upper extremity. NIOSH investigators determined that a health hazard did not exist from airborne exposures to either 4,4'- MDA or methanol at the time of this evaluation, although two employees had reported health effects possibly related to excessive short-term exposure to methanol in the past. No documented evidence of work-related liver or renal abnormalities was found, and the use of PPE to prevent dermal exposure was appropriate. Recommendations are included on methanol spraying techniques and biological monitoring to more thoroughly assess workers' exposures to 4,4'-MDA.