Health Hazard Evaluation of Exposures in a Steel Coil Pickling Plant

1271 

Professional Poster 

J Li¹

¹CDC/NIOSH, Cincinnati, OH

Jessica Li, MSPH  
CDC/NIOSH

Steel pickling is a metal surface treatment in which oxide (rust) and scale are removed from the surface of the steel using acid. Pickling occurs after steel production and before the steel can be used for further manufacturing. A Health Hazard Evaluation (HHE) request was submitted by a management representative at a steel coil pickling plant after concerns of respiratory symptoms in the plant that were thought to be associated with a change in the oil used to coat and protect the steel following the pickling process.

Employees at a steel coil pickling plant were experiencing respiratory symptoms following a change in the oil that was electrostatically applied to steel coils to prevent them from rust after the pickling process. Before the HHE site visit, the oil was changed back to the original oil that was not associated with respiratory symptoms, but concerns persisted. This led management at the plant to request an HHE to help evaluate employee exposures and health effects; the main exposures of that management was concerned with were the oil, diesel exhaust from trucks, and environmental dust.

Utilizing three employees (closest to the oil application) in the exit area of the pickling line, personal air samples were collected for: a) oil mist (NIOSH 5026); b) hydrochloric acid (NIOSH 1403); and c) diethylene glycol monobutyl ether (DGME, NIOSH 7907). Hydrochloric acid, a potential respiratory irritant, is used for pickling and is . DGME is a solvent and a dispersant in the oil. We collected area air samples for oil mist near the quality control station, hydrochloric acid on the pickling line and in crane cabs, and elemental carbon (NIOSH 5040, surrogate for diesel exhaust) in crane cabs and outdoors.

During our discussions with management, we determined that noise was also a potential exposure in the pickling plant. We collected personal noise sampling on three employees in the exit area and area noise sampling in the exit area of the pickling line and in crane cabs. We conducted short-duration sound level checks during various processes in the plant and determined the main source of noise.

Fifty employees across all 3 shifts were interviewed about work history, work practices, relevant medical history, and work-related health symptoms in the previous 3 months. We compared the prevalence of work-related irritant symptoms (e.g., nasal congestion, sore throat, cough, and/or eye irritation) between production and office employees, entry and exit employees on the pickling line, and crane operators and all other production employees. We made workplace observations, visually evaluated the ventilation, and reviewed relevant documents including audiometric records.

Full-shift personal air sampling results for DGME and oil mist were several orders of magnitude below the lowest occupational exposure limits. Personal air sampling results for hydrochloric acid were 0.021 ppm for the exit operator and not detected (MDC = 0.003 ppm) for the exit laborers. Full-shift area air sampling results for: 1) oil mist was 0.088 mg/m3 for the quality control area; 2) hydrochloric acid levels were not detected in the quality control area and in both crane cabs; and 3) elemental carbon were 2 to 4 times higher than outdoors. Diesel exhaust is considered to be a carcinogen and should therefore be kept at the lowest feasible levels. Area air samples in the crane cabs were collected to estimate the worst-case scenario exposures for employees if they were to spend the entire shift in the crane cabs.

One exit laborer and the exit operator had overexposures to noise using NIOSH REL criterion and OSHA AL criterion. Area noise measurements in the entry area of the pickling line indicate that employees in that area may also be overexposed to noise. Personal noise sampling should be conducted for entry area employees. Sources of noise on the pickling line included: a) the steel coil passing through line entry (104.2-115.4 dBA); b) threading a new steel coil through the line (82.6-91.5 dBA); d) cutting a new coil (108.4 dBA), and d) the tank farm area (95 dBA). Hearing protection use was voluntary. One employee had an OSHA recordable standard threshold shift.

Thirty-one (62%) employees reported work-related irritant symptoms including nasal congestion, sore throat, cough, and/or eye irritation. Production area employees had higher prevalence of work-related irritant symptoms than office employees (prevalence ratio: 3.38, 95% confidence interval: 2.14, 5.34). The prevalence of work-related irritant symptoms was similar among employees in the entry and exit areas, the cranes, and other production areas.

We found high prevalence of work-related irritant symptoms among production employees. Industrial hygiene sampling measured low levels of oil mist, HCl, and DGME in the air. Area elemental carbon levels were high. It is possible that the combination of these exposures and exposures to environmental allergens such as dust could have contributed to employees' symptoms. Employees with the title of exit laborer and exit operator had noise exposures above the NIOSH REL and OSHA AL. One employee's audiogram showed a standard threshold shift.

Sampling and Analysis

Engineering Controls and Ventilation

Noise