Health hazard evaluation report: Republic Conduit

Evaluation of Worker Exposures to Noise, Metalworking Fluids, Welding Fumes, and Acids During Metal Conduit Manufacturing

Health Hazard Evaluation Report

HETA 2006-0332-3058

Authors: Manuel Rodriguez, MS, CIH, CSP; Christine A. West, RN, MSN/MPH; Scott E. Brueck, MS, CIH


On August 8, 2006, NIOSH received a confidential employee request for an HHE at Republic Conduit in Louisville, Kentucky. The requestors expressed concerns about workplace exposures to acids, unsafe confined space entry procedures, and inadequate PPE for handling acids. We conducted an initial site visit to Republic Conduit on November 13, 2006, during which we performed a walk-through of the facility and interviewed workers. Based on our observations, workers were potentially exposed to acids, Cr(VI), MWFs, welding fumes, and noise.

Of the 13 employees who we selected for medical interviews, two reported acute upper respiratory symptoms and exacerbation of asthma symptoms related to a brief exposure to HCL during a leak. Four reported injuries not associated with acid exposure, which included back pain, skin irritation, lacerations, and crushed fingers. A review of OSHA’s Form 300 Log of Work-Related Injuries and Illnesses for 2006 revealed that of 21 entries, 11 listed crushed fingers or lacerations caused by contact with conduit. We conducted a follow-up site visit to Republic Conduit during March 5-8, 2007, to sample for acid mists, MWFs, elements from welding fumes, and Cr(VI) from chromic acid; conduct noise dosimetry; and review the company’s written health and safety programs. All sampling results were below applicable OELs except for noise and MWFs.

Of the 35 personal noise exposure measurements taken during this evaluation, 33 exceeded the NIOSH REL of 85 dBA. Because OSHA uses different criteria to measure noise exposure, only six exceeded the OSHA PEL of 90 dBA, though 29 exceeded the OSHA AL of 85 dBA. Three of 21 PBZ sample results equaled or exceeded the NIOSH REL-TWA for MWFs of 0.4 mg/m3 (thoracic particulate mass). During the March 2007 site visit, we provided all 168 production workers on three shifts a survey form asking about their workplace exposures, use of PPE, hazard communication, and confined space entry procedures. Sixty-nine workers (41%) completed the voluntary survey. In general, workers were concerned about their workplace exposures, specifically to acids and zinc oxide dust.

Based on PBZ air sampling conducted during this evaluation, we recommend that Republic Conduit enclose the mills and install local exhaust ventilation to reduce airborne MWF concentrations below the NIOSH REL. We recommend mill operators use respiratory protection until airborne concentrations of MWFs are below the NIOSH REL-TWA. After the controls are installed, additional PBZ air sampling should be conducted to determine if the airborne concentration of MWFs has been reduced and if respiratory protection is still needed. Controls should be installed to reduce impact noise generated by metal to metal contact, and hearing protection should be used properly to reduce the risk of hearing loss. We also provide recommendations for protecting workers while performing maintenance on systems with acids, reducing injuries, and revising the written respiratory protection and confined space entry programs. Further recommendations are provided in the recommendations section of this document.

This article originally appeared in the February 2009 issue of Occupational Health & Safety.

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