Health hazard evaluation report: HETA-2007-0053-3092, employees' exposures to organic solvent vapors during screen printing, Inter Sign National Incorporated, Baltimore, Maryland.
On November 14, 2006, NIOSH received a request for an HHE from the management of Inter Sign National, Inc., in Baltimore, Maryland. Management of the company was concerned about potential adverse health effects from employees' exposures to organic solvents in lacquer thinner and screen printing inks. In response to these concerns, NIOSH conducted a site visit on December 5-6, 2007. During the site visit NIOSH met with management and employee representatives, observed work activities, assessed PPE use, evaluated ventilation for the screen printing and spray painting operations, and measured exposures to toluene, n-hexane, isopropyl alcohol, acetone, and cyclohexanone. Full-shift monitoring results indicated that air contaminant concentrations for the screen printer, screen printer helper, spray painter, and an area sample in the screening area were below OELs. Additionally, exposure to the combined mixture (additive exposure) of toluene, n-hexane, isopropyl alcohol, acetone, and cyclohexanone was low, based on NIOSH RELs and OSHA PELs. However, using ACGIH TLVs, additive exposure for the screen printer helper and the area sample indicated slight overexposure to the organic solvent mixture, and the screen printer was nearly overexposed to the mixture of solvents. Short-term air samples for toluene, isopropyl alcohol, and acetone revealed isopropyl alcohol concentrations during screen printing and screen washing have the potential to exceed the NIOSH and ACGIH STELs. Short term concentrations of toluene and acetone were well below applicable STELs. We recommend that the company investigate replacing solvent-based screen printing products with nonsolvent or low solvent alternatives. We observed employees leaving cleaning towels or tissue paper soaked with lacquer thinner on a work desk near the screen printing tables. Evaporation of solvents from these items can contribute to worker exposures. We recommend that employees only use what is needed for the immediate task and promptly dispose of solvent soaked towels and tissue paper in closed containers after use. The screen printing area did not have exhaust ventilation. Ventilation smoke tubes indicated little air movement in the work area. Opening the window near the screen printing table and operating the fan at the window would improve ventilation. We noted that the window is only opened and the fan used during warm weather. Therefore, we recommend installing an exhaust ventilation system for screen printing. Ventilation of the spray paint booth was found to be sufficient. We recommend that all employees performing screen printing and screen washing wear NIOSH-approved respiratory protection until engineering or administrative controls reduce exposures to the mixture of organic solvents to below the ACGIH TLV. Based on the measured exposure, elastomeric half-mask respirators equipped with organic vapor cartridges would provide adequate protection. Employees wearing respirators must be properly fitted with the respirators, receive training on respirator use, and undergo medical evaluations for respirator use. The company must also prepare a written respirator program that documents how they comply with OSHA respiratory protection program requirements. We observed work activities that might cause splashing of screen printing chemicals into the eyes or onto the hands of workers. Protective eyewear was not worn, and available gloves were not appropriate to protect against the chemicals in lacquer thinner and screen printing inks. We recommend that the company provide gloves made of Viton®/butyl combination or laminate plastic film. Employees should consistently wear gloves and protective safety glasses or goggles when using chemicals. An emergency eyewash station should also be installed in the work area. The company needs to complete a PPE hazard assessment including written documentation of a hazard assessment and PPE training, as is required by OSHA PPE standards. Fire safety hazards in the workplace were observed, including improper plastic containers used for lacquer thinner, excessive quantities of lacquer thinner stored in the spray paint booth, and dispensing and receiving containers of flammable liquids without proper bonding. Containers in the screening area were not properly labeled according to OSHA hazard communication program requirements. Additionally, the company had not completed a written hazard communication program or completed employee training, which are both required by OSHA to inform workers about the dangers of chemicals they are exposed to in the workplace.
Region-3; Printing-industry; Printers; Solvents; Solvent-vapors; Ventilation; Ventilation-systems; Exhaust-ventilation; Engineering-controls; Control-technology; Work-operations; Work-practices; Protective-equipment; Personal-protective-equipment; Respiratory-protective-equipment; Respiratory-protection; Respirators; Skin-exposure; Gloves; Eye-protection; Eye-protective-equipment; Eyes;
Author Keywords: Sign Manufacturing; screen printing; silk screening; organic solvent; lacquer thinner; toluene; n-hexane; isopropyl alcohol; acetone; cyclohexanone; dermal exposure; PPE