The volume and physical properties of chemicals found in sawmills pose a wide range of health hazards. A complete discussion of this topic is beyond the scope of this eTool; however, a general discussion of common hazards and related control measures are provided below.
Potential Health Hazards
A wide range of adhesives and coating agents are used in finishing wood products. Many of these are hazardous to the health of employees. Chemicals can enter the body in three ways: inhalation (breathing), ingestion (eating), or contact with the skin. The skin readily absorbs many chemicals, such as solvents, allowing them to enter the bloodstream. Woodworkers generally are exposed to chemicals through inhalation and contact with the skin. Both nitrocellulose topcoats (lacquers) and acid-catalyzed coatings (conversion varnishes) contain solvents that are toxic to humans. The solvents most commonly used in these coatings include toluene, xylenes, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), and methanol. The acid-catalyzed coatings contain formaldehyde. All of these solvents have short-term effects such as irritation of the eyes, nose, and throat, and headaches, dizziness, confusion, fatigue, and nausea. The longer-term effects include reproductive problems, central nervous system disorders, and damage to the lungs, liver, and kidneys. Toluene exposure increases the risk of miscarriage. Developmental effects have been noted in children born to mothers who were exposed to toluene and xylenes. Studies have shown that formaldehyde can cause lung and nasal cancer. Many of the adhesives used in finishing wood products also contain toxic chemicals. The most hazardous are the solvent-based, epoxy resin, and urea-formaldehyde resin adhesives. Many of the solvents used in the coating agents are used in the adhesives. The epoxy resin adhesives are particularly toxic. Methylene chloride, which has been shown to cause cancer in laboratory animals, is often the base for these adhesives. Some of the components of the epoxy resins may also be cancer-causing. Epoxy resin adhesives can also cause dermatitis and a sensitization reaction.
Use automated systems for applying coatings and adhesives when feasible. Ventilate automated systems.
Substitute the traditional solvent-based coatings and adhesives with coatings and adhesives that are less toxic. Hot melt, heat seal, aqueous-based, and polyvinyl acetate adhesives are good, less-toxic alternatives to solvent-based adhesives. Higher-solids nitrocellulose, aqueous-based, ultraviolet-cured, and polyester/polyurethane coatings also are less toxic than are solvent-based coatings.
Provide adequate local exhaust ventilation for all coating and gluing processes. This includes manual spray, rolling, and brushing operations, automated coating processes, and dip coating. Perform manual spray operations in a spray booth or a separate, ventilated spray area.Ventilate dip coating should be ventilated with an enclosure or capture hood. Consult the OSHA standard on dip coating (open surface tanks), 29 CFR 1910.108, for detailed requirements on dipping operations.
The OSHA standard for spray finishing operations, 29 CFR 1910.107, provides detailed requirements for the design and construction of spray booths and rooms, air filters, velocity and air flow requirements, and the (make-up) air supplied to the booth. It is important to maintain the proper air flow in a spray booth. Excessive air pressure decreases the efficiency of the operation, wastes material, and may cause a backlash of vapors and overspray into adjacent work areas. Dirty air filters can decrease the air flow in the booth. Clean and replace filters as needed. Although these provisions are designed to prevent the occurrence of a fire or explosion in spray finishing operations, they also assist in protecting workers from the health hazards of the chemicals used in the operation by removing the chemicals from the atmosphere.
Employers shall provide employees with effective information and training on hazardous chemicals. 1910.1200(h)(1)
Employees must not be exposed to airborne concentration of toxic dusts, fumes, vapors, mists or gases that exceed the threshold limit values set forth by 1910.1000. 1910.265(c)(17)(i)
Employees must be protected from harmful exposure to toxic materials. Where necessary, employees are required to wear protective equipment that will provide adequate protection against harmful exposure. 1910.265(c)(17)(ii)
Open surface tank operations need to conform to the requirements of 1910.94(d). 1910.265(c)(17)(iii)