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Engineering Controls Database

Controlling Hazardous Dust in Dyeing Operations

Dry powdered dyes of many chemical types are used extensively in the coloring of textiles. These dyes are typically provided in bulk containers holding several hundred pounds and are removed as needed in measured amounts to be used alone or combined with measured quantities of other dyes to produce a desired color.

Exposure to powders or dyes can be through four primary routes: inhalation, ingestion, dermal or mucous membrane contact. The process where the powders are manually transferred from open containers and dumped into smaller containers is the time of greatest potential exposure to workers. Because the toxicity of many of these powder dyes is not well defined, it is prudent to control workers’ exposures.
The manual transfer of powder dyes from bulk containers to smaller process containers generates significant amounts of dust. Worker exposure to dye dust can result in adverse health effects such as occupational asthma, eczema, and severe allergic reactions. In addition, NIOSH recognizes certain dyes as potential occupational carcinogens.
Work on this study was done was done in cooperation between NIOSH and the United States Operating Committee of the Ecological and Toxicological Association of the Dyestuffs Manufacturing Industry (ETAD). ETAD is an international organization comprising representatives from various dye manufacturing companies. ETAD organized a steering committee that included members from the ETAD, NIOSH, U.S. EPA, and the American Textile Worker’s Union (ACTWU). The steering committee identified dye-weighing operations requiring research to develop improved techniques to reduce worker exposure to dyes.

ECTB conducted a number of field studies that evaluated the effectiveness of three techniques for controlling exposure to powdered dyes. These techniques were: 1) a down draft hood to move dust away from the workers’ breathing zone, 2) the size of the containers used to ship and store the dyes, and 3) the addition of a “de-dusting agent,” typically a light oil (226-11). The use of a de-dusting agent appeared to reduce the amount of airborne dust when ventilation was off. However, additional studies would be necessary to verify this result.

Based on the studies, the following recommendations were provided:

• To minimize dust exposures during powder handling operations, workers should perform the tasks inside a semi-downdraft ventilated hood (figure 1). The vertical air shower from the ceiling of the booth does an effective job of capturing generated dust and exhausting it from workers’ breathing zones until the dust is captured and exhausted from the work area. All tasks associated with the manual handling of powdered dyes should be performed inside the ventilated hood.

• Most powder dyes are shipped in drums that range in height from 30 to 36 inches. When manually transferring dye from these drums, many workers must lean forward and place their heads inside the drum to scoop out dye near the bottom. In this position, the worker is greatly exposed to airborne dye dust, even in a ventilated booth. Shorter drums should be used to eliminate the need for workers to place their heads inside the drum. Maintaining a space between the worker's face and the top of the drum enables the booth ventilation to capture the dust before it reaches the worker's breathing zone. Limiting the drum height to 25 inches significantly reduces worker dust exposures.

• Workers should use slow, smooth movements when handling dye to keep dust concentrations low. Dye transport distances between the bulk and process containers should be kept to a minimum. The height at which the dye is dropped into a container should also be kept to a minimum. Workers should avoid skin contact with the dyes by using protective clothing such as gloves, long-sleeved shirts, and aprons.
Figure 1

Figure 1

Figure 1. Filtered air enters from the ceiling of the booth, collects dust as it flows past the worker, and exhausts out the back of the booth through grates
197-11-A; 197-12-A; 197-13-A; 197-14-A; 226-11; 226-12-A;
NIOSH [1997]: NIOSH hazard control: Control of dust from powder dye handling operations. Cincinnati, OH: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 97-107.
dye weigh-out workers
powder handlers
textile dyehouse
textile dyeing
textile workers
Workers in powder dye handling operations are often poorly protected from dust exposures. NIOSH research has shown that worker exposures to dye dust can be effectively reduced by as much as 70% with the following combination of controls: adequate ventilation, redesigned bulk containers, and appropriate work practices.