Dunn-KH; Echt-A; Couch-J; Myers-DV
Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, EPHB 322-12a, 2008 Jul; :1-42
Researchers from the National Institute for Occupational Safety and Health (NIOSH) conducted an evaluation of engineering controls installed for the control of exposure to chemicals during liquid and powder flavoring production at Mastertaste, Inc. The engineering controls were developed by Mastertaste in conjunction with an industrial ventilation contractor to reduce the potential for employee exposure to harmful flavoring chemicals. The systems evaluated included: 1) a ventilated lid developed to contain chemical vapors from a large mixing tank; 2) a bag dump hood installed on a powder blender; 3) a fume extraction hood used during liquid and powder flavor packaging; and, 4) a ventilated workstation used to contain vapors during small batch mixing activities. Evaluations were based on a variety of tests including air velocity measurements, airflow visualization (smoke tracer), and control on/off testing using real-time monitoring techniques. The experiments showed that the ventilated mixing tank lid contained vapors during mixing and pouring. The results of control on/off tests on the new mixing tank ventilated lid hood showed a reduction of 76% during the actual production of a liquid caramel flavoring. Some tasks performed outside of the envelope of the hood were not adequately controlled. The mixing of pre-cursor key ingredients were conducted in the open room without controls and contributed to elevated worker exposure. The use of a fume-extraction hood during the packaging of the liquid caramel mix resulted in a reduction of 93% compared to the standard packaging procedures without controls. Face velocity measurements were taken on each hood within the powder mixing room. While air velocities were high at the face for all hoods, the decay in face velocity moving across the width of the larger blenders may result in poor capture. The local exhaust ventilation (LEV) hood for the smallest capacity blender (250 pounds) showed that the ventilated side-draft slot hood reduced dust exposure by 96% during bag dumping activities. The discharge hood reduced dust exposure by 96% during emptying of the blender, and the use of the fume extraction hood reduced dust exposure by 65% during powder packaging. Smoke tracer and control on/off tests conducted on selected hoods in the H2 mixing room showed good capture characteristics. The evaluation of one ventilated bench-top workstation in the H2 mixing room showed an exposure reduction of 97% during staged tasks such as weighing, hand-whisking, and pouring. Based on the results in this report, the following recommendations are made to further improve the local exhaust ventilation in the liquid compounding room: a) Consider re-designing local exhaust ventilation hoods on the large ribbon blenders. The slotted rim exhaust has limited effectiveness and can only capture chemical contaminants up to about 18-24 inches from the hood face. A better enclosure design could improve performance while reducing required flowrate and energy usage. b) Consider adding an articulating arm to the fume extraction hood used in the powder packaging area. This arm could better support the weight of the hood and allow the worker to position the hood so that the dust could be collected more effectively. c) Consider process changes such as pre-mixing of key ingredients which include diacetyl or other high-priority chemicals. Use the ventilated workstations in the H2 room for premixing before adding these chemicals in the larger mixers to reduce worker exposure during preparation. d) Install static pressure gauges on each hood to provide important information on hood performance. Include the recording of hood static pressure and performance of hood airflow checks into the preventative maintenance schedule. e) Consider installing an indication of exhaust fan operating status (on/oft) such as a light for each hood in the H2 room so that workers know that they are being protected when working with the hoods. f) Provide worker training on proper techniques for using ventilated workstations, such as clearing the bench of unnecessary chemicals/materials and as much as possible reducing the obstruction of airflow into the slot exhaust (storing chemicals and supplies on benches obstructs airflow). Also, opening chemical containers outside of the workstation enclosure can result in migration of chemical vapors and potentially expose other employees working inside the room.
Control-technology; Engineering-controls; Region-9; Food-additives; Food-processing-industry; Food-processing-workers; Respiratory-system-disorders; Lung-disease; Ventilation; Ventilation-equipment; Ventilation-systems; Exposure-assessment; Control-methods; Exhaust-hoods; Exhaust-ventilation; Industrial-exposures; Vapors; Air-flow; Air-monitoring
National Institute for Occupational Safety and Health, Division of Applied Research and Technology, Engineering and Physical Hazards Branch, Mail Stop R-5 , 4676 Columbia Parkway, Cincinnati, OH 45226-1998
Field Studies; Control Technology
NTIS Accession No.
National Institute for Occupational Safety and Health