Canadian Occupational Safety

February/March 2017 21 STEPS FOR EMPLOYERS If an employer is using diacetyl or 2,3-pentanedione in any aspect, it first needs to conduct air monitoring to see if there is a problem, says Agnew. Additionally, all employees who work in areas where these chemi- cals are used should be in a medical monitoring program, says Bailey. A physician conducts breathing tests, such as spirometry, and looks for any abnormalities in lung function. These tests are repeated over time to identify lung function declines. And because of the rapid onset and progression of diacetyl-related lung disease, evalua- tions need to be done more regularly than employers may think. For exam- ple, monitoring that is suitable for slowly developing diseases, such as silicosis and coal employees' pneu- moconiosis, would not be sufficient. Medical surveillance not only helps identify particular workers who are having issues and determine if symp- toms are work related, it also helps to identify particular areas of a facility where symptoms may be prevalent, says Bailey. When it comes to controlling worker exposure, eliminating the hazardous substance or substituting it with something else are ideal solu- tions. However, substitutes may need to be controlled as well, especially for those substitutes where toxicity infor- mation is limited. If the amount of the substance being used can be reduced, that is also a step in the right direction. "With every chemical exposure, the risk of it causing disease is a func- tion of the amount of the chemical, the dose. It's the dose that makes the poison," says Wheeler. "There are safe exposures for most things." In the Missouri popcorn plant, NIOSH found evidence of a "dose- response relationship," meaning higher diacetyl exposure resulted in more employees being affected or the diagnosed employees had a worse lung disease. Local exhaust ventilation is an effective way to protect workers from flavouring chemicals. "This is the best way to control worker exposures," says Agnew. "The point is you want to remove the chem- icals before they reach the workers' breathing zone." For example, chemicals that are released from a coffee roaster are sucked up by a duct and fan system before a worker opens the roaster, he explains. Various exhausts and hoods can be used to reduce employee exposure when blending, mixing and handling flavouring compounds in liquid and powder form. Employers should look at what engineering controls they can design for bag and drum emptying and filling, charging tanks and benchtop weighing and handling, says NIOSH. It's important to have effective preventive maintenance programs in place for these pieces of equipment, Agnew says. "If you install a big duct and fan today and you know you are exhaust- ing so much air from this piece of equipment, you want to make sure six months from now that's not blocked and that it's working right," he says. Another engineering control is to isolate rooms where flavourings are handled from the rest of the plant. At the Missouri popcorn plant, five of the affected employees were working in the room where butter flavourings, salt and colourings were combined with heated soybean oil. The other four employees were working in the adjacent room in the packaging area where the oil and flavouring mixture was combined with kernel popcorn in microwavable bags. Flavouring mixing rooms and areas where flavourings are handled should be maintained under negative air pressure. After the plant put engineering con- trols in place — specifically ventilation and isolating the flavour — it had one to three orders of magnitude reduc- tion in diacetyl air concentrations, says NIOSH. Employees who started at the company after the interventions were put in place had fewer symptoms and higher lung functioning than their veteran colleagues. Administrative controls for pro- tecting workers from flavouring chemicals are also an important step, and include things like training and safe work procedures. "The workers need to know the hazards they are dealing with… And know, for example, they have to wait five minutes for the air to be cleared out of the grinder or roaster before opening it up," says Agnew. Workers should know how to prop- erly read safety data sheets and label elements and be well-versed in emer- gency handling procedures. Job rotation, where workers are rotated between different areas in the plant, can also be effective in reduc- ing worker exposure, says Wheeler. Employers should structure work tasks to minimize the amount of time employees spend near hazardous chemicals. Due to the volatile nature of diacetyl and 2,3-pentanedione, proper han- dling procedures must be followed to limit worker exposure. For example, workers should avoid open pouring, measuring and transferring of the chemicals; add the chemicals into the tank last; keep tanks of the com- pounds sealed at all times; and use the compounds at the lowest possible temperature within the manufacturer's recommended range. Good housekeeping is also impor- tant. Areas should be cleaned regularly and spills cleaned up quickly. A high-efficiency particulate air (HEPA)- filtered vacuum should be used. Warning labels and signs describ- ing the health risks associated with flavouring compounds should be posted at entrances to work areas as well as inside. Workers should also be wearing proper personal protective equipment (PPE), which may include protective face shields and eyewear, gloves, chemi- cal resistant arm sleeves and respiratory protection. But the problem with PPE is that it is the last barrier between the worker and exposure, says Wheeler. "If he's not wearing his respirator properly and there's a leak, a seal problem, so it does not fit properly to the face, that person could be exposed," he says. "It's important to fit test the respirators to make sure they seal properly." All workers need to be trained on the proper use of respirators, includ- ing putting them on and removing them. The respirator chosen should match the worker's exposure. There should also be a schedule for clean- ing, disinfecting, inspecting and repairing the respirators. While research has determined that 2,3-pentanedione is a problematic substitute for diacetyl, there may be other substitutes that cause signifi- cant health risks for workers as well. Some substitutes that have come into question include 2,3-hexanedione, 2,3-heptanedione and 3,4-hexanedi- one. But there are likely many more that may cause issues. In a 2012 document, the Flavor and Extract Manufactures Association identified 27 "high priority" flavouring sub- stances that could pose a respiratory hazard for workers. It also identified 62 "low priority" substances. "The word is getting out about diacetyl in particular and there are companies that have eliminated or reduced it's content, so we will prob- ably see reduced use of this chemical in flavourings," says Wheeler. "But they will be substituted by something else and the health effects of those we don't know yet." 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