Health hazard evaluation report: HETA-2005-0248-3077, exposure to flour dust and sensitization among bakery employees, Sara Lee Bakery, Sacramento, California.
In May 2005, NIOSH received a confidential employee request for an HHE at the Sara Lee Bakery in Sacramento, California. The request concerned rashes, respiratory symptoms, and problems with ventilation and indoor environmental quality. In an August 2005 work site visit we met with management and union representatives, toured the plant, and held confidential medical interviews with employees. We observed potential exposure to flour dust and BAA and received reports of employees with work-related hand dermatitis, cough, eye irritation, and aggravation of pre-existing asthma. We also learned of at least one employee who was diagnosed with baker's asthma. We returned to the bakery in March 2006. All bakery employees were asked to participate in an evaluation designed to compare sensitization and symptom prevalences between groups categorized as having higher and lower potential exposure to BAA and to more accurately characterize exposure in the different bakery departments. PBZ and GA air monitoring was performed to measure inhalable flour dust and total dust. The inhalable flour dust samples were further analyzed for alpha-amylase and wheat. The study included a questionnaire, and blood tests for total IgE; IgE specific to flour dust, wheat, and alpha-amylase; and for a variety of common aeroallergens. Of 186 bakery employees present during our site visit, 161 (87%) completed the questionnaire. Of these, 96 allowed their blood to be drawn. We observed the process in the bakery and also used information in the scientific literature to assign "lower-exposure" and "higher-exposure" categories to participants. Participants were assigned to either a lower-exposure group or a higher-exposure group based upon their job title at the time of the survey. We collected 83 PBZ and 19 GA air measurements for inhalable flour dust in the bread and bun production, distribution, engineering, and sanitation departments; and the office and plant management areas. The inhalable flour dust concentrations for PBZ and GA samples for certain job titles in the lower-exposure group had a GM of 0.235 mg/m3, a median of 0.245 mg/m3, with a range between ND (less than 0.12 mg/m3, based on an average sample volume) and 1.4 mg/m3. Of the 23 PBZ measurements for employees in this group, 8 reached or exceeded the CalOSHA PEL and ACGIH TLV of 0.5 mg/m3 TWA for inhalable flour dust. The inhalable flour dust concentrations for PBZ and GA samples in the higher-exposure group had a GM of 3.01 mg/m3, a median of 2.75 mg/m3, with a range between trace (between 0.12 and 0.42 mg/m3, based on an average sample volume) and 65 mg/m3. Of the 60 PBZ measurements for employees in this group, 56 reached or exceeded the CalOSHA PEL and ACGIH TLV for inhalable flour dust. Employees in the higher-exposure group had a significantly higher prevalence of work-related wheezing than those in the lower-exposure group (14.8% vs. 1.1%). They also had significantly higher prevalences of work-related runny nose, stuffy nose, and frequent sneezing. The higher-exposure group had a significantly higher prevalence of rash on their face, neck, hands, or arms in the month prior to the study. The prevalences of IgE specific to wheat, inhalable flour dust, and alpha-amylase were higher in the higher-exposure group at both the >/= 0.10 kU/L and the >/= 0.35 kU/L cutoffs, but the differences were not statistically significant. The prevalence of IgE specific to wheat was significantly higher among employees who reported either a current or past job in the higher-exposure group or in production at another bakery at both the >/= 0.10 kU/L and the >/= 0.35 kU/L cutoffs, and to flour dust and alpha-amylase at the >/= 0.10 kU/L cutoff, compared to the lower-exposure group. The prevalences of work-related wheezing were 3.5 times higher in employees sensitized to wheat than those who were not sensitized. This difference was statistically significant at the >/= 0.10 kU/L cutoff for IgE but was not significant at the >/= 0.35 kU/L cutoff. The prevalences of work-related runny nose was significantly higher among those sensitized to wheat at the >/= 0.35 kU/L cutoff, but not at the >/= 0.10 kU/L cutoff. We found no statistically significant differences in work-related symptom prevalences between those above and below the cutoffs for sensitization to alpha-amylase. Work-related runny nose was significantly more prevalent among those sensitized to flour than those who were not sensitized at the >/= 0.35 kU/L cutoff, but was not significant at the >/= 0.10 kU/L cutoff. Atopics (defined by a positive AlaTOP) were significantly more likely to be sensitized to wheat and flour dust at both the >/= 0.10 kU/L cutoff and >/= 0.35 kU/L cutoff, and to alpha-amylase at the >/= 0.10 kU/L cutoff. In conclusion, a health hazard exists at the Sara Lee Bakery in Sacramento, California, from exposure to flour dust and other BAA. Recommendations include implementing a variety of engineering and work practice controls, as well as the use of respiratory protection until these controls are implemented. Management should provide a medical surveillance program for employees exposed to BAA.