¹University of California, San Francisco, United States
²University of Iowa, Iowa City, United States

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Background: From 2018 to 2020, the United States Department of Agriculture granted waivers to 53 poultry processing establishments allowing them to increase evisceration line speeds from 140 birds per minute (BPM) to 175 BPM. To address concerns that higher evisceration line speeds would expose workers to unacceptable levels of ergonomic hazards, a study was conducted to examine the effects of two measures of work pace on quantitative measures of ergonomic hazard among poultry processing plant workers.

Methods: This was a cross-sectional study of associations between (i) evisceration line speed and (ii) worker task rate and the ACGIH peak force index threshold limit value (PFI-TLV) score among 456 poultry processing plant workers employed by establishments operating over a range of evisceration line speeds. Evisceration line speed, worker task rate, and PFI-TLV score were ascertained using a wearable 8-sensor surface electromyography forearm cuff (Mindrove, Kft., Győr, Hungary) and detailed video analysis (Multivideo Task Analysis, NexGen Ergonomics, Pointe Claire, Québec, Canada).

Results: Among the 11 processing plants that were included in this study, evisceration line speed was not associated with the primary measure of MSD hazard, the PFI-TLV score (p=0.96). Worker task rate, a proxy for job-specific line speed and job-specific staffing levels, was statistically significantly associated with MSD hazard (p=0.02). A majority (81%) of the poultry processing plant workers in this study were exposed to high levels of MSD hazard (i.e., PFI-TLV score >1.0) regardless of the evisceration line speed category.

Discussion: A large proportion of poultry plant workers were exposed to high levels of ergonomic hazard and were, consequently, at substantially increased risk of MSD. Although no association was observed between the PFI-TLV score and evisceration line speed, an association was observed with worker task rate. The difference in the strength of association between (i) evisceration line speed and PFI-TLV score and (ii) worker task rate and PFI-TLV score likely occurred as a result of adjustments made to job-specific line speeds and job-specific staffing levels in response to higher evisceration line speeds. Well-established administrative and engineering controls applicable to poultry processing should be implemented to mitigate high MSD hazard levels.

Conclusion: Poultry processing evisceration line speed was not associated with increased ergonomic hazard but task rate, defined as the number of pieces handled to perform a task, was associated with higher ergonomic hazard scores that are predictive of musculoskeletal disorders.