Occupational Safety and Prevention Strategies for Threshers and Chaff Cutters: A Systematic Review of Global Trends

Tractors and their associated implements are indispensable to crop production agriculture but remain major contributors to machinery-related injuries and fatalities worldwide. Within this context, agricultural threshers and chaff cutters represent particularly high-risk machines in smallholder and resource-constrained crop production systems.

This systematic literature review synthesized global evidence on the epidemiology of occupational injuries, causal determinants, and prevention strategies associated with these machines. Peer-reviewed studies published between 2000 and 2025 were retrieved from major scientific databases using predefined eligibility criteria.

Included in the synthesis were 171 documents authored by 252 researchers from 211 organizations across 33 countries and published in 97 sources. The findings indicate severe injuries, particularly amputations, entanglements, and crush injuries, are primarily associated with exposed moving components, unsafe feeding practices, inadequate guarding, and limited operator training. Evidence consistently shows that most injuries related to threshers and chaff cutters are preventable through context-appropriate engineering and behavioral interventions. Effective prevention strategies include improved guarding of feeding and transmission systems, safer feeding chute designs, emergency stop mechanisms, ergonomic improvements to operator-machine interfaces, and targeted safety training to address unsafe work practices and risk perception. User-centered design approaches further enhance the usability and acceptance of safety devices, particularly for legacy machines widely used in low-resource settings.

Overall, the review highlights that injury prevention should prioritize low-cost, robust, and easily maintainable engineering solutions, supported by standards enforcement, machine retrofitting programs, and machine-specific safety training to reduce the occupational injury burden in crop agriculture.