Washington State Ergonomics Tool: predictive validity in the waste industry
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This study applies the Washington State Ergonomics Tool to waste industry jobs in Texas. Exposure data were collected by on-site observation of fourteen different multi-task jobs in a major national solid waste management company employing more than 26,000 employees. This company has nationwide operations, and these jobs represent the majority of workers involved in the collection and processing of solid waste. The WSET uses observational checklist methodology to evaluate generic risk factors in the following six major categories: awkward posture, highly repetitive motion, high hand force, repeated impact, lifting, and hand-arm vibration. The assessment tool incorporates these risk factors and combinations of risk factors into checklists for identifying three levels of potential exposure: safe, -caution zone" and -hazard zone" jobs. The tool was developed for employers to use in determining whether a job was likely to increase the risk of workplace musculoskeletal disorders (WMSDs) to their employees. OSHA 200 logs were used as the main source of morbidity data. If there was one recorded WMSD, the job was classified as -positive. "If there was no recorded WMSD, the job was classified as -negative. "-Safe"jobs were those predicted not to expose workers to increased risk of WMSDs. Those that possessed one or more -caution zone"criteria but still fell below the -hazard zone" threshold required the employer to provide -awareness education" for employees and to further analyze the job for the presence of -hazard zone" risk factors. If hazard zone risk factors were not present, no further action was required. Jobs that upon further analysis possessed one or more of the -hazard zone"criteria were labeled -hazardous" jobs. If the further analysis shows the presence of risk factors established in the hazard zone criteria (Appendix B), the employer would be required to take corrective action to reduce exposures to below the hazardous level. Of the three jobs predicted to be -safe"by -caution zone" criteria, two did not have injuries and one did. Of the eleven jobs predicted by -caution zone"criteria to increase the risk of WMSDs, six resulted in injuries and five did not. Of the four jobs predicted by -hazard zone"criteria to be -problem"jobs, two jobs did result in injury and two did not. This study found that the WSET -caution zone"criteria were more effective at predicting which jobs were likely to increase the risk of WMSDs than was the -hazard zone"checklist. The caution zone had high sensitivity and low specificity. The hazard zone criteria reflect a low sensitivity and a low specificity. Further analysis revealed the WSET was helpful in predicting back injuries associated with lifting but not effective at predicting jobs with the potential for upper extremity injuries.
Eppes, Susan Elise (2006). Washington State Ergonomics Tool: predictive validity in the waste industry. Master's thesis, Texas A&M University. Texas A&M University. Available electronically from