Sunday, October 02, 2005

Taking the Work Organization Bait, Falling into the Psychosocial Trap

Another Annals abstract, likely a meeting presentation. A very distinguished group of investigators take the work organization bait and fall into the psychosocial causes of MSD trap.

Plus, they publish the relative risks and never give you an anchor, so a public health authority has no reference rate for prevalence.

The problem is, if piece work causes carpal tunnel syndrome, what are you going to do about that? Plus, if stress causes this physical ailment, or symptoms complaints, then mechanical interventions such as OSHA can order don’t mean much. Where’s your biological plausibility? Just hire happy workers, or train them how to cope. Gene Scalia frequently argued that CTS or whatever was all in the workers’ head.

The problem is, if there is a narrow range of exposure to risk factors in your population, then host factors dominate in the model. If there were no difference in ergo risk factors in the population, then ergo risk factors would disappear from the model.

The next problem is that the job content questionnaire is not appropriate [sucks?] when applied to factory work. The Dodger has read the questions, they are mostly subjective responses of the employee to the work environment, not observable and not meaningful especially for assembly line work.

In the Dodger’s real world of summer jobs experience, there’s not much difference between the basics of sewing machine operators in small shop sewing jobs. Except, there are a couple of ?safety stitch machine operators [not sure the Dodger actually remembers the name right, machine sews the seam and cuts the excess material] on piecework who go like bats. This is the high skilled job assembling the garment, maybe for shirts these are single or double needle machines. These people can make money on piece rates, and feed the whole line downstream. You aren’t going to move them off their machine. If their machine goes down, they are distinctly unhappy. There’s a variety of other machines, like the bar tack [where belt loops are put down] where nobody much can beat the rate and which are substantially lower skilled.

So this confounds working on one machine, piece work, repetitiveness, plus maybe a more forceful pinch grip controlling the tension when feeding the machine.

This study would be much more likely to demonstrate risk factors if pressers or the floor workers were included. They have little or no repetitive upper extremity work, even if some back injury risk and walking and standing risks.

A useful reanalysis of this work would be a matrix showing the association of piece rate with the physical risks.

Annals of Epidemiology Volume 15, Issue 8 , September 2005, Page 655
Work organization and work-related musculoskeletal disorders for sewing machine operators in garment industry
P.C. Wang1, B. Ritz1, D. Rempel2, R. Harrison3, J. Chan3 and I. Janowitz2 1Department of Epidemiology, University of Los Angeles, Los Angeles, CA2University of San Francisco/Berkeley Ergonomics Laboratory, Richmond, CA3California Department of Health Services, Oakland, CA
We recruited 314 Hispanic and Chinese sewing machine operators from 12 garment shops in Los Angeles, California from 2003 to 2004. Data were collected through physical exams and standardized interviews. Cases are defined as workers reporting pain at least one day per week with a pain score higher than 2 out of 5 during a 1-month period. Symptoms were assessed by anatomical regions and are summarized here as pain in neck/shoulder, back/hips, upper or lower extremity.
We found that pain symptoms were reported more often by workers who were paid via a piece rate … (In neck/shoulders adjusted odds ratio (aOR) = 2.25; 95% confidence interval (CI): 1.1–4.8; in back/hips aOR = 2.54; 95%CI: 1.3–5.2; in upper extremity aOR = 2.94; 95%CI: 1.1–8.0; in lower extremity aOR = 2.69; 95%CI: 1.0–7.4), and who work on monotonous and repetitive work such as single machine users especially for pain in back/hips (aOR = 2.30; 95% CI: 1.1–4.7). Low decision authority was associated with an increased risk of reporting pain in upper extremity (aOR = 2.87; 95%CI: 1.1–7.6) and back/hips (aOR = 2.31; 95%CI: 1.0–5.2). High psychological job demand was associated with an increased risk of reporting pain in upper extremity (aOR = 2.07; 95%CI: 1.0–4.1). An exposure-response trend was observed for physical exertion and pain in four body sections, and physical isometric loads above the mean increased neck/shoulders and lower extremity pain.
Conclusion Our results suggest that work organizational factors are associated with an increased risk of reporting WRMDs in sewing machine operators.

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