The Incidence of Ergonomic Disorders Among Workers
at a U.S. Automobile Manufacturer

Gordon R. Reeve, Ph.D. and Susan T. Pastula, M.P.H.

Ford Motor Company
402 World Headquarters
Dearborn, Michigan 48121

INTRODUCTION

The reported incidence of ergonomic disorders in the U.S. varies widely. This variation leads to strong differences of opinion regarding the importance of ergonomic disorders as a regulatory priority. A considerable amount of this variation is due to actual differences in risk associated with existing manufacturing processes or work practices. Another source of variation is associated with the differences in diagnostic practices across geographic regions and regulatory recordkeeping practices across industries.

Prior to 1990, Ford Motor Company was susceptible to both types of variation. It operated over 60 manufacturing facilities ranging from final vehicle assembly to fuel pump manufacture. These facilities were located in 16 different states. Each facility also had a medical department that was essentially left to its own devices to interpret OSHA recordkeeping guidelines for ergonomic disorders.

In 1989 the Company received a significant fine for OSHA recordkeeping violations, many of which were associated with ergonomically-related disorders. Over the next several years, the Company took decisive steps to eliminate their legal exposure resulting from inappropriate variations in recordkeeping. These steps included development and company-wide installation of an Occupational Health and Safety (OHS) data system to capture information pertaining to all unscheduled visits to plant medical departments. The codes for diagnosis, treatment, restrictions and medical leaves were used by the System to assign cases to the OSHA Log. All medical staff received rigorous training in OSHA recordkeeping through a four-day class which included a certification examination. Successful completion of the class became a condition of employment for senior medical staff of each location. As part of a legal settlement between the Company and OSHA, the Company agreed to review all its medical records and correct its OSHA Logs from 1991 through 1995. Pursuant to the settlement agreement with OSHA, this recordkeeping correction effort was audited by a third party agreeable to OSHA, the Company and the United Auto Workers Union. The audit demonstrated that the recordkeeping errors had been corrected.

Given these efforts to improve the Company's injury/illness data , we feel that the information contained in the OHS Data System is a genuine reflection of the impact of ergonomic disorders in heavy manufacturing and has value in the regulatory discussion. The experience of our workforce with ergonomic disorders will be presented on a company-wide basis for all of the various operations combined. It will also be presented by specific types of manufacturing processes, some of which are unique to automobile manufacture and others which can be generalized to other workplaces.

METHODS and RESULTS

The data source for this study was the Company's OHS Data System which contains records for all unscheduled medical visits to plant medical departments for 55 of the Company's manufacturing facilities from 1991 to present. Information associated with each First Time Occupational Visit (FTOV) includes: demographic information; type of injury; body part affected; department/operation where the injury occurred; and information about tools involved. The System also contains demographic information, job assignments and hours worked for all hourly employees, whether or not they had been seen by the plant medical departments. This level of information permits the evaluation of specific diagnoses by case count as well as by rates for specific manufacturing processes.

This series of analyses was limited to all FTOVs recorded for hourly workers in the Company's OHS Data System for calendar 1995. The FTOVs were analyzed on a company-wide basis as well as by general process groupings. The 55 locations were analyzed as the following three major process groupings: final vehicle assembly; general manufacturing; and parts distribution. Findings for "final vehicle assembly" could be compared to other automobile manufacturers, but represents a specialized manufacturing process with limited application to manufacturers outside the automotive sector. The grouping "general manufacturing" includes manufacture and assembly of smaller components from engines to printed circuit boards. The findings of these operations could be compared to data from many other types of manufacturing operations. The findings from the "parts distribution" grouping could be compared to operations that occur throughout the country in any packaging and distribution center.

Case or day counts and rates were computed for all FTOVs, OSHA recordable cases, Cases with Days Away on a company-wide basis for 1995. Company-wide severity rates were also computed. The corresponding rates for ergonomic disorders were computed on a company-wide basis for 1995. Counts and rates were also computed for three selected process groupings.

On a company-wide basis, there were 112,723 FTOVs yielding a rate of 113.1 visits per 200,000 hours worked. (See Table 1.) This translates to slightly more than one FTOV for every worker in 1995. Half of the FTOVs (52%) were classified as OSHA recordable injuries or illnesses and 7.5% of the FTOVs cases resulted in Days Away from Work. The number of Days Away from Work for 1995 was 200,403 or approximately 2 days for each worker.

The classification of Ergonomic Disorder includes all the illnesses classified as "Disorders associated with repeated trauma" (Column F of the OSHA Log) and injuries classified as "sprain or strain of the back". Using this definition, there were 30,804 FTOVs for Ergonomic Disorders. Ergonomic disorders accounted for 27% of all FTOVs, 44% of all OSHA recordable cases, 59% of all cases with Days Away from Work and 56% of all Days Away from Work.

The comparison of Ergonomic Disorders between the three process groupings documented significant levels of variation. (See Table 2.) The FTOV rate for Vehicle Assembly was more than twice as high as General Manufacturing and Parts Distribution. The rate was 47.6 per 200,000 compared to rates of 19.3 and 23.3, respectively. An equivalent picture was seen for OSHA Recordable Ergonomic Disorders. The picture changed when considering cases associated with Days Away from Work and the Severity Rate (Days Away per 200,000 hours worked). The rates for Cases with Days Away were identical for Vehicle Assembly and Parts Distribution at 7.9. The rate for General Manufacturing was significantly lower at 2.8. The Severity Rate for Parts Distribution was actually higher than the rate for Vehicle Assembly. They were 216.6 and 174.4, respectively. The Severity Rate for General Manufacturing was 60.6.

The higher rate for Ergonomic Disorders in Vehicle Assembly are generally attributed to the fact that the part (vehicle) being assembled is larger than the worker. In many cases the worker must "adapt" to the position of the vehicle (part) and do so many times per hour. The lower rates for General Manufacturing and Parts Distribution are attributed to the worker being able to manipulate the position of the part.

The finding of the Part Distribution workers having the highest Severity Rates is attributed to two factors. The work at the Parts Distribution Centers involves many opportunities for free lifting. This is in contrast to the manufacturing and even vehicle assembly where lifting is minimized or assisted with articulating arms or other devices. This would result in perhaps more severe injury to the back. (We are currently exploring this issue further.) The second factor is the lack of opportunity to place workers with medical restrictions in a variety of "light duty" jobs. The only jobs at a Parts Distribution Center are to pack and load parts for shipment. This results in workers, who could stay on the job but doing different tasks, being put on medical leave.

CONCLUSIONS

These findings indicate significant variation among the various processes in a single industry, automobile manufacturing. The differences mirror obvious differences in the processes involved. They seem to also reflect less obvious differences, such as, the ability to easily modify the process; or manage risk by rotating workers through different types of assignments until the job tasks can be modified. This picture of one industry drawn through these descriptive analyses illustrates that ergonomic disorders are a significant issue in occupational health. The variation seen in this one example, automobile manufacturing, also illustrates that need to explore many different approaches to reducing the burden of ergonomic disorders in the workplace.

Table 1: Counts and Rates for All Types of Injury/Illness and For Ergonomic Disorders Among Hourly Workers
U.S. Automobile Manufacturer, 1995

Table 2: Rates for Ergonomic Disorders By Three Selected Process Groupings Among Hourly Workers
U.S. Automobile Manufacturer, 1995