MEGAPHYS - Development of a compendium of methods for the analysis of the risks induced by physical exposures – A cooperative study of BAuA and DGUV

Status:

completed 08/2018

Aims:

• Collating of a comprehensive portfolio of methods within the intended cooperative study to enable an adequate risk assessment in occupational settings
• Improvement of the spectrum of methods with respect to load mode
• Describing and extension of the state of knowledge regarding the relationships between load and overload, on the one hand, and complaints and diseases of the primarily affected body regions, on the other hand

Activities/Methods:

Subproject IfADo:

A first main topic of IfADo research is the documentation of methods for recording, evaluating and assessing physical exposures primarily focussing on spinal load. For this purpose, 25 procedures or studies were outlined on the basis of 10 characteristics.

As a further subgoal of MEGAPHYS it was formulated to combine the instruments CUELA of the Institute for Occupational Safety and Health of the DGUV (IFA) and IfADo's "The Dortmunder" in order to utilize the respective advantages – non-stationarity and proximity to the workplace, on the one hand, and detailed lumbar-load determination, on the other hand. In this regard, "Dortmunder's" modelings of the skeletal and lowertrunk's muscular structures as well as of the effects of intra-abdominal pressure were adapted in "CUELA". Applying the coupled system "CUELA-Dortmunder", compressive forces at the lumbosacral disc were determined particularly in the field measurements.

Furthermore, the data base of the Dortmund Recommendations was updated; these critical values – derived from compressive-strength measurements on isolated spinal segments – were characterised as suggested limits for low-back load during single actions up to working shifts; subsequently, the Revised Dortmund Recommendations were specified.

Another focus of the IfADo subproject aims to the biomechanical evaluation of established screening methods, such as the Key-Indicator Methods (LMM) of the BAuA and the Ergonomic Assessment Worksheet (EAWS) of the Institute of Ergonomics of Darmstadt University of Technology (IAD), with regard to lumbar overload. Based on posture replication in the laboratory and subsequent biomechanical-model calculations by means of applying "The Dortmunder", a clear correspondence of the weightings for posture and object mass or for the exerted action forces, on the one hand, and of the reaction forces at the lumbar spine, on the other hand, was found for all 7 screening tools examined; nevertheless, adjustments of weightings are also encouraged.

Appropriate criteria for protocolling measurements and evaluating exposures at different body regions were essentially defined by the IFA. Feasible procedures for describing and assessing the situational and cumulative low-back load, including how to deal with the "uncertainty of reference values", were specified by IfADo. With respect to branch-specific activities such as patient transfer, 9 previous, partly very extensive studies were described regarding methodology and essential results.

With respect to cross-sectoral materials-handling activities such as lifting or pushing, about 900 action-specific model calculations with varied task conditions were performed so that the available data spectrum was more than quadrupled, which simplifies load estimates in the future.

Subprojekt IAD:

In a first step on level 2, existing expert screenings for physical workloads categories – working postures (Kh), body/ action forces (AK), manual material handling (HvL), repetitive movements of the upper extremities (Rep.) were extended by specific load criteria. These criteria are: the whole body movement, work organization and work density distribution as well as the performance conditions for the activities.

Furthermore, for the workloads manual material Handling (HvL) and actions forces (AK), an evaluation of heterogeneous load and force cases was supplemented and converted into computer-aided tools (level 3: "Megaphys-MonKras", "Megaphys-MultipLa").

For the description of the temporal sequence of workload sections, a recording method ("workload matrix") was developed (level 4). An exposure assessment does not take place at this level and is intended for further development. A new body segment related evaluation - level 5 - was introduced. With this method the workloads can be evaluated not only time-related, but also body-segment related. This segment-related approach was tested in an exemplary manner for the evaluation of the load category "working posture" (Kh) and represents in further development an interface to the results of the measurement analysis (e.g. CUELA).

Results:

Subproject IfADo:

With the only exception of integration in field measurements, the main topics were dealt with comprehensively and in accordance with the objectives. With respect to the biomechanical evaluation of screening tools regarding lumbar load or overload, not only established but also newly developed methods were analysed, and additional load indicators such as disc-related shear forces were included in the analysis. As a particular result, the concretisation of the Revised Dortmund Recommendations is emphasized enabling an evaluation of lumbar load on an extended scientific database.

Subproject IAD:

Results of the whole workload evaluation were analysed with regard to convergence with the subjective assessment data from questionnaires according to Corlett-Bishop (N=160 persons) and Borg-RPE scale (N=135 persons). This evaluation of the expert screening (categorical - risk categories 1-4) correlates significantly with the subjective assessment of stress according to the Borg scale, both for men (rs, men = 0.245; p = 0.029) and for women (rs, women = 0.249; p = 0.027). No significant correlation was found for the subjective assessment according to Corlett-Bishop questionnaire.

The criterion validity of the expert screening was tested and discussed on the basis of the agreement of the assessment (for individual categories of workload and whole work load) with the epidemiological data (e.g. annual and weekly prevalence, subjective assessment according to Borg RPE, lumbar diseases).

Implementation for practice: Heterogeneous workload situations, which are typical for practice, can be well analysed with the expert screenings (level 2), in particular also with the computer-aided tools (level 3). The combination of expert screening for the body segment related assessment (level 5) with measurement methods (e.g. CUELA) is promising. A promising future development is possible here, as more and more good sensors are being used in practice. In this context, it is advisable to carry out a body segment related evaluation with expert screenings at the workplace first in order to check the need for action and, if necessary, to derive concrete hints for design possibilities through a subsequent analysis of the evaluation results in the case of corresponding measurement data which indicate an increased load.

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