Stephen D. Hudock

Clinical guidelines for occupational lifting in pregnancy: evidence summary and provisional recommendations

Empirically based lifting criteria established by the National Institute for Occupational Safety and Health (NIOSH) to reduce the risk of overexertion injuries in the general US working population were evaluated for application to pregnant workers. This report proposes criteria to guide decisions by medical providers about permissible weights for lifting tasks performed at work over the course of an uncomplicated pregnancy. Our evaluation included an extensive review of the literature linking occupational lifting to maternal and fetal health. Although it has been 29 years since the American Medical Associations Council on Scientific Affairs published its report on the Effects of Pregnancy on Work Performance, these guidelines continue to influence clinical decisions and workplace policies. Provisional clinical guidelines derived from the NIOSH lifting criteria that account for recent evidence for maternal and fetal health are presented and aim to improve the standard of care for pregnant workers.

Biomechanical Assessment of Three Rebar Tying Techniques

The National Institute for Occupational Safety and Health (NIOSH) conducted a study of ironworkers to evaluate their risk for developing back and hand injuries from hand-tying reinforcing steel bar and to investigate whether power tying tools can be an effective intervention for the prevention of work-related musculoskeletal disorders. A field investigation of biomechanical loading when using 3 techniques to tie together rebar was conducted. Researchers measured employees ‘ wrist and forearm movement with goniometers and videotaped and analyzed trunk postures. Manually tying rebar at ground level involved sustained deep trunk bending and rapid, repetitive, and forceful hand-wrist and forearm movements. Using a power tier significantly reduced the hand-wrist and forearm movements and allowed the ironworkers to use one free hand to support their trunk posture while tying. Adding an extension handle to the power tier allowed the ironworkers to tie rebar while standing erect, minimizing sustained trunk flexion.

Provisional Recommended Weight Limits for Manual Lifting During Pregnancy

Objective: The National Institute for Occupational Safety and Health (NIOSH) Revised Lifting Equation (RNLE) was adapted to derive recommended weight limits (RWLs) for pregnant workers and to develop corresponding guidelines for clinicians. Background: In the past three decades there has been a large increase in the number of women employed outside the home and remaining in the workforce during pregnancy. Practical authoritative guidelines based on accumulated evidence are needed to inform allowable work activity levels for healthy pregnant workers. Method: Empirically based lifting criteria established by NIOSH to reduce the risk of overexertion injuries in the general U.S. working population were evaluated for application to pregnant workers. Our evaluation included an extensive review of the literature linking occupational lifting to maternal and fetal health. Decision logic and supporting literature are presented, along with computational details. Results: Provisional RWLs for pregnant workers were derived from the RNLE, along with guidelines for clinicians. The guidelines advise against pregnant workers lifting below midshin and overhead. Conclusion: Based on our review of the available evidence, we present lifting thresholds that most pregnant workers with uncomplicated pregnancies should be able to perform without increased risk of adverse maternal and fetal health consequences. Except for restrictions involving lifting from the floor and overhead, the provisional guidelines presented are compatible with NIOSH lifting recommendations adopted in the early 1990s for the general working population. Application: Implementation of these provisional guidelines could protect millions of female workers in the workplace from fetal and maternal lifting-related health problems.

Finger Tendon Travel Associated with Sequential Trigger Nail Gun Use.

OCCUPATIONAL APPLICATIONS This article reports a method for assessing finger tendon motion associated with the use of a sequential actuation trigger pneumatic nail gun. The two-stage actuation process of the sequential actuation trigger reduces risk of nail puncture injury from unintended nail discharge (relative to the higher risk of the contact actuation trigger). However, widespread adoption of the sequential actuation trigger nail gun throughout the construction industry has been hindered by beliefs about productivity and musculoskeletal concerns about the repetitive trigger actuation and finger motion for each nail fired. Though existing guidelines for finger tendon travel exposure are not well established, predictions derived with the present method combined with productivity standards suggest insufficient evidence to contradict the safety-based recommendation to adopt the sequential actuation trigger trigger. TECHNICAL ABSTRACT Background: Pneumatic nail guns used in wood framing are equipped with one of two triggering mechanisms. Sequential actuation triggers have been shown to be a safer alternative to contact actuation triggers because they reduce traumatic injury risk. However, the sequential actuation trigger must be depressed for each individual nail fired as opposed to the contact actuation trigger, which allows the trigger to be held depressed as nails are fired repeatedly by bumping the safety tip against the workpiece. As such, concerns have been raised about risks for cumulative trauma injury, and reduced productivity, due to repetitive finger motion with the sequential actuation trigger. Purpose: This study developed a method to predict cumulative finger flexor tendon travel associated with the sequential actuation trigger nail gun from finger joint kinematics measured in the trigger actuation and productivity standards for wood-frame construction tasks. Methods: Finger motions were measured from six users wearing an instrumented electrogoniometer glove in a simulation of two common framing tasks—wall building and flat nailing of material. Flexor tendon travel was calculated from the ensemble average kinematics for an individual nail fired. Results: Finger flexor tendon travel was attributable mostly to proximal interphalangeal and distal interphalangeal joint motion. Tendon travel per nail fired appeared to be slightly greater for a wall-building task than a flat nailing task. The present study data, in combination with construction industry productivity standards, suggest that a high-production workday would be associated with less than 60 m/day cumulative tendon travel per worker (based on 1700 trigger presses/day). Conclusion and Applications: These results suggest that exposure to finger tendon travel from sequential actuation trigger nail gun use may be below levels that have been previously associated with high musculoskeletal disorder risk.

Ergonomics: An Assessment of Occupational Safety and Health Hazards in Selected Small Businesses Manufacturing Wood Pallets—Part 1. Noise and Physical Hazards

1National Institute for Occupational Safety and Health, Education and Information Division, Cincinnati, Ohio 2National Institute for Occupational Safety and Health, Division of Applied Research and Technology, Cincinnati, Ohio R esearchers from the National Institute for Occupational Safety and Health (NIOSH) investigated occupational safety and health concerns in the small business wood pallet manufacturing industry. The investigation consisted of interviews with employees and managers and walkthrough tours of seven wood pallet manufacturing companies while taking measurements at several of them. The purpose of the project was to assess and characterize occupational safety and health hazards in the industry and to offer suggestions as to how exposure to the hazards might be mitigated. Noise level measurements and ergonomic observations were made at each facility. This column describes the assessments and suggestions to minimize ergonomic and noise exposures from the occupational risk factors at the facilities. (A companion paper will address the respiratory hazards evaluated during the investigation: i.e., Part 2—airborne particulate and chemical hazards.) The main findings are as follows:

Unstable sitting in the workplace--are there physical activity benefits?

The increasingly popular practice of using a stability ball (exercise/fitness ball) as a sitting surface runs counter to conventional human factors/ergonomics guidelines for seated workspace design. Employees sitting on stability balls in an office environment present safety risks that might be justifiable if the practice has a definitive benefit to the promotion of health. However, the published studies and best evidence to date call into question even the theoretical basis for this practice and do not suggest significant health benefits. First, biomechanical studies do not confirm the intended trunk muscle activation. Second, energy expenditure studies show a small (if any) increase in metabolic demand that is unlikely to be effective in combating sedentary work risk factors. Until studies demonstrate more conclusive benefits, the practice of stability ball sitting should be viewed skeptically as a general workplace recommendation in the interest of health or wellness.

Preface to the Special Section on the Impact of Thomas Waters on the Field of Ergonomics

the field of occupational ergonomics for 24 years while working at the National Institute for Occupational Safety and Health (NIOSH). Although his work focused on musculoskeletal disorders (MSDs) across many industries, including manufacturing, retail trade, warehousing, agriculture, and health care, he is most known for leading the development and validation of the Revised NIOSH Lifting Equation (RNLE) starting in 1993. The RNLE has become the most widely used ergonomic assessment tool in the world. Researchers across the world are now revising and expanding this equation to ensure wide applicability of the RNLE. Waters published 27 articles on the RNLE, with one of the last articles being awarded the 2000 Alice Hamilton Award for Excellence in the Human Studies (Waters et al., 1999) and another expanding the RNLE to be used by pregnant workers lifting at work (MacDonald et al., 2013). The reach of this tool has been phenomenal, with almost 65,000 downloads of the RNLE documentation from the NIOSH Web page between 2007 and 2012, more than 72,000 page views from 2009 to 2012, and more than 25,000 copies of the RNLE distributed by NIOSH. More than 130 articles have been published that employ the RNLE as an assessment tool, providing one indication of the impact that this tool has had on the field. Lu, Putz-Anderson, Garg, and Davis (2016) have reviewed the literature to assess the impact and application of the RNLE. Three other articles in this special issue provide insight into modifications to the RNLE, including the cumulative RNLE (Garg & Kapellusch, 2016) and the variable-task RNLE (Battevi, Pandolfi, & Cortinovis, 2016; Waters, Occhipinti, Colombini, Alvarez-Casado, & Fox, 2016). In all, the articles continue the legacy of the RNLE as it can be more applicable to a wider number of jobs. Waters was a major advocate for safe patient handling. He published 27 publications that focused on safe patient handling. He also assisted in the development of guidelines for safe patient handling for the Veterans Health Administration, the American Nursing Association, the Association of periOperative Registered Nurses, the National Association of Orthopaedic Nurses, the Critical Care Nursing Task Force, and the Indian Health Service. His passion to protect nurses from patienthandling injuries culminated with the development of recommendations for schools of nursing (Waters, Nelson, Hughes, & Menzel, 2009). Two articles are included in this special issue that represent the research that Waters fostered in safe patient handling. First, a review by Wilson and Davis (2016) provides a summary of his work in safe patient handling, identifying his contribution to the health care field and beyond. Second, a study by Wiggermann (2016) investigates how a novel feature of a bed can assist the turning and lateral transferring of patients, thus reducing the stress on the caregiver. This research fits well with many of the research priorities that Waters championed in the health care ergonomics field. Waters also had an impact in youth agriculture ergonomics, where he developed a twodimensional biomechanical model for adolescents, developed instrumentation to look at bone density and quality, and evaluated interventions for common tasks performed by farm youth. The later focus resulted in three separate studies that were funded by NIOSH and overseen by Waters. In one study, the authors investigated the impact of wheelbarrow design and add-on handles for scoop shovels on trunk kinematics for farm youth (Kotowski, Davis, & Waters, 2009a, XXX10.1177/0018720816652150Human FactorsPreface to the Special Section

Hand/Arm Forces with Pneumatic Nail Gun Actuation Systems

A biomechanical model is presented to estimate cumulative user hand/arm force associated with two pneumatic nail gun trigger systems. The contact actuation trigger (CAT) can fire a nail when the user holds the trigger depressed first and then “bumps” the nail gun safety tip against the workpiece. With a full sequential actuation trigger (SAT) the user must press the tip against the workpiece prior to activating the trigger. The SAT is demonstrably safer in reducing traumatic injury risk, but increases the duration (and magnitude) of tip force exertion. Time integrated hand force was calculated for a single user from measurements of the tip contact force with the workpiece and transfer time between nails as inputs to a quasi-dynamic model of nailing in two task orientations. Application of the model shows the hand/arm force dependence upon the orientation of the workpiece in addition to the trigger system. Based on standard time allowances from work measurement systems (i.e. MTM - 1) the model results suggest that efficient application of tip contact force with the SAT would reduce total hand/arm force exertion attributable to this trigger system for this user. The present model is useful for considering differences in cumulative hand/arm force exposure between the SAT and CAT systems and the user perceptions and practices that result from these differences.