Integrating science and business models of sustainability for environmentally-challenging industries such as secondary lead smelters: a systematic review and analysis of findings.

Secondary lead smelters (SLS) represent an environmentally-challenging industry as they deal with toxic substances posing potential threats to both human and environmental health, consequently, they operate under strict government regulations. Such challenges have resulted in the significant reduction of SLS plants in the last three decades. In addition, the domestic recycling of lead has been on a steep decline in the past 10 years as the amount of lead recovered has remained virtually unchanged while consumption has increased. Therefore, one may wonder whether sustainable development can be achieved among SLS. The primary objective of this study was to determine whether a roadmap for sustainable development can be established for SLS. The following aims were established in support of the study objective: (1) to conduct a systematic review and an analysis of models of sustainable systems with a particular emphasis on SLS; (2) to document the challenges for the U.S. secondary lead smelting industry; and (3) to explore practices and concepts which act as vehicles for SLS on the road to sustainable development. An evidence-based methodology was adopted to achieve the study objective. A comprehensive electronic search was conducted to implement the aforementioned specific aims. Inclusion criteria were established to filter out irrelevant scientific papers and reports. The relevant articles were closely scrutinized and appraised to extract the required information and data for the possible development of a sustainable roadmap. The search process yielded a number of research articles which were utilized in the systematic review. Two types of models emerged: management/business and science/mathematical models. Although the management/business models explored actions to achieve sustainable growth in the industrial enterprise, science/mathematical models attempted to explain the sustainable behaviors and properties aiming at predominantly ecosystem management. As such, there are major disconnects between the science/mathematical and management/business models in terms of aims and goals. Therefore, there is an urgent need to integrate science and business models of sustainability for the industrial enterprises at large and environmentally-challenging industrial sectors in particular. In this paper, we offered examples of practices and concepts which can be used in charting a path towards sustainable development for secondary lead smelters particularly that the waste generated is much greater outside the industrial enterprise than inside. An environmentally-challenging industry such as secondary lead smelters requires a fresh look to chart a path towards sustainable development (i.e., survivability and purposive needs) for all stakeholders (i.e., industrial enterprise, individual stakeholders, and social/ecological systems). Such a path should deal with issues beyond pollution prevention, product stewardship and clean technologies.

Evidence-based integrated environmental solutions for secondary lead smelters: pollution prevention and waste minimization technologies and practices.

An evidence-based methodology was adopted in this research to establish strategies to increase lead recovery and recycling via a systematic review and critical appraisal of the published literature. In particular, the research examines pollution prevention and waste minimization practices and technologies that meet the following criteria: (a) reduce/recover/recycle the largest quantities of lead currently being disposed of as waste, (b) technically and economically viable, that is, ready to be diffused and easily transferable, and (c) strong industry interest (i.e., industry would consider implementing projects with higher payback periods). The following specific aims are designed to achieve the study objectives: Aim 1 - To describe the recycling process of recovering refined lead from scrap; Aim 2 - To document pollution prevention and waste management technologies and practices adopted by US stakeholders along the trajectory of LAB and lead product life cycle; Aim 3 - To explore improved practices and technologies which are employed by other organizations with an emphasis on the aforementioned criteria; Aim 4 - To demonstrate the economic and environmental costs and benefits of applying improved technologies and practices to existing US smelting operations; and Aim 5 - To evaluate improved environmental technologies and practices using an algorithm that integrates quantitative and qualitative criteria. The process of identifying relevant articles and reports was documented. The description of evidence was presented for current practices and technologies used by US smelters as well as improved practices and technologies. Options for integrated environmental solutions for secondary smelters were introduced and rank ordered on the basis of costs (i.e., capital investment) and benefits (i.e., production increases, energy and flux savings, and reduction of SO(2) and slag). An example was provided to demonstrate the utility of the algorithm by detailing the costs and benefits associated with different combinations of practices and technologies. The evidence-based methodology documented in this research reveals that it is technically and economically feasible to implement integrated environmental solutions to increase lead recovery and recycling among US smelters. The working example presented in this research can be confirmed with US stakeholders and form the basis for implementable solutions in the lead smelter and product industries to help reverse the overall trend of declining life-cycle recycling rates.

An exploratory study of lead recovery in lead-acid battery lifecycle in US market: an evidence-based approach.

BACKGROUND: This research examines lead recovery and recycling in lead-acid batteries (LAB) which account for 88% of US lead consumption. We explore strategies to maximize lead recovery and recycling in the LAB lifecycle. Currently, there is limited information on recycling rates for LAB in the published literature and is derived from a single source. Therefore, its recycling efforts in the US has been unclear so as to determine the maximum opportunities for metal recovery and recycling in the face of significant demands for LAB particularly in the auto industry. OBJECTIVES: The research utilizes an evidence-based approach to: (1) determine recycling rates for lead recovery in the LAB product lifecycle for the US market; and (2) quantify and identify opportunities where lead recovery and recycling can be improved. METHODS: A comprehensive electronic search of the published literature was conducted to gather information on different LAB recycling models and actual data used to calculate recycling rates based on product lifecycle for the US market to identify strategies for increasing lead recovery and recycling. RESULTS: The electronic search yielded five models for calculating LAB recycling rates. The description of evidence was documented for each model. Furthermore, an integrated model was developed to identify and quantify the maximum opportunities for lead recovery and recycling. Results showed that recycling rates declined during the period spanning from 1999 to 2006. Opportunities were identified for recovery and recycling of lead in the LAB product lifecycle. CONCLUDING REMARKS: One can deduce the following from the analyses undertaken in this report: (1) lead recovery and recycling has been stable between 1999 and 2006; (2) lead consumption has increased at an annual rate of 2.25%, thus, the values derived in this study for opportunities dealing with lead recovery and recycling underestimate the amount of lead in scrap and waste generated; and (3) the opportunities for maximizing lead recovery and recycling are centered on spent batteries left with consumers, mishandled LAB sent to auto wreckers, slag resulting from recycling technology process inefficiencies, and lead lost in municipal waste.

An epidemiological appraisal instrument - a tool for evaluation of epidemiological studies.

In recent years, ergonomics practices have increasingly relied upon the knowledge derived from epidemiological studies. In this regard, there is limited research devoted to the exclusive evaluation of the methodological qualities of ergonomics epidemiological studies. The aim of this study was to develop and test a general purpose 'epidemiological appraisal instrument' (EAI) for evaluating the methodological quality of existing or new ergonomic epidemiological studies using a critical appraisal system rooted in epidemiological principles. A pilot EAI version was developed and tested by a team of epidemiologists/physicians/biostatisticians, with the team leader being both epidemiologist and ergonomist. The pilot version was further tested with regard to other raters with/without a background in epidemiology, biostatistics and ergonomics. A revised version was evaluated for criterion validity and reliability. An assessor with a basic background in epidemiology and biostatistics would be able to correctly respond on four out of five questions, provided that subject matter expertise is obtained on specific items. This may improve with the article's quality. Training may have an effect upon assessors with virtually no background in epidemiology/biostatistics, but with a background in ergonomics. In this latter case, the inter-rater degree of agreement is largely above 90% and assessors can resolve their differences in a subsequent round. The EAI proved to be a valid and reliable appraisal instrument that may be used in various applications, such as systematic reviews and meta-analyses.

Musculoskeletal outcomes in multiple body regions and work effects among nurses: the effects of stressful and stimulating working conditions.

This study investigated the various stressors encountered by the nursing profession. In particular, the following hypotheses were tested: (1) working conditions of nurses significantly affect perceived risk of injury and illness, work dissatisfaction, work satisfaction, energy state at the end of workday, the effort exerted by the registered nurse (RN), psychosomatic outcomes, and musculoskeletal symptoms (in multiple body regions); (2) both intermediate work effects (i.e., effort, perceived risk of injury/illness, work satisfaction/dissatisfaction, energy state at end of workday) and psychosomatic outcomes significantly affect musculoskeletal outcomes (in multiple body regions); (3) both working conditions and effects significantly affect musculoskeletal outcomes. In a preliminary study conducted on 34 registered nurses, results show that: (1) stressful working conditions affect musculoskeletal outcomes in multiple body regions, and (2) physical maladies such as lower back problems are not only associated with physical factors but also with a complex interaction of working conditions. Further research is warranted to obtain a better understanding of the complex interaction and the synergistic effects of the various nursing working conditions.

What is a demanding lifting job for manual handling workers in Hong Kong?

Although lifting tasks are traditionally evaluated by researchers, through the use of methods which depend on one or more approaches (i.e., psychophysical, biomechanical and physiological methods), none of these approaches makes use of expert workers in the evaluation of lifting activities. Given that 97% of lower back symptoms are aches, pains and discomfort and rely on self-reports, it is intuitive to use expert workers in evaluating the stressfulness of lifting activities. In this investigation, 217 workers from three industries in the Hong Kong area were surveyed to determine what constitutes a demanding lifting job from a worker standpoint. This was achieved by asking workers to map, in numerical terms, the level of lifting task parameter described in linguistic values. For example, the weight of load was described in three linguistic descriptors, namely, 'light', 'moderate' and 'heavy'. Then, each worker was asked to assess the meaning of these linguistic descriptors in numerical terms, based on their perception and experience with manual handling work. In this study, workers were asked to map the physical analogue of linguistic descriptors for seven lifting task parameters which are utilized in the NIOSH lifting equation, that is, weight of load, horizontal distance, vertical travel distance, vertical origin of lift, angle of asymmetry, frequency of handling and task duration. The data obtained from the workers were then subjected to validity testing in relation to norms and values reported in the published literature. On a preliminary basis, it appears that workers' assessments are logical and valid. The results suggest that the worker-based methodology is a promising approach and that it is worthwhile to pursue this approach further in the evaluation of industrial lifting activities.

Strength and fatigue resistance of thoracolumbar spine implants: an experimental study of selected clinical devices.

Results of strength and endurance tests of several screw/rod thoracolumbar spinal implants are presented. The devices tested were: AcroMed ISOLA, CD systems, Depuy systems, and Synergy systems. The AcroMed ISOLA devices had the greatest stiffness and strength. The Synergy and AcroMed systems had the greatest fatigue resistance. The predominant failure mode was screw bending, although several instances of rod fracture and screw fracture were observed. A number of design improvements are identified, including reducing the number of components, thereby reducing the number of failure mechanisms; avoiding notches and knurled surfaces to provide greater resistance to crack initiation; and strengthening attachments between components, particularly between pedicle screws and horizontal rods.

Effects of cross-linkage on fatigue life and failure modes of stainless steel posterior spinal constructs.

This study tested the effects of cross-linkage on the fatigue performance of posterior spinal constructs (i.e., AcroMed stainless steel Isola systems). The failure modes encountered during fatigue were also examined. The results of this study confirmed earlier findings that the use of cross-linkage does not significantly affect the stability of posterior constructs during axial loading. Their influence in torsion loading is much more pronounced. During the fatigue tests, posterior stainless steel spinal implants instrumented without cross-linkage reached 1 million cycles at 500- and 750-N loads. When the load was increased to 1,000 N, the number of cycles to failure dropped by two-thirds. These findings demonstrate that the endurance limit was between 750 N and 1,000 N for spinal constructs without cross-linkage, with the limit being closer to 750 N. Devices equipped with one or two cross-linkages reached 1 million cycles at 500 N. The number of cycles to failure dropped dramatically as the load was increased to 750 and 1,000 N. It appears that the endurance limits for spinal devices using cross-linkage should be 500 and 750 N, with the limit closer to the 500-N load. All rod fractures occurred near the junction between the longitudinal and transverse rods. Stress concentration was greatly in the vicinity of that contact point. These results should provide a basis for future improvement in endurance limits of spinal implants equipped with cross-linkage. Higher endurance limits will reduce the toxic effects encountered during fracture modes. The implants will also be better able to withstand the high physiologic loads experienced by obese individuals.

What is 'heavy'?

One of the work practices frequently taught to employees is to estimate the heaviness of load before it is actually handled. If it is 'heavy', then one should ask for help. However, limited information can be found in the ergonomics literature about what a person perceives as a 'heavy load'. This study was conducted on 20 male and 20 female workers in the package delivery industry to estimate the amounts of load that correspond to various levels of load heaviness (e.g. 'somewhat heavy'). Experienced employees were used for this purpose. The distribution of loads within each heaviness level was developed using fuzzy sets theory. The maximum load (i.e. 23 kg) defined by the US National Institute for Occupational Safety and Health represents a 'somewhat heavy' load based on the analysis of load distribution (corresponding to a 1.0 certainty factor). Also, the 40 kg considered in the 1981 NIOSH guidelines may be classified as a 'very heavy' load. A comparative analysis of the results of this study with norms established in prior research indicates that one should be more careful in the interpretation of statistical norms for human perception of load handling. A 'moderate' level of load heaviness (i.e. 14 kg) can be handled by 85% of the worker population.

Biomechanical assessment of titanium and stainless steel posterior spinal constructs: effects of absolute/relative loading and frequency on fatigue life and determination of failure modes.

The goal of this study was to examine the effects of absolute/relative loads and frequency on the fatigue life of titanium and stainless steel posterior spinal constructs, and to determine the failure fracture modes. The stainless steel constructs had higher stiffness and yield strength than the titanium constructs, but the ultimate static strength was almost equal for both types of constructs. Titanium constructs, however, exhibited higher variability than the stainless steel constructs. In fatigue tests, the stainless steel constructs were significantly affected by the external load and were frequency independent. It appears from fatigue curves that 500 N can be approximated as the endurance limit for the stainless steel constructs. Titanium constructs were load-frequency dependent, and their endurance limit was somewhere between the 500 and 750 N load levels. There were no differences in performance between the stainless steel and titanium constructs at 16 Hz. At 4 Hz, titanium constructs performed as well or better than stainless steel constructs. Also, the titanium constructs resulted in better performance than the stainless steel constructs in the elastic region, and with smaller differences in the plastic region. Most of the failure modes for stainless steel constructs were in screw bending at 16 Hz with a smaller percentage of rod fractures at high loads, with a higher percentage of rod fractures observed for the stainless steel constructs at 4 Hz. Most of the failure modes for titanium constructs occurred in screw bending or fracture.

Use of visual perception in estimating static postural stresses: magnitudes and sources of errors.

Very little is known about the magnitudes and sources of errors associated with the visual estimation of postural classification displayed on TV screens. This study was conducted to address this issue. Sixty-three subjects participated in the experiments. The findings indicate that: (1) subjects found it difficult to evaluate upper extremity postures (particularly the elbow and the wrist), while the postures around the lower back were the easiest to evaluate; (2) the lower extremity positions affected the ability of the subjects to accurately classify postures around the wrist, elbow, shoulder, neck, and lower back, with the estimates being > 70% for sitting and > 60% for standing (except for the elbow); and (3) in general, flexion and extension are easier to evaluate than neutral and non-neutral postures.

Can back supports relieve the load on the lumbar spine for employees engaged in industrial operations?

In recent years, there has been an increased use of back supports in US industry to reduce the frequency and concomitant costs of lower-back disorders. The obvious question is, 'Can back supports relieve the load on the lumbar spine for employees engaged in industrial operations?'. This paper is directed towards answering this question because there have been mixed conclusions in the literature reporting on the efficacy of back supports. The literature concerning the biomechanical, physiological and psychophysical effects of back supports on the human spine has been reviewed as well as the use of back supports to control injury in the workplace. A critical assessment of the findings reported by various investigators has been made together with a discussion of the mechanisms used by the trunk muscles to provide extrinsic stability to the spine. It is hypothesized that the extrinsic stability of the spine is manifested through more than one mechanism. These mechanisms may act simultaneously or sequentially to stabilize the trunk. Finally, the ergonomics of back supports as a corporate policy are discussed.

Active microbreak effects on musculoskeletal comfort ratings in meatpacking plants.

This study was conducted to examine whether a system of active microbreaks can reduce the discomfort perceived by employees in a meatpacking plant. Moreover, the relationship between the discomfort perceived on the job and musculoskeletal capability was investigated. Twenty-eight men employed in a local meatpacking plant participated in a study conducted over a period of four weeks. Results indicated that active microbreaks significantly reduced the level of discomfort perceived by employees during the course of the working day. The subjective ratings of perceived discomfort correlated significantly with anthropometric, strength and background information (R2 = 0.66). The physical characteristics of Caucasian employees were higher than those of their Hispanic counterparts. Moreover, the physical characteristics of meatpacking employees were significantly lower than those reported in the literature for employees engaged in manual handling tasks.

Postural stress analysis in industry.

Both observational and instrumentation-based techniques have been used to conduct postural stress analysis in industry. As observational methods are more widespread than instrumentation-based techniques and can be used as a practical tool in the workplace, this study reviews and assesses the scientific literature on observational techniques. Techniques are classified into macropostural, micropostural and postural-work activity. The basis for each classification is outlined and evaluated. Postural recording is performed either continuously or intermittently. Intermittent postural recording procedures lack the criteria for determining the optimum number of observations for low and high repetitive jobs. Research is warranted to examine the sources and magnitudes of errors associated with postural classification. Such information is required to train job analysts in the ergonomics of working postures.

The effects of neutral posture deviations on perceived joint discomfort ratings in sitting and standing postures.

There is a pressing need to rank body deviations from neutral postures which occur due to variety of body movements around different joints. Such knowledge is needed to better understand potentially adverse effects of poor working postures on the industrial population. The main objective of this study was to examine the effects of postural deviations on perceived joint discomfort ratings assessed under similar working conditions. Twelve males and seven females participated in the laboratory study. The results revealed several distinct classes of joint deviations from neutral postures, which need to be assigned different weights of postural stress. A preliminary ranking system for assessment of stressfulness of human body deviations about different joints was proposed.

Ergonomic risk assessment: preliminary guidelines for analysis of repetition, force and posture.

High repetition, excessive forces and awkward postures are a major cause of musculoskeletal disorders in industry. Thus, the main objective of this paper is to develop, based on the published literature, preliminary ergonomic guidelines for repetition, force, and posture task analysis. A method is also proposed which can be used to compute the interactive effects of repetition, force and posture.

A psychophysical approach to determine the frequency and duration of work-rest schedules for manual handling operations.

The primary objectives of this study were: (1) to test whether rest allowances could be ascertained using a psychophysical methodology; and (2) to examine the effects of gender and frequency of handling on work-rest schedules. Two experiments were conducted, each experimental session at 4h. A psychophysical methodology was used where the subject was given control of the working and resting durations. The results of the study indicated that: (1) the total working time decreased and the total resting time decreased with an increase in the frequency of handling; (2) high frequency tasks required more frequent rest allowances; (3) for the same manual handling tasks, women needed more frequent and longer allowances than men; (4) experience with the manual handling of material reduced the variability collected from the psychophysical methodology. The application of the psychophysical methodology in industry is discussed.

Can visual perception be used to estimate body part angles?

For two decades, observational methods have been used to measure postural loads in industry. These methods depend on the analyst's judgment to characterize correctly the working postures. The errors associated with estimating the body part's angular deviation from the neutral position are not known. Recently, videotaping of a work situation, followed by examination of the tape to assess postural position has become more commonly practised. This study was conducted to determine the error which accompanies the judging (without tools) of postural angles. In the present study, a method was used whereby 20 subjects were asked to report the perceived angles which closely matched the actual shoulder flexion angle displayed on the TV screen. The results showed no significant differences among the three angular ranges ('low', 1-60 degrees; 'medium', 61-120 degrees; and 'high', 121-180 degrees) of shoulder flexion, in terms of algebraic and absolute errors. Subjects tended to slightly overestimate the true angle in the low range and to slightly underestimate the true angle in the medium and high angle ranges. This study suggests that visual perception can be used to estimate shoulder flexion angles displayed on a VDT.

Spinal compression tolerance limits for the design of manual material handling operations in the workplace.

Spinal compression tolerance limits (SCTL) have been widely used by ergonomists in setting work tolerance limits for manual materials handling (MMH) operations. Thus, the effect of personal and experimental factors on spinal compression tolerance limits (SCTL) is reviewed with the aid of regression and correlation analyses performed on data compiled from the published literature. Tables of SCTL from various sources utilizing large number of specimens and personal factors are presented so that they can be accessed by ergonomists easily. Integrated biomechanical guidelines based on SCTL are provided for the design of MMH operations in the workplace. It is suggested that, in order to reduce the probability of MMH injuries, biomechanical tolerance limits should be set at the damage load instead of the load at fracture. The damage load is the weight which causes the first gross signs of damage such as tissue fluid and blood. An algorithm is described to demonstrate the use of a biomechanics approach to the design of MMH operations.

Occupational biomechanics of the neck: a review and recommendations.

Musculoskeletal disorders of the neck are becoming a major concern in industry. Several studies reported the association of neck pain, discomfort, and symptoms with different occupations in industry. Thus, the main objective of this study is to review and evaluate biomechanical techniques used in analyzing the occupational factors leading to neck pain and disorders. Recommendations for future research are also discussed.