The effect of aerosol exposure on foundry workers and arc welders at a large engineering plant in South Africa

ThesisSouth African data regarding the extent of aerosol exposure and health effects in the workplace are limited . Furthermore, a shortage of industrial hygiene- and epidemiological data from large scale studies exist. Given the increasing concern about the health of industrial metal workers, an inhalation exposure study of South African iron foundry workers and welders at a large engineering plant in Bloemfontein, was undertaken. The aim of the study was to compile a source inventory, identifying and characterising all health related inorganic aerosols to which metal workers of the plant are potentially or actually exposed. In addition, the exposure risk was assessed by the integration of aerosol concentrations and biological data from urine analyses. Aerosols were sampled by means of time sequence particulate sampling on streaker filter frames and analysed with Particle Induced X-ray Emission (PIXE) on the Tandem van de Graaff accelerator of the University of the Witwatersrand, Johannesburg. The streaker is analysed in 1 mm steps, corresponding to 1 hour of exposure. PIXE analysis yielded concentrations or detection limits of elements AI, Si , P, S, CI , K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, In, Br and Pb. The urine of selected exposed workers was sampled according to NIOSH method 8310 and analysed using Atomic Absorption (AA) spectrometry for the urine-metal concentrations In, Cd, Co, Ni, Mn, Cu, Cr, AI , Fe, Pb, Si and V. Forced vital capacity (FVC), forced expiratory volume in one second (FEV1 ), peak expiratory flow (PEF), peak inspiratory flow (PIF), average expiratory flow between 25 % and 75 % of FVC (FEF2s-7S), expiratory flow at 25 % of FVC (Vma>e2S), expiratory flow at 50 % of FVC (VmaxSO) , expiratory flow at 75 % of FVC (Vmax7s) and forced expiration time (100 % FVC) (FET1oo), was conducted with a Cosmed Pony spirometer. This was done to provide a physical image of the workers' lungs. A new method for the assessment of aerosol inhalation exposure risk, called AIER, using aerosol concentrations and metal urine concentrations, is proposed for estimation of the inhalation risk. The assumptions and calculation for the new method are presented. A number of sources or source categories have been identified in the foundry's and welding shop's air by making use of patterns of time variations and elemental ratios. Six sources namely crustal particles, sulphur, In-Pb-CI, two distinct components of different castings and other heavy metals were identified as sources. The main pollutants and the relative contributions from other sources have been identified for iron foundries and welding shops with recognised air quality problems. Overexposure occurred during specific operations which was also quantified for rectification. The urine analysis of the foundry workers yielded high concentrations of Cd, Cu, Fe and Si. It is assumed that the Fe and Si concentrations are exposure related. The analysis of urine from the welders yielded high concentrations of Ni, Cr and Fe. Although Ni concentrations in the workroom air were low, the occurrence of all three elements in the urine may ·be as a result of chronic exposure to welding fumes in their workplace. Except for vanadium, no statistical significant differences (P > 0.05) were found between the different metal urine concentrations of the workers of the two localities. The total exposed foundry population showed a significant decrease in FEV1 and FVC which indicates that the pollution in the workplace contributes to the development of restrictive lung disorders in foundry workers. The dust created during the welding of steel in the welding shop is a contributing agent in the development of obstructive respiratory disorders in the welder population. Examination of the relationship between elemental variations has allowed identification of several sources and activities contributing to airborne particles. The aerosol profiles did not show similar diurnal time variation patterns in the foundry or the welding shop due to irregularities in the continuation of the processes. The AIER for the foundry resulted in a maximum value of 92.3 % while the corresponding value for the welding environment was 71.7 %. The results present the worst case scenario during winter conditions and it is expected that conditions will be more healthy during summer time when windows and doors are open. The planning and prioritisation for the improvement of indoor air quality in both workplaces can proceed , using the data on the sources of the pollutants. It can be concluded that workers exposed to conditions as found during this project, will experience health problems after chronic exposure. The results emphasised the importance of exposure characterisation in order to provide for identification of pollutants, control of sources and the application of industrial hygiene principles for the protection of human health. It is recommended that all industries implement exposure characterisation programmes as a tool in applying good occupational and environmental hygiene

The effect of aerosol exposure on foundry workers and arc welders at a large engineering plant in South Africa

ThesisSouth African data regarding the extent of aerosol exposure and health effects in the workplace are limited. Furthermore, a shortage of industrial hygiene- and epidemiological data from large scale studies exist. Given the increasing concern about the health of industrial metal workers, an inhalation exposure study of South African iron foundry workers and welders at a large engineering plant in Bloemfontein, was undertaken. The aim of the study was to compile a source inventory, identifying and characterising all health related inorganic aerosols to which metal workers of the plant are potentially or actually exposed. In addition, the exposure risk was assessed by the integration of aerosol concentrations and biological data from urine analyses. Aerosols were sampled by means of time sequence particulate sampling on streaker filter frames and analysed with Particle Induced X-ray Emission (PIXE) on the Tandem van de Graaff accelerator of the University of the Witwatersrand, Johannesburg. The streaker is analysed in 1 mm steps, corresponding to 1 hour of exposure. PIXE analysis yielded concentrations or detection limits of elements AI, Si, P, S, CI, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, In, Br and Pb. The urine of selected exposed workers was sampled according to NIOSH method 8310 and analysed using Atomic Absorption (AA) spectrometry for the urine-metal concentrations In, Cd, Co, Ni, Mn, Cu, Cr, AI, Fe, Pb, Si and V. Forced vital capacity (FVC), forced expiratory volume in one second (FEV1 ), peak expiratory flow (PEF), peak inspiratory flow (PI F), average expiratory flow between 25 % and 75 % of FVC (FEF25-7S), expiratory flow at 25 % of FVC (Vmax2S), expiratory flow at 50 % of FVC (VmaxSO) , expiratory flow at 75 % of FVC (Vma>c7S) and forced expiration time (100 % FVC) (FET1oo), was conducted with a Cosmed Pony spirometer. This was done to provide a physical image of the workers' lungs. A new method for the assessment of aerosol inhalation exposure risk, called ,~ER, using aerosol concentrations and metal urine concentrations, is proposed for estimation of the inhalation risk. The assumptions and calculation for the new method are presented. A number of sources or source categories have been identified in the foundry's and welding shop's air by making use of patterns of time variations and elemental ratios. Six sources namely crustal particles, sulphur, In-Pb-CI, two distinct components of different castings and other heavy metals were identified as sources. The main pollutants and the relative contributions from other sources have been identified for iron foundries and welding shops with recognised air quality problems. Overexposure occurred during specific operations which was also quantified for rectification. The urine analysis of the foundry workers yielded high concentrations of Cd, Cu, Fe and Si. It is assumed that the Fe and Si concentrations are exposure related. The analysis of urine from the welders yielded high concentrations of Ni, Cr and Fe. Although Ni concentrations in the workroom air were low, the occurrence of all three elements in the urine may be as a result of chronic exposure to welding fumes in their workplace. Except for vanadium, no statistical significant differences (P > 0.05) were found between the different metal urine concentrations of the workers of the two localities. The total exposed foundry population showed a significant decrease in FEV1 and FVC which indicates that the pollution in the workplace contributes to the development of restrictive lung disorders in foundry workers. The dust created during the welding of steel in the welding shop is a contributing agent in the development of obstructive respiratory disorders in the welder population. Examination of the relationship between elemental variations has allowed identification of several sources and activities contributing to airborne particles. The aerosol profiles did not show similar diurnal time variation patterns in the foundry or the welding shop due to irregularities in the continuation of the processes. The AIER for the foundry resulted in a maximum value of 92.3 % while the corresponding value for the welding environment was 71.7 %. The resu lts pres~t the worst case scenario during winter conditions and it is expected that conditions will be more healthy during summer time when windows and doors are open. The planning and prioritisation for the improvement of indoor air quality in both workplaces can proceed, using the data on the sources of the pollutants. It can be concluded that workers exposed to conditions as found during this project, will experience health problems after chronic exposure. The results emphasised the importance of exposure characterisation in order to provide for identification of pollutants, control of sources and the application of industrial hygiene principles for the protection of human health. It is recommended that all industries implement exposure characterisation programmes as a tool in applying good occupational and environmental hygiene

Risk evaluation techniques in a general insurance environment

Please read the abstract in the section 00front of this documentDissertation (MCom (Actuarial Science))--University of Pretoria, 2005.Insurance and Actuarial Scienceunrestricte

Die effek van bakteriee en swaarmetale in behandelde rioolwater op die baber

ThesisHealth risks associated with the utilization of waste water for fish production were studied by investigating the possible incorporation of pathogenic micro-organisms and heavy metals into ftllets of fish. Fish were grown in cages in a stabilization pond at the Bloemspruit sewage works, while another group of fish was kept in a similar cage in the Krugersdrift dam. Water and fish were analysed for total and faecal coliforms, Salmonella, colifages and Escherichia coli. Chemical analyses were also conducted on the water and fish for heavy metals and related trace elements. Even though high numbers of faecal coliforms and colifages were detected in the treated waste water, and in some instances Salmonella was isolated, none of these micro-organisms were found in fish fillets. Concentrations of heavy metals showed no toxic evidence in fillets although chromium might be of some concern in future, should the concentration of the metal Increase. Results of this study indicate that fillets of Clarias gariepinus grown in treated waste water like the water of the Bloemspruit sewage works, are microbiologically and chemically safe for human consumption, provided that simple precautions are maintained in food-handling and -processing. The ponds are restricted to domestic waste with a minimum of industrial waste. The fish in the Krugersdrift dam are also microbiologically and chemically safe for human consumption, although the concentrations of chemical compounds were generally higher in fillets of this fish group. Urgent attention must be given to the maintenance of stricter control of natural waters to prevent water pollution in this catchment area

Die effek van bakteriee en swaarmetale in behandelde rioolwater op die baber

ThesesHealth risks associated with the utilization of waste water for fish production were studied by investigating the possible incorporation of pathogenic micro-organisms and heavy metals into ftllets of fish. Fish were grown in cages in a stabilization pond at the Bloemspruit sewage works, while another group of fish was kept in a similar cage in the Krugersdrift dam. Water and fish were analysed for total and faecal coliforms, Salmonella, colifages and Escherichia coli. Chemical analyses were also conducted on the water and fish for heavy metals and related trace elements. Even though high numbers of faecal coliforms and colifages were detected in the treated waste water, and in some instances Salmonella was isolated, none of these micro-organisms were found in fish fillets. Concentrations of heavy metals showed no toxic evidence in fillets although chromium might be of some concern in future, should the concentration of the metal Increase. Results of this study indicate that fillets of Clarias gariepinus grown in treated waste water like the water of the Bloemspruit sewage works, are microbiologically and chemically safe for human consumption, provided that simple precautions are maintained in food-handling and -processing. The ponds are restricted to domestic waste with a minimum of industrial waste. The fish in the Krugersdrift dam are also microbiologically and chemically safe for human consumption, although the concentrations of chemical compounds were generally higher in fillets of this fish group. Urgent attention must be given to the maintenance of stricter control of natural waters to prevent water pollution in this catchment area

Does prolonged post-mortem cold ischemic harvesting time influence cryopreserved pulmonary homograft tissue integrity?

Published ArticleThis study investigated cryopreserved pulmonary homograft (CPA) structural integrity after prolonged cold ischemic harvesting times in a juvenile sheep model. Three groups with different post-mortem cold ischemic harvesting times were studied, i.e. Group 1 (24 h, n = 10); group 2 (48 h, n = 10); group 3 (72 h, n = 10). In each group, 5 CPAs were studied in vitro after cryopreservation and thawing. The other 5 CPAs were implanted in juvenile sheep for a minimum of 180 days. Serology samples were obtained and echocardiography was performed before euthanasia. Hematoxylin and eosin (H&E), scanning electron microscopy (SEM), von Kossa, Picrosirius red, α-actin, immunohistochemistry [von Willebrand factor (vWF), CD4, CD31 and CD34] and calcium content analyses were performed on explanted CPAs. The in vitro and in vivo studies failed to demonstrate any change in tensile strength, Young's Modulus and thermal denaturation (Td) results between the groups. SEM demonstrated a reduction in endothelial cells (50 % at 24 h, 60.9 % at 48 h and 40.9 % at 72 h), but H&E could not demonstrate autolysis in any CPA in vitro. All cultures were negative. In the explanted groups, IgE, IgM and IgG results were inconclusive. Echocardiography demonstrated normal valve function in all groups. H&E and Picrosirius red staining confirmed tissue integrity. vWF, CD31 and CD34 staining confirmed a monolayer of endothelial cells in all explanted valves. Calcium content of explanted CPA leaflets was similar. This experimental study supports the concept of prolonging the cold ischemic harvesting time of cryopreserved homografts to reduce homograft shortage

A framework for simulating systemic risk and its application to the South African banking sector

We present a network-based framework for simulating systemic risk that considers shock propagation in banking systems. In particular, the framework allows the modeller to reflect a top-down framework where a shock to one bank in the system affects the solvency and liquidity position of other banks, through systemic market risks and consequential liquidity strains. We illustrate the framework with an application using South African bank balance sheet data. Spikes in simulated assessments of systemic risk agree closely with spikes in documented subjective assessments of this risk. This indicates that network models can be useful for monitoring systemic risk levels. The model results are sensitive to liquidity risk and market sentiment and therefore the related parameters are important considerations when using a network approach to systemic risk modelling.The National Research Foundation (NRF) and the Absa chair in Actuarial Science.https://www.actuarialsociety.org.za/assa-news/sa-actuarial-journal-and-articlesam2019Mathematics and Applied Mathematic

Cadaver donation: structural integrity of pulmonary homografts harvested 48 h post mortem in the juvenile ovine model

Published ArticleAbstract Cryopreserved pulmonary homograft (CPH) implantation remains the gold standard for reconstruction of the right ventricular outflow tract (RVOT). Harvesting homografts\24-h post mortem is the international norm, thereby largely excluding cadaveric donors. This study examines the structural integrity and stability of ovine pulmonary homografts harvested after a 48-h post mortem period, cryopreserved and then implanted for up to 180 days. Fifteen ovine pulmonary homografts were harvested 48-h post mortem and cryopreserved. Five CPH served as a control group (group 1; n = 5). CPH were implanted in the RVOT of juvenile sheep and explanted after 14 days (group 2; n = 5) and 180 days (group 3; n = 5). Leaflet integrity was evaluated by strength analysis, using tensile strength (TS), Young’s modulus (YM) and thermal denaturation temperature (Td), and morphology, including haematoxylin and eosin (H&E), Picrosirius red staining, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and von Kossa stains. Echocardiography confirmed normal function in all implants. In explants, no reduction in TS, YM or Td could be demonstrated and H&E showed mostly acellular leaflet tissue with no difference on Picrosirius red. TEM demonstrated consistent collagen disruption after cryopreservation in all three groups, with no morphological deterioration during the study period. von Kossa stains showed mild calcification in group 3. No deterioration of structural integrity could be demonstrated using strength or morphological evaluations between the controls and implant groups over the study period. Extending the post mortem harvesting time of homografts beyond 24 h did not appear to negatively affect the long-term performance of such transplanted valves in this study

Development and testing of a transcatheter heart valve with reduced calcification potential

IntroductionPatients from developing countries who require heart valve surgery are younger and have less access to open heart surgery than those from developed countries. Transcatheter heart valves (THVs) may be an alternative but are currently unsuitable for young patients because of their inadequate durability. We developed and tested a THV utilizing two new types of decellularized bovine pericardial leaflets in an ovine model.MethodsThe two decellularized tissues [one with a very low dose (0.05%) of monomeric glutaraldehyde (GA) fixation and detoxification (DF) and the other without glutaraldehyde (DE)] were compared to an industry standard [Glycar—fixed with the standard dose (0.625%) of glutaraldehyde]. THVs were manufactured with the three tissue types and implanted in the pulmonary position of nine juvenile sheep for 180 days. Baseline and post-explantation evaluations were performed to determine the hemodynamic performance of the valves and their dynamic strength, structure, biological interaction, and calcification.ResultsHeart failure occurred in one animal due to incompetence of its Glycar valve, and the animal was euthanized at 158 days. The gradients over the Glycar valves were higher at the explant than at the implant, but the DE and DF valves maintained normal hemodynamic performance throughout the study. The DF and DE tissues performed well during the mechanical testing of explanted leaflets. Glycar tissue developed thick pannus and calcification. Compared to Glycar, the DF tissue exhibited reduced pannus overgrowth and calcification and the DE tissue exhibited no pannus formation and calcification. All tissues were endothelialized adequately. There was a striking absence of host ingrowth in the DE tissue leaflets, yet these leaflets maintained integrity and mechanical function.ConclusionIn the juvenile sheep THV model, Glycar tissue developed significant pannus, calcification, and hemodynamic deterioration. Using a very low dose of monomeric GA to fix the decellularized bovine pericardium yielded less pannus formation, less calcification, and better hemodynamic function. We postulate that the limited pannus formation in the DF group results from GA. Bovine pericardium decellularized with our proprietary method resulted in inert tissue, which is a unique finding. These results justify further development and evaluation of the two decellularized tissue types in THVs for use in younger patients

Impact of Three Different Processing Techniques on the Strength and Structure of Juvenile Ovine Pulmonary Homografts

Homografts are routinely stored by cryopreservation; however, donor cells and remnants contribute to immunogenicity. Although decellularization strategies can address immunogenicity, additional fixation might be required to maintain strength. This study investigated the effect of cryopreservation, decellularization, and decellularization with additional glutaraldhyde fixation on the strength and structure of ovine pulmonary homografts harvested 48 h post-mortem. Cells and cellular remnants were present for the cryopreserved group, while the decellularized groups were acellular. The decellularized group had large interfibrillar spaces in the extracellular matrix with uniform collagen distribution, while the additional fixation led to the collagen network becoming dense and compacted. The collagen of the cryopreserved group was collapsed and appeared disrupted and fractured. There were no significant differences in strength and elasticity between the groups. Compared to cryopreservation, decellularization without fixation can be considered an alternative processing technique to maintain a well-organized collagen matrix and tissue strength of homografts