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The Occupational Safety and Health Act of 1970 assigns to the federal government specific responsibilities for regulating safety and health in industry. At the same time, occupational health programs have traditionally been, and continue to be, one responsibility of local and state health agencies. In California, local health agencies are required to provide occupational health services in larger jurisdictions. Professional level positions which may be required include: Occupational health physician, occupational health nursing consultant, industrial hygienist or occupational health sanitarians, industrial hygiene engineer, and industrial hygiene chemist. Frequently a local health agency may satisfy its occupational health requirements by training a registered sanitarian to become an occupational health sanitarian.
An 18-month survey of 31 water systems in North America was conducted to determine the factors that contribute to the occurrence of coliform bacteria in drinking water. The survey included analysis of assimilable organic carbon (AOC), coliforms, disinfectant residuals, and operational parameters. Coliform bacteria were detected in 27.8% of the 2-week sampling periods and were associated with the following factors: filtration, temperature, disinfectant type and disinfectant level, AOC level, corrosion control, and operational characteristics. Four systems in the study that used unfiltered surface water accounted for 26.6% of the total number of bacterial samples collected but 64.3% (1,013 of 1,576) of the positive coliform samples. The occurrence of coliform bacteria was significantly higher when water temperatures were > 15 degrees C. For filtered systems that used free chlorine, 0.97% of 33,196 samples contained coliform bacteria, while 0.51% of 35,159 samples from chloraminated systems contained coliform bacteria. The average density of coliform bacteria was 35 times higher in free-chlorinated systems than in chloraminated water (0.60 CFU/100 ml for free-chlorinated water compared with 0.017 CFU/100 ml for chloraminated water). Systems that maintained dead-end free chlorine levels of < 0.2 mg/liter or monochloramine levels of < 0.5 mg/liter had substantially more coliform occurrences than systems that maintained higher disinfectant residuals. Free-chlorinated systems with AOC levels greater than 100 micrograms/liter had 82% more coliform-positive samples and 19 times higher coliform levels than free-chlorinated systems with average AOC levels less than 99 micrograms/liter. Systems that maintained a phosphate-based corrosion inhibitor and limited the amount of unlined cast iron pipe had fewer coliform bacteria. Several operational characteristics of the treatment process or the distribution system were also associated with increased rates of coliform occurrence. The study concludes that the occurrence of coliform bacteria within a distribution system is dependent upon a complex interaction of chemical, physical, operational, and engineering parameters. No one factor could account for all of the coliform occurrences, and one must consider all of the parameters described above in devising a solution to the regrowth problem.
By drawing from the examples of two dissimilar irrigation development projects it is concluded that for the success of a healthy land development project: (i) by deliberate design a suitable management organization must be set up which has the willing support of all the interested parties, which is given substance by statute and loan agreement, and which has the active support of government; (ii) the staffing should be headed by an enthusiastic person of high rank to provide historical continuity with an adequate secretariat to give effective technical and administrative support; (iii) a deterioration in health may actually threaten the continued existence of a development programme, and health services should be considered part of the development process and integrated with it at all stages from initial planning to several years after commissioning; (iv) health programmes should be responsive to the changing health needs of the settled populations which should be monitored to allow appropriate intervention and which must involve community participation; (v) although the operation of nationally accepted levels of health care facilities should be the responsibility of the national health authority, interventions attributable to the development should be part of the development cost; (vi) interventions should be based on pre-project epidemiology surveys and forecasts of its changes taking account of the disease experience of the settlement populations; (vii) to limit intervention to disease specific problems begs the basic issues. It should be possible to provide better cost-effective health facilities for populations of development projects than for their rural counterparts because they are better defined and more settled; (viii) such interventions by way of changes in fundamental design criteria for the primary engineering works are unlikely to be cost effective; (ix) adequate health facilities must be in place and capable of operation before settlement commences.
The potential contribution by engineers to the control of schistosomiasis in irrigation schemes is examined with reference to work in Zimbabwe. In larger schemes, snail control using molluscicides has proved effective. In smaller schemes, where this is impracticable, careful design and operation may reduce transmission. Appropriate measures are currently being assessed in a pilot project.
A review of the research on the kinetics of nitrification and denitrification is presented including an explanation of reaction engineering models. The results of laboratory scale experiments with high rate nitrification processes are discussed using kinetic results for oxygen limitation as well as for substrate limitation and inhibition. It can be demonstrated that reaction engineering models are helpful for a better understanding of the processes and for the design of reactors. Pilot scale investigations from the last 15 years show remarkable advances in the increase in nitrification efficiency and in the stabilization of the process. The time is ripe for nitrogen removal from industrial effluents in full scale processes!
PURPOSE: We postulate that computer keyboards and faucet handles are significant reservoirs of nosocomial pathogens in the intensive care unit (ICU) setting. METHODS: Sterile swab samples were obtained from 10 keyboards and 8 pairs of faucet handles in the medical ICU at Tripler Army Medical Center during a period of 2 months. Methicillin-resistant Staphylococcus aureus (MRSA) obtained from the environmental and patient specimens were sent for DNA identification by using pulsed-field gel electrophoresis. RESULTS: A total of 144 samples were obtained (80 keyboards and 64 faucet handles), yielding 33 isolates. The colonization rate for keyboards was 24% for all rooms and 26% in occupied rooms. Rates for faucet handles in all rooms and occupied rooms were 11% and 15%, respectively. The environmental isolates annd their prevalence were: MRS, 49%; Enterococcus, 18%; Enterobacter, 12%; and all other gram-negative rods, 21%. Fourteen individual patient isolates were recorded: MRSA, 43%; Enterobacter, 21%; other gram-negative rods, 36%; and Enterococcus, 0%. By using pulsed-field gel electrophoresis, an indistinguishable strain of MRSA was identified in two patients, the keyboards and faucet handles in their respective rooms, and on other keyboards throughout the ICU, including the doctors' station. CONCLUSIONS: The colonization rate for keyboards and faucet handles, novel and unrecognized fomites, is greater than that of other well-studied ICU surfaces in rooms with patients positive for MRSA. Our findings suggest an associated pattern of environmental contamination and patient infection, not limited to the patient's room. Pulsed-field gel electrophoresis results have documented an indistinguishable strain of MRSA present as an environmental contaminant on these two fomites and in two patients with clinical infections patients during the same period. We believe these findings add evidence to support the hypothesis that these particular surfaces may serve as reservoirs of nosocomial pathogens and vectors for cross-transmission in the ICU setting. New infection control policies and engineering plans were initiated on the basis of our results.
Accurate simulation of the temperature distribution in a cooling lake or reservoir is often required for feasibility studies of engineering options that increase the cooling capacity of the waterbody. A three-dimensional hydrodynamic and temperature model has been developed and applied to several cooling lakes in the south-eastern United States. In this paper, the details of the modeling system are presented, along with the application to the Flint Creek Lake.
This paper characterizes the present situation in public baths in the district of Leipzig from the aspects of civil engineering (building construction and water hygiene). Out of 59 existing baths, 8 are closed mainly for building construction reasons. 29 baths had considerable faults. Only 27 public baths have a work circulation plant. The poor building-technical situation has an important influence on the quality of the water, a fact illustrated by the high rates of contaminated and hence rejected water samples.
This paper considers the question of which is better: the batch or the continuous activated sludge processes? It is an important question because dissension still exists in the wastewater industry as to the relative merits of each of the processes. A review of perceived differences in the processes from the point of view of two related disciplines, process engineering and biotechnology, is presented together with the results of previous comparative studies. These reviews highlight possible areas where more understanding is required. This is provided in the paper by application of the flexibility index to two case studies. The flexibility index is a useful process design tool that measures the ability of the process to cope with long term changes in operation.
The results of larval surveys were used to assess the relative numbers of mosquitoes breeding in different types of habitat and in different parts of the town of Pondicherry, India. The results illustrate an effective method to set priorities for mosquito control by identifying the most significant breeding sites in a town, and show that they are not necessarily the most obvious, the most extensive or those intuitively most likely.
The intention of this work is to offer, within the shortest time, an appropriate sorption separation process for almost any odour problem. The development is based on the preparation and characterisation of new adsorbents, the strategy for the selection of the best adsorbent, the process engineering and the choice of a suitable regeneration procedure. In this context a new method for the characterisation of the adsorbents - the adsorption profile analysis - was developed. The classification of the adsorbents was carried out by means of a cluster analysis, which simplifies the selection of the most suitable adsorbent for a particular problem. The physical and chemical behaviour of silica-adsorbents could be tailored by silanisation of the surfaces. Methods for the determination of process engineering parameters were developed, established and used. Adsorption kinetics and isotherms were determined with a magnetic adsorption balance. In a laboratory-scale fixed bed adsorber, breakthrough curves of different support materials were investigated and compared. For the investigations of different regeneration procedures, four innovative methods were employed: microwave desorption, ultrasonic desorption, ultrasonic-water desorption and extraction with water. Of the four desorption methods examined, microwave desorption and ultrasonic-water desorption demonstrated the best results.
OBJECTIVES: This report chronicles an outbreak of a multiply resistant strain of Pseudomonas aeruginosa and the measures required to contain this outbreak. METHODS: Laboratory-based ward-liaison surveillance allowed the detection of a multiply resistant strain of P. aeruginosa infecting patients in our hematology/oncology unit. Sampling of the immediate environment was carried out. Pulsed field gel electrophoresis was used to compare the patients' organisms with those found in the environment. Extensive dismantling of the drainage system, repeated cleaning and disinfection, and a review of the departmental antibiotic policy were some of the infection control measures instigated. RESULTS: During a period of 11 months, three patients in the hematology department and two patients in the oncology department were infected with multiply resistant P. aeruginosa. There were two cases of pneumonia, one of which was fatal, and two cases of neutropenic septicaemia. Pulsed field gel electrophoresis performed on the isolates showed that the isolates from geographically separate areas could be divided into two strains that were closely related but distinct. Two genotypically identical strains were also isolated from the plumbing systems in the areas of each ward where patients had been treated. CONCLUSIONS: The potential for serious nosocomial infections with P. aeruginosa is well recognized. Eradication of the organism from the environment may require the co-ordinated efforts of clinicians, nurses, pharmacy and hospital engineers, working in collaboration with the hospital infection control team. To date, the same strains have not been isolated despite repeated surveillance over the past 18 months and therefore these measures have, in our opinion, successfully removed the potential for nosocomial infection with this resistant organism in our hospital.
INTRODUCTION: Infectious acute respiratory disease (ARD) is a significant cause of worldwide morbidity, disproportionately affecting individuals living in crowded conditions, such as found at military training centers, school dormitories, and correctional facilities. Vaccines have been used to protect against ARD; however, these are not always available or effective. METHODS: The medical literature (1963-2004) on preventive nonvaccine ARD interventions (NOVARDIs) for infectious diseases, which addressed personal measures, administrative controls, and engineering controls, was studied during 2000 to 2004. Population-based studies in community settings (non-health care) were reviewed in detail to evaluate the effectiveness of NOVARDIs. Budgetary and logistic factors as well as acceptance were considered in formulating recommendations for implementation of NOVARDIs in military training centers. RESULTS: Thirty-eight population-based studies contained in 35 publications were examined. Three studies contained information on multiple NOVARDIs. Nine studies supported the use of personal measures relating to hand hygiene. Ten studies supported administrative controls such as cohorting military training units to reduce contact between units (4 studies), providing adequate personal space to reduce crowding (5), and cloth barriers between beds (1); and 14 studies supported the use of engineering controls such as increased indoor air dilution and ventilation (2), dust suppression (4), and air sterilization (8). CONCLUSIONS: Promoting hand hygiene and reducing crowding through the provision of adequate living space and cohorting of training units may offer benefits in respiratory disease control. These interventions, along with UV lights and air dilution/ventilation, deserve further evaluation in controlled studies to assess their efficacy. NOVARDIs could benefit military and other populations living in close contact.
An anonymous postal survey was undertaken to assess the frequency of hygiene service engineers finding sharp objects (including needles) in the washrooms in which they worked. Data on the type of sharps found and their exact location were collected along with information on the type and number of accidents which had occurred. As a result of the survey it was clear that, although the number of recorded accidents was small, a significant number of accidents were not being reported and that finding sharps was a common occurrence for these workers. Recommendations to management on working practises and procedures and on the need for immunization are outlined.
Traditionally, engineering and environment-based interventions have contributed to the prevention of malaria in Asia. However, with the introduction of DDT and other potent insecticides, chemical control became the dominating strategy. The renewed interest in environmental-management-based approaches for the control of malaria vectors follows the rapid development of resistance by mosquitoes to the widely used insecticides, the increasing cost of developing new chemicals, logistical constraints involved in the implementation of residual-spraying programs and the environmental concerns linked to the use of persistent organic pollutants. To guide future research and operational agendas focusing on environmental-control interventions, it is necessary to learn from the successes and failures from the time before the introduction of insecticides. The objective of this paper is to describe the experiences gained in Asia with early vector control interventions focusing on cases from the former Indian Punjab, Malaysia and Sri Lanka. The paper deals primarily with the agricultural engineering and land and water management vector control interventions implemented in the period 1900-1950. The selected cases are discussed in the wider context of environment-based approaches for the control of malaria vectors, including current relevance. Clearly, some of the interventions piloted and implemented early in the last century still have relevance today but generally in a very site-specific manner and in combination with other preventive and curative activities. Some of the approaches followed earlier on to support implementation would not be acceptable or feasible today, from a social or environmental point of view.
Environmental agencies at both federal and state levels have enormous powers to control economic activities, yet these agencies must use these powers knowing very little about the actual effects of pollutants on human health or the environment. The author describes how this situation came about by reviewing (1) the history of the 19th-century sanitarians and how their traditions (especially of taking preventive action in the absence of definitive data, in order to ensure a margin of safety) later influenced the policies of the U.S. Public Health Service and, more recently, those of the Environmental Protection Agency (EPA); (2) the tradition of recovering damages from someone who harms your property or person; (3) the tradition of engineers to eliminate pollutants without concern for their effects; and (4) the value system of conservationists and ecologists. He then outlines four difficulties that these sometimes-conflicting traditions and values create for the EPA and other similar bodies. After reviewing the progress that has been made despite these difficulties, the author states the global nature of the environmental challenge that is upon us and how the public health tradition of prudent action will compel us to gather more data about global problems, which in turn will lead to more fine-tuned and appropriate actions. Finally, he states how important it is for health professionals to use their technical and scientific knowledge--especially their "habits of mind"--to help develop more intelligent and prudent environmental policies, and describes the crucial role of "citizen-health professionals" in the environmental arena of the future.
To prevent fatal outbreaks of Legionnaires' disease, particularly in hospitals and other health-care premises, building services engineers are recommended to store and operate hot water systems at a temperature of 60 degrees C. However, water at this temperature can cause serious scalding. It is therefore advised that mixing valves be installed in the hot water supply pipework to provide hot water at safe temperatures for washing and bathing. Electricity Association Technology Ltd (EATL) investigated the performance of three makes of automatic mixing valve. Tests showed that with constant supply conditions there was little difference in performance between the three valves when blending hot and cold water. However, the ability of the valves to respond to the loss of the cold water supply was quite valve was able, consistently, to shut the hot water off in the event of cold water failure. These results suggest that where it is necessary to safeguard people or patients against any risk of scalding, e.g. young children and handicapped patients, a quality thermostatic valve should be installed rather than a cheaper tempering valve.