Aims: This study was undertaken to determine the effectiveness of biological indicators currently being employed during formaldehyde decontamination. Data suggest that detectable amounts of formaldehyde are absorbed into the paper strips contained in currently used biological indicators. Absorbed formaldehyde has the potential to inhibit the growth of indicator spores, thus leading to false negative results. Indicators composed of either stainless steel carriers or paper strips were investigated to determine whether stainless steel carriers can be used as an alternative to paper strip indicators. Methods and Results: Biological indicators were exposed to formaldehyde gas and were tested for the presence of formaldehyde and any possible inhibition of spore growth. Absorbed formaldehyde was detected in the paper strip carriers while no formaldehyde was detected from any of the stainless steel carriers. Exposed paper strips were found to inhibit growth of up to 1 × 106 spores while the stainless steel carriers did not inhibit the growth of spores. Conclusions: During decontamination, biological indicators composed of paper spore strips absorb formaldehyde and inhibit growth of any surviving spores. Stainless steel carriers do not absorb formaldehyde and are an ideal alternative substrate for biological indicators. Significance and Impact of the Study: The popular paper strip biological indicator can lead to false negative results during decontamination and is unsuitable for validating formaldehyde decontamination.
The objective of this study was to evaluate both condensing (wet) and non-condensing (dry)
This article gives an historical perspective on the development of irrigation. lt places this history into four periods, each of which represents a particular combination of stakeholders: government, private corporations and water users, all interested in the maintenance or expansion of the system.The first period, from the mid-1890s to 1914, involved the federal government and private corporations. The Canadian Pacific Railway, the Alberta lrrigation Company (later renamed the Canadian North West lrrigation Company) and the Southern Alberta Land Company were the corporate partners of the federal government on the Bow and St. Mary Rivers. The decision of the CPR to reduce its role in irrigation development in 1914 resulted in the passage of the lrrigation District Act in 1915 and the inauguration of the second era of development. From 1915 to 1935 the farmers located adjacent to existing districts or in areas proposed for development by the federal government took the initiative to create irrigation districts and expand the irrigated acreage. The role of government during this period was to provide technical assistance. The provincial government provided guarantees for district bonds to encourage continued private investment in the industry. The third period began in 1935 with the creation of the Prairie Farm Rehabilitation Administration that resulted, for the first time, in direct government expenditures on irrigation infrastructure. The fourth period began in the 1960s when the water users and the provincial government became the principal stakeholders through the passage of the new irrigation act, and new programs such as the lrrigation Capital Works Program came into effect. The Act created the Bow River and the St. Mary River lrrigation Districts. The 1960s marked the total reorganization of the irrigation industry in Alberta. The changes ranged from new administrative procedures to the application of new technology for the delivery of water to the farm gate and its distribution on the land. The industry thus became progressively more efficient in its use of water and land. The trend towards greater efficiency will continue into the new millennium with the Year 2000 Steering Committee, a joint industry/government initiative to determine future water allocations on the South Saskatchewan River. R6sum6Le pr6sent article donne une perspective historique de l'6volution de l'irrigation. ll situe l'histoire en quatre p6riodes, dont chacune repr6sente une combinaison particuliere d'intervenants : gouvernement, soci6t6s priv6es et consommateurs d'eau, tous int6ress6s au maintien ou d l'expansion du systdme. La premiere 1. Executive Director, Alberta lrrigation Projects Association and Co-chair of theYear 2000 Steering Committee
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