BIOLOGICAL AGENTS
Jolanta Skowroń, Department of Chemical and Aerosol Hazards, Central Institute for Labour Protection – National Rearch Institute, Warsaw, Poland.
1. Introduction
Biological agents are organisms or toxins that have illness-producing effects on people, livestock, and crops. They are found in many ctors of employment. They are rarely visible and so workers are not always able to appreciate the risk they po. Biological agents include bacteria, virus, fungi (yeasts and moulds), parasites, other micro-organisms and their associated toxins. They have ability to adverly affect human health in a variety of ways, ranging from relatively mild, allergic reactions to rious conditions, even death. The organisms are ubiquitous in the natural environment; they are found in water, soil, plants, and animals. Becau many microbes reproduce rapidly and require minimal resources for survival, they are a potential danger in a wide variety of occupational ttings.
常平隐贤山庄Whenever people are in contact with natural or organic materials such soil, clay, plant materials (hay, straw, cotton, etc.), substances of animal origin (wool, hair, etc.), food, organic dust (e.g., flour, paper dust, from animals), waste, wastewater, blood and other body fluids, they may be expod to biological 为什么会有口臭
agents. Micro-organisms can enter the human body via damaged skin or mucous membranes. They can be inhaled or swallowed, leading to infections of the upper respiratory tract or the digestive system.
2. Definitions
There are many definitions of biological agents. In European legislation (Directive
2000/54/EC) biological agents are “micro-organisms (microbiological entity, cellular or non-cellular, capable of replication or transferring genetic material), including tho which have been genetically modified, cell cultures (the in vitro growth of cells derived from multicellular organisms) and human endoparasites, which may be able to provoke any infections, allergy or
toxicity”. In this definition there are not any animals and plants toxins, egzoparasites, allergens or toxins produced by microorganisms (endotoxin, mycotoxin, glucans) (Dutkiewicz, Górny, 2002).
According to ACGIH®(2004) “b iologically derived airborne contaminants include bioaerosols (airborne particles compod of or derived from living organisms) and volatile organic compounds that organisms relea. Bioaerosols include micro-organisms (i.e., culturable, nonculturable, and de
ad microorganisms) and fragments, toxins, and particulate waste products from all varieties of living things”. ACGIH® has developed and parately published guidance on the asssment, control, remediation, and prevention of biologically derived contamination in indoor environments. Indoor biological contamination is defined as the prence of (a) biologically derived aerosols, gas, and vapors of a kind and concentration likely to cau dia or predispo people to dia; (b) inappropriate concentrations of outdoor bioaerosols, especially in buildings designed to prevent their entry; or (c) indoor microbial growth and remnants of biological growth that may become aerosolized and to which people may be expod. The term biological agents refer to a substance of biological origin that is capable of producing an adver effect, e.g., an infection or hypernsitivity, irritant, inflammatory, or other respon.
3. Classification of biological agents
Biological agents can cau three types of dias: (a) infections caud by parasites, virus or bacteria; (b) allergies initiated by exposure to mould, organic dust like flour dust and animal dander, enzymes and mites; and (c) poisoning or toxic effects.
Biological agents usually are classifies into four risk categories according to their potential to cau d
ias and the possibilities of prevention and treatment: group 1 – biological agents that are unlikely to cau human dia; group 2 – biological agents that can cau human dia and might be a hazard to workers but there is usually effective prophylaxis or
treatment available; group 3 – biological agents that can cau vere human dia and prent a rious hazard to workers but there is usually effective prophylaxis or treatment available; group 4 – biological agents that can cau vere human dia and is a rious hazard to workers but there is no effective prophylaxis or treatment available.
孕妇可以吃荸荠吗4. Measurement of airborne micro-organisms
Measurements could aim to locate sources emitting micro-organisms, to measure a worker’s daily or work shift exposure, to identify peaks in exposure, to test the efficiency of control measures, or to control actions taken to diminish the exposure. The following measurement options can be ud to measure micro-organisms and endotoxin: (-) microbial cells by direct counting (the total number); (-) microbial cells and cell aggregates by culturing on agar media (the culturable number); (-) cellular components of micro-organisms, from viable, non-viable or disintegrated micro-organisms, e.g., constituents of cell structure which may also have inflammatory properties, such as endotoxin and gl
ucans; (-) primary metabolites (e.g., ATP) which may rve as markers of micro-organisms or of their vital activity; (-) condary metabolites (e.g. mycotoxins) which may be found in the micro-organisms and other particles in the aerosol. Sampling of aerosols of microbiological origin should be made in accordance with the principles of sampling to asss worker’s exposure to other substances hazardous to health. Static or personal exposure to bioaerosols can be intermittent and of short duration, and it can be related to specific work activities. The sampler ud shall have known and documented sampling efficiency, e.g., capable of sampling total micro-organisms, viable micro-organisms or microbial components. The methods ud for analysing the sample should be lected according to the kind of micro-organisms or microbial components (cultivation methods, microscopic methods, endotoxin – LAL method) (EN 13098).
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Non-viable micro-organisms are not living organisms; as such, they are not capable of reproduction. The bioaerosol is collected on a “gread” surface or a membrane filter. The
micro-organisms are then enumerated and identified using microscopy, classical microbiology, molecular biological, or immunochemical techniques. When sampling for culturable bacteria and fungi, the bioaerosol is generally collected by impaction onto the surface of a broad spectrum solid medium (agar), filtration through a membrane filter, or impingement into an isotonic liquid medium (w
ater-bad). Organisms collected by impaction onto an agar surface may be incubated for a short time, replica-plated (transferred) onto lective or differential media, and incubated at different temperatures for identification and enumeration of micro-organisms. Impingement collection fluids are plated directly on agar, rially diluted and plated, or the entire volume of fluid is filtered through a membrane filter. The membrane filter is then placed on an agar surface and all colonies may be replica-plated. Culturable micro-organisms may be identified or classified by using microscopy, classical microbiology, or molecular biology techniques such as restriction fragment length polymorphic (RFLP) analysis. Classical microbiology techniques include obrvation of growth characteristics; cellular or spore morphology; simple and differential staining; and biochemical, physiological, and nutritional testing for culturable bacteria. Analytical techniques which may be applied to both non-viable and viable micro-organisms, but which do not distinguish among them, include polymera chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA). Such methods may be ud to identify specific micro-organisms and to locate areas of contamination (Jenn, Sch afer, 1994; Skowroń, Gołofit-Szymczak, 2004).破坏的反义词是什么
When microbial numbers have been derived from counting colonies grown on agar plates, the results shall be expresd as colony forming units per cubic metre (CFU/m3). When microbial numb
ers have been derived from microscoping counting, the results shall be expresd as the total number of micro-organisms per cubic metre of air sampled. Endotoxin shall be expresd as endotoxin unit per cubic metre (EU/m3) air sampled and related to the reference standard ud.
There are currently no occupational exposure limits for biological contaminants. The esntial difference between biological agents and other hazardous substances is their ability to reproduce. A small amount of a micro-organism may grow considerably in a very short time under favourable conditions.
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Bioaerosols may contain different micro-organisms and/or different components from the. Micro-organisms may be classified in different taxonomic groups like Gram-positive and Gram-negative bacteria, actinomycetes, fungi, protozoa, algae and virus. The may be further classified to genus or species level. Immunologic reactions, e.g., allergic and/or toxic reactions can result from exposure to micro-organisms irrespective of their viability.
智慧农贸Exposure to biological agents very often leads to adver health effects in susceptible individuals. Elaboration of values for biologically derived airborne contaminants ems to be necessary to prevent harmful exposure in occupational and non-occupational environments, to ensure reliability of measurement methods and proper interpretation of the results.
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ACGIH® (2004) actively solicits information, comments, and data in form of peer-reviewed literature on health effects associated with bioaerosol exposures in occupational and related environments that may help the Bioaerosols Committee evaluate the potential for proposing exposure guidelines for lected biologically derived airborne contaminants: Gram negative bacterial endotoxin, (1-3) beta, D-glucan.
The Scandinavian CFU-oriented projects for Occupational Exposure Limit (OEL) suggest 5 ÷ 10 x 103 CFU/m3 for total micro-organisms, 1 x 103 CFU/m3 for Gram-negative bacteria and 1 ÷ 2 x 102 ng/m3 for endotoxin (Malmros, Sigsgaard, Bach, 1992). The project prepared in Poland suggests 1 x 105 CFU/m3 for total micro-organisms, 5 x 104 CFU/m3 for fungi, 2 x 104 CFU/m3 for Gram-negative bacteria and thermophilic actinomycetes, with a reduction of the values by half if the respirable fraction equals to or exceeds 50% of the total count and 2 x 102 ng/m3 for endotoxin. This project is bad on the fact that at a continuous exposure to
