Use of Reclaimed Water and Sludge in Food Crop Production (1996) / Chapter Skim
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5 Public Health Concerns About Infectious Disease Agents
5 Public Health Concerns About Infectious Disease Agents
Pages 89-99
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From page 89... ...
INFECTIOUS DISEASE TRANSMISSION Three conditions are necessary to produce infectious disease in a population: (~) the disease agent must be present, (2)
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From page 90... ...
The final link in the infectious disease transmission chain is the exposure of the susceptible human depopulation to infectious agents. The primary route of exposure to wastewaterassociated pathogens is by ingestion, although other routes, such as respiratory and ocular, can be involved.
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From page 91... ...
Such reliability must be a critical element in the design and operation of wastewater treatment plants or other facilities producing these materials. In California, treatment processes specified by the Water Reclamation Criteria (California Water Code, 1994)
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From page 92... ...
Site restrictions would be required to limit public access and to allow adequate time for pathogen reduction prior to crop planting, harvesting, or domestic animal grazing. INFECTIOUS DISEASE RISK Where wastewater or sludge treatment is the primary mechanism to protect the public from infectious disease, acceptable microbiological quality standards must be oeve~oceo case of treated effluents used for crop irrigation, these values have developed over time and are based upon the use of standard water quality bacterial indicator microorganisms (e.g., coliform group or fecal conform bacteria)
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From page 93... ...
A different approach to infectious disease risk assessment modeling starts from a population perspective and carries the analysis beyond the simple individual risk of infection or disease by estimating the probability distribution of the number of infected or diseased people in the exposed population (Cooper et al., 1986; Olivieri et al., 1986, 1989~. This type of dynamic model allows for the evaluation of the sensitivity of the risk distribution to varying the dose and to varying the dose-response assumptions.
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From page 94... ...
Their presence in the environment, particularly the fecal coliforms, is an indication of the presence of animal and human fecal matter, and thus the possible presence of many associated pathogens. Intestinal bacterial pathogens will react to environmental phenomena in much the same manner as coliforms, so the rates of removal of coliforms during water reclamation or sludge processing should reflect a similar reduction in pathogenic bacteria.
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From page 95... ...
There have been no reported outbreaks of infectious disease associated with a population's exposure-either directly or through food consumption pathways-to adequately treated and properly distributed reclaimed water or sludge applied to agricultural land. Reports of the occurrence of infectious disease transmission linked to the irrigation of food crons with wastewater are associated with untreated sewage or treated wastewater of ~ rip · ~ ~ ~ ~ ~ - ~ · · ~ · ~ · 1 · ~ ~ ~ ~ ~ questionable quality.
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From page 96... ...
The limited number of epidemiological studies that have been conducted in the United States on treatment plant workers exposed to municipal wastewater or sludge or populations exposed to reclaimed water or treated sludge land application projects indicate that exposure to these materials was not a significant risk factor. However, the value of prospective epidemiological studies on reclaimed water or sludge use is limited because of a number of factors, including a low illness rate if any documented as resulting from these reuse practices, insufficient sensitivity of current epidemiological techniques to detect low-level disease transmission, population mobility, and difficulty in assessing actual levels of exposure.
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From page 97... ...
1987. Monterey wastewater reclamation study for agriculture final report, April 1987.
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From page 98... ...
1983. Operation, Maintenance and Performance Evaluation of the Potomac Estuary Experimental Water Treatment Plant.
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From page 99... ...
1990. Monterey Wastewater reclamation study for agriculture.
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