Tanner Benjamin D, Brooks John P, Gerba Charles P, Haas Charles N, Josephson Karen L, Pepper Ian L
Antimicrobial Test Labs., 3000 Joe DiMaggio Blv., Ste. 32, Round Rock, TX 78665, USA.
J Environ Qual. 2008 Oct 23;37(6):2311-21. doi: 10.2134/jeq2007.0193. Print 2008 Nov-Dec.
Some speculate that bioaerosols from land application of biosolids pose occupational risks, but few studies have assessed aerosolization of microorganisms from biosolids or estimated occupational risks of infection. This study investigated levels of microorganisms in air immediately downwind of land application operations and estimated occupational risks from aerosolized microorganisms. In all, more than 300 air samples were collected downwind of biosolids application sites at various locations within the United States. Coliform bacteria, coliphages, and heterotrophic plate count (HPC) bacteria were enumerated from air and biosolids at each site. Concentrations of coliforms relative to Salmonella and concentrations of coliphage relative to enteroviruses in biosolids were used, in conjunction with levels of coliforms and coliphages measured in air during this study, to estimate exposure to Salmonella and enteroviruses in air. The HPC bacteria were ubiquitous in air near land application sites whether or not biosolids were being applied, and concentrations were positively correlated to windspeed. Coliform bacteria were detected only when biosolids were being applied to land or loaded into land applicators. Coliphages were detected in few air samples, and only when biosolids were being loaded into land applicators. In general, environmental parameters had little impact on concentrations of microorganisms in air immediately downwind of land application. The method of land application was most correlated to aerosolization. From this large body of data, the occupational risk of infection from bioaerosols was estimated to be 0.78 to 2.1%/yr. Extraordinary exposure scenarios carried an estimated annual risk of infection of up to 34%, with viruses posing the greatest threat. Risks from aerosolized microorganisms at biosolids land application sites appear to be lower than those at wastewater treatment plants, based on previously reported literature.
一些人推测，将生物固体用于土地会产生生物气溶胶，从而带来职业风险，但很少有研究评估生物固体中微生物的气溶胶化情况或估计感染的职业风险。本研究调查了土地施用作业下风向空气中的微生物水平，并估计了气溶胶化微生物带来的职业风险。在美国各地的生物固体施用地点下风向共采集了300多个空气样本。对每个地点的空气和生物固体中的大肠菌群、大肠杆菌噬菌体和异养平板计数（HPC）细菌进行了计数。结合本研究期间在空气中测得的大肠菌群和大肠杆菌噬菌体水平，利用生物固体中相对于沙门氏菌的大肠菌群浓度以及相对于肠道病毒的大肠杆菌噬菌体浓度，来估计空气中沙门氏菌和肠道病毒的暴露情况。无论是否施用生物固体，HPC细菌在土地施用地点附近的空气中普遍存在，其浓度与风速呈正相关。仅在将生物固体施用于土地或装入土地施用器时才检测到大肠菌群。仅在少数空气样本中检测到大肠杆菌噬菌体，且仅在将生物固体装入土地施用器时检测到。一般来说，环境参数对土地施用下风向空气中微生物的浓度影响很小。土地施用方法与气溶胶化的相关性最大。根据这些大量数据，估计生物气溶胶感染的职业风险为每年0.78%至2.1%。特殊暴露情况下估计每年的感染风险高达34%，其中病毒构成的威胁最大。根据先前报道的文献，生物固体土地施用地点气溶胶化微生物带来的风险似乎低于污水处理厂。
