Nag Rajat, Russell Lauren, Nolan Stephen, Auer Agathe, Markey Bryan K, Whyte Paul, O'Flaherty Vincent, Bolton Declan, Fenton Owen, Richards Karl G, Cummins Enda
University College Dublin, School of Biosystems and Food Engineering, Belfield, Dublin 4, Ireland.
Teagasc, Ashtown Food Research Centre, Ashtown, Dublin 15, Ireland; University College Dublin, School of Veterinary Medicine, Belfield, Dublin 4, Ireland.
Sci Total Environ. 2022 Feb 1;806(Pt 3):151227. doi: 10.1016/j.scitotenv.2021.151227. Epub 2021 Oct 27.
Farmyard manure and slurry (FYM&S) and anaerobic digestate are potentially valuable soil conditioners providing important nutrients for plant development and growth. However, these organic fertilisers may pose a microbial health risk to humans. A quantitative microbial risk assessment (QMRA) model was developed to investigate the potential human exposure to pathogens following the application of FYM&S and digestate to agricultural land. The farm-to-fork probabilistic model investigated the fate of microbial indicators (total coliforms and enterococci) and foodborne pathogens in the soil with potential contamination of ready-to-eat salads (RTEs) at the point of human consumption. The processes examined included pathogen inactivation during mesophilic anaerobic digestion (M-AD), post-AD pasteurisation, storage, dilution while spreading, decay in soil, post-harvest washing processes, and finally, the potential growth of the pathogen during refrigeration/storage at the retail level in the Irish context. The QMRA highlighted a very low annual probability of risk (P) due to Clostridium perfringens, norovirus, and Salmonella Newport across all scenarios. Mycobacterium avium may result in a very high mean P for the application of raw FYM&S, while Cryptosporidium parvum and pathogenic E. coli showed high P, and Listeria monocytogenes displayed moderate P for raw FYM&S application. The use of AD reduces this risk; however, pasteurisation reduces the P to an even greater extent posing a very low risk. An overall sensitivity analysis revealed that mesophilic-AD's inactivation effect is the most sensitive parameter of the QMRA, followed by storage and the decay on the field (all negatively correlated to risk estimate). The information generated from this model can help to inform guidelines for policymakers on the maximum permissible indicator or pathogen contamination levels in the digestate. The QMRA can also provide the AD industry with a safety assessment of pathogenic organisms resulting from the digestion of FYM&S.
农家肥和粪肥（FYM&S）以及厌氧消化残余物是潜在的有价值的土壤改良剂，能为植物的发育和生长提供重要养分。然而，这些有机肥料可能会对人类健康构成微生物风险。为此开发了一个定量微生物风险评估（QMRA）模型，以研究在农田施用FYM&S和消化残余物后人类接触病原体的潜在风险。这个从农场到餐桌的概率模型研究了微生物指标（总大肠菌群和肠球菌）以及食源性病原体在土壤中的归宿，以及在人类消费点即食沙拉（RTE）可能受到的污染情况。所考察的过程包括嗜温厌氧消化（M-AD）过程中病原体的失活、厌氧消化后的巴氏杀菌、储存、撒施时的稀释、在土壤中的衰减、收获后的清洗过程，最后是在爱尔兰环境下零售层面冷藏/储存期间病原体的潜在生长情况。QMRA强调，在所有情况下，产气荚膜梭菌、诺如病毒和纽波特沙门氏菌导致的年度风险概率（P）非常低。鸟分枝杆菌可能会导致在施用未处理的FYM&S时出现非常高的平均P值，而微小隐孢子虫和致病性大肠杆菌显示出高P值，单核细胞增生李斯特菌在施用未处理的FYM&S时显示出中等P值。使用厌氧消化可降低这种风险；然而，巴氏杀菌能更大程度地降低P值，使其风险非常低。总体敏感性分析表明，嗜温厌氧消化的失活效果是QMRA中最敏感的参数，其次是储存和田间衰减（均与风险估计呈负相关）。该模型生成的信息有助于为政策制定者提供有关消化残余物中最大允许指标或病原体污染水平的指导方针。QMRA还可为厌氧消化行业提供对FYM&S消化产生的致病生物的安全评估。
