Institute for Pathogen Control Engineering, School of Civil Engineering, University of Leeds, Leeds LS2 9JT, UK.
J Water Health. 2010 Mar;8(1):39-43. doi: 10.2166/wh.2009.140.
A quantitative microbial risk analysis-Monte Carlo method was used to estimate norovirus infection risks to consumers of wastewater-irrigated lettuce. Using the same assumptions as used in the 2006 WHO guidelines for the safe use of wastewater in agriculture, a norovirus reduction of 6 log units was required to achieve a norovirus infection risk of approximately 10(-3) per person per year (pppy), but for a lower consumption of lettuce (40-48 g per week vs. 350 g per week) the required reduction was 5 log units. If the tolerable additional disease burden is increased from a DALY (disability-adjusted life year) loss of 10(-6) pppy (the value used in the WHO guidelines) to 10(-5) pppy, the required pathogen reduction is one order of magnitude lower. Reductions of 4-6 log units can be achieved by very simple partial treatment (principally settling to achieve a 1-log unit reduction) supplemented by very reliable post-treatment health-protection control measures such as pathogen die-off (1-2 log units), produce washing in cold water (1 log unit) and produce disinfection (3 log units).
采用定量微生物风险分析-蒙特卡罗方法来估计经污水灌溉的生菜对消费者的诺如病毒感染风险。使用与 2006 年世界卫生组织（WHO）农业废水安全使用指南中相同的假设，需要将诺如病毒减少 6 个对数单位，才能使诺如病毒感染风险达到约 10(-3)每（person per year，pppy），但对于较低的生菜食用量（每周 40-48 克，而不是每周 350 克），所需减少量为 5 个对数单位。如果可耐受的额外疾病负担从 10(-6) pppy（WHO 指南中使用的值）增加到 10(-5) pppy，则需要降低一个数量级的病原体。通过非常简单的部分处理（主要通过沉淀实现 1 个对数单位的减少），并辅以非常可靠的事后健康保护控制措施，如病原体死亡（1-2 个对数单位）、冷水清洗（1 个对数单位）和消毒（3 个对数单位），可实现 4-6 个对数单位的减少。
