Microbial Risks from Wastewater Irrigation of Salad Crops: A Screening-Level Risk Assessment

• Published in: Water environment research 2001-11, Vol.73 (6), p.667-672
• Main Authors: Petterson, S. R., Ashbolt, N. J., Sharma, A.
• Format: Article
• Language: English
• Subjects: Agriculture; Air. Soil. Water. Waste. Feeding; Applied sciences; Biological and medical sciences; Conservation of Natural Resources; Consumers; Crops; Density distributions; Density estimation; Effluents; Enterovirus; Environment. Living conditions; Exact sciences and technology; Food industries; Food toxicology; Fundamental and applied biological sciences. Psychology; Humans; Infections; Investigations; Irrigation; Lettuce; Medical sciences; MICROBIAL RISK ASSESSMENT; Models, Theoretical; Monte Carlo simulation; Non agrochemicals pollutants; Pathogens; Phytopathology. Animal pests. Plant and forest protection; Pollution; Pollution effects and side effects of agrochemicals on crop plants and forest trees. Other anthropogenic factors; Pollution effects. Side effects of agrochemicals; Probability distribution; Public Health; Public health. Hygiene; Public health. Hygiene-occupational medicine; QUANTITATIVE; Research Papers; Risk analysis; Risk Assessment; SALAD CROPS; Salads; Vegetables; Viral infections; VIRUS DECAY; Viruses; Waste Disposal, Fluid; Wastewater; Wastewater irrigation; WASTEWATER REUSE; Wastewaters reuse. Miscellaneous; Water Microbiology; Water Supply - standards; Water treatment and pollution
• ISSN: 1061-4303; 1554-7531
• DOI: 10.2175/106143001x143402

The potential health risk from viruses, associated with the consumption of lettuce crops spray irrigated with secondary-treated municipal effluent, has been evaluated in the first level investigation of a tiered microbial risk assessment. The study assessed the impact of two factors on the estimated risk of infection: a suitable probability density function for the occurrence of human enteroviruses in irrigation water and appropriate die-off rates for viruses on lettuce crops. A Monte Carlo simulation using a log-normal and a nonparametric, kernel estimated probability density function indicated that slight changes in the upper tail of the probability density function had a relatively low effect on the estimated infection rates. Predicted infection rates were much more sensitive to the decay rate of viruses than occasional high virus numbers. The median and 99th percentile risks of infection from the overall model were 0.10 and 0.51/10 000 lettuce consumers, respectively, indicating possible human health concern, and the justification of a more detailed microbial risk assessment.