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Table 7 Median norovirus infection risks to farmers from the involuntary ingestion of 10 - 100 mg of wastewater-saturated soil per day for 337 and 132 days per year estimated by 10, 000 Monte Carlo (MC) simulations

From: A faecal exposure assessment of farm workers in Accra, Ghana: a cross sectional study

Soil quality (E. coli/g soil) dReported exposure frequency (337 days exposure) Observed exposure frequency (132 days exposure)
  aMedian norovirus risk pppy 95-percentile norovirus risk pppy aMedian norovirus risk pppy 95-percentile norovirus risk pppy
104.1b 0.42 0.44 0.19 0.21
103 – 104 0.21 0.23 9.3 × 10-2 1.0 × 10-1
102 – 103 2.3 × 10-2 2.5 × 10-2 9.7 × 10-3 1.1 × 10-2
102.3c 8.5 × 10-3 9.1 × 10-3 3.4 × 10-3 3.7 × 10-3
101 – 102 2.4 × 10-3 2.6 × 10-3 9.7 × 10-4 1.1 × 10-3
  1. aKaravarsamis-Hamilton MC simulations. Assumptions: 0.1-1 norovirus per 105 E. coli, no pathogen die-off, disease/infection ratio 1:1, b Maximum soil contamination, c Average soil concentration. dReported exposure frequency reflects only the days farmers report in the field but does not necessarily reflect the actual time farmers spent in the field, or were engaged in risky activities that expose them to faecal pathogens (observed exposure frequency)