Sensitivity analysis of agroenvironmental indicators of the hygienic pressure from livestock production on population health

Two Agroenvironmental hygienic pressure indicators (AHPIs) were developed to evaluate the effects of livestock production on water contamination and the risk for human health by expressing a complex public health risk via simple quantifiable figures. The first of the two AHPIs is addressing the aspect of surface water contamination while the second one is dealing with groundwater contamination. Each of the two AHPIs is built from a multiplicative model based on 25 parameters related to the transmission of bacteria through excretion by animals, survival in manure, and by run-off or infiltration water produced by rainfall. A global sensitivity approach was used to identify the most significant parameters in regard to the AHPIs output results. This analysis found that bacterial survival on the soil after manure spreading or grazing of animals (Ks), the proportion of bacteria able to reach surface water with run-off from manure on the soil (Brun-off), bacteria concentration in faeces Bconc, within-herd proportion of animals shedding the pathogenic bacteria targeted (Bprev) and the area used for pasture (A) – on bovine farms – are the most influential parameters with respect to the estimation of the AHPIs. With the exception of the latter element, these factors are all directly related to bacterial characteristics and parameters for which obtaining high quality data is most challenging. The identification of these most influential parameters will guide further research to enhance both the precision application of the AHPIs, and their use in managing public health risks.