**Author details**

strategies and risk mitigation. As such they are applicable for the planning and implementation of health aspects, especially related to pathogens, of use schemes for organic fertilizers, whether defined as biosolids, faecal sludge, manure, urine or different mixtures of these and with plant materials. The guidelines are building on microbial risk assessment (MRA) with identification and characterization of hazards, exposure assessment and risk characterization and management that can be applied with different levels of sophistication. This can be part of a scenario or model approach or built into a management approach. With modifications but with its different components it formed the base for "Human Health Risk Assessments of Pathogens in Land-applied Biosolids" [154] in the USA, with a model and scenario-based approach. It further forms a base for the simplified risk management approaches within the

For organic fertilizers in agriculture, the major differences in the hazard identification and characterization are locally specific, partly driven by the sources of the organic fertilizers used and partly reflecting the regional and socio-economic situations. In this context, the risk may partly be regarded higher in transient and developing global economies. It further relates to the treatment and application barriers, where regulations and enforcement against most often

The WHO guidelines are further framed around a risk-reduction strategy accounting for a multiple risk barrier approach, which embrace both technical and handling barriers. This is applied to ensure a reduced exposure risk, which in relation to the application of biosolid, faecal sludge or manure etc. should reduce the risks in relation to both the crop and soil, to agricultural workers, communities or due to secondary run-off and impact. The technical reduction barriers here naturally play a fundamental role where different treatment methods have different efficiency. In the USA, a pathogen equivalency committee [159] should be able to assess new methods to ensure a high level of safety. Safety is also ensured in the way that the application is made in the agricultural fields, the crop selection and the impact of environmental factors (e.g. sunlight, temperature etc) on pathogen die-off. Again, large differences occur locally, seasonally and between different economic regions and social strata.

Even if the different risks and the level of risk can be identified, the epidemiological evidences are still poor for different types of organic fertilizers and especially if we should value this transmission route in relation to others. This further relates to different global regions and socio-economic conditions. The study outcomes from specified investigations in the USA, in EU or in Australia, for example, cannot be directly transferred to the conditions and situations

Low-cost treatment and handling approaches applicable for developing regions need further

The evidence base related to microbial die-off under different field conditions need to be substantially broadened and performed studies so far systematized in relation to effect.

The relationship between animal waste, water and environmental quality and human health have been addressed from a zoonotic livestock perspective, including management practices,

attention, where seasonal variations also need to be further accounted for.

will be more stringent in developed regions and economies [156–158].

WHO sanitation safety plans (SSPs) [155].

360 Organic Fertilizers - From Basic Concepts to Applied Outcomes

on other continents and vice versa.

Anthony A. Adegoke1,2\*, Oluyemi O. Awolusi1 and Thor A. Stenström1

\*Address all correspondence to: anthonya1@dut.ac.za; aayodegoke@gmail.com

1 Institute for Water and Wastewater Technology, Durban University of Technology, Durban, South Africa

2 Department of Microbiology, University of Uyo, Uyo, Akwa Ibom State, Nigeria
