InTechOpen uses cookies to offer you the best online experience. By continuing to use our site, you agree to our Privacy Policy.

Agricultural and Biological Sciences » "Organic Fertilizers - From Basic Concepts to Applied Outcomes", book edited by Marcelo L. Larramendy and Sonia Soloneski, ISBN 978-953-51-2450-4, Print ISBN 978-953-51-2449-8, Published: June 30, 2016 under CC BY 3.0 license. © The Author(s).

Chapter 16

Organic Fertilizers: Public Health Intricacies

By Anthony A. Adegoke, Oluyemi O. Awolusi and Thor A. Stenström
DOI: 10.5772/64195

Article top


The cycling of potential pathogens in faecal materials for making organic fertilizer.
Figure 1. The cycling of potential pathogens in faecal materials for making organic fertilizer.
Prevalence and concentration of zoonotic pathogens observed in British livestock manure (modified based on Ref. [84]).
Figure 2. Prevalence and concentration of zoonotic pathogens observed in British livestock manure (modified based on Ref. [84]).
Pathogens’ deposition (A) and internalization (B) in crop on an organically fertilized farm.
Figure 3. Pathogens’ deposition (A) and internalization (B) in crop on an organically fertilized farm.

Organic Fertilizers: Public Health Intricacies

Anthony A. Adegoke1, 2, Oluyemi O. Awolusi1 and Thor A. Stenström1
Show details


Organic fertilizers are an essential source for plant nutrients and a soil conditioner in agriculture. Due to its sources and the composition of the organic inputs as well as the type, functionality and failures of the applied treatment process, the organic fertilizer may contain various amounts of infectious agents and toxic chemicals, especially the antibiotics that can be introduced to the subsequent food chain. A range of human and animal pathogens of bacterial, viral and parasitic origin have been the cause of food-borne epidemics due to unintended contamination from organic fertilizers. The use of antibiotics by humans and in animal feeds will also end up in the organic fertilizers. These antibiotics and other chemicals, depending on the sources of the organics, will enhance the likelihood of occurrence of resistant and multi-resistant strains of microorganisms in society and have been reported to cause ecotoxicological environmental effects and disruption of the ecological balance. Exposure of microorganisms to sublethal concentration of antibiotics in the organic products induces antibiotic resistance. WHO guidelines for the reuse of excreta and other organic matters identify the risk for the exposed groups to the reuse of the excreta and are applicable in the use of organic fertilizers in agriculture.

Keywords: organic fertilizers, food-borne illnesses, pathogens, antibiotics, ecotoxicity, WHO

1. Introduction

The potential health intricacies linked with organic fertilizers relate to their origin, their treatment and human exposure within a system perspective from origin to use, including products like crop type. Since organic fertilizers mainly are “faecal material/manure and urine from different animals and/or humans, with the addition of plant materials (organic solid wastes), or in special situations waste materials [1] from food or plant processing industries”, the origin of the different fractions and their amounts partly defines the risk. Usually the risk is outbalanced by a wide range of benefits that the use of organic fertilizer exerts in agriculture as nutritional fertilizers and for soil conditioning. It has been further implied as more environmental friendly than the inorganic fertilizers [1] and its effect more tender on biotic components of the ecosystem without much shift in the ecological balance [2]. This is partly reflected by organisms like earthworms which may be negatively affected by inorganic fertilizers but promoted by the use of organic fertilizers and also incorporated as decomposers in aerobic composting processes [3, 4].

As this chapter deals with the public health aspects and risks involved, we define the organic materials utilized by its sources and thus relate to the following:

  • Human faecal materials (also sludge from domestic treatment plants and from on-site sanitation, e.g. pit latrine emptying).

  • Human urine (if separated).

  • Animal manure (some risk differences depending on the species of animals/birds).

  • Animal urine (often collected/spread separately, but impacted by the animal faeces).

  • Other types of organic solid wastes (plant materials, domestic, industrial from organic food/fodder processing industries).

Additionally, the risk may relate to some storage-specific factors like

  • Regrowth of specific bacterial pathogens or opportunistic ones (occurs when the material that, for example should be/are composted, are not well stabilized or broken down. During these circumstances, for example Escherichia coli, Salmonella sp., Listeria sp. and spore formers will regrow in the material if present).

  • When the collected/stored/kept organic fractions or mixture thereof (see above) function as a breeding site for flies and mosquitoes that serve as vectors of parasitic diseases.

  • Development of spore-forming thermophilic fungi and Actinomycetes in composting processes, where the spores can cause diseases in both immune-competent and immune-compromised individuals upon inhalation. An example of such an organism is Aspergillus fumigatus.

Based on source, the risk will vary to a great extent, depending on the health of the animals/humans that primarily defines the microbial concentration and partly occurrence of antibiotics and chemical components in the organic wastes (from domestic or animal sludge fractions) that may be conveyed to the agricultural sites and crops fertilized. Additional components may apply if organic industrial wastes are utilized. An indirect organic fertilization may occur through irrigation using wastewater effluent, where the nutrient load serves as an advantage. This is widely applied in developing countries [5]. However, this may result in additional inputs of antibiotics, toxic organic and inorganic compounds and pathogens. All these concepts are further deliberated in this chapter. The possibilities of recycling food-borne pathogens via agricultural crops to the final end consumers of the crops will additionally be discussed. Food-borne pathogens are especially important for animal faecal-based fertilizers used on fruits and vegetables farms meant to supply salads in restaurants. Other dynamics are residual antibiotics which are sometimes locked in the components of the organic fertilizers with attending public health implications to be further enumerated in this chapter.

2. Treatment and risk reduction

The concept of organic fertilization is ever worthwhile, with combined considerations of the public health intricacies that cannot be overemphasized [6]. Several alternative treatment methods can be employed to stabilize the organic fertilizers before use and at the same time reduce the concentrations of potential pathogens, thereby the risks. The efficiency of these will vary based on time, load and different external factors.

PathogensTreatment option or processLog
1 Escherichia
Settling ponds2.26[7, 8]
Unplanted drying/dewatering beds
(for pretreatment)
Composting (window, thermophilic)44[10]
pH elevation >921[11]
Anaerobic (mesophilic)20.67[12]
2 Helminths eggs (WHO, 2006)Settling ponds34[13]
Planted dewatering drying
beds (constructed wetlands)
drying/dewatering beds (for pretreatment)
Composting (window, thermophilic)1.5–2.03[16]
pH elevation >936[17]
Anaerobic (mesophilic)0.50.5–1.0[18, 19]
3 VirusesSettling ponds (enteroviruses)1.53.3[20]
Planted dewatering
drying beds (constructed wetlands)
99.9% with
Unplanted drying/dewatering beds
(for pretreatment)
pH elevation >9 (Porcine circovirus type 2)21[23]
Anaerobic (mesophilic) (Norovirus) 1.1–1.40.8[24]

Table 1.

Efficiency of some pathogens’ reduction techniques for low-cost sludge treatment strategies.

Low-cost options for pathogen reduction and nutrient recovery from faecal sludge are of special importance to low-income countries. They include settling ponds, planted dewatering drying beds (constructed wetlands), unplanted drying/dewatering beds (for pretreatment), composting (window, thermophilic), pH elevation > 9, anaerobic (mesophilic) and simple storage. They have varying pathogen reduction efficiencies on bacteria, parasitic protozoa and viruses. Table 1 summarizes the efficiencies of these pathogen reduction techniques with E. coli as an example for the bacterial group, helminth’s eggs for parasites and some viral examples as stated. The figures serve as examples. Variations can be large based on prevailing local conditions.

Other methods most commonly used in developed countries to treat the sludge include incineration and pasteurization. The former one ensures a total destruction of all pathogenic organisms while the efficiency of the later one depends on time and applied temperature (normally 70°C for at least 1 h). Irradiation with β- or γ-rays is an approved method in the USA, and it reduces the pathogenic content to a high extend but is not widely used.

2.1. Organic waste stabilization

Organic wastes can be used as soil amendments or organic fertilizers after an effective stabilization and disinfection. Effective stabilization and disinfection of sewage sludge prior to land application are important not only to protect human health. Currently, some of the most commonly used waste stabilization methods are composting (solid state), aerobic digestion (liquid state), anaerobic digestion, lime stabilization [25, 26] and sludge drying. The aerobic and anaerobic methods of waste stabilization are among the most prominent [27]. Furthermore, there have been growing concerns about the survival of pathogenic microorganisms in sewage treatment processes, resulting in the release of antibiotic resistant microbial species to the environment [28, 29]. These are further considered below.

2.2. Composting

Composting is defined as the biological conversion of organic wastes, under controlled conditions, into a hygienic, humus-rich, relatively biostable product that improves land and fertilizes plants [30]. It has the combined effect of pathogen reduction while at the same time stabilizes and converts the organic wastes into product that can be easily handled [31, 32]. The type and concentration of pathogens present in sewage sludge is largely determined by a number of factors including population’s state of health, presence of hospitals, abattoirs and factories processing meat [33]. Composting is one of the essential decontamination processes to reduce the load of pathogens in animal wastes. The composting efficiency to ensure inactivation of pathogens depends on allotted time and temperature. Inefficient composting leaves loads of pathogenic bacteria which may be passed on to the end consumers.

Metals such as zinc, copper, cadmium, lead, arsenic, chromium, mercury, vanadium and nickel are usually of great concern [34] when sludge from industrial effluent are used as feed stock for composting both from a health perspective and in the degradation of the productivity of land. Industrial sludge may contain elevated heavy metal concentration which makes them unsafe for garden use. Despite the fact that copper and zinc are important micronutrients, the possibility of bioaccumulation to phytotoxic or deleterious level for human consumption still makes them a concern.

Zoonoses are among the public health concerns associated with improperly sanitized organic fertilizer. Zoonotic diseases and emerging zoonoses that could be associated with organic fertilizer includes salmonellosis, entrohaemorrhagic E. coli (EHEC), anthrax and Newcastle diseases just to mention a few [35]. Thermoactinomyces vulgaris is another organism of importance. It produces heat-resistant endospores that can survive high temperature during composting. This organism is the causative agent of “farmer’s lung” which is an allergic disease of the respiratory system of agricultural workers. The pathogens present in soil amendments are directly related to the organic waste source. The reduction or removal of pathogens in a compost will depend on the composting temperature and the process used [36]. This implies that improperly carried out composting leaves the organic matter poorly sanitized with the compost becoming a source of recontamination with pathogenic or parasitic organisms [37]. E. coli, Salmonella sp. and a few others possess advantage for regrowth in compost [38, 39]. Also, due to rich nutrient composition, contaminating E. coli grows very rapidly in pre-sanitized organic fertilizers [4043] that is not properly composted or stabilized. Salmonella spp. equally grow in composted sewage sludge if the carbon/nitrogen ratio is >15 and the manure content 0.2 index.

OrganismsLethal temperature and necessary time
Salmonella spp.15–20 at 60°C; 1 h at 55°C
Escherichia coli15–20 at 60°C; 1 h at 55°C
Entamoeba histolytica68°C; time not given
Taenia saginata5 min at 71°C
Necator americanus50 min at 50°C
Shigella spp.1 h at 55°C
Mycobacterium tuberculosis20 min at 70°C
Corynebacterium diphtheria45 min at 55°C; 4 min at70°C
Ascaris lumbricoides eggs60 min at 50°C; 7 min 55°C
Viruses25 min at 70°C

Table 2.

Temperature-time relationship required for killing specific pathogens [35, 36, 49].

There is therefore need to ensure that the mature compost does not contain plant and human pathogens. In composting, the thermophilic temperature is the effective determinant of destroying the pathogen and the efficiency further related to the exposure time. The required time at a given temperature for efficient pathogen inactivation, according to USEPA [44] can be estimated using a time-temperature formula:

D = 131700000/100.1400t

where D is time in days and t is temperature (°C).

OrganismsUSNew ZealandUKNew South WalesEU
Class AClass BClass AClass A
Escherichia coliN/A<100 MPN/g1000 CFU/gN/A0/50 g
Faecal coliforms<1000 MPN/g<2,000,000 MPN/gN/A<1000 MPN/g
Salmonella spp.<3 MPN/4 g
total solids
<1/25 gNil0/50 g<103 MPN/ g
Enteric viruses<1 PFU/4 g<1 PFU/4 g<1 PFU/4 g
Helminth ova<1/4 g1/4 g<1/4 g

Table 3.

Standards for maximum concentrations of pathogens in biosolids and composts used as organic fertilizers [49, 52, 53].

[i] - MPCN, most probable cytophatic number; MPN, most probable number; PFU, plaque-forming unit.

In a properly ventilated composting pile, the temperature usually reaches between 55 and 68°C. This temperature level can last for a few days to months depending on the size of the system and the composition of the ingredients [4547] and is the determinant for the sanitization effectiveness. The average time required for killing specific pathogen is exemplified below (Table 2). Salmonella spp. and E. coli have been known as pathogen indicator bacteria in organic fertilizer, supplemented with soil-transmitted helminths [48] and enteric viruses when a broader spectrum of organisms needs to be assessed. Several national and international standards/guidelines have been established to ensure public health safety when using these organic fertilizers (Table 3). Due to high heat resistance of some bacteriophages, they have been suggested as an indicator of properly sterilized compost [35].

2.3. Aerobic digestion

This occurs in engineered ecosystems where biomass consisting of a mixed microbial community and other solids are constantly maintained in a suspension in an aerobic basin supported by mixing [50]. This is usually used in stabilizing sewage and wastewater, producing high-quality treated effluent through the metabolic reactions of the microbial community [51]. The sanitation efficiency of this system depends largely on time, temperature and loading rates [28, 50]. This process still yields poorly stabilized organic matter with a fluid product, having little or no volume reduction and pathogen reduction efficiency is usually low [28].

Moreover, using them as organic fertilizers in an inefficiently sanitized stage can further result in direct microbial contamination of surface water or via runoff from lands amended with such organic waste [28] in addition to their direct exposure effects and effects through crops. Most aerobic sewage sludge treatment plants operate at mesophilic temperatures (30–35°C). Within this temperature range, the stabilization processes are inefficient in the removal of viruses, bacteria and Parasite’s eggs [28].

2.4. Anaerobic digestion

Anaerobic digestion involves the breakdown of complex organic material into simple monomerics or fraction and production of biogas (bioenergy) in closed system through the activity of anaerobic microorganisms [54]. Anaerobic digestion can be carried out either at mesophilic (30–38°C) or at thermophilic (50–55°C) temperatures. Compared to composting, there is lesser heat generation during anaerobic decomposition, which reduces the sanitizing effect of the process on organic waste [37]. Digesting organics at high temperatures reduces the time required for bacterial inactivation, which eventually results in faster bacterial kill during thermophilic digestion compared to mesophilic [55]. Bacterial spores including Bacillus cereus and Clostridium perfringens are normally resistant to temperature inactivation at both mesophilic and thermophilic ranges [5557]. Chauret et al. [58] also noted the resistance of Cryptosporidium sp. oocysts and Giardia sp. cysts to anaerobic sludge digestion. This finding is of importance since Cryptosporidium sp. oocysts can persist in soil amended with sludge for at least 30 days [59].

Type of treatmentVirusesBacteriaParasite egg
Pasteurization (heat, 30 min at 70°C)GoodGoodGood
Irradiation (ionizing radiation, 300 rad)PoorGoodGood
Lime treatment
Slacked lime (high pH)GoodGoodGood
Quick lime (High pH; 80°C)GoodGoodGood
Anaerobic digestion
Mesophilic (30–35°C)PoorPoorPoor
Thermophilic (50–55°C)GoodGoodGood
Aerobic digestion
Mesophilic (up to 20°C)PoorPoorPoor
Thermophilic (50–55°C)GoodGoodGood
Compost (50–60°C)GoodGood

Table 4.

Pathogen-reduction performance of the different treatments of sludge [28, 63, 64].

2.5. Lime (alkaline) stabilization

Lime stabilization is a preferred alternative compared to anaerobic and aerobic stabilization processes due to its cost efficiency and enhanced sanitizing effect [25, 60]. It effectively reduces the concentration of pathogens in sludge (Table 4), heavy metal availability and enhances its agricultural uses [25]. Free calcium ions resulting from the lime solution form complexes with odorous sulphur species and organic mercaptans; moreover, the high pH precipitates metals from the sludge thereby reducing their solubility and availability. Alkaline stabilization involves the addition of lime slurry in the form of Ca(OH)2 or CaO to the liquid sludge in order to raise its pH to about 12 or higher [60]. Apart from the high pH, the addition of quicklime to the liquid sludge can result in thermophilic temperature (up till 70°C) which inactivates the viruses, bacteria and other microorganisms [61,62]. In a study by Farzadkia and Bazrafshan [25], addition of lime slurry to sewage sludge resulted in a reduction of faecal coliforms with more than 99.99% in stabilized sludge. Arthurson [26] noted that there is a need for further investigation on the potential of alkaline stabilization methods since this process is an effective sewage sludge sanitization method but some contradictory results exist.

3. Potential human pathogens in organic fertilizers from faecal materials and implications

Pathogen-free organic fertilizer can be developed and microbiological safety assured for the reuse of sludge and manure. Various factors affecting the survival of pathogens in composting include time, temperature, pH, aerobic/anaerobic, biological activity, UV or irradiation, moisture, combination and chemical effects (e.g. ammonia). These factors are considered with regard to some pathogens discussed in Sections 3.1 and 3.2.

PathogensT (°C)DT (s)References
Protozoan parasitesSoil-transmitted helminths (STHs)20–30°CSeveral[69]
BacteriaCampylobacter sp.55.4–61.289–10.3[70]
Escherichia coli55–701281.6–1.86[71]
Escherichia coli O157:H7551500[72]
Listeria sp.55–703370.14–7.56[73]
Salmonella sp.55–703370.14–7.56[74]
VirusHepatitis A8073.2–733.2[76]
FungiBotrytis cinerea40–481800–36[77]
Monilinia fructigena39–451302–150[77]
Monascus ruber702238–4379[78]

Table 5.

Heat inactivation: values of decimal reduction time (D) at test temperature (T) (Adapted from Romdhana [68]).

The inherent pathogens in an organic fertilizer depend on the animal source of the faecal materials used. When considering heat-dependent anoxic degradation of product for manure from dairy cattle, studies have shown the rate of kill of E. coli O157:H7 at 55°C to be 3 logs per 30 min and 4 logs per 100 min [70]. Table 5 show the heat-based inactivation of some pathogens with values of decimal reduction time (D) at test temperature (T) Thermal death times for Salmonella to achieve reduction of 9 log has been reported to be 40 min at 55°C. Some pathogens can survive for longer periods of time in compost especially when they are located on the surface part of the compost pile where the heat effects may be inefficient. They also survive better in mesophilic composting (<45°C) than at elevated temperature. Moisture availability in biowaste compost (denoted by water activity, aw) is also an important determinant for the survival time of many pathogens.

3.1. Soil-transmitted helminths

Both human and animal waste and wastewater may contain different soil-transmitted helminths (STHs). These are among the most resistant microorganisms and will develop in soils or poorly treated biosolids from the non-invasive stages that are excreted to an infective one. Thus, when poorly handled, soil and crops get contaminated with eggs or larvae of STHs, which in turn will be transmitted orally through crops or due to accidental ingestion (e.g. Ascaris sp.) or penetrate bare skin (hookworms). Due to their resistance to environmental stress, helminth parasite eggs are widely used as hygiene indicators. STHs are resistant to sublethal composting temperatures and they require longer time at alkaline pH (months at pH 9–10, but much more rapid at pH 11–12) to effect appreciable die-off. A report by Jensen and Vrsle [65] showed that it would take a period of 117 days to achieve 99% die-off of an Ascaris suum eggs when placed on human excreta with pH levels between 9.4 and 11.6. When temperatures of above 50°C are reached, a rapid die-off occurs. Thus, a properly composted night soil with crop residues can destroy the parasitic infective stages efficiently.

When assessing the effectiveness of composting, A. suum eggs from pigs may be utilized as a model for the survival of human parasitic roundworm, A. lumbricoides [66,67].

3.2. Zoonotic organisms in waste dung as components of organic fertilizer

Chicken litters and pig dungs are rich in nutrients and are valuable animal wastes as organic fertilizer. However, chicken litter exemplify one organic fertilizer that may contain important human pathogens like Salmonella sp., Campylobacter jejuni and Listeria monocytogenes. If not properly sanitized these pathogens can easily get deposited on crop/plants, with transmission to consumers with, for example, fruits and vegetables [79,80]. Several human pathogens have been reported in organic fertilizer and may be conveyed to human, while other may function as animal or plant pathogens [81]. L. monocytogenes is a typical example of a pathogen easily conveyed via food crop.


Figure 1.

The cycling of potential pathogens in faecal materials for making organic fertilizer.


Figure 2.

Prevalence and concentration of zoonotic pathogens observed in British livestock manure (modified based on Ref. [84]).

Boulter et al. [82] reported that Salmonella sp. was observed among several other Gram negative bacterial potential pathogens in green compost for organic fertilizer. Even some Gram positive bacteria may occur, for example Bacillus cereus which is associated mainly with food poisoning and as a cause of serious and potentially fatal non-gastrointestinal-tract infections [83]. This resembles contamination of the farmland through poorly formulated organic fertilizers that circulates egested pathogens from human or animal back to them or another is pictorial as a cycle (Figure 1). Pathogens from wastes like E. coli, Salmonella sp., Listeria sp., Cryptosporidium sp. and Campylobacter sp. among others are usually conveyed to the farmland through poorly composted organic fertilizers or through contaminated irrigation water. Figure 2 illustrates the occurrence of a number of different zoonotic pathogens found in manure [84].

Treated wastewater effluents contain nutrients (nitrogen, phosphorus and potassium), inorganic matter (dissolved minerals) and other chemicals which can complement the enrichment of the farmland in enhancing plants’ growth. Enhanced concentrations of different excreted pathogens may also occur in wastewater being used for irrigation. Most of these pathogens are of known aetiologies of various infection (exemplified in Table 6). This is likely more prevalent in developing countries where wastewater for irrigation is not pretreated and disease prevalence may be higher. Intestinal nematodes released with the irrigated water are of special concern. The risk becomes higher in a farmland in which organic fertilizer is already in use, as it enriches the environment for the pathogens to thrive.

PathogensPotential disease (s) /Symptoms
Gram positive
Staphylococcus sp.Osteomyelitis, furuncles, carbuncles,
impetigo, wound infections, food poisoning
Streptococcus sp.Skin infection, otitis media, respiratory
Clostridium perfringensGas gangrene, gastroenteritis (food poisoning)
Clostridium botulinumBotulism
Bacillus anthracisAnthrax
Z-N positive
Mycobacterium spp.Leprosy, tuberculosis
Gram negative
Salmonella spp.Gastroenteritis, typhoid fever
Shigella spp.Bacillary dysentery
Escherichia coli
(enteropathogenic strains)
Pseudomonas aeruginosaOtitis externa, skin and wound infections
(opportunistic pathogen)
Yersinia enterocoliticaGastroenteritis
Campylobacter jejuniCampylobacteriosis: diarrhoea, fever, nausea,
vomiting, abdominal pain, headache
Listeria monocytogenesListeriosis
Vibrio choleraCholera
V. parahaemolyticusAcute gastroenteritis
VirusesCoronavirus HKU1, Klassevirus and
Severe acute respiratory, gastrointestinal
and hepatic illnesses
Enteric viruses including Adenovirus
(AdV), hepatitis A virus (HAV) and
Rotavirus (RV)
Enteric infection
ParasitesSoil-transmitted helminths (Ascaris
, whipworm and hookworm)
Giardia sp.Giardiasis
Cyclospora sp.Cyclosporiasis
Cryptosporidium sp.Cryptosporidiosis

Table 6.

Potential human pathogens identified in municipal wastewater and sewage sludge being used for fertilizing farmland [26].

Table 6 gives the summary of potential human pathogens found in wastewater effluent and sewage sludge as components that are used for organic fertilizers. Some of these pathogens have been reported in zoonotic infection as discussed hereafter.

3.3. Pathogens from organic fertilizers into crops and vegetables

Pathogen can be passed on to crop plants through direct contact, through deposition on the surface or in splash contamination. Human pathogens may also get internalized in plants from fertilizers in the soil, where the probability for internalization may be increased by mechanical damage. The pathogens may migrate within the plants’ tissues. Figure 3 gives a pictorial illustration of the process of internalization of pathogens from organic fertilizers into crops and vegetables. Pathogens in the organic fertilizers are deposited on the surface of the crops and/or vegetables. The pathogens in subsurface parts of the crops are difficult to be removed or disinfected. The potential for enteric pathogens to be absorbed by roots has been considered [85].


Figure 3.

Pathogens’ deposition (A) and internalization (B) in crop on an organically fertilized farm.

Enteric pathogens may further enter plant tissues through both natural apertures (stomata, lateral junctions of roots) and damaged (wounds, cut surfaces) tissue (Figure 3). Researchers [8688] have demonstrated the internalization of E. coli from soil into hypocotyl of spinach, lettuce and cabbage using different bioluminescent labels.

Regrowth contribute to high concentration of pathogens. Either E. coli O157:H7 or Salmonella may Multiply, get internalized into the tissues of raddish [8991] and mung bean [87]. Surface sterilization will then have little effect as the pathogens are already within the tissues. Similar experiment involving Salmonella and alfalfa seeds was demonstrated by Gandhi et al. [92] in which the bacterium penetrated into the hypocotyls.

3.4. Fate of pathogens in consumers of the plants products

Pathogens associated with plant products can be conveyed to consumers through crops mainly eaten raw from contaminated organic fertilizers. Surface washing will reduce surface-associated pathogens [48, 93]. Fruit- and vegetable-related outbreaks have been reported globally, affecting from a few infected person to causing major epidemics [9496]. One recent outbreak was in 2011, affecting several countries in Europe involving ingestion of E. coli O157 from fruits and vegetables [94]. About 46 million food-related cases with 400,000 hospitalization and 3000 deaths were summarized by Scallan et al. [95,96]. The increasing numbers of immunocompromised individuals globally will enhance the effects of pathogens from contaminated fruits and vegetables. The risk to public health exists, and it is imperative for each country to remodel the agriculture extension to address this challenge.

The original source before food contamination differs. Some pathogens like norovirus and Salmonella sp. serotype Typhi are sustained in human reservoirs, but several others are sustained in animal reservoir. Surface contamination and/or internalization of pathogens in fruits and vegetable may not be the major pathway for contamination of food supply. However, the outbreaks via this channel may have high public health significance [97, 98]. An estimated, 131 produce-related food-borne outbreaks were reported in the USA between 1996 and 2010. A large E. coli O157:H7 outbreak of food-related illness involving vegetable occurred in 1996 in Japan in which >11,000 individuals were reported severely ill. Several deaths occurred among young school children [98].

In England, 60 outbreaks of food-related illnesses from fruit- and vegetable-related infections were reported during 7 years, beginning from 1992. Contamination with human pathogens on farms can be attributed not only to faeces from human, and manure from farm and wild animal but also to poor environmental waste handling [99]. A report of an E. coli outbreak confirmed the contributions of water, manure from cattle dung and wild pig faeces, etc. towards contamination on spinach [100]. The same strains of pathogens found in spinach fields have also been found internalized in the spinach. This informed the initiation of safety plan against E. coli O157 infection through pathogens in vegetables [101].

When fruits harbour internalized pathogens, they pose an enhanced risk especially when used for sprouted seeds and unpasteurized fruit juices [102104]. This is more important for internalized fruits as surface contaminant are usually steam washed away in processing companies.

3.5. Exposure pathway and health risks when reusing contaminated organic materials as agricultural fertilizers

Consumption of crops, including fodder crops, serves as the most common transmission pathway to chemical and pathogens from biosolids used as fertilizer. Investigations have also been performed related to contamination of crops used for medicinal products and supplements [105]. The direct exposure of agricultural workers is also significant and relates to different transmission routes, as well as the frequency and duration of exposure. Farmworker exposure has been examined [106, 107], including the impact on family members [108]. Direct exposure relates to the level of manual work and mechanization. The risk further relates to the type of fertilizer, from human and animal urine to untreated or treated wastewater, manure or human excreta. A special situation is when stored organic fractions or mixture thereof function as breeding site for fly/mosquito vectors of parasitic disease or attract vermin’s that can act as carriers of pathogens. This is for example considered in the USEPA guidelines [109].

In addition to microbiological contaminants, organic fertilizers may, especially when sludge constitute parts of the input material, contain metals and other chemicals that may affect the receiving soils as well as be of relevance for occupational exposures. To appropriately assess human risk from chemicals found in biosolids, the form of the chemicals, and their fate, transport and bioavailability needs to be known, for example, arsenic, lead, mercury, antibiotics.

Jerkins et al. [110] reported two studies that were suggestive that compost workers were affected by fungi. One cross-sectional study in Germany reported a significant increase in symptoms from lungs and airways as well as dermal effects and related these to increased exposure to fungi and Actinomycetes. The other was a prospective study in multiple US cities where significant increases in eye and skin irritation occurred and fungal colonization was documented but no serological evidence of other infections was reported. Indirect evidences were presented by Harrison and Oakes [111] that reported 39 incidence of illness among neighbours to biosolids application sites. The evidences were however not appropriately backed up.

The infection risks have been estimated using quantitative microbial risk assessment (QMRA) when urine or human faeces are used for garden fertilization [112]. A study in South Africa reported enhanced infection risks of Salmonella sp. and Ascaris sp. associated with spinach or carrots fertilized with human excreta [113]. An assessment of the health risk associated with daily consumption of vegetables (lettuce, 11.5 g) fertilized with compost was done by Watanabe et al. [114]. If the concentration of pathogenic virus in compost, for example is 10−1–102 PFU/g of lettuce, the risk would still be higher than the WHO tolerable annual infection risks.

4. Residual antibiotics (AB) and antibiotic-resistance genes (ARGs) in organic fertilizers

Veterinary drugs are introduced into the environment through a number of routes like direct applications as in aquaculture, application of manure and/or slurry to agricultural fields and through disposal of wastes during the production processes. An investigation also indicate a link between the proximity of swine farms exposed to these antibiotics through contact with animal feed and development of antibiotic resistance in bacteria among small wild animal accessing into barns and feed storage areas [115]. The presence of drugs and their metabolites in the environment have frequently been reported. For instance, low levels (<1 μg/L) of antibiotic residues have been detected in surface water samples in both Germany and the USA collected from sites considered susceptible to contamination [116]. The residual antibiotics in organic fertilizers using animal manure from large-scale livestock farms (mainly including slurry and dung from pigs, cows and chicken) have been investigated with their presence confirmed [117].

The residual antibiotics found in organic fertilizers may emanate from administration to humans either as prophylaxis or for therapeutic purposes. They are also being used as components of animal feeds to promote growth, to treat or prevent diseases of farm animals and sometimes against diseases in plants [118126]. Hence, tetracycline concentration, for example, in liquid organic fertilizer could be as high as 20 mg kg−1 [127]. So, the use of manures as organic fertilizers on farmland containing antibiotics is fast becoming a serious environmental issue of concern [128]. Up to 200,000 tons of antibiotics are both used per annum by humans and administered to farm animals [129]. About 70% are consumed as growth promoters [131, 131], irrespective of the 1998 EU embargo [132, 133]. Massive utilization of antibiotics in veterinary practices remains in China, Russia, Europe and the USA [134, 135] where the largest producer and user of antibiotic is China. Tens of thousands tons of penicillin and tetracycline derivatives were produced in early 2000s [136]. The prescription in China is/was equally over double the amount in the Americas [137].

Therefore, antibiotics that end up in manure or fertilizers might have come from any of the following:

  1. Feed additives (especially in fish farming)

  2. Human and veterinary drugs

  3. Effluents from pharmaceutical industries [138, 139]

Pharmaceuticals are excreted to the environment through the excreta (either mainly through the urine or through the faeces) from humans or animals in a semi-digested active form or as derivatives and end up in wastewater or biosolid. Some of them may be retained in the final organic fertilizers (biosolids), as well as in wastewater and reach surface water and sediments [127, 140, 141]. All kinds of manures, wastewater sludge and excreta from human are vehicles for carrying residual antibiotics in the environment [142146]. Zhang et al. [146, 147] reported that residual antibiotics were highest in pig manure, followed by chicken manure and cow manure in that order, but this is mainly a reflection of the local situation. The concentration is, as expected, higher from large-scale agriculture farm than from subsistence farm. Rainfall will naturally add to the run-off of these from agricultural land to surface and groundwater. It also enhances the potential for distribution to other biomes with ecotoxic effects. They also get lodged in the soil organisms like earthworms, soil arthropods, fungi and bacteria.

Like internalized pathogens, the potential high uptake of antibiotics by vegetables fertilized with biosolids globally is of enhanced public health concern [148, 149].

Future attention is needed in the issue of bioaccumulation in vegetable with residual antibiotic because

  1. Vegetable rapidly take up harmful substance(s) during short growth cycle. The acute and long-term cytotoxicity effects on the consumers are unclear.

  2. Vegetables, either leafy or root, are often consumed raw. Thermal effect in cooking may affect advantageous sublimation of some harmful compounds, but this is not guaranteed and

  3. They are stored for short-term and consumed fresh, bringing about timely delivery of residual bioaccumulated antibiotics and other pollutants.

Therefore, they bring about any of the following environmental impacts:

  1. Emergence of bacterial resistance through long-time exposure to sublethal concentration of the residual antibiotics, genetic variation resulting from innate adaptative drives of the bacteria and also provide a pseudo-biofilm environment for exchange of antibiotic-resistant genes (ARGs) [150152]. It is an established fact that exposure to low-level or sublethal or sub-minimum inhibitory concentration (sub-MIC) of antibiotic drug has effects on the bacterial physiology and its genetic or phenotypic variability, and the potentials of antibiotics to function as signalling molecules. All these factors contribute to prompt emergence and spread of antibiotic-resistant bacteria among humans and animals.

    Laboratory-based methods have been developed to determine the effect of exposing bacteria to sublethal concentrations (sub-MIC) of antibiotics. This has affirmed the implication of the antibiotics in environment, including those in organic fertilizers, on the emergence of antibiotic resistance. These kinds of research also encompass the in vitro pharmaco dynamic models, concentration and exposure time of susceptible bacteria to selected conventional antibiotics before the emergence of resistance. The concentration variations to be employed for such studies will be informed by the concentration of the extracted antibiotics in the organic fertilizers.

  2. As it is a generally accepted fact that all drugs, including antibiotics have their side effect. It is only advantageous if taken to remove a more serious infection. Continuous exposure of farmers to residual antibiotics in dust [127] from soil fertilized with organic fertilizer exposes them to risk associated with accumulative effect of the gradual exposure.

  3. Ecotoxic effects on other biotic components of the environment.

5. Guidelines for reuse of human and animal waste products as organic fertilizers

The WHO operational monitoring guidelines for the reuse of wastewater, excreta and greywater to fertilize crop strictly advocate certain validation requirements, operation monitoring parameter and technical measures, and verification monitoring are as stated in Table 7 for safe reuse of waste. WHO guidelines [48] exemplify the die-off efficiency with a temperature of 50°C for at least 1 week before compost or ecohumus is considered safe for reuse. If this temperature is not achieved, a longer composting/storage time has been advocated by WHO. One to two years of storage is recommended for systems that generate ecohumus for proper removal of bacterial pathogens and appreciable reduction of viral and parasitic protozoa. WHO [48] identified the risk on the exposed groups to the reuse of the excreta and wastewater, and recommended health protective measures. The guidelines also include standards for chemical in fish and vegetables. According to the guideline, ≤1 helminth’s eggs (arithmetic mean number) per litre or per gram total solid applies for excreta to be used on edible products and organic fertilizers to which agriculture workers would be exposed. The guidelines also contain threshold values for bacterial pathogens (based on ≤ 104–≤ 105 CFU E. coli per 100 mL or g total solid) and for trematode eggs (absent) in aquaculture.

Control measuresValidation requirementsOperation monitoring
parameter and technical
Verification monitoring
Fertilizer handling Reduce direct contact with insufficiently
treated material and environmental
Wearing glovesInformed farmers
Washing of hands andusing excreta
equipment usedspecial equipment available
Fertilized fieldTime needed for pathogen die-off under
different climatic conditions and
withholding time between waste
application and crop harvest to
ensure minimal contamination
Working excreta into
the ground, information
and signs avoiding
Analyse plants'
Fertilized crop-
Survey of product consumers to identify
species always eaten after thorough
Harvesting and transport
Testing of excreta/
greywater to ensure that it
meets WHO microbial
reduction targets
Analysis of marketability of different
species/crops Economic viability
of growing products not for
human consumption. Harvesting,
transport and trade consumption
Withholding time between
fertilization and harvest
Types of crops grown in
excreta use areas
crops cooked before eating 
Proper preparation and
cooking of food products
Domestic and food
Contamination of hands, kitchen utensils,
Hand washing

Table 7.

Validation requirements, operation mornitoring parameter and technical measures, and verification monitoring for reuse in fertilization (adapted from WHO [48]).

6. Conclusions and research gaps

The WHO guidelines Vol 2 (Wastewater Use in Agriculture) and Vol 4 (Excreta and Greywater Use in Agriculture) [48, 153] form an evidence base and referral point for risk management 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 WHO sanitation safety plans (SSPs) [155].

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 will be more stringent in developed regions and economies [156158].

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 on other continents and vice versa.

Low-cost treatment and handling approaches applicable for developing regions need further attention, where seasonal variations also need to be further accounted for.

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, exposure interventions and risk analysis but need much further attention related to organic fertilizers [160].

Crop contamination is documented but the relative impact between pre-harvest contamination by organic fertilizers and irrigation water on the one hand and post-harvest handling and storage contamination on the other needs to be further addressed. The specific situation with the potential impact of internalization and uptake of pathogens as compared to deposition on outer surfaces need much more attention and documentation, before long-term handling and management practices can be issued and related to modes of application.

Also, the specific situation, partly addressed in this chapter with uptake of antibiotics (and other organic contaminants) as well as the impact of use of these in livestock and among humans and the further fate in agricultural fields need to be addressed. Linked to this is also the large problem complex with the occurrence, transmission and impact of antibiotic-resistant bacteria especially, but also including other antimicrobial drugs.

At the current stage, the authors believe and conclude that the benefits with human- and animal-based organic fertilizers in the field far outmaster the potential negative impacts. However, we also firmly believe that a broadened evidence base and application of this in a risk-management perspective and framework will further enhance the positive benefits and counteract negative impact.


1 - Gebremedhin AR and Tesfay G (2015). Evaluating the effects of integrated use of organic and inorganic fertilizers on socioeconomic performance of upland rice (Oryzasativa L.) in Tselemti Wereda of North-Western Tigray, Ethiopia. Journal of Biology, Agriculture and Healthcare, 5(7):39–52.
2 - Altieri MA (2002). Agroecology: the science of natural resource management for poor farmers in marginal environments. Agriculture in Ecosystem and Environment, 93:1–24.
3 - Pramanik P, Ghosh GK, Ghosal PK and Banik P (2007). Changes in organic-C, N, P and K and enzyme activities in vermicompost of biodegradable organic wastes under liming and microbial inoculants. Journal of Bioresource Technology, 98:2485–2494.
4 - Arancon NQ, Edwards CA, Babenko A, Cannon J, Galvis P and Metzger JD (2008). Influences of vermicomposts, produced by earthworms and microorganisms from cattle manure, food waste and paper waste, on the germination, growth and flowering of petunias in the greenhouse; Applied Soil Ecology, 39:91–99.
5 - Qadir M and Scott CA (2010). Non-pathogenic trade-off s of wastewater irrigation. In: Drechsel P, Scott CA, Raschid-SallyL, Redwood M and Bahri A (eds) Wastewater Irrigation and Health: Assessing and Mitigating Risks in Low-Income Countries. International Development Research Centre (IDRC), International Water Management Institute (IWMI), Earthscan, London, pp. 101–126.
6 - Miller C, Heringa S, Kim J and Jiang X (2013). Analyzing indicator microorganisms, antibiotic resistant Escherichia coli, and regrowth potential of foodborne pathogens in various organic fertilizers. Foodborne Pathogens and Disease, 10(6) 520-527. DOI:10.1089/fpd.2012.1403.
7 - Ketelaars HAM (1995). Occurrence of Cryptosporidium oocysts and Giardia cysts in the River Meuse and removal in the Biesbosch reservoirs. Aqua, 44:108–111.
8 - van Breemen LWCA and Waals JMJ (1998). Storage of surface water in the Netherlands: challenges of the future. Water Supply, 16:375–381.
9 - Collins MR (1994). Evaluation of Roughing Filtration Design Variables. Water Works Association Research Foundation and the American Water Works Association, American Denver, CO.
10 - Berendes D, Levy K, Knee J, Handzel T and Hill VR (2015). Ascaris and Escherichia coli inactivation in an ecological sanitation system in Port-au-Prince, Haiti. PLoS ONE, 10(5):e0125336. DOI:10.1371/journal.pone.0125336.
11 - Viancelli A, Kunz A, Fongaro G, Kich JD, Barardi CRM and Suzin L (2015). Pathogen inactivation and the chemical removal of phosphorus from swine wastewater. Water Air Soil Pollution, 226:263. DOI:10.1007/s11270-015-2476-5.
12 - Sweet N, McDonnell E, Cochrane J and Prosser P (2001). The new sludge (use in agriculture) regulations. In: Proceedings of the Joint CIWEM Aqua Enviro Consultancy Services 6th European Biosolids and Organic Residuals Conference, Wakefield, UK, 12–14 November.
13 - Fernandez RG, Ingallinella AM, Sanguinetti GS, Ballan GE, Bortolotti V, Montangero A and Strauss M (2004). Septage treatment in waste stabilization ponds’. In: Proceedings, 9th International IWA Specialist Group Conference on Wetlands Systems for Water Pollution Control and to the 6th International IWA Specialist Group Conference on Waste Stabilization Ponds, Avignon, France, 27 September–1 October,
14 - Koottatep T, Polprasert C, Oanh NTK, Surinkul N, Montangero A and Strauss M (2002). Constructed wetlands for septage treatment – towards effective faecal sludge management. In: Proceedings, 8th International Conference on Wetland Systems for Water Pollution Control (IWA/University of Dar es Salaam), Arusha, Tanzania, 16–19 September. Available at:
15 - Heinss U, Larmie SA and Strauss M (1998). Solid separation and pond systems for the treatment of faecal sludges in the tropics: lesson learnt and recommendations for preliminary design, SANDEC report no 05/98, EAWAG/SANDEC, Dubendorf, Switzerland.
16 - Koné D, Brissaud F and Vasel J-L (2004). State of the art of facultative ponds in West Africa: removal performances and design criteria. In: Proceedings, 6th IWA Specialist Conference, Avignon, France, 27 September–1 October 2004.
17 - Chien BT, Nga NH, Stenström TA and Winblad U (2001). Biological study on retention time of microorganisms in faecal materials in urine-diverting eco-san latrines in Vietnam. In: 1st International Conference on Ecological Sanitation, Nanning, People’s Republic of China, internet dialogue on ecological sanitation, bui.html
18 - Feachem RG, Bradley DJ, Garelick H and Mara DD (1983). Sanitation and Disease: Health Aspects of Excreta and Wastewater Management, John Wiley & Sons, Chichester.
19 - Gantzer C, Maul A, Audic JM and Schwartzbrod L (1998) Detection of infectious enteroviruses, enteroviruses genomes, somatic coliphages, and bacteriodes fragilis phages in treated wastewater. Applied and Environmental Microbiology, 64:4307–4311.
20 - Kors LJ, Bosch AD (1995). Catchment protection of a multi-functional reservoir. Aqua, 44:80–84.
21 - Beddow V (2010) …..downladed on 20 th February, 2016. Coagulation and flocculation in water and wastewater treatment. Available at: WaterandWastewaterTreatment
22 - Kraus S and Griebler C (2011). Pathogenic Microorganisms and Viruses in Groundwater, Acatech Materialien, Munchen, Nr. 6.
23 - Fongaro G, Viancelli A, Magri ME, Elmahdy EM, Biesus LL, Kich JD, Kunz A and Barard CRM (2014). Utility of specific biomarkers to assess safety of swine manure forbiofertilizing purposes. Science of the Total Environment, 479–480(1):277–283. DOI:10.1016/j.scitotenv.2014.02.004.
24 - Pedersen, D. (1981) Density levels of pathogenic organisms in municipal wastewater sludge: a literature review. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/2-81/170 (NTIS PB82102286).
25 - Farzadkia M and Bazrafshan E (2014). Lime stabilization of waste activated Sludge. Health Scope, 3(3):1–5. DOI:10.17795/jhealthscope-16035.
26 - Arthurson V (2008). Proper sanitization of sewage sludge: a critical issue for a sustainable society. Applied and Environmental Microbiology, 74(17):5267–5275.
27 - Goldfarb W, Krogmann U and Hopkins C (1999). Unsafe sewage sludge or beneficial biosolids? Liability, planning, and management issues regarding the land application of sewage treatment residuals. Boston College of Environmental Affairs Law Review, 26:687–768.
28 - Dumontet S, Scopa A, Kerje S and Krovacek K (2001). The importance of pathogenic organisms in sewage and sewage sludge. Journal of Air Waste Management and Association, 51:848–860. DOI:10.1080/10473289.2001.10464313.
29 - Tello A, Austin B and Telfer TC (2012). Selective pressure of antibiotic pollution on bacteria of importance to public health. Environmental Health Perspectives, 120:1100–1106
30 - Mathur SP (1991). Composting processes. In: Martin A.M. (ed.) Bioconversion of Waste Materials to Industrial Products. Elsevier Applied Science, New York, USA, p. 147–183.
31 - Martin DL and Gershuny G (1992). The Rodale Book of Composting. Rodale Press Inc., Emmaus, PA. New, rev. ed. Emmaus, PA: [New York]: Rodale Press; St. Martin’s Press.
32 - Zhu N (2006). Composting of high moisture content swine manure with corncob in a pilot-scal aerated static bin system. Bioresource Technology, 97(15):1870–1875. DOI:10.1016/j.biortech.2005.08.011.
33 - Bruce JR, Paul KSL and Michael M (2005). Emerging chemicals of concern: pharmaceuticals and personal care products (PPCPs) in Asia, particular reference to Southern China. Marine Pollution Bulletin, 50:913–920.
34 - MacDonald JM (2008). The economic organization of U.S. broiler production. Economic Information Bulletin, 38. 26. Available at: (verified 14.03.2016). USDA ERS, Washington, DC.
35 - Jones P and Martin M (2003). A review of the literature on the occurrence and survival of pathogens of animals and humans in green compost. WRAP Standards Report, The Waste and Resources Action Programme, Oxon, UK.
36 - Strauch D (1996). Occurrence of microorganisms pathogenic for man and animals in source separated biowaste and compost – importance, controls, limits, epidemiology. In: de Bertoldi M, Sequi P, Lemmes B and Papi T (eds) The Science of Composting. CEC, Blackie Academic and Professional, London, pp. 224–232.
37 - Hulit DM (2011). A review of existing scientific literature and current good agricultural 18 practices (GAPs) guidelines for composting in vegetable production, Technical paper submitted to Virginia Polytechnic Institute and State University, College of Agriculture and Life Sciences, 104 Hutcheson Hall (0402), Blacksburg, VA 24061, pp. 1–33.
38 - Sidhu J, Gibbs RA, Ho GE and Unkovich I (2001). The role of indigenous microorganisms in suppression of Salmonella regrowth in composted biosolids. Water Research, 35:913–920.
39 - Kim J and Jiang X (2010). The growth potential of Escherichia coli O157:H7, Salmonella spp. and Listeria monocytogenes in dairy manure-based compost in a greenhouse setting under different seasons. Journal of Applied Microbiology, 109:2095–2140.
40 - Soares AC, Straub TM, Pepper IL and Gerba CP (1994). Effect of anaerobic digestion on the occurrence of enteroviruses and Giardia cysts in sewage sludge. Journal of Environmental Science and Health, A29:1887–1897.
41 - Pietronave S, Fracchia L, Rinaldi M and Martinotti MG (2004). Influence of biotic and abiotic factors on human pathogens in a finished compost. Water Research, 38:1963–1970.
42 - Lemunier M, Francou C, Rousseaux S, Houot S, Dantigny P, Piveteau P and Guzzo J (2005). Long-term survival of pathogenic and sanitation indicator bacteria in experimental biowaste composts. Applied and Environmental Microbiology, 71:5779–5786.
43 - You Y, Rankin SC, Aceto HW, Benson CE, Toth JD and Dou Z (2006). Survival of Salmonella enterica serovar Newport in manure and manure-amended soils. Applied and Environmental Microbiology, 72:5777–5783.
44 - Epstein E (2011). Industrial Composting: Environmental Engineering and Facilities Management. CRC Press. Florida. DOI:10.120.1/ b10726.
45 - Ponsa S, Pagans E and Sánchez A (2009). Composting of dewatered wastewater sludge with various ratios of pruning waste used as a bulking agent and monitored by respirometer. Biosystems Engineering, 102(4):433–443.
46 - Tiquia SM, Richard T and Honeyman MS (2002). Carbon, nutrient, and mass loss during composting. Nutrient Cycling in Agroecosystems, 62(1):15–24.
47 - Trautmann N and Olynciw E (2011). Compost Microorganisms. Cornell University, New York. Available at: (Accessed 26 April 2016).
48 - WHO (2006). WHO Guidelines for the Safe Use of Wastewater, Excreta and Greywater (Volume IV: Excreta and greywater use in agriculture). World Health Organization (WHO), Geneva, Switzerland, ISBN: 92 4 154685 9
49 - Sunar NM, Stentiford EI, Stewart DI and Fletcher LA (2009). The Process and Pathogen Behaviour in Composting: A Review. Proceeding UMT-MSD 2009 Post Graduate Seminar 2009. Universiti Malaysia Terengganu, Malaysian Student Department UK – Institute for Transport Studies University of Leeds. pp: 78–87
50 - Seviour RJ (2010). An overview of the microbes in activated sludge. In: Seviour R, Nielsen PH (eds) Microbial Ecology of Activated Sludge. IWA Publishing, London, pp. 1–56
51 - Awolusi OO, Kumari SKS and Bux F (2015). Ecophysiology of nitrifying communities in membrane bioreactors. International Journal of Environmental Science and Technology, 12(2):747–762. DOI:10.1007/s13762-014-0551-x
52 - Horswell J, Ambrose V, Clucas L, Leckie A, Clinton P and Speir TW (2007). Survival of E. coli and Salmonella spp. after application of sewage sludge to a Pinus radiata forest. Journal of Applied Microbiology, 103(4):1321–1331.
53 - Teng J (2012). Microbial risk assessment modeling for exposure to land-applied Class B biosolids. Ph.D. Drexel University, Philadelphia, Pennsylvania.
54 - Enitan AM (2014). Microbial community analysis of a UASB reactor and application of an evolutionary algorithm to enhance wastewater treatment and biogas production. Ph.D., Durban University of Technology, Durban.
55 - Sahlström L (2003). A review of survival of pathogenic bacteria in organic waste used in biogas plants. Bioresource Technology, 87(2):161–166.
56 - Forshell LP (1993). Composting of Cattle and Pig Manure. Zentralbl. Veterinarmed. B, 40:634–640.
57 - Goss MJ, Tubeileh A and Goorahoo D (2013). A review of the use of organic amendments and the risk to human health. Advances in Agronomy, 120:275–379. Elsevier. DOI:10.1016/B978- 0-12-407686-0.00005-1.
58 - Chauret C, Springthorpe S and Sattar S (1999). Fate of Cryptosporidium oocysts, Giardia cysts, and microbial indicators during wastewater treatment and anaerobic sludge digestion. Canadian Journal of Microbiology, 45:257–262.
59 - Whithemore TN and Robertson LJ (1995). The effect of sewage sludge treatment on oocysts of Cryptosporidium parvum. Journal of Applied Bacteriology, 78:34–38.
60 - Czechowski F and Marcinkowski T (2006). Sewage sludge stabilisation with calcium hydroxide: effect on physicochemical properties and molecular composition. Water Research, 40:1895–1905.
61 - Lue-Hing C (1998). Municipal Sewage Sludge Management: A Reference Text on Processing, Utilization and Disposal. Technomic Publishing Company, Lancaster.
62 - Lancaster Vinneras B, Holmqvist A, Bagge E, Albihn A and Jonsson H (2003) The potential for disinfection separated faecal matter by urea and by peracetic acid for hygienic nutrient recycling. Bioresource Technology, 89:155–161.
63 - Dumontet S, Dinel H and Baloda SB (1999). Pathogen reduction in sewage sludge by composting and other biological treatments: a review. Biological Agriculture and Horticulture, 16:409–430.
64 - Havelaar AH, Butler M, Farrah SR, Jofre J, Marques E, Ketratanakul A, Martins MT, Ohgaki S, Sobsey MD and Zaiss U (1991). Bacteriophages as model viruses in water quality control. Water Research, 25:529–545.
65 - Jensen PD and Vrsle L (2003). Greywater treatment in combined biofilter/constructed wetlands in cold climate. In: Warner C et al. (eds.) Ecosan-Closing the Loop. Proceedings of the 2nd International Symposium Ecological Sanitation, Lubek, 7–11 April 2003, GTZ, Germany, pp. 875–881.
66 - Holmqvist A and Stenström TA (2001). Survival of Ascaris suum ova, indicator bacteria and Salmonella typhimurium phage 28B in mesophilic composting of household waste. 1st International Conference on Ecological Sanitation, Nanning, People’s Republic of China. Available at:
67 - Carlander A and Westrell T (1999). A microbiological and sociological evaluation of urine- diverting double-vault latrines in Cam Duc, Vietnam. Minor Field Studies No. 91, ISSN 1402-3237. International Office, Swedish University of Agricultural Sciences, Uppsala, Sweden.
68 - Romdhana MH (2009). Conception, modelization and evaluation of environnemental procedures for preparation of organic solid. Doctoral thesis from University of Toulouse, Available at: romdhana.pdf
69 - NSW EPA (1997). Environmental Guidelines: Use and Disposal of Biosolids Products. Environmental Protection Agency; NSW, Australia: pp. 1–109.
70 - Moore JE and Madden RH (2001). The effect of thermal stress on Campylobacter coli. Journal of Applied Microbiology, 89:892–899.
71 - Murphy RY, Davidson MA and Marcy JA (2006). Process lethality prediction for Escherichia coli O157: H7 in raw franks during cooking and fully cooked franks during post-cook pasteurization. Journal of Food Sciences, 69:112–116.
72 - Zhao T, Zhao T, West JW, Bernard JK, Cross HJ and Doyle MP (2006). Inactivation of enterohemorrhagic E. coli in rumen content- or feces-contaminated drinking water for cattle. Applied and Environmental Microbiology, 72(5):3268–3273.
73 - Murphy RY, Duncan LK, Berrang ME, Marcy JA and Wolfe RE (2002). Thermal inactivation d- and z-values of Salmonella and Listeria innocua in fully cooked an vacuum packaged chicken breast meat during postcook heat treatment. Poultry Sciences, 81:1578–1583.
74 - Mocé-Llivina L, Muniesa M, Pimenta-Vale H, Lucena F and Jofre J (2003). Survival of bacterial indicator and bacteriophages after thermal treatment of sludge and sewage. Applied and Environmental Microbiology, 69:1452–1456.
75 - Deboosere N, Legeay O, Claudrelier Y and Lange M (2004). Modelling effect of physical and chemical parameters on heat inactivation kinetics of hepatitis a virus in a fruit model system. International Journal Food Microbiology, 93:73–85.
76 - Nappier SP, Aitken MP and Sobsey MD (2006). Male-specific coliphages as indicators of thermal inactivation of pathogens in biosolids. Applied and Environmental Microbiology, 72(4):2471–2475.
77 - Marquenie D, Lammertyn J, Geeraerd AH, Soontjens C, Van Impe JF, Nicolai BM and Michiels CW (2002). Inactivation of conidia of Botrytis cinerea and Monilinia fructigena using UV-c and heat treatment. International Journal of Food Microbiology, 74:27–35.
78 - Efstathios ZP, Constantinos ZK and George-John EN (2002). Heat resistance of Monascus Rubber ascospores isolated from thermally processed green olives of the conservolea variety. International Journal of Food Microbiology, 76:11–18.
79 - Wilkinson KG, Tee E, Tomkins RB, Hepworth G and Premier R (2011). Effect of heating and aging of poultry litter on the persistence of enteric bacteria. Poultry Science, 90:10–18.
80 - Chinivasagam HN, Redding M, Runge G and Blackall PJ (2010). Presence and incidence of foodborne pathogens in Australian chicken litter. British Poultry Science, 51:311–318.
81 - Ndubuisi-Nnaji UU, Adegoke AA, Ogbu HI, Ezenobi NO and Okoh AI (2011). Effect of long-term organic fertilizer application on soil microbial dynamics. African Journal of Biotechnology, 10(4):556–559.
82 - Boulter JI, Trevors JT and Boland GJ (2002). Microbial studies of compost: bacterial identification and their potential for turf grass pathogen suppression. World Journal of Microbiology and Biotechnology, 18:661–671.
83 - Bottone EJ (2010). Bacillus cereus, a volatile human pathogen. Clinical Microbiological Review, 23(2):382–398.
84 - Hutchison ML, Walters LD, Avery SM, Synge BA and Moore A (2004). Levels of zoonotic agents in British livestock manures. Letters in Applied Microbiology, 39:207–214.
85 - Hirneisen KA, Sharma M and Kniel KE (2012). Human enteric pathogeninternalization by root uptake into food crops. Foodborne Pathogenic Diseases, 9:396–405.
86 - Charkowski AO, Barak JD, Sarreal CZ and Mandrell RE (2002). Differences in growth of Salmonella enterica and Escherichia coli O157:H7 on alfalfa sprouts. Applied and Environmental Microbiology, 68:3114–3120.
87 - Delaquis P, Bach S and Dinu LD (2007). Behavior of E. coli O157:H7 in leafy vegetables. Journal of Food Protection, 70:1966–1974.
88 - Warriner K, Spaniolas S, Dickinson M, Wright C and Waites WM (2003). Internalization of bioluminescent Escherichia coli and Salmonella montevideo in growing bean sprouts. Journal of Applied Microbiology, 95:719–727.
89 - Erickson MC, Liao J, Ma L, Jiang X and Doyle MP (2009). Inactivation of Salmonella spp. in cow manure composts formulated to different initial C:N ratios. Bioresource Technolology, 101:1014–1020.
90 - Hara-Kudo Y, Konuma H, Iwaki M, Kasuga F, Sugita-Konishi Y, Ito Y and Kumagai S (1997). Potential hazard of radish sprouts as a vehicle of E. coli O157:H7. Journal of Food Protection, 60:1125–1127.
91 - Itoh Y, Sugita-Konishi Y, Kasuga F, Iwaki M, Hara-Kudo Y, Saito N, Noguchi Y, Konuma H and Kumagai S (1998). Enterohemorrhagic E. coli O157:H7 present in radish sprouts. Applied and Environmental Microbiology, 64:1532–1535.
92 - Gandhi M, Golding S, Yaron S and Matthews KR (2001). Use of green fluorescent protein expressing Salmonella Stanley to investigate survival, spatial location, and control on alfalfa sprouts. Journal of Food Protection, 64:1891–1898.
93 - De Roever C (1998). Microbiological safety of evaluations and recommendations on fresh produce. Food Control, 9:321–347.
94 - Okoh AI, Adegoke AA, Adesemoye OO, Babalola OO, Igbinosa INH and Aghdasi F (2012). Escherichia coli, a beneficial bug, but a dynamic threat to public health: call to caution. Journal of Pure and Applied Microbiology, 6(3):1069–1085.
95 - Scallan E, Griffin PM, Angulo FJ, Tauxe RV and Hoekstra RM (2011). Foodborne illnesses acquired in the United States—unspecified agents. Emerging Infectious Diseases, 17(1):16–22.
96 - Scallan E, Hoekstra RM, Angulo FJ, Tauxe RV, Widdowson MA, Roy SL, Jones JL and PM Griffin. (2011). Foodborne illness acquired in the United States – major pathogens. Emerging Infectious Diseases, 17(1):7–15.
97 - Olsen SJ, Miller G, Kennedy M, Higgins C, Walford J, McKee G, Fox K, Bibb W and Mead P (2002). A water-borne outbreak of E. coli O157:H7 infections and haemolytic uremic syndrome: implications for rural water systems. Emerging Infectious Diseases, 8:370–375.
98 - Ministry of Health and Welfare of Japan (1997). National Institute of Infectious Diseases and Infectious Disease Control Division. Verocytotoxin producing Escherichia coli (enterohaemorrhagic E. coli) infection, Japan, 1996–June 1997, Infectious Agents Surveillance Report, 18:153–154.
99 - Lynch MF, Tauxe RV and Hedberg CW (2009). The burden of foodborne outbreaks due to contaminated fresh produce: risk and opportunities. Epidemic Infectious Diseases, 137:307–315.
100 - Wendel AM, Sharapov U, Grant J, Archer JR, Monson T, Koschmann C and Davis JP (2009). Multistate outbreak of Escherichia coli O157:H7 infection associated with consumption of packaged spinach, August–September 2006: the Wisconsin investigation. Clinical Infectious Diseases, 48(8):1079–1086.
101 - FDA (Food and Drug Administration) (2006). Ensuring Food Safety: Tracking and Resolving the E. coli Spinach Outbreak. Food and Drug Administration, Rockville, MD. Available at: (Accessed 8 April 2012).
102 - Griffin PM (1998). Epidemiology of Shiga toxin-producing Escherichia coli infections in humans in the United States. In: Kaper JB and O’Brien AD (eds) Escherichia coli and Other Shiga Toxin-producing E. coli Strains. ASM Press, Washington, DC, p. 15.
103 - Hilborn ED, Mermin JH, Mshar PA, Hadler JL, Voetsch A, Wojtkunski C, Swartz M, Mshar R, et al. (1999). A multistate outbreak of E. coli O157:H7 infections associated with consumption of mesclun lettuce. Archive of Internal Medicine, 159:1758–1764.
104 - Heaton JC and Jones K (2007). Microbial contamination of fruit and vegetables and the behaviour of enteropathogens in the phyllosphere: a review. Journal of Applied Microbiology, 104:613–626.
105 - Farahat E and Linderholm HW (2013). Effects of treated wastewater irrigation on size-structure, biochemical products and mineral content of native medicinal shrubs. Ecological Engineering, 60:235–241.
106 - Forslund A, Ensink JHJ, Battilani A, Kljujev I, Gola S, Raicevic V, et al. (2010). Faecal contamination and hygiene aspect associated with the use of treated wastewater and canal water for irrigation of potatoes (Solanum tuberosum). Agricultural Water Management, 98:440–450.
107 - Zhang J, Yang JC, Wang RQ, Hou H, Du XM, Fan SK, et al. (2013). Effects of pollution sources and soil properties on distribution of polycyclic aromatic hydrocarbons and risk assessment. Science of Total Environment, 463:1–10.
108 - An YJ, Yoon CG, Jung KW and Ham JH (2007). Estimating the microbial risk of E. coli in reclaimed wastewater irrigation on paddy field. Environmental Monitoring and Assessment, 129(1–3):53–60.
109 - US-Environmental Protection Agency (EPA) (2003). Control of pathogens and vector 8 attraction in sewage sludge. EPA/625/R-92/013. Available at: /9 625R92013.pdf (Accessed 10 December, 2015)
110 - Jerkins SR, Armstrong CW and Monti MM (2007). Health effecs of biosolids applied to land: available scientific evidence. Virginia Department of Health. Available online:
(Accessed 20 December, 2015)
111 - Harrison EZ and Oakes SR (2002). Investigation of alleged health incidents associated with land application of sewage sludges. New Solutions, 12:397–408.
112 - Westrell T, Schonning C, Stenstrom TA and Ashbolt NJ (2004). QMRA (quantitative microbial risk assessment) and HACCP (hazard analysis critical control points) for management of pathogens in wastewater and sewage sludge treatment and reuse. Water Science and Technology, 50(2):23–30.
113 - Jimenez B, Austin A, Cloete E, Phasha C and Beltran N (2007). Biological risks to food crops fertilized with Ecosan sludge. Water Science and Technology, 55(7):21–29.
114 - Watanabe T, San D and Omura D (2002). Risk evaluation for pathogenic bacteria and viruses in sewage sludge compost. Water Science and Technology, 46(11–12):325–330.
115 - Kozak GK, Boerlin P, Janecko N, Reid-Smith RJ and Jardine C (2009). Antimicrobial resistance in E. coli isolates from swine and wild small mammals in the proximity of swine farms and in natural environments in Ontario, Canada. Applied and Environmental Microbiology, 75(3):559–566.
116 - Hirsch R, Ternes T, Haberer K and Kratz KL (1999). Occurrence of antibiotics in the aquatic environment. Science of Total Environment, 225:109–118.
117 - Winckler C and Grafe A (2001). Use of veterinary drugs in intensive animal production: evidence for persistence of tetracycline in pig slurry. Journal of Soils Sediments, 1:66–70.
118 - Butaye P, Devriese LA and Haesebrouck F (2003). Antimicrobial growth promoters used in animal feed: effects of less well known antibiotics on gram-positive bacteria. Clinical Microbiology Review, 16(2):175–188.
119 - Smith DL, Harris AD, Johnson JA, Silbergeld EK and Morris JG Jr (2002). Animal antibiotic use has an early but important impact on the emergence of antibiotic resistance in human commensal bacteria. Proceedings of the National Academy of Sciences, USA, 99:6434–6439.
120 - McManus PS, Stockwell VO, Sundin GW and Jones AL (2002). Antibiotic use in plant agriculture. Annual Review in Phytopathology, 40:443–465.
121 - Kumar K, Gupta SC, Baidoo SK, Chander Y and Rosen CJ (2005). Antibiotic uptake by plants from soil fertilized with animal manure. Journal of Environmental Quality, 34:2082–2085.
122 - Kumar K, Gupta SC, Chander Y, and Singh AK (2005). Antibiotic use in agriculture and their impact on terrestrial environment. Advance Agronomy, 87:1–54.
123 - McEwen SA and Fedorka-Cray PJ (2002). Antimicrobial use and resistance in animals. Clinical Infectious Diseases 34(suppl 3):S93–S106. DOI:10.1086/340246.
124 - Carbello FC (2006). Heavy use of prophylactic antibiotics in aquaculture: a growing problem for human and animal health and for the environment. Environmental Microbiology, 8:1137–1144.
125 - Aust MO, Godlinski F, Travis GR, Hao X, McAllister TA and Leinweber P (2008) Distribution of sulfamethazine, chlortetracycline and TYL in manure and soil of Canadian feedlots after subtherapeutic use in cattle. Environmental Pollution, 156:1243–1251.
126 - Stone JJ, Clay SA, Zhu ZW, Wong KL, Porath LR and Spellman GM (2009). Effect of antimicrobial compounds TYL and chlortetracycline during batch anaerobic swine manure digestion. Water Research, 43:4740–4750.
127 - Hamscher G, Pawekzick HT, Sczesny S, Nau H and Hartung J (2003). Antibiotics in dust originating from a pig-fattening farm: a new source of health hazard for farmers? Environmental Health Perspectives, 111(13):1590–1594.
128 - Baguer AJ, Jensen J and Krogh PH (2000). Effects of the antibiotics oxytetracycline and TYL on soil fauna. Chemosphere, 40:751–757.
129 - Wang M and Tang JC (2010). Research of antibiotics pollution in soil environments and its ecological toxicity. Journal of Agro-Environmental Science, 29(supl):261–266.
130 - Sassman SA and Lee LS (2005). Sorption of three tetracyclines by several soils: role of pH and cation exchange. Environmental Science and Technology, 39:7452–7459.
131 - UCS (Union of Concerned Scientist) (2001). Hogging it!: estimates of antimicrobial abuse in livestock, Washington DC, UCS, p. 4, Available at:
132 - CEC (1998). Council regulation 2788/98. Official Journal European Community Legislation, L347:32.
133 - CEC (1998). Council Regulation 2821/98. Official Journal European Community Legislation, L351:4.
134 - Kolpin DW, Furlong ET, Meyer MT, Thurman EM, Zaugg SD and Barber LB (2002). Pharmaceuticals, hormones, and other organic wastewater contaminants in U.S. streams, 1999–2000: a national reconnaissance. Environmental Science and Technology, 36:1202–1211.
135 - Zhao L, Dong YH and Wang H (2010). Residues of veterinary antibiotics in manures from feedlot livestock in eight provinces of China. Science of Total Environment, 408:1069–1075.
136 - Yang YD, Chen DH and Huang MH (2010). The source of antibiotics in the environment and progress of its ecological impact research. Environmental Science Management, 35(1):140–143.
137 - Priha E, Rantio T, Riala R, Bäck B and Oksa P (2005). Quantitative risk assessment in relation to occupational exposure to polychlorinated biphenyls in the removal of old sealants from buildings. Scandinavian Journal of Work, Environment and Health, 31(suppl 2):43–48.
138 - Bouwman GM and Reus JAWA (1994). Persistence of Medicines in Manure. Centre for Agriculture and Environment, CLM, 163, Belfeld, Netherlands p. 26.
139 - Dolliver H, Gupta S and Noll S (2008). Antibiotic degradation during manure composting. Journal of Environmental Quality, 37:1245–1253.
140 - Giger W, Alder AC, Golet EM, Kohler HPE, McArdell CS, Molnar E, Siegrist H and Suter MJF (2003). Occurrence and fate of antibiotics as trace contaminants in wastewaters sewage sludge and surface waters. Chimia, 57:485–491.
141 - Gobel A, McArdell CS, Suter MJF and Giger W (2004). Trace determination of macrolide and sulfonamide antimicrobials a human sulfonamide metabolite and trimetoprim in wastewater using liquid chromatography coupled to electrospray tandem mass spectrometry. Anal of Chemistry, 76:4756–4764.
142 - Kim SV and Carlson K (2005). LC-MS2 for quantifying trace amounts of pharmaceuticals compounds in soil and sediment matrices. Trends in Analytical Chemistry, 24(7):635–644.
143 - Kim J, Luo F and Jiang X (2009). Factors impacting the regrowth of E. coli O157:H7 in dairy manure compost. Journal of Food Protection, 72:1576–1584.
144 - Burkhardt M, Stamm C, Waul C, Singer H and Muller S (2005). Surface runoff and transport of sulfonamide antibiotics and tracers on manured grassland. Journal of Environmental Quality, 34:1363–1371.
145 - Kay P, Blackwell PA and Boxall ABA (2005). Transport of veterinary antibiotics in overland flow following the application of slurry to arable land. Chemosphere, 59:951–959.
146 - Zhang H, Luo Y and Zhou QX (2008). Research advancement of ecotoxicity of tetracycline antibiotics. Journal of Agro-Environmental Science, 27(2):407–413.
147 - Zhang HM, Zhang MK and Gu GP (2008). Residues of tetracyclines in livestock and poultry manures and agricultural soils from North Zhejing provinces. Journal of Ecology and Rural Environment, 24(3):69–73.
148 - Smukler SM, Jackson LE, Murphree L, Yokota R, Koike ST and Smith RF (2008). Transition to large-scale organic vegetable production in the Salinas Valley, California. Agric Ecosystem Environment, 126:168–188.
149 - Siderer Y, Maquet A and Anklam E (2005). Need for research to support consumer confidence in the growing organic food market. Trends Food Science and Technology, 16:332–343.
150 - Khachatourians GG (1998). Agricultural use of antibiotics and the evolution and transfer of antibiotic-resistant bacteria. Canadian Medical Association Journal, 159:1129–136.
151 - Milić N, Milanović M, Letić NG, Sekulić MT, Radonić J, Mihajlović I and Milor adov MV (2013). Occurrence of antibiotics as emerging contaminant substances in aquatic environment. International Journal of Environmental Health Research, 23(4):296–310.
152 - Boxall ABA, Kolpin D, Halling-Sørensen B and Tolls J (2003). Are veterinary medicines causing environmental risks? Environmental Science and Technology, 37(15):286–294.
153 - WHO (2006). Guidelines for the Safe Use of Wastewater, Excreta and Greywater: Wastewater Use in Agriculture. World Health Organization, France, vol. II, pg. 101, 102.
154 - US-Environmental Protection Agency (USEPA). (2011). Problem Formulation for Human Health Risk Assessments of Pathogens in Land-Applied Biosolids. National Center for Environmental Assessment, Cincinnati, OH. EPA/600/R-08/035F.
155 - WHO (2015). Sanitation Safety Planning. Manual for Safe Use and Disposal of Wastewater, Greywater and Excreta. (authored by D Jackson, T A Stenström, M Winkler, K Medlicott). WHO, Geneva. ISBN: 9789241549240.
156 - USEPA (US-Environmental Protection Agency) (1999). Environmental Regulations and Technology: Control of Pathogens and Vector Attraction in Sewage Sludge (Including Domestic Septage). Office of Research and Development, Washington, DC. EPA 625/R- 92/013. Available at: (U.S. EPA, 1999, 624938).
157 - EU Council Directive 86/278/EEC of 12 June 1986. Protection of the Environment, and in particular of the soil, when sewage sludge is used in Agriculture. Available online: (Accessed 20 December, 2015)
158 - EU Revision of the Fertilisers Regulation (EC) No 2003/2003. Available online: (Accessed 20 December, 2015)
159 - U.S. EPA (2015). Basic information: Pathogen Equivalency Committee. Available at: https:// biosolids/basic-information-pathogen-equivalency-committee (Accessed 20 March, 2016)
160 - WHO (2012). Animal waste, water quality and human health. Dufour A, Bartram J, Bos R and Gannon V (eds) IWA Publishing, London, UK. ISBN: 9781780401232.