How Safe is Chicken Litter for Land Application as an Organic Fertilizer? A Review

Abstract

Chicken litter application on land as an organic fertilizer is the cheapest and most environmentally safe method of disposing of the volume generated from the rapidly expanding poultry industry worldwide. However, little is known about the safety of chicken litter for land application and general release into the environment. Bridging this knowledge gap is crucial for maximizing the benefits of chicken litter as an organic fertilizer and mitigating negative impacts on human and environmental health. The key safety concerns of chicken litter are its contamination with pathogens, including bacteria, fungi, helminthes, parasitic protozoa, and viruses; antibiotics and antibiotic-resistant genes; growth hormones such as egg and meat boosters; heavy metals; and pesticides. Despite the paucity of literature about chicken litter safety for land application, the existing information was scattered and disjointed in various sources, thus making them not easily accessible and difficult to interpret. We consolidated scattered pieces of information about known contaminants found in chicken litter that are of potential risk to human, animal, and environmental health and how they are spread. This review tested the hypothesis that in its current form, chicken litter does not meet the minimum standards for application as organic fertilizer. The review entails a meta-analysis of technical reports, conference proceedings, peer-reviewed journal articles, and internet texts. Our findings indicate that direct land application of chicken litter could be harming animal, human, and environmental health. For example, counts of pathogenic strains of Eschericia coli (105–1010 CFU g−1) and Coliform bacteria (106–108 CFU g−1) exceeded the maximum permissible limits (MPLs) for land application. In Australia, 100% of broiler litter tested was contaminated with Actinobacillus and re-used broiler litter was more contaminated with Salmonella than non-re-used broiler litter. Similarly, in the US, all (100%) broiler litter was contaminated with Eschericia coli containing genes resistant to over seven antibiotics, particularly amoxicillin, ceftiofur, tetracycline, and sulfonamide. Chicken litter is also contaminated with a vast array of antibiotics and heavy metals. There are no standards set specifically for chicken litter for most of its known contaminants. Even where standards exist for related products such as compost, there is wide variation across countries and bodies mandated to set standards for safe disposal of organic wastes. More rigorous studies are needed to ascertain the level of contamination in chicken litter from both broilers and layers, especially in developing countries where there is hardly any data; set standards for all the contaminants; and standardize these standards across all agencies, for safe disposal of chicken litter on land.

Potential contaminants and hazards in alternative chicken bedding materials and proposed guidance levels: a review

“…To date, there has been a number of studies on potential hazards and contaminants regarding the use of spent chicken litter for land application (reviewed by Kyakuwaire et al., 2019 ). However, very few studies have investigated potential contaminants that are detrimental to animals and humans in bedding materials before their use, and those are restricted to recycled wood and paper and cardboard by-products ( Beauchamp et al., 2002 ; Asari et al., 2004 ; Fernandes et al., 2019 ).…”

Phenomenal Bombardment of Antibiotic in Poultry: Contemplating the Environmental Repercussions

“…Wet and dry poultry litter samples exhibited the presence of bacterial strains such as Aerococcus viridans , Atopostipes suicloacalis , Bacillus hackensackii , Brevibacterium avium , Corynebacterium ammoniagenes , Facklamia sourekii , Jeotgalicoccus sp., Salinicoccus halodurans , Staphylococcus arlettae , Staphylococcus cohnii and Virgibacillus marismortui in which Staphylococcus , Salinicoccus , Virgibacillus , Jeotgalicoccus , Facklamia , Brevibacterium and Bacilli were found to be dominant. In addition to these, fungal species such as Candida sp., Penicillium pimiteouiense , Penicillium decumbens , Aspergillus sydowii and Euroteum amstelodami were also identified from the above samples [ 43 ]. Food borne bacterial pathogens namely E. coli , Salmonella , Campylobacter , Staphylococcus , Clostridium , Listeria , Actinobacillus and Mycobacterium were also frequently detected in poultry litter [ 44 ].…”

Environmental and Nutritional “Stressors” and Oligodendrocyte Dysfunction: Role of Mitochondrial and Endoplasmatic Reticulum Impairment

“…To date, the presence of heavy metals in the environment has increased exponentially as a result of human activity, which includes industrialization, anthropogenic waste, and the use of fertilizers and pesticides. It is also worth mentioning the occupational exposure to heavy metals that occurs in the workplace [87]. The main metals considered dangerous if present in abundant concentrations are lead (Pb), cadmium (Cd), mercury (Hg), arsenic (As), chromium (Cr), copper (Cu), nickel (Ni), aluminum (Al), cesium (Cs), cobalt (Co), molybdenum (Mo), strontium (Sr), and uranium (U) [88].…”