Decay of human enteric pathogens in agricultural soil amended with biosolids: Key findings from a comprehensive research project to examine potential health risks.

Abstract

A comprehensive study was undertaken to examine the survival potential of enteric microorganisms in biosolids-amended soil, wheat plant phyllosphere, and stored grains. The presence of these microorganisms in the dust at harvesting time was also evaluated. In situ field experiments were conducted to examine the decay of E. coli (indicator bacteria), Salmonella enterica, bacteriophage MS2 and human adenovirus in biosolids-amended soils and in dust generated during harvesting of wheat. Glasshouse experiments were conducted to determine the survival potential of enteric microorganisms in the wheat phyllosphere and stored grains to determine any possible risks to humans or livestock through consumption of contaminated grains or fodder. The results of this study suggest that the target microorganisms decayed faster in the biosolids-amended soil compared with the unamended soil in the field, that the decay times were specific to the microorganism type; and that microorganism decay was correlated to declining soil moisture levels and increasing soil temperature. The risk of transmission of disease-causing microorganisms (human pathogens) from cereal crops fertilised with biosolids was considered to be low.