Organic chemicals entering agricultural soils in sewage sludges: screening for their potential to transfer to crop plants and livestock.

This paper presents a review and assessment of the pathways and transfers of organic contaminants applied to agricultural soils in sewage sludge. The purpose of the assessment has been to develop a simple screening approach to highlight different chemical fates of organic chemicals in soil and their potential transfers from soil to groundwaters, crop plants and grazing livestock using data on the physico-chemical properties of the compounds of interest. The fate of 46 compounds known to be present in sewage sludges are compared to illustrate the applicability of the procedure. Compounds are screened for their potential to adsorb, volatilise, degrade and leach in soils and to be transferred to plants via retention by root surfaces, root uptake and translocation and foliar uptake and to transfer to animal tissues via soil and herbage ingestion. Recommendations for experimental and field studies are made. It is envisaged that this screening approach can be applied to other chemicals and that it will focus research and aid risk assessments of organic compounds in sewage sludge following land application.