Uptake and Effects of Pharmaceuticals in the Soil-Plant-Earthworm System

The reuse of wastewater to meet increasing demands on freshwater resources coupled with the use of biosolids as soil amendments in agricultural landscapes provides many pathways for exposure to pharmaceuticals into the agroecosystem. Wastewater and both agricultural and municipal biosolids are known reservoirs for the potentially hundreds of pharmaceuticals that are in use throughout the world. Over the past 15 years, research has focussed on gaining an understanding of the extent of exposure, the fate and uptake of these compounds and the potential toxicological impacts these compounds may have once introduced. The agricultural system is a complex web of micro and macro fauna that includes microbes, fungi, invertebrates and plants which all may act as sinks for bioaccumulation and receptors for these biological active xenobiotic compounds. In this review, we describe how different experimental designs have been utilised to provide insights into the extent of uptake into plants and invertebrates, the mechanisms that govern this fate process and the evidence of biological effects that makes up our current understanding of pharmaceutical exposure in agricultural systems. We highlight the types of compounds as well as the model plant and invertebrate organisms that have been most studied. Furthermore, we discuss how geographical and economic drivers have influenced where research has been conducted and how this may bias our current understanding of pharmaceutical exposure risk as it relates to low- and middle-income countries.