The potential impact of veterinary and human therapeutic agents in manure and biosolids on plants grown on arable land: a review

The fate of human and veterinary therapeutic agents has aroused attention in recent years as a potential pollutant of the environment. Prescription drugs are a US$ 91 billion industry in the United States alone and a major part of the economy in other developed countries. Substantial quantities of these compounds and their metabolites are excreted, flushed down the drain, discarded as waste, or left over in animal feedlots. When they enter the sewer, several of these compounds are not adequately eliminated by the methods that are currently used in sewage treatment. Substantial quantities of biosolids and livestock manure end up on agricultural land. In laboratory studies, the growth and development of Phaseolus vulgaris L., Glycine max, Medicago sativa, Zea mays, and several other plants are affected by some commonly used therapeutic agents. However, most of the phytotoxicity studies have been conducted in vitro. The few studies conducted in soil suggest that phytotoxicity varies between species. The bioavailability of these compounds is greatly dependent on the sorption kinetics of the respective compound, soil organic matter, and soil pH. Some research needs, such as establishing concentrations that prevail in soil, potential effects to microbial processes in soil, and effects on crops under field conditions, are highlighted.