Heavy metals and emerging organic contaminants in Japanese sewage sludge

Because of its high dependence on imported phosphorus, Japan is striving to increase the reuse of phosphorus-rich sewage sludge (via direct application or composting) in agriculture rather than using incineration. However, the occurrence and behavior of pollutants in sewage sludge may pose environmental risks and have received limited attention until now. In this study, sewage sludge collected across Japan during a single sampling campaign was analyzed for heavy metals, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), per- and polyfluoroalkyl substances (PFASs), extractable organic fluorine, brominated flame retardants (BFRs), pharmaceuticals and personal care products (PPCPs), and endocrine-disrupting compounds (EDCs). One sludge sample exceeded the Japanese Cd limit more than elevenfold, while five of twelve samples exceeded the German regulatory limit for the sum of PFOA and PFOS. However, regulatory limits in Japan are currently available only for selected heavy metals among the analyzed pollutants. Therefore, the use of sewage sludge and sludge compost without comprehensive knowledge of their composition and appropriate regulatory limits on heavy metals and various organic pollutants, including emerging contaminants, could result in the uncontrolled release of these pollutants into agricultural soils and broader ecosystems.