Occurrence of Priority Phthalates Esters in Sewage Sludge and the Human Health Risks Associated with the Use of Sludge as Soil Improver for Agricultural Purposes
摘要
Phthalates (PAEs) in treated sewage sludge pose human health impacts, which restricts sludge utilization in agriculture. In this study, sewage sludge collected from three waste water treatment plants in Gauteng Province, South Africa was first characterized then concentrations of benzyl butyl phthalate (BBP), dibutyl phthalate (DBP), diethyl phthalate (DEP), di (2- ethyl hexyl) phthalate (DEHP), and di-n-octyl phthalate (DnOP), determined using Gas Chromatography Time of Flight Mass Spectrometry, prior to human health risk analysis of the sludge utilization in agriculture. Although sewage sludge zinc (803–2026.48 mg kg−1) and nickel (235.24–265.65 mg kg−1) concentration ranges were high across all WWTPs, all investigated heavy metal concentrations were below the European Union (EU) and South African allowable limit levels for natural utilization. Except for DnOP, detected PAEs concentrations were high and ranged from 3.82 to 331.43 mg kg−1. DEHP concentration often exceeded the recommended European Union limit (100 mg kg−1) for agriculture land application, which raises human health safety concerns. However, human health risk assessment revealed negligible carcinogenic and non-carcinogenic risks from the non-dietary exposure routes. A long-term comprehensive health risk assessment of heavy metals and phthalates in sludge used for agricultural, is therefore urgent to guide monitoring programs in South Africa.
Graphical Abstract