Flame-Retardants and Other Organohalogens Detected in Sewage Sludge by Electron Capture Negative Ion Mass Spectrometry

Abstract

Numerous halogenated organic compounds have been identified as pollutants of concern. Those with high persistence and hydrophobicity may concentrate in biota, sediments, and wastewater sludge. Nonetheless, the release to the environment of many remains largely unrecognized. Stabilized sewage sludge (biosolids) is increasingly being land-applied as a soil amendment. However, understanding the risks of land application has been hampered by the compositional complexity of biosolids. Compound specific analytical approaches may also underestimate environmental impact of land application by overlooking additional contaminants. However, utilizing an alternative analytical approach based on compound functional group (i.e., alkyl halides) enhanced the information content of the analysis. To illustrate, 49 organohalogens were observed by gas chromatography with electron capture negative ionization mass spectrometry in sewage sludge; 23 identified as flame-retardants: that is, PBDEs, hexabromocyclododecane, 2-ethylhexyl 2,3,4,5-tetrabromobenzoate (TBB), 2-ethylhexyl tetrabromophthalate, decabromodiphenyl ethane, 1,2-bis (2,4,6-tribromophenoxy) ethane and Dechlorane Plus. Concentrations ranged from 25 to 1 600 000 ng g⁻¹ total organic carbon. An additional 16 compounds were tentatively identified as triclosan, chlorinated-methoxy triclosan, chlorinated pesticides, hexachlorobiphenyl, TBB degradation products, brominated furans and nonabromochlorodiphenyl ethers. Such an analytical approach may enhance evaluations of the risks associated with biosolids land-application and assist in prioritizing specific chemicals for future environmental fate and toxicology studies.