Using Estrogenic Activity and Nontargeted Chemical Analysis to Identify Contaminants in Sewage Sludge

Diverse
organic compounds, many derived from consumer products,
are found in sewage sludge worldwide. Understanding which of these
poses the most significant environmental threat following land application
can be investigated through a variety of predictive and cell-based
toxicological techniques. Nontargeted analysis using high-resolution
mass spectrometry with predictive estrogenic activity modeling was
performed on sewage sludge samples from 12 wastewater treatment plants
in California. Diisobutyl phthalate and dextrorphan were predicted
to exhibit estrogenic activity and identified in >75% of sludge
samples,
signifying their universal presence and persistence. Additionally,
the application of an estrogen-responsive cell bioassay revealed reductions
in agonistic activity during mesophilic and thermophilic treatment
but significant increases in antagonism during thermophilic treatment,
which warrants further research. Ten nontarget features were identified
(metoprolol, fenofibric acid, erythrohydrobupropion, oleic acid, mestranol,
4′-chlorobiphenyl-2,3-diol, medrysone, scillarenin, sudan I,
and N,O-didesmethyltramadol) in
treatment set samples and are considered to have influenced the in vitro estrogenic activity observed. The combination of
predictive and in vitro estrogenicity with nontargeted
analysis has led to confirmation of 12 estrogen-active contaminants
in California sewage sludge and has highlighted the importance of
evaluating both agonistic and antagonistic responses when evaluating
the bioactivity of complex samples.