Detection of retinoic acid receptor agonistic activity and identification of causative compounds in municipal wastewater treatment plants in Japan

Abstract

Retinoic acid (RA) receptor (RAR) agonists are potential toxicants that can cause teratogenesis in vertebrates. To determine the occurrence of RAR agonists in municipal wastewater treatment plants (WWTPs), we examined the RARα agonistic activities of influent and effluent samples from several municipal WWTPs in Osaka, Japan, using a yeast two-hybrid assay. Significant RARα agonistic activity was detected in all the influent samples investigated, suggesting that municipal wastewater consistently contains RAR agonists. Fractionations using high-performance liquid chromatography, directed by the bioassay, found several bioactive peaks from influent samples. The RAR agonists, all-trans RA (atRA), 13-cis RA (13cRA), 4-oxo-atRA, and 4-oxo-13cRA, possibly arising from human urine, were identified by liquid chromatography ion trap time-of-flight mass spectrometry. Quantification of the identified compounds in municipal WWTPs confirmed that they were responsible for the majority of RARα agonistic activity in WWTP influents, and also revealed they were readily removed from wastewater by activated sludge treatment. Simultaneous measurement of the RARα agonistic activity revealed that although total activity typically declined concomitant with the reduction of the four identified compounds, it remained high after the decline of RAs and 4-oxo-RAs in one WWTP, suggesting the occurrence of unidentified RAR agonists during the activated sludge treatment.

Systematic Review of Toxicity Removal by Advanced Wastewater Treatment Technologies via Ozonation and Activated Carbon

“…Retinoids control vertebrate morphogenesis, growth, cellular differentiation, and tissue homeostasis, and an imbalance of retinoids and related substances can induce teratogenic effects in amphibians and fish . Retinoid acid receptor α (RARα) activity was frequently detected in (un)­treated wastewater and surface waters. ,− Compared to that, retinoid X receptor (RXR) activity is less common. , Nevertheless, RARα activity in conventionally treated wastewater is mostly low or below the LOD due to the effective removal by CT. ,, Three studies investigated retinoid-like activity during advanced wastewater treatment in five assays. ,, The first study reported no activity above the LOD for the RXR and RARα . In contrast, Cao et al observed a very effective reduction of RARα activity by ozonation, even at a low ozone dose of 2 mg L –1 .…”

Highlighting the gaps in hazard and risk assessment of unregulated Endocrine Active Substances in surface waters: retinoids as a European case study

“…Humans, as well as animals, excrete retinoids most often as 4-oxo derivatives [277][278][279]. Even though retinoids are sensitive to oxidation and isomerization processes that significantly alter their bioactivity, in municipal wastewater treatment plants the treatment efficiency may not be sufficient for their complete removal and, consequently, retinoids can be released to the receiving water bodies at concentrations of up to 11.5 ng REQ × L −1 [253,271,[280][281][282][283]. Amongst the detected isomers, oxidized (i.e.…”

Insights into the Influence of Natural Retinoic Acids on Imposex Induction in Female Marine Gastropods in the Coastal Environment

“…RAs and their oxidative metabolites 4-oxo-RAs could be eliminated from humans and wildlife through urinary excretion, as well as used as RA-containing drugs for treating skin and blood diseases . As a result, RAs and 4-oxo-RAs are commonly found in effluents of sewage treatment plants (STPs), − which would be a source of RAs and 4-oxo-RAs into aquatic environments. Nevertheless, these chemicals usually showed relatively low levels in seawater.…”