In vitro thyroid hormone–disrupting activity in effluents and surface waters in Thailand

Abstract

The thyroid hormone (TH)-disrupting activity of effluents and environmental water samples in Thailand was surveyed by three in vitro bioassays with different endpoints. These assays test the potency of competitive binding with the active form of TH, 3,3',5-[(125)I]triiodo-l-thyronine (T(3)), to the plasma transport protein transthyretin (TTR) and TH receptor (TR; the TTR assay and TR assay, respectively) and the interference with the cellular T(3)-signaling pathway through TR-mediated luciferase gene activation (the luc assay). The TH-disrupting activity in water samples collected from paper manufacturing plants (PMPs), the canal Khlong U-Taphao, and a sewage-treatment plant (STP) was detected predominantly in the dichloromethane/methanol or methanol fractions of solid-phase extraction, suggesting a similar hydrophobic nature of the causative contaminants. The TR assay was relatively more sensitive than the TTR assay to the competitively potent contaminants. The luc assay indicated that the dichloromethane/methanol fractions of most water samples contained anti-T(3)-like activity. Our assays demonstrated that wastewater treatment effectively removed the TH-disrupting contaminants from wastewater in the PMP and the STP. The potencies for TH disruption at the three sampling points of the STP exhibited positive correlations among the three bioassays, whereas those from the canal and PMP water were not correlated among the three bioassays. Furthermore, the influent contaminants that were competitively potent in the TTR assay partially affected the luc assay. These bioassays are useful monitoring tools that give results relevant for evaluating the health of amphibian populations.

Novel cell-based assay for detection of thyroid receptor beta-interacting environmental contaminants

“…Indeed, we studied transcriptional activity of a number of translocation-positive samples using HepG2 cells which express TRβ1 (Chan and Privalsky 2009) and demonstrated a complex and gene-specific pattern of gene regulation that could reflect the presence of a mixture of TRβ-interacting chemicals. Previously published studies using TR-mediated luciferase gene expression assay detected T3-like activity in water and effluents from water treatment plants (WWTP) in Japan (Murata and Yamauchi 2008) and anti-T3 hormonal activity in WWTP effluent in Thailand (Ishihara et al 2009), demonstrating that both agonists and antagonists could be present in the environment. Our data are the first report demonstrating the presence of TRβ-interacting contaminants in US water sources.…”

Endocrine potency of wastewater: Contents of endocrine disrupting chemicals and effects measured by in vivo and in vitro assays

“…Wastewater contains multiple chemical substances, some of which have the potential to disrupt endocrine processes in living organisms [1][2][3][4]. In industrialized countries, most of the sewage produced is treated in a sewage treatment plant (STP) before it is discharged to receiving environmental water streams.…”

“…Few reports have been published on thyroid hormone-like compounds in wastewater plants; however, recently triiodothyronine (T3)-like activity of effluents from STPs in Japan [3] was reported, whereas anti-T3-like activity of STP effluent was observed in Thailand [2]. For both reports, the STP effects were detected using the same thyroid hormone receptor-mediated luciferase gene transactivity assay.…”

Thyroid Disrupting Activities in Wastewater and Surface Waters: A Review of Their <i>in Vitro</i> Analyses

“…Evaluating the thyroid disrupting activity in effluents of two paper manufacturing plants (PMPs) in Songkhla province, and canal Khlong U-Tapahao, Thailand, Ishihara et al [12] μg DBP/L) was also detected in most of the surface water samples analyzed.…”

“…The numbers of toxic chemicals that are being released into the environment, especially surface waters, are disturbingly on the increase [12] [13]. Of these chemicals, a wide spectrum has been shown to possess various (anti)thyroid activities in wastewater and surface waters, posing serious developmental threats to wildlife and humans.…”