Effect assessment of reclaimed water and carbamazepine exposure on the thyroid axis of X. laevis: Apical and histological effects.

There is increasing environmental concern about the constant presence of pharmaceuticals and personal care products (PPCPs) in surface water, generally attributed to water discharge from wastewater treatment plants (WWTPs) that are unable to completely remove these compounds. The slight, but continuous, presence of these contaminants in reclaimed water (RW) poses a risk of chronic and sublethal toxicity, and the thyroid axis can likely be a target of many of these PPCPs. In this work, we addressed the effects of RW on the Xenopus laevis thyroid system. The Amphibian Metamorphosis Assay (AMA test) was used with modifications by exposing X. laevis tadpoles to RW samples, and to RW spiked with carbamazepine (CBZ) at 100 and 1000 higher than the average levels environmentally relevant (RW 100× and RW 1000×, respectively). Carbamazepine was selected because it is considered a marker of anthropogenic pollution and could have a potential effect on the thyroid axis. The morphological endpoints and histological alterations to the thyroid gland were evaluated. The results suggested the stimulation of the thyroid gland from exposures to the RW samples, supported by tadpoles' accelerated development and by the histological alterations observed in the thyroid gland. Developmental acceleration was also seen in the tadpoles exposed to the RW-100× and -1000× samples at comparable levels to those seen in exposures to RW samples alone. Hence CBZ did not seem to increase the effects of RW on the thyroid axis. Overall, our results suggested endocrine effects of these RW samples regardless of the CBZ concentration.

Occurrence of pharmaceutically active compounds in surface waters of the Henares-Jarama-Tajo River system (Madrid, Spain) and a potential risk characterization.

The Henares-Jarama-Tajo river system is the largest drainage basin in the Province of Madrid, Spain. This area is characterized by the presence of intensive urban and industrial activities influenced by a continental Mediterranean climate with rainfalls presenting substantial fluctuations along the different seasons. This research aimed to monitor seasonal variations in concentrations of 22 pharmaceutically active compounds (PhACs) in this river system and to establish the potential risk of sublethal effects on aquatic organisms. A total of 10 sampling sites were selected along the river system with samples collected in each of the four seasons during a year-round schedule. Most of the PhACs detected were present in sampling sites downstream in the vicinity of the most populated cities (i.e. Madrid, Guadalajara and Alcalá de Henares). Only two PhACs, fluoxetine and paraxantine, were detected in all sites regardless of the season, and showed median (+/- interquartile range) concentrations of 21.4 (+/-31.2) ng L(-1) and 8.5 (+/-5.3) ng L(-1), respectively. Other PhACs were detected with a frequency >80% and included, caffeine, diphenylhydantoin, hydrochlorotiazide, ibuprofen, ketoprofen, diclofenac, sulfamethoxazole, atenolol, naproxen, carbamazepine and propanolol. Seasonal variations were observed with the highest concentrations in December and the lowest in September. By combining measured environmental concentrations with toxicity data (either publicly available or obtained experimentally in our laboratory), and by calculating an Maximum Risk Index (MaxRI) that each combination of PhACs should have for non exceeding the risk threshold, a high potential for long-term risk (MaxRI<10) was estimated for most of the sampling sites and sampling dates. This research allowed the characterization of the potential risk for each of the PhACs to exert sublethal effects on aquatic organisms using acute screening methods, justifying the need for chronic data in order to refine the risk of these compounds to aquatic organisms.

Stage-specific toxicity of cypermethrin to medaka (Oryzias latipes) eggs and embryos using a refined methodology for an in vitro fertilization bioassay.

Using original artificial fertilization methods with medaka (Oryzias latipes), the effects of exposure to cypermethrin on gametes, fertilization, and embryonic development were investigated. The relative sensitivity was studied with 96-hour duration, 24-hour renewal exposures to six nominal concentrations of cypermethrin ranging from 3.1 100.0 microg cypermethrin/L. Tests were initiated at different developmental stages: unfertilized egg (stage 0), late morula (stage 9), eminence of swim bladder (stage 29), and maximum flexion of the atrioventricular region (stage 34). Cypermethrin did not affect the fertilization process. Predominant sublethal effects in embryos included transient visceral edemas intimately associated to the gall bladder with subsequent pericardial edemas. Other sublethal effects were observed in surviving larvae and included spastic movements with or without ability to respond to stimulus (>/=6.3 microg cypermethrin/L), spinal curvatures, and delayed or absence of swim bladder inflation (>/=12.5 microg cypermethrin/L). The exposure of the gametes (stage 0) or animals during earlier embryonic development (stages 9 or 29) was not a critical window for cypermethrin exposure. Although the incidence of edemas in embryos occurred mainly during exposure of these early developmental stages, embryo and larva lethality and the incidence of transient sublethal effects in hatchlings showed that the later exposure window (stage 34) was the most sensitive. The stage 34 group involved advanced organogenetic stages in which the chorion partially degraded before hatching. Our studies reinforced the idea that a combination of morphologic and functional impairment evaluation is a more sensitive response to developmental toxicants than morphologic defects alone.