Sex-Related Embryotoxicity of Pulp Mill Effluent Extracts in Medaka (Oryzias latipes) Female Leucophore-free FLFII Strain.

The aim of the present study was to evaluate the effects of exposure to Chilean pulp mill effluent extracts on developing postfertilized medaka embryos before and after sex definition relative to sex steroids (testosterone and 17beta-estradiol) and a wood phytoestrogen (beta-sitosterol). Our study included 2 waterborne semichronic exposure experiments, using a 24-h post fertilization (hpf) unknown-sex FLFII (female leucophore free) group and a second 72-hpf FLFII phenotypic sex-identified group (male autofluorescence leucophore) strain of medaka embryos. Chronic exposure of both FLFII strain embryo groups showed similar delay in time to hatch and decreased hatchability. Teratogenic responses such as vertebral malformation (fusion, incomplete formation, and lack of vertebral formation process) and pericardial edema were observed in both experiments, with a high percentage related to FLFII fluorescent leucophore-identified males. In addition, high mortality associated with severe malformations was observed in male and female embryos exposed to testosterone. Our research has demonstrated that exposure to Chilean mill effluent extracts caused severe male medaka embryotoxicity (in postfertilized embryos) before and after sex definition and, irrespective of the experimental group and effluent treatment, suggests partial removal following secondary treatment. Furthermore, differences in the severity and type of teratogenic effects with previous experiments (d-rR medaka strain), are associated with the unique phenotypes of this medaka mutant strain. Environ Toxicol Chem 2021;40:2297-2305. © 2021 SETAC.

The Effects of 17α-Ethinylestradiol on the Heart Rate of Embryonic Japanese Medaka (Oryzias latipes).

Estrogen toxicity has been an area of priority in aquatic toxicology over the last 20 yr. Currently, estrogen toxicity is primarily linked to classical estrogen signaling, the interaction of estrogen receptors alpha and beta (ERα and ERß). Recent evidence has indicated that a rapid, nongenomic, nonclassical estrogen signaling pathway exists via the G protein-coupled estrogen receptor (GPER), which is expressed in many biological systems, with roles in the cardiovascular system. The objective of the present study was to investigate the effect of 17α-ethinylestradiol (EE2) on the heart rate of embryonic Japanese medaka (Oryzias latipes). A significant decrease (bradycardia) in embryonic heart rate was observed at all treatment concentrations (0.1, 1, 10, 100, and 1000 ng/L EE2) at 144, 168, and 192 h postfertilization (hpf; p ≤ 0.05), whereas 120 and 216 hpf embryos experienced a significant decrease from the control at 10, 100, and 1000 ng/L EE2 and 0.1, 100, and 1000 ng/L EE2, respectively (p ≤ 0.05). In addition, using select estrogen receptor modulators, it was demonstrated that estrogen-induced bradycardia appears to be linked to GPER and not ERα and ERß. The present study highlights GPER as a novel and alternative mode of action for EE2 toxicity at environmentally relevant concentrations. Environ Toxicol Chem 2020;39:904-912. © 2020 SETAC.

Chronic effects of hydroxypropyl-ß-cyclodextrin on reproduction in the American flagfish (Jordanella floridae) over one complete life cycle.

Understanding the environmental risks of pharmaceuticals and personal care products (PPCPs) has become very important in the field of aquatic toxicology. Hydroxylpropyl-ß-cyclodextrin (HPßCD) is an amphiphilic, toroidal shaped molecule with the ability to form noncovalent inclusion complexes with a variety of guest molecules. The molecule can reduce volatility as well as improve the aqueous solubility of apolar guest compounds and is an emerging PPCP. As such, HPßCD is the active ingredient in Febreze (Procter & Gamble) and is extensively used as an excipient in the pharmaceutical industry. With the potential for entering the environment through waste-water treatment plant (WWTP) effluent, HPßCD poses an unknown risk to nontarget aquatic biota. A 145-d chronic full life-cycle exposure using American flagfish (Jordanella floridae) was completed using flow-through nominal concentrations of 0 µg/L (control), 5 µg/L, 16 µg/L, 50 µg/L, 160 µg/L, 500 µg/L, and 1600 µg/L of HPßCD maintained via a peristaltic pump. Fecundity, growth, and liver somatic index were all monitored, and no significant difference was found between treatments and controls (p > 0.05). However, a significant increase in the gonadosomatic index was observed in females exposed to HPßCD (p ≤ 0.05). Reduced offspring growth was observed after exposure in the same manner as the parental generation (p ≤ 0.05). Furthermore, an acute copper toxicity challenge assay was conducted on second-generation flagfish larvae, and a decrease in copper tolerance was observed in larval progeny from parents exposed to HPßCD. Environ Toxicol Chem 2016;35:1358-1363. © 2015 SETAC.

Pharmaceuticals and personal care products: A critical review of the impacts on fish reproduction.

Research in environmental toxicology involving pharmaceuticals and personal care products (PPCPs) has increased greatly over the last 10-15 years. Much research has been focused on the endocrine-disrupting potential of PPCPs, as they relate to negative population impacts of aquatic organisms. This review assesses the current data on the reported effects of PPCPs on fish reproduction with an emphasis on fecundity, a predictor of population effects. Studies of both individual PPCPs and PPCP mixtures are presented. As the majority of individual PPCP studies reviewed demonstrate negative effects on fish fecundity, we relate these findings to detected surface water concentrations of these compounds. Very few studies involving PPCP mixtures have been conducted; however, the need for these types of studies is warranted as fish are most likely exposed to mixtures of PPCPs in the wild. In addition, laboratory and field assessments of wastewater treatment plant (WWTP) effluents, a major source of PPCPs, are reviewed. Much of the data provided from these assessments are variable and do not generally demonstrate negative impacts on reproduction, or the studies are unable to directly associate observed effects with WWTP effluents. Finally, future research considerations are outlined to provide an avenue into understanding how wild populations of fish are affected by PPCPs. These considerations are aimed at determining the adaptation potential of fish exposed to mixtures of PPCPs over multiple generations. As global use of PPCPs continually rises, the need to discern the effects of chronic exposure to PPCPs is greatly increased.

The acute and chronic effects of endosulfan pulse-exposure on Jordanella floridae (Florida flagfish) over one complete life-cycle.

Endosulfan is an organochlorine pesticide, which is used worldwide and has known toxic effects on non-target organisms including fish. This research investigated the acute and chronic effects of pulse-exposed endosulfan on Florida flagfish (Jordanella floridae). A 4-h pulse-exposure of endosulfan to larval flagfish caused a significant increase in mortality after 96 h at nominal concentrations equal to or greater than 100 µg/L. Some of the acute sub-lethal observations included hyperactivity, convulsions, and axis malformation. Seven-eight day old post-hatch flagfish were pulse-exposed for 4h to endosulfan and then monitored over one full life-cycle for chronic effects on growth, reproduction, and survivability. There were no growth or reproductive effects of endosulfan pulse-exposure up to the highest exposure concentration of 10.8 µg/L. Thus, the life-cycle 4-h pulse-exposure no observed effect concentration (NOEC) and lowest observed effect concentration (LOEC) were 3.3 and 10.8 µg/L endosulfan, respectively, based on significantly higher larval and juvenile mortality.

Comparative embryotoxicity of pulp mill extracts in rainbow trout (Oncorhynchus mykiss), American flagfish (Jordanella floridae) and Japanese medaka (Oryzias latipes).

This study evaluated the effects of Chilean pulp mill effluent extracts (untreated, primary and secondary treated pulp mill effluents), along with steroid standards (testosterone and 17ß-estradiol) and a wood extractive standard (beta-sitosterol) on developing post-fertilized fish embryos. Our study included a cold freshwater species, rainbow trout (Oncorhynchus mykiss), and two warm freshwater species American flagfish (Jordanella floridae) and Japanese medaka (Oryzias latipes). Embryotoxicity results included delay in time to hatch and decreased hatchability but no significant egg and larvae mortality was observed in the pulp mill extract exposed embryos. By contrast, significant early hatching and increased hatchability were observed in beta-sitosterol exposed embryos, along with high mortality of testosterone exposed embryos across species. Teratogenic responses were observed in medaka embryos in all treatments. Abnormalities were detected starting at development stages 19-20 (2-4 somite stages) and included optical deformities (micro-opthalmia, 1 or 2 eyes) and lack of development of brains and hearts. Additionally, phenotypic sex identification of surviving offspring found female-biased sex-ratios in all treatments except testosterone across species. Overall, our study indicated that Chilean pulp and paper mill extractives caused embryotoxicity (post-fertilized embryos) across species and irrespective of the effluent treatment. The effects were mainly associated with delayed time to hatch, decreased hatchability, and species-specific teratogenesis.