Isolation and identification of ligands for the goldfish testis androgen receptor in chemical recovery condensates from a Canadian bleached kraft pulp and paper mill

Combined effects of binary mixtures of 17β-estradiol and testosterone in western mosquitofish (Gambusia affinis) after full life-cycle exposure

Estrogens and androgens are typical steroid hormones and often occur together in contaminated aquatic environments, but their mixed effects in aquatic organisms have been less well reported. In this study, the endocrine disrupting effects of binary mixtures of 17β-estradiol (E2) and testosterone (T) in western mosquitofish (Gambusia affinis) were assessed by analyzing the sex ratio, secondary sex characteristics, gonadal histology, and transcriptional expression of target genes related to the hypothalamic-pituitary-gonadal (HPG) axis in G. affinis (from embryos) continuously exposed to E2 (50 ng/L), T (T1: 50 ng/L; T2: 200 ng/L), and mixtures of both (E2 + T1: 50 + 50 ng/L; E2 + T2: 50 + 200 ng/L) for 119 d. The results showed that exposure to E2 + T1 and E2 + T2 reduced the length ratio of ray 4/6 ratio in male G. affinis, suggesting feminized phenomenon in male G. affinis. Furthermore, 16.7-38.5 % of female G. affinis showed masculinized anal fins and hemal spines when exposed to T alone and in combination with E2. Importantly, the transcriptional levels of certain target genes related to the HPG axis were significantly altered in G. affinis following exposure to E2 and T alone and in combinations. Moreover, exposure to E2 and T in combinations can lead to combined effects (such as synergistic and antagonistic effects) on the transcriptional levels of some genes. These results collectively suggest that exposure to environmentally relevant concentrations of E2 and T alone and in mixtures can impact the endocrine system of G. affinis, and may pose potential risks in aquatic systems.

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.

Pollutants released from the pulp paper industry: Aquatic toxicity and their health hazards

The pulp paper industries release wastewater containing very complex organic and inorganic pollutants. These pollutants are discharged mainly pulping and bleaching process during paper manufacturing. The main gaseous pollutants hydrogen sulfides, sodium sulfide, methyl mercaptan, sulfur, and chlorine dioxide is reported for chronic, respiratory disorder and irritation to skin, eyes and cardiac problem along with nausea and headache. The major inorganic pollutants include ferrous, copper, zinc, nickel, and magnesium, which is reported for neurotoxicity, toxic to juvenile channel catfish (Ictalurus punctatus) and Accumulation to gill > liver > ovary > muscle. The detected major organic and inorganic pollutants are hexadecanoic acids, octacosane, β-sitosterol trimethylsilyl ether, 1-tetradecane, 2-methoxy phenol, trichlorocatechol, tetrachlorocatechol, chlorophenols, chloroguaiacols, chlorosyringols, chlorocatechols, terpenes, methanol, phenol, alkylated phenols, decalone, benzoic acid, abietic acid, and dehydroabietic acid. Several of these compounds are reported as endocrine-disrupting chemicals (EDCs). Therefore, direct toxicity of effluent to the reproductive system in aquatic flora and fauna are reported. Several reports have highlighted reduced gonad size, change in secondary sexual character, delayed maturity and suppression of sex hormone in fish rainbow trout (Oncorhynchus mykiss) and mosquitofish (Gambusia holbrooki) further the in-vitro studies of organic compounds on fish, Salmonella typhimurium, Vibrio fischeri, and Saccharomyces have shown inhibition in growth and luminescence properties. The presence of organic and inorganic pollutants in pulp paper industry wastewater causes phytotoxicity chromosomal aberration in Allium cepa. Thus the manuscript has concluded that detected pollutants produced foul odors and cause hermaphroditism in fish, hepatotoxicity and mutagenic effect. In addition, the growth of coliform bacteria in River and other aquatic resources has been reported due to contamination of PPI effluent. The studies also highlighted the presence of tannins, chlorophenols, dioxins, furans, biocide, fatty acids, and resin acids along with chlorolignine compounds as persistent organic pollutants (POP), which needs special attention for pollution prevention of rivers, lakes and other aquatic resources.

Assessing wild fish exposure to ligands for sex steroid receptors from pulp and paper mill effluents in the Biobio River Basin, Central Chile

Bioactive substances in the Biobio River Basin in Chile were examined by deploying Semi Permeable Membrane Devices (SPMDs) upstream and downstream of 4 pulp mill effluent discharges. Androgenic and estrogenic activity of SPMD extracts were then evaluated using in vitro fish sex steroid receptor binding assays. The results indicated the occurrence of estrogenic type compounds associated with one of the mill discharges. A significant correlation among the presence of these compounds, an increase in gonadosomatic index GSI and induction of hepatic EROD activity of two native fish species was observed. However, no significant presence of mature oocytes in female gonads was detected. Although EROD induction was observed in sites impacted by mill effluents, an increase of its activity occurred towards the downstream areas, suggesting other non-mill sources. More research is needed to understand the environmental changes in context of the new technological improvements in treatment systems to MBBR (Moving Bed Biofilm Reactor) recently implemented by the pulp mill industries.

Comparison of steroidogenic gene expression in mummichog (Fundulus heteroclitus) testis tissue following exposure to aromatizable or non-aromatizable androgens

Androgens are a recognized class of endocrine disrupting compounds with the ability to impact reproductive status in aquatic organisms. The current study utilized in vitro exposure of mummichog (Fundulus heteroclitus) testis tissue to either the aromatizable androgen 17α-methyltestosterone (MT) or the non-aromatizable androgen 5α-dihydrotestosterone (DHT) over the course of 24 h to determine if there were differential effects on steroidogenic gene expression. Testis tissue was exposed to androgen concentrations of 10^-12 M, 10^-9 M and 10^-6 M for 6, 12, 18 or 24 h, after which a suite of steroidogenic genes, including steroidogenic acute regulatory protein, 3β-hydroxysteroid dehydrogenase (3βhsd) and cytochrome P450 17A1 (cyp17a1), were quantified using real-time polymerase chain reaction. Both androgens affected steroidogenic gene expression, with most alterations occurring at the 24-hour time point. The gene with the highest fold-change, and shortest interval to expression alteration, was 3βhsd for both androgens. Potential differences between the two model androgens were observed in increased expression of cyp17a1 and 11β-hydroxysteroid dehydrogenase (11βhsd), which were only altered after exposure to DHT and in expression levels of cytochrome P450 11A1 (cyp11a1), which was upregulated by MT but not altered by DHT. Results from this study show both androgens interact at the gonadal level of the hypothalamus-pituitary-gonadal axis and may possess some distinct gene expression impacts. These data strengthen the current research initiatives of establishing in vitro test systems that allow toxic potential of untested chemicals to be predicted from molecular perturbations.

Evaluating the potential of effluent extracts from pulp and paper mills in Canada, Brazil, and New Zealand to affect fish reproduction: Estrogenic effects in fish

The authors examined the potential of pulp mill effluent from pulp-producing countries (Canada, Brazil, New Zealand) to affect fish reproduction. Specifically, the estrogenic effects in juvenile rainbow trout (Oncorhynchus mykiss) pulse-exposed to 11 different mill effluent extracts (intraperitoneal injections of solid-phase extraction-dichloromethane nonpolar fraction). The results indicated that effluent extracts were estrogenic in juvenile trout irrespective of the gender, as reflected by increasing level of plasma vitellogenin (VTG; Brazil > New Zealand > Canada). Despite the high variability observed among mills, differences in VTG levels were related to the type of mill process (kraft > elementary chlorine-free kraft > thermomechanical pulping). Moreover, effluent treatments did not appear to significantly decrease VTG induction. A consistent estrogenic effect was observed in those mills that process a combination of feedstocks (softwood and hardwood), with the highest increase in VTG related to eucalyptus feedstock. The results demonstrate significant estrogenic effects of pulp mill effluents on chronically exposed juvenile trout, suggesting that in vivo metabolic activation of precursors is necessary to cause the observed increases in VTG levels. This molecular estrogenic response provides a useful starting point for predicting population-level impacts through the adverse outcome pathway methodology. Environ Toxicol Chem 2017;36:1547-1555. © 2016 SETAC.

The Relationship between Organic Loading and Effects on Fish Reproduction for Pulp Mill Effluents across Canada

This study builds upon the work of a multiagency consortium tasked with determining cost-effective solutions for the effects of pulp mill effluents on fish reproduction. A laboratory fathead minnow egg production test and chemical characterization tools were used to benchmark 81 effluents from 20 mills across Canada, representing the major pulping, bleaching, and effluent treatment technologies. For Kraft and mechanical pulp mills, effluents containing less than 20 mg/L BOD₅ were found to have the greatest probability of having no effects. Organic loading, expressed as the total detected solvent-extractable components by gas chromatography/mass spectrometry (GC/MS), also correlated with decreased egg laying. Exceptions were found for specific Kraft, mechanical, and sulfite mills, suggesting yet unidentified causative agents are involved. Recycled fiber mill effluents, tested for the first time, were found to have little potential for reproductive effects despite large variations in BOD₅ and GC/MS profiles. Effluent treatment systems across all production types were generally efficient, achieving a combined 82-98% BOD₅ removal. Further reductions of final effluent organic loadings toward the target of less than 20 mg/L are recommended and can be realized through biotreatment optimization, the reduction of organic losses associated with production upsets and selecting best available technologies that reduce organic loadings to biotreatment.

Estrogenicity and intersex in juvenile rainbow trout (Oncorhynchus mykiss) exposed to Pine/Eucalyptus pulp and paper production effluent in Chile

Pulp and paper mill effluents (PPMEs) have been shown to increase gonad size, cause early maturation, and disrupt hormone functions in native and non-native Chilean fish. In this study, we assessed reproductive (plasma vitellogenin; VTG, gonad development) and metabolic (ethoxyresorufin-O-deethylase activity; EROD) end points, relative liver size (LSI) and condition factor (K) of juvenile female and male rainbow trout exposed to effluents. Unlike previous studies, which have focus either on the specific effects of effluent on fish in laboratory exposures or biotic population statuses downstream of discharge sites, we simultaneously assessed the impacts of PPMES on trout using two approaches: (1) laboratory exposures of tertiary treated PPME produced from processing Eucalyptus globulus or Pinus radiata; and (2) in situ bioassay downstream of the combined discharge of the same pulp mill. Despite an increase in the average gonadosomatic index (GSI) in exposed fish, no statistical differences in gonad size between exposed and unexposed individuals was detected. However, both female and male fish exposed to effluents showed significantly higher concentrations of plasma VTG, so more in fish exposed to Eucalyptus-based effluent when compared to Pinus PPME. In addition, male fish showed intersex characteristics in all exposure assays (Eucaliptus and Pinus) and, despite the low concentration of effluent in the river (<1% [v/v]), similar responses were observed in the caged fish. Finally, EROD activity was induced in both in situ exposures and laboratory assays at the higher PPME concentration (60-85% PPME). This study confirms estrogenic effects in Chilean fish exposed to PPME and the necessity for biological effects monitoring in addition to the assessment of physical-chemical endpoints as required in current government regulations.

Effects of model aromatizable (17α-methyltestosterone) and non-aromatizable (5α-dihydrotestosterone) androgens on the adult mummichog (Fundulus heteroclitus) in a short-term reproductive endocrine bioassay

Androgens originating from pulp mill processing, sewage treatment facilities and agricultural activities have the potential for discharge into aquatic receiving environments. To assess androgen effects on reproductive endocrine status in fish in estuarine environments, male and female adult northern mummichog (Fundulus heteroclitus macrolepidotus) were exposed to an aromatizable androgen (17α-methyltestosterone; MT) and a non-aromatizable androgen (5α-dihydrotestosterone; DHT) in a short-term reproductive endocrine bioassay. Fish were nominally exposed to 10 μg/L or 100 μg/L DHT, or 0.1 μg/L or 1 μg/L MT for 14 days during gonadal recrudescence. Actual concentrations of androgens, as measured by enzyme immunoassay (EIA), were 10-49% of nominal MT 0.1, 3-6% of nominal MT 1, 5-10% of nominal DHT 10 and 3-25% of nominal DHT 100. Female mummichog were impacted to a greater degree by androgen exposure, with increased plasma testosterone (T) at 100 μg/L DHT, depressed plasma 17β-estradiol (E2) at both DHT concentrations and at 1 μg/L MT, as well as depressed in vitro E2 at both MT concentrations and 100 μg/L DHT. Males had depressed plasma T in the 10 μg/L DHT treatment and depressed in vitro 11-ketotestosterone production for both MT concentrations and 10 μg/L DHT. Ovarian aromatase gene expression was induced in females exposed to 1 μg/L MT. DHT at 100 μg/L increased hepatic vitellogenin-1 (VTG1) expression in males and depressed VTG1 expression in females. The range of responses between sexes and among species provides evidence for modes of actions and potential impacts of androgens in aquatic receiving environments.

Rapid fluorescent detection of (anti)androgens with spiggin-gfp medaka

Widespread environmental antiandrogen contamination has been associated with negative impacts on biodiversity and human health. In particular, many pesticides are antiandrogenic, creating a need for robust and sensitive environmental monitoring. Our aim was to develop a sensitive and specific transgenic medaka (Oryzias latipes) model bearing an androgen responsive fluorescent reporter construct for whole organism-based environmental screening of pro- and antiandrogens. We analyzed the 5' regions of the androgen responsive three-spined stickleback (Gasterosteus aculeatus) spiggin genes in silico, revealing conserved blocks of sequence harboring androgen response elements. Identified putative promoters were cloned upstream of GFP. Germinal transgenesis with spg1-gfp led to stable medaka lines. GFP induction was exclusive to the kidney, the site of spiggin protein production in sticklebacks. Significant GFP expression was induced by three or four-day androgen treatment of newly hatched fry, but not by estrogens, mineralocorticoids, glucocorticoids or progestogens. The model responded dose-dependently to androgens, with highest sensitivity to 17MT (1.5 μg/L). In addition to flutamide, the biocides fenitrothion, vinclozolin and linuron significantly inhibited 17MT-induced GFP induction, validating the model for detection of antiandrogens. The spg1-gfp medaka model provides a sensitive, specific, and physiologically pertinent biosensor system for analyzing environmental androgen activity.

Evaluating the potential of effluents and wood feedstocks from pulp and paper mills in Brazil, Canada, and New Zealand to affect fish reproduction: chemical profiling and in vitro assessments

This study investigates factors affecting reproduction in fish exposed to pulp and paper mill effluents by comparing effluents from countries with varying levels of documented effects. To explore the hypothesis of wood as a common source of endocrine disrupting compounds, feedstocks from each country were analyzed. Analyses included in vitro assays for androgenic activity (binding to goldfish testis androgen receptors), estrogenic activity (yeast estrogen screen), and neurotransmitter enzyme inhibition (monoamine oxidase and glutamic acid decarboxylase). Chemical analyses included conventional extractives, known androgens, and gas chromatograph index (GCI) profiles. All effluents and wood contained androgenic activity, particularly in nonpolar fractions, although known androgens were undetected. Effluents with low suspended solids, having undergone conventional biotreatment had lower androgenic activities. Estrogenic activity was only associated with Brazilian effluents and undetected in wood. All effluents and wood inhibited neurotransmitter enzymes, predominantly in polar fractions. Kraft elemental chlorine free mills were associated with the greatest neurotransmitter inhibition. Effluent and wood GCI profiles were correlated with androgenic activity and neurotransmitter enzyme inhibition. Differences in feedstock bioactivities were not reflected in effluents, implying mill factors mitigate bioactive wood components. No differences in bioactivities could be discerned on the basis of country of origin, thus we predict effluents in regions lacking monitoring would affect fish reproduction and therefore recommend implementing such programs.