How estrogenic is nonylphenol? A transgenerational study using rainbow trout (Oncorhynchus mykiss) as a test organism

Reproductive toxicity in marine medaka (Oryzias melastigma) due to embryonic exposure to PCB 28 or 4'-OH-PCB 65

Previous studies have shown that juvenile or adult exposure to polychlorinated biphenyls (PCBs) induces alterations in reproductive functions (e.g., reduced fertilization rate) and behavior (e.g., reduced nest maintenance) in fish. Embryonic exposures to other endocrine disrupting chemicals have been reported to induce long-term reproductive toxicity in fish. However, the effects of embryonic exposure to PCBs or their metabolites, OH-PCBs, on long-term reproductive function in fish are unknown. In the present study, we used the marine medaka fish (Oryzias melastigma) as a model to assess the reproductive endpoints in response to embryonic exposure to either PCB 28 or 4'-OH-PCB 65. Our results showed that the sex ratio of marine medaka was feminized by exposure to 4'-OH-PCB 65. Fecundity was decreased in the medaka treated with either PCB 28 or 4'-OH-PCB 65, whereas the medaka from embryonic exposure to 4'-OH-PCB 65 additionally exhibited reduced fertilization and a reduction in the hatching success rate of offspring, as well as decreased sperm motility. Serum 11-KT concentrations were reduced in the PCB 28-treated medaka, and serum estradiol (E2)/testosterone (T) and E2/11-ketotestosterone (11-KT) ratios were decreased in the 4'-OH-PCB 65-treated medaka. To explain these observations at the molecular level, transcriptomic analysis of the gonads was performed. Bioinformatic analysis using Gene Ontology and Ingenuity Pathway Analysis revealed that genes involved in various pathways potentially involved in reproductive functions (e.g., steroid metabolism and cholesterol homeostasis) were differentially expressed in the testes and ovaries of either PCB- or OH-PCB-treated medaka. Thus, the long-term reproductive toxicity in fish due to embryonic exposure to PCB or OH-PCB should be considered for environmental risk assessment.

Studies of Endocrine Disruptors: Nonylphenol and Isomers in Biological Models

Certain emerging pollutants are among the most widely used chemicals globally, causing widespread concern in relation to their use in products devoted to cleaniness and asepsis. Nonylphenol ethoxylate (NPEOn) is one such contaminant, along with its degradation product, nonylphenol, an active ingredient presents in nonionic surfactants used as herbicides, cosmetics, paints, plastics, disinfectants, and detergents. These chemicals and their metabolites are commonly found in environmental matrices. Nonylphenol and NPEOn, used, are particularly concerning, given their role as endocrine disruptors chemical and possible neurotoxic effects recorded in several biological models, primarily aquatic organisms. Limiting and detecting these compounds remain of paramount importance. The objective of the present review was to evaluate the toxic effects of nonylphenol and NPEOn in different biological models. Environ Toxicol Chem 2023;00:1-12. © 2023 SETAC.

Tiered ecological risk assessment of nonylphenol and tetrabromobisphenol A in the surface waters of China based on the augmented species sensitivity distribution models

The ecological risks of nonylphenol (NP) and tetrabromobisphenol A (TBBPA) have received continued attention owing to their large consumption, frequently detection, adverse effects on the reproductive fitness, and lack of risk assessment technical systems. The geometric mean of the median concentrations of NP in the 22 surface waters was 0.278 μg/L, and TBBPA in the seven surface waters was 0.014 μg/L in China. The species sensitivity distribution (SSD) models were augmented by extrapolated reproductive toxicity data of native species to reduce uncertainty. The SSD models and the hazardous concentrations for 5% of species exhibited good robustness and reliability using the bootstrap method and minimum sample size determination. The acute and reproductive predicted no-effect concentrations (PNECs) were derived as 9.88 and 0.187 μg/L for NP, and 56.6 and 0.0878 μg/L for TBBPA, respectively. The risk quotients indicated that 11 of 22 locations for NP, and 3 of 7 locations for TBBPA were at high ecological risk levels based on the reproductive PNECs. Furthermore, the higher tier ecological risk assessment (ERA) based on potential affected fraction and joint probability curves indicated that the ecological risks in the four of above locations needed further concern. The ERA based on both the acute and reproductive toxicity is essential for assessing the ecological risks of NP and TBBPA, otherwise using acute PNECs only may result in an underestimation of ecological risk. The developed tiered ERA method and its framework can provide accurate, detailed, quantitative, locally applicable, and economically technical support for ERA of typical endocrine-disrupting chemicals in China.

A practical guide to unbiased quantitative morphological analyses of the gills of rainbow trout (Oncorhynchus mykiss) in ecotoxicological studies

Rainbow trout (Oncorhynchus mykiss) are frequently used as experimental animals in ecotoxicological studies, in which they are experimentally exposed to defined concentrations of test substances, such as heavy metals, pesticides, or pharmaceuticals. Following exposure to a broad variety of aquatic pollutants, early morphologically detectable toxic effects often manifest in alterations of the gills. Suitable methods for an accurate and unbiased quantitative characterization of the type and the extent of morphological gill alterations are therefore essential prerequisites for recognition, objective evaluation and comparison of the severity of gill lesions. The aim of the present guidelines is to provide practicable, standardized and detailed protocols for the application of unbiased quantitative stereological analyses of relevant morphological parameters of the gills of rainbow trout. These gill parameters inter alia include the total volume of the primary and secondary gill lamellae, the surface area of the secondary gill lamellae epithelium (i.e., the respiratory surface) and the thickness of the diffusion barrier. The featured protocols are adapted to fish of frequently used body size classes (300-2000 g). They include well-established, conventional sampling methods, probes and test systems for unbiased quantitative stereological analyses of light- and electron microscopic 2-D gill sections, as well as the application of modern 3-D light sheet fluorescence microscopy (LSFM) of optically cleared gill samples as an innovative, fast and efficient quantitative morphological analysis approach. The methods shown here provide a basis for standardized and representative state-of-the-art quantitative morphological analyses of trout gills, ensuring the unbiasedness and reproducibility, as well as the intra- and inter-study comparability of analyses results. Their broad implementation will therefore significantly contribute to the reliable identification of no observed effect concentration (NOEC) limits in ecotoxicological studies and, moreover, to limit the number of experimental animals by reduction of unnecessary repetition of experiments.

Does electrolysis facilitate simultaneous nitrogen removal and toxicity reduction of low C/N dyeing wastewater by sulfur-based denitrification biofilter?

The concern about wastewater effluent toxicity has motivated the innovation of enhancement technologies on sulfur-based denitrification biofilter in recent years. Electrolysis is a common technology to reduce or remove toxic pollutants. However, the effect of electrolysis on simultaneous total nitrogen (TN) removal and toxicity reduction in sulfur-based denitrification biofilter has not been reported yet. Herein, for the first time, this study investigated the synergistic effects of electrolysis-induced TN removal and toxicity reduction of secondary effluent of dyeing wastewater containing 20 μg/L of nonylphenol (NP), at different carbon to nitrogen ratios (C/N) in several sulfur-based denitrification biofilters. All of the biofilters achieved the denitrification rate of 300.15 g∙N/m³∙d during the stabilization period at C/N = 5. The CSAHD (ceramisite and sulfur as filters) biofilter had highest TN removal rate to achieve the denitrification rate of 257.46 g∙N/m³·d at C/N = 2. Siderite and dolomite both facilitated TN removal efficiency by 9.3%-12.6% under low C/N ratio and acted as the buffer agent in biofilters. Toxicity characteristic leaching procedure (TCLP) test showed that the amount of leached heavy metals was lower than the concentration limit standard of USEPA. Electrolysis did not promote the removal of TN, however, it could reduce NP concentration and increase the biotoxicity relative inhibition rate of effluent by 12.5%-167%, and affect the functional microbial community structure. Our work clarified some misunderstandings about the application of electrolysis-based strengthening technology and enlightened the future development of simultaneous TN removal and toxicity reduction of dyeing wastewater.

Disruptive effects of nonylphenol on reproductive hormones, antioxidant enzymes, and histology of liver, kidney and gonads in Caspian trout smolts

The endocrine-disrupting effect of pollutants such as alkylphenols has been considered a major concern during recent years. Although the effects of nonylphenol on the reproductive hormones of fish have been investigated in several studies, the effect of this endocrine disruptor on reproductive hormones of immature fish and salmonid smolts has been less addressed. The present work studied the effects of 1, 10 and 100 μg/l concentrations of nonylphenol on the levels of plasma reproductive hormones and liver antioxidant enzymes as well as on histopathology of reproductive and non-reproductive organs of male and female Caspian brown trout (Salmo trutta caspius) smolts after 21 days of exposure. The results of the present study showed that environmentally relevant concentrations of nonylphenol affected plasma levels of sex steroids; gonadotropins, phosphorus, estradiol to testosterone ratio, and also caused histopathological lesions in liver, kidney and testis tissues of immature Caspian brown trout during smolting. Nonylphenol significantly increased the levels of estradiol in plasma of both male and female smolts exposed to nonylphenol compared with the control groups. Exposure to nonylphenol decreased testosterone and FSH levels in both genders. It has also increased plasma levels of LH in females but did not affect LH levels in male fish. Liver SOD and CAT content was decreased in nonylphenol-exposed smolts. Therefore, the release of this economically valuable and endangered species into the rivers contaminated with nonylphenol should be avoided as it can have significant effects on the development and reproductive function of smolts.

Experimental Approaches for Characterizing the Endocrine-Disrupting Effects of Environmental Chemicals in Fish

Increasing industrial and agricultural activities have led to a disturbing increase of pollutant discharges into the environment. Most of these pollutants can induce short-term, sustained or delayed impacts on developmental, physiological, and behavioral processes that are often regulated by the endocrine system in vertebrates, including fish, thus they are termed endocrine-disrupting chemicals (EDCs). Physiological impacts resulting from the exposure of these vertebrates to EDCs include abnormalities in growth and reproductive development, as many of the prevalent chemicals are capable of binding the receptors to sex steroid hormones. The approaches employed to investigate the action and impact of EDCs is largely dependent on the specific life history and habitat of each species, and the type of chemical that organisms are exposed to. Aquatic vertebrates, such as fish, are among the first organisms to be affected by waterborne EDCs, an attribute that has justified their wide-spread use as sentinel species. Many fish species are exposed to these chemicals in the wild, for either short or prolonged periods as larvae, adults, or both, thus, studies are typically designed to focus on either acute or chronic exposure at distinct developmental stages. The aim of this review is to provide an overview of the approaches and experimental methods commonly used to characterize the effects of some of the environmentally prevalent and emerging EDCs, including 17 α-ethinylestradiol, nonylphenol, BPA, phthalates, and arsenic; and the pervasive and potential carriers of EDCs, microplastics, on reproduction and growth. In vivo and in vitro studies are designed and employed to elucidate the direct effects of EDCs at the organismal and cellular levels, respectively. In silico approaches, on the other hand, comprise computational methods that have been more recently applied with the potential to replace extensive in vitro screening of EDCs. These approaches are discussed in light of model species, age and duration of EDC exposure.

Distribution patterns and ecological risk of endocrine-disrupting chemicals at Qingduizi Bay (China): A preliminary survey in a developing maricultured bay

The occurrence and estrogenic activities of seven phenolic endocrine-disrupting chemical (EDC) compounds (nonylphenol (NP), octylphenol (4-OP), 2,4-dichlorophenol (2,4-DCP), 4-tertbutylphenol (4-t-BP), 4-tert-octylphenol (4-t-OP), tetrabromobisphenol A (TBBPA), and bisphenol A (BPA)) in the sediments of Qingduizi Bay (NorthernYellow Sea, China) in superficial sediments were investigated to evaluate their potential ecological impacts on the health of aquaculture organisms. All compounds, except 4-OP and 4-t-BP, were recorded in most sampling sites (1.06-28.07 ng g^-1 dw in maricultural ponds (MPs), 1.98-8.22 ng g^-1 dw in outer bay (OB)). BPA and 4-t-OP were the predominant EDC compounds in MPs and OB, respectively. Correlation between BPA and 4-t-OP indicated these compounds may share a similar source or pathway. Analyzed estrogenic activity revealed a low risk of total EDCs. The ranking of risk quotient showed 4-t-OP posed a median risk and TBBPA posed a high risk to the aquatic ecosystem.

Long-term exposure to waterborne nonylphenol alters reproductive physiological parameters in economically important marine fish

Low concentrations of nonylphenol (NP) in aquatic environment can induce drastic effects on the endocrine system in animals. In this study, we examined the modulatory effects of NP on reproductive and physiological parameters in juveniles of the red seabream and black rockfish following waterborne NP exposure (0, 1, 10, and 50 μg L^-1) for 60 days. In red seabream exposed to 50 μg L^-1 NP, plasma levels of 17β-estradiol (E2) and 11-ketotestosterone (11-KT) were significantly lower at 30 and 60 days, while E2 levels were slightly higher in 10 μg L^-1-exposed individuals at day 30. Similarly, significantly lower levels of E2 and 11-KT were observed in 10 and 50 μg L^-1-exposed black rockfish at 60 days, whereas the E2 level was higher in 1 μg L^-1-exposed individuals at day 30. After exposure to NP, plasma and mRNA levels of vitellogenin (VTG) were significantly higher in both species at 30 and 60 days, similar to the inducible effects from synthetic estrogen. Plasma cortisol levels were significantly elevated by relatively higher concentrations of NP (10 and 50 μg L^-1) at 30 and 60 days. Finally, 60 days of exposure of 50 μg L^-1 NP significantly decreased the gonadosomatic index (GSI) and increased the hepatosomatic index (HSI) in both species. The results obtained from this study provide an evidence of the endocrine disrupting potential of waterborne NP on early stages of economically important marine fish. The NP-triggered endocrine modulation can induce effects on the development of reproductive and metabolic organs in fish species.

Female masculinization and reproductive success in Cnesterodon decemmaculatus (Jenyns, 1842) (Cyprinodontiforme: Poeciliidae) under anthropogenic impact

Aquatic organisms are exposed to a myriad of chemical compounds, with particular concerns focused on endocrine disruptors. Growing scientific evidence indicates that these compounds interfere with normal endocrine function and could affect the reproductive system of humans and wildlife. We analyzed the proportion of masculinized females, defined by elongation and fusion of the anal fin rays, and the extent of masculinization, masculinization index, defined by anal fin length divided by the standard length, of Cnesterodon decemmaculatus resident to areas of agricultural and urban-industrial activities in the Arroyo Colorado basin. Additionally, a bioassay was carried out to assess the potential effects of masculinization on reproductive success, measured as the number of viable progenies, using pregnant females from the site downstream of the urban-industrial zone. Masculinized females were observed in all sampling sites, particularly downstream of the urban-industrial area, where over 80% of females presented abnormal sexual characteristics and the highest masculinization index was registered. In the laboratory, masculinized adult females showed male mating behavior, and survival of their progeny was lower than those of normal females. To our knowledge, this is the first report of endocrine disruption in field-collected C. decemmaculatus, and the first evaluation of the reproductive success of masculinized females. Finally, our results support C. decemmaculatus as an excellent sentinel species due to its wide distribution, easy culture in laboratory conditions, and its potential capability to respond to sources of pollution, particularly endocrine disruptors.

Contamination and risk implications of endocrine disrupting chemicals along the coastline of China: A systematic study using mussels and semipermeable membrane devices

A systematic study has been carried out to assess the contamination of endocrine disrupting chemicals (EDCs) in five highly urbanized coastal cities spanning from temperate to subtropical environments along the coastline of China. In each of these cities, species of native mussels (Mytilus galloprovincialis, M. coruscus or Perna viridis) were deployed alongside with semipermeable membrane devices (SPMDs) for one month at a reference site and a polluted site. The level of 4-nonylphenol (4-NP), bisphenol A (BPA), 17β-estradiol (E2) and 17α-ethynylestradiol (EE2) in SPMDs and transplanted mussels were determined and compared. The concentration of EDCs in mussels from polluted sites of Qingdao and Shenzhen ranged from 99.4±9.40 to 326.1±3.16ng/g dry wt. for 4-NP, Dalian and Shanghai from 170.3±4.00 to 437.2±36.8ng/g dry wt. for BPA, Dalian and Shenzhen from 82.9±3.03 to 315.6±6.50ng/g dry wt. for E2, and Shenzhen and Shanghai from 124.5±3.25 to 204.5±9.26ng/g dry wt. for EE2, respectively. These results demonstrate that concentrations of EDCs in mussels along the coastline of China are substantially higher than levels reported in mussels and seafood elsewhere. Despite high levels of EDCs and per capita seafood consumption in China, analysis indicated that 4-NP and BPA intake from mussels at polluted sites per se are still below the Tolerable Daily Intake (TDI). In contrast, the daily intake of E2 and EE2 (6.5 and 5.5μg/person/day, respectively) from mussel consumption exceeded the Acceptable Daily Intake (ADI) established by the WHO, USA and Australia by large margins, suggesting significant public health risks. A strong correlation was found between EDC concentrations in SPMDs and transplanted mussels, and the advantages of using mussels and SPMDs for monitoring EDCs in the aquatic environment are discussed.

Seasonal and spatial distribution of 4-nonylphenol and 4-tert-octylphenol in the sediment of Kaohsiung Harbor, Taiwan

The 4-nonylphenol (4-NP) and 4-tert-octylphenol (4-t-OP) were investigated in the surface sediments of Kaohsiung Harbor, Taiwan. The concentrations were between 18 and 27,882 ng g(-1)dw (average 101 ± 3,580 ng g(-1)dw) and 1.1 and 1,150 ng g(-1)dw (average 44 ± 174 ng g(-1)dw) for 4-NP and 4-t-OP, respectively. The concentrations of 4-NP and 4-t-OP in the river mouths' sediments are apparently higher and gradually decrease nearer the Harbor. The results showed that the river mouths' alkylphenol (AP) concentration in the wet season was higher than that in the dry season; in the channels and Harbor entrances, the AP values in the dry season were similar or even higher than those in the wet season. The correlation analysis indicated that total organic carbon (TOC) and organic matter (OM) played an important role in controlling the concentration level of 4-NP and 4-t-OP in the sediments. However, in the pollution hotspot, the direct inflow of pollutants would be the crucial factor that determines the concentration and distribution of organic pollutants in sediments. According to the evaluation of the potential ecological risk, the 4-NP concentration in the harbor had an 87% probability of exceed PNEC (39 ng g(-1), predicted no effect concentration) which means that the sediments of Kaohsiung Harbor probably pose a potential ecological risk to aquatic life, as is especially the case with those in the river mouths with relatively high EEQ values (estrogen equivalent concentration).

Parental effects of endocrine disrupting compounds in aquatic wildlife: Is there evidence of transgenerational inheritance?

The effects of endocrine disrupting compounds (EDCs) on aquatic wildlife are increasingly being recognized for their complexity. Investigators have detected alterations at multiple levels of biological organization in offspring exposed to EDCs through the blood or germ line of the parents, suggesting that generational consequences of EDCs are evident. Exposure to EDCs through the parents is concerning because if the resulting phenotype of the offspring is heritable and affects fitness, then evolutionary consequences may be evident. This review summarizes the evidence for transgenerational effects of EDCs in aquatic wildlife and illustrates cases where alterations appear to be transmitted maternally, paternally, or parentally. The literature indicates that EDC exposure to the parents induces developmental, physiological, endocrinological, and behavioral changes as well as increased mortality of offspring raised in clean environments. What is lacking, however, is a clear demonstration of heritable transgenerational effects in aquatic wildlife. Therefore, it is not known if the parental effects are the result of developmental or phenotypic plasticity or if the altered phenotypes are durably passed to subsequent generations. Epigenetic changes to gene regulation are discussed as a possible mechanism responsible for EDC induced parental effects. Additional research is needed to evaluate if heritable effects of EDCs are evident in aquatic wildlife, as has been demonstrated for terrestrial mammals.

Exploring the impacts of two separate mixtures of pesticide and surfactants on estrogenic activity in male fathead minnows and rainbow trout

In this study, male fathead minnows (FHM) (Pimephales promelas) and juvenile rainbow trout (RT; Oncorhynchus mykiss) were exposed to two different surfactant mixtures of analytical-grade nonlyphenol, 4-tert octyphenol, octylphenol ethoxylates, nonylphenol ethoxylates, and the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). After a 7-days exposure to environmentally relevant concentrations of these compounds, there was no difference in the relative mRNA expression of vitellogenin (VTG) in male juvenile RT exposed to individual compounds or the 2,4-D-surfactant mixture compared with the control. In male FHM, there was a significant increase in VTG mRNA expression in the high individual treatments of 2,4-D and the surfactants but not the 2,4-D-surfactant mixtures compared with the control. These results were compared with another study exposing male FHM to individual and a mixture of alkylphenols and alkylphenol ethoxylates in two different combinations with the herbicide diuron and the insecticide bifenthrin. There were no differences in the relative expression of VTG mRNA amongst individual exposures and the control. Interestingly, when the ethoxylate mixture was combined with diuron, there was a significant decrease in the relative mRNA expression of VTG compared with the control. However, when the ethoxylate mixture was combined with both diuron and bifenthrin, there was a significant increase in the relative mRNA expression of VTG in male compared with all other groups in the multichemical mixture. The results of this study highlight differences between species and measurements of VTG in assessing the risk of mixtures to aquatic organisms.

Characteristics of nonylphenol and bisphenol A accumulation by fish and implications for ecological and human health

Fish populations constitute an important part of aquatic ecosystems. Thus, their accumulation of nonylphenol (NP) and bisphenol A (BPA) may pose risks to ecosystems and human health. This study analyzed the concentrations of NP and BPA in four types of fishes (i.e., wild/farmed freshwater fishes and wild/farmed marine fishes). Wild freshwater fishes contained higher concentrations of NP and BPA than the other three types of fishes. The concentrations of NP in the wild freshwater fishes ranged from 1.01 to 277 μg/kg ww, with bioconcentration factors (BCFs) and biota-sediment accumulation factors (BSAFs) ranging from 74.0 to 2.60 × 10(4)L/kg and from 0.003 to 18.3, respectively. The wild freshwater fishes contained relatively low amounts of BPA, varying from ND to 25.2 μg/kg ww, with the BCFs and BSAFs ranging from 1.00 to 274L/kg and from 0.003 to 3.40, respectively. Five fish species particularly showed high BCFs and BSAFs, indicating that they could be an important source of NP for higher trophic levels, most likely resulting in ecological risks. The demersal fishes showed a greater ability to accumulate NP than the pelagic ones. The fact that the 95th percentile values of the risk quotient (RQ) for NP and BPA were higher than the acceptable threshold indicated that these two compounds would have adverse effects on aquatic organisms in Taiwanese rivers. The consumption of wild marine fishes had the highest 95th percentile values of hazard quotient (HQ) for NP and BPA among the four types of fishes, particularly for the population aged 0-3 years. However, the 95th percentile values of HQ for NP and BPA were all less than 1, suggesting that exposure to NP and BPA through fish consumption posed no remarkable risk to human health in Taiwan.

Effects of nonylphenol and ethinylestradiol on copper redhorse (Moxostoma hubbsi), an endangered species

The copper redhorse, Moxostoma hubbsi, is an endangered species endemic to Quebec. The presence of contaminants, in particular endocrine disrupting chemicals (EDCs), in its habitat has been advanced as partly responsible for the reproductive difficulties encountered by the species. In the present study, immature copper redhorse were exposed to the estrogenic surfactant nonylphenol (NP; 1, 10 and 50µg/l) and the synthetic estrogen 17α-ethinylestradiol (EE2; 10ng/l) for 21 days in a flow-through system. The endpoints investigated included general health indicators (hepatosomatic index and hematocrit), thyroid hormones, sex steroids, brain aromatase activity, plasma and mucus vitellogenin (VTG), cytochrome P4501A protein expression and ethoxyresorufin-O-deethylase activity, heat shock protein 70 (HSP70) and muscle acetylcholinesterase. Exposure to 10ng EE2/l significantly increased brain aromatase activity. Exposure to 50µg NP/l resulted in a significant reduction of plasma testosterone concentrations and a significant induction of hepatic HSP70 protein expression. NP at 50µg/l also induced plasma and mucus VTG. The presence of elevated VTG levels in the surface mucus of immature copper redhorse exposed to NP, and its correlation to plasma VTG, supports the use of mucus VTG as a non-invasive biomarker to evaluate copper redhorse exposure to EDCs in the environment and contribute to restoration efforts of the species. The results of the present study indicate that exposure to high environmentally relevant concentrations of NP and EE2 can affect molecular endpoints related to reproduction in the copper redhorse.

Complex effects of two presumably antagonistic endocrine disrupting compounds on the goldfish Carassius aumtus: a comprehensive study with multiple toxicological endpoints

We studied the effects of endocrine disrupting compounds nonylphenol (NP) and letrozole (LE) on the male goldfish Carassius aumtus. Exposure to NP (20 μg l(-1)) alone caused a significant up-regulation in the expression of aromatase, estrogen receptors and vitellogenin (VTG) genes, an increase in hepatic and plasma VTG concentration, but no obvious testicular impairment. Exposure to LE (1 mg kg(-1)) alone resulted in a significant decline in aromatase activity, reduced levels of plasma 17β-estradiol (E2), and enhanced sperm maturation. Co-exposure with LE (1 mg kg(-1)) could only partially affect some of the estrogenic effects caused by NP (20 μg l(-1)) (i.e. expression of hepatic and brain estrogen receptor genes, hepatic VTG concentration), but inhibit other estrogenic effects (i.e. brain and testicular aromatase activity, plasma E2). In addition, co-exposure resulted in impairment of liver mitochondria (i.e. detachment of ridges from the membrane, and uneven distribution of the cytoplasm with clusters of glycogen granules), but did not cause significant damage to the testes (i.e. the morphology, the spermatogonia and spermatozoa densities). Our results clearly showed that nonylphenol and letrozole co-exposure could induce profound effects on fish, and highlighted the importance of adopting multiple toxicological endpoints when evaluating the combined effects of endocrine disrupting compounds.

Intersex occurrence in rainbow trout (Oncorhynchus mykiss) male fry chronically exposed to ethynylestradiol

This study aimed to investigate the male-to-female morphological and physiological transdifferentiation process in rainbow trout (Oncorhynchus mykiss) exposed to exogenous estrogens. The first objective was to elucidate whether trout develop intersex gonads under exposure to low levels of estrogen. To this end, the gonads of an all-male population of fry exposed chronically (from 60 to 136 days post fertilization – dpf) to several doses (from environmentally relevant 0.01 µg/L to supra-environmental levels: 0.1, 1 and 10 µg/L) of the potent synthetic estrogen ethynylestradiol (EE2) were examined histologically. The morphological evaluations were underpinned by the analysis of gonad steroid (testosterone, estradiol and 11-ketotestosterone) levels and of brain and gonad gene expression, including estrogen-responsive genes and genes involved in sex differentiation in (gonads: cyp19a1a, ER isoforms, vtg, dmrt1, sox9a2; sdY; cyp11b; brain: cyp19a1b, ER isoforms). Intersex gonads were observed from the first concentration used (0.01 µg EE2/L) and sexual inversion could be detected from 0.1 µg EE2/L. This was accompanied by a linear decrease in 11-KT levels, whereas no effect on E2 and T levels was observed. Q-PCR results from the gonads showed downregulation of testicular markers (dmrt1, sox9a2; sdY; cyp11b) with increasing EE2 exposure concentrations, and upregulation of the female vtg gene. No evidence was found for a direct involvement of aromatase in the sex conversion process. The results from this study provide evidence that gonads of male trout respond to estrogen exposure by intersex formation and, with increasing concentration, by morphological and physiological conversion to phenotypic ovaries. However, supra-environmental estrogen concentrations are needed to induce these changes.

Effects of 4-nonylphenol on balance of steroid and thyroid hormones in sexually immature male yellowfin seabream (Acanthopagrus latus)

Nonylphenol (NP) is an endocrine disrupting chemical which has been shown to be able to modulate the endocrine system of various organisms by different mechanisms. The objective of this study was to investigate the potential effects of 4-NP on steroid and thyroid hormone levels in sexually immature male yellowfin seabream (Acanthopagrus latus), a protandrous hermaphrodite species. For this, the fish were injected with ascending doses (10, 50, 100, and 200 μg g(-1) body weight) of 4-nonylphenol (4-NP) or vehicle during 2 weeks. After 7 and 14 days the fish were anesthetized, blood sample were collected and plasma steroid and thyroid hormone concentrations were quantified by radioimmunoassay. The result showed that 4-NP induced a significant increase in 17β-etradiol levels at dose 10 μg g(-1) , while the levels of this hormone in the higher doses decreased compared with the control group. However, 4-NP treatment did not have any significant effect on plasma levels of testosterone. In addition, it was observed that 4-NP affect the level of thyroid hormones in fish. Plasma thyroxine levels increased in a dose-dependent manner after 7 and 14 days of the exposure. In contrast, a significant decrease in triiodothyronine levels was observed during the experiment period. Moreover, no significant change was detected for thyroid stimulating hormone levels in 4-NP-treated fish. These results indicated that 4-NP could lead to disturb the balance of steroid and thyroid hormones with potential consequences for sexually immature male yellowfin seabream.

Short-term responses of selected endocrine parameters in juvenile rainbow trout (Oncorhynchus mykiss) exposed to 4-nonylphenol

The synthetic organic compound 4-nonylphenol (4-NP) has been shown to have a wide range of adverse effects on the endocrine system of various animals including fish. The present study evaluated the potential effects of 4-NP on vitellogenin (VTG) synthesis, steroid, and thyroid hormone concentrations in both juvenile male and female rainbow trout ( Oncorhynchus mykiss). Fish were exposed by intraperitoneal injection to different doses of 4-NP (1, 10, 50, and 100 μg g−1) or vehicle (coconut oil) over a period of 14 days. Blood samples were collected 7 and 14 days after initiation of treatment. Plasma VTG levels in 4-NP-treated fish were detected by sodium dodecyl sulfate polyacrylamide gel electrophoresis as a high molecular weight protein band of 180 KDa. In addition, plasma VTG concentrations were quantified indirectly using plasma alkali-labile phosphate (ALP) and plasma calcium. Both ALP and calcium levels in plasma showed similar and parallel increase patterns after exposure to 4-NP that were significantly higher compared with controls. The analysis of plasma sex steroid levels revealed a significant increase in 17β-estradiol and testosterone in plasma of juvenile males and females, respectively. Furthermore, a significant increase was observed in plasma cortisol levels. On the other hand, 4-NP decreased both plasma triiodothyronine and thyroxine after 7 and 14 days of treatment. These results suggest that 4-NP can affect different parts of the endocrine system, which may lead to serious impairments in physiological homeostasis of juvenile rainbow trout.

Seasonal variation of nonylphenol concentrations and fluxes with influence of flooding in the Daliao River Estuary, China

Nonylphenol is an endocrine disruptor with harmful effects including feminization and carcinogenesis on various organisms. This study aims to investigate the distribution and ecological risks of nonylphenol in the Daliao River Estuary, China. Nonylphenol, together with other phenolic endocrine disruptors (bisphenol A, 4-t-butylphenol, 4-t-octylphenol, and 2,4-dichlorophenol), was detected in surface water and sediment on three cruises in May 2009, June 2010, and August 2010, respectively. A large flooding occurred during our sampling campaign in August and its effect on nonylphenol concentrations and fluxes in the estuary was therefore evaluated. The results showed that nonylphenol with a concentration range between 83.6-777 ng l(-1) and 1.5-456 ng g(-1) dw in surface water and sediment was the most abundant among the phenolic compounds, accounting for 59.1-81.0 and 79.9-92.1 % of the total phenolic concentration in surface water and sediment, respectively. The concentrations recorded in May and June were comparable, whereas those in August were considerably higher, mainly due to the flush of flooding. The flooding also caused a 50 times increase in nonylphenol flux from the estuary into the adjacent Bohai Sea. Nonylphenol concentrations in the estuary have exceeded the threshold level of undesirable effects with a potential risk of harm to local species, especially benthic organisms.

The potential role of water quality parameters on occurrence of nonylphenol and bisphenol A and identification of their discharge sources in the river ecosystems

Nonylphenol (NP) and bisphenol A (BPA) have attracted great attention due to their estrongenic activities and occurrence in different environments. This study investigated concentrations of NP and BPA in water and sediments of 16 major rivers in Taiwan to determine their association with water quality parameters on their distribution. The sources of NP and BPA discharged into river environments were also identified. The results showed that concentrations of NP and BPA were in the range of 0.02-3.94 and 0.01-44.65μgL(-1) in water and 6.59-47797.69 and 0.37-491.54μgkg(-1) dry weight in sediments. High levels of NP and BPA in water and sediments were measured in sampling sites near highly industrialized and urbanized areas. Construction of the sewage system and wastewater treatment plant has decreased these chemicals discharged into Love River. Dilution effects and erosion of surface sediments in the high-flow season resulted in lower concentrations of NP and BPA detected in sediments of most rivers than those in the low-flow season. Occurrence characteristics of NP and BPA in water and sediments were mainly related to organic carbon contents in sediments and several water quality parameters such as dissolved oxygen, pH, concentrations of ammonia-nitrogen and total organic carbon in water. Effluents from NP/BPA-related factories appeared to be the major discharge sources of NP and BPA. Use and waste of BPA-containing products in household activity was the another discharge source of BPA, but handling NP-containing products became an important source of NP only in the low-flow season.

HPLC-FLD determination of 4-nonylphenol and 4-tert-octylphenol in surface water samples

A simple, sensitive and reliable HPLC-FLD method for the routine determination of 4-nonylphenol, 4-NP and 4-tert-octylphenol, 4-t-OP content in water samples was developed. The method consists in a liquid-liquid extraction of the target analytes with dichloromethane at pH  3.0-3.5 followed by the HPLC-FLD analysis of the organic extract using a Zorbax Eclipse XDB C8 column, isocratic elution with a mixed solvent acetonitrile/water 65:35, at a flow rate of 1.0 mL/min and applying a column temperature of 40°C. The method was validated and then applied with good results for the determination of 4-NP and 4-t-OP in Ialomiţa River water samples collected each month during 2006. The concentration levels of 4-NP and 4-t-OP vary between 0.08-0.17 μg/L with higher values of 0.24-0.37 μg/L in the summer months for 4-NP, and frequently <0.05 μg/L but also between 0.06-0.09 μg/L with higher values of 0.12-0.16 μg/L in July and August for 4-t-OP and were strongly influenced by sesonial and anthropic factors. The method was also applied on samples collected over 2 years 2007 and 2008 from urban wastewaters discharged into sewage or directly into the rivers by economic agents located in 30 Romanian towns. Good results were obtained when the method was used for analysis of effluents discharged into surface waters by 16 municipal wastewater treatment plants, during the year 2008.

Reproductive biomarkers to identify endocrine disruption in Clarias gariepinus exposed to 4-nonylphenol

The present study investigated the hormones concentrations and gonads alterations of Clarias gariepinus caused by sublethel concentrations of 4-nonylphenol (0, 0.05, 0.08 and 0.1 mg/l). The changes in the activities of the hormones after exposure to these sublethel doses of 4-nonylpenol referred to endocrine disruption in Clarias gariepinus in association with histopathological changes in reproductive tissues. The levels of thyroid stimulating hormone (TSH), triiodothyronine (T3), total thyroxine (T4), follicle stimulating hormone (FSH), luteinizing hormone (LH) and testosterone concentrations significantly decreased (P<0.05) in the treated fish in comparison with control. 17-β-estradiol increased significantly (P<0.05) with 4-nonylphenol concentrations increase. Reduction in the gonadosomatic index was evident with increase of sublethal doses of 4-nonylphenol. The histopathological changes of NP-treated were recorded in gonads of Clarias gariepinus reflecting their sensitivity to NP-estrogenic like effects.

Effects of 17α-ethynylestradiol and nonylphenol on liver and gonadal apoptosis and histopathology in Chalcalburnus tarichi

Chalcalburnus tarichi is an endemic cyprinid fish living in the Lake Van basin located in the Eastern Turkey. Fish (3+ ages) were exposed to 17α-ethynylestradiol (EE(2); 1, 10, 100 ng L(-1); nominal concentrations) and nonylphenol (NP; 10, 60, 200 μg L(-1) ; nominal concentrations) for 32 days under semistatic daily renewal conditions. The exposure period was followed by an evaluation of liver and gonadal apoptosis and gonad histopathology in males and females. Exposure to the highest concentrations of EE(2) (100 ng L(-1)) and NP (200 μg L(-1) ) caused significant increases in the extent of apoptosis in liver and gonads. Treatment with 100 ng L(-1) of EE(2) and 200 μg L(-1) NP increased the number of TUNEL positive hepatocytes significantly in both sexes compared to controls. The rates of apoptosis in testicular germ cells and ovarian follicular cells were significantly greater at the same concentrations. Exposure to EE(2) (100 ng L(-1)) and NP (60 and 200 μg L(-1)) caused thickening of interstitial connective tissue (fibrosis) in the seminiferous tubule wall and testis-ova formation in males. In females treated with 100 ng L(-1) EE(2) , increased percentage of atretic ooctytes and fibrotic areas in the ovarian somatic stromal tissue were found in the ovaries. Increase in atresia, without a statistical significance, and fibrotic stromal tissue were also noted in 60 and 200 μg L(-1) NP treatments. Results suggest that EE(2) - and NP-dependent hepatotoxicity and gonadotoxicity are causally related to the increase in apoptosis in C. tarichi.

Development of an enzyme-linked immunosorbent assay for quantifying vitellogenin in Pacific salmon and assessment of field exposure to environmental estrogens

A competitive enzyme-linked immunosorbent assay was developed to quantitate vitellogenin (VTG) in plasma and serum of coho (Oncorhynchus kisutch) and chinook (O. tshawytscha) salmon. The working range of the assay was 9 to 313 ng/ml (80-20% binding), with 50% binding at 54 ng/ml. The intra-assay and interassay variations at approximately 50% binding were 8.1% (n = 9) and 9.0% (n = 9), respectively. Dilution curves of plasma or serum from coho and chinook females and estrogen-treated males were parallel to the purified coho VTG standard curve. Male plasma samples could be assayed at a minimum dilution of 1:40 (chinook) or 1:75 (coho) without assay interference because of high sample concentration, whereas minimum acceptable dilutions of male serum samples were 1:200 (chinook) or 1:600 (coho). Identification of proper techniques for preserving VTG integrity in plasma and serum samples showed that VTG from both species was robust; both sample types required no protease inhibitor despite subjection to two freeze-thaw cycles. To test its applicability, this assay was used to measure VTG in out-migrating juvenile chinook that were collected from urban and nonurban areas in Puget Sound, Washington, USA. Results showed a small but significant plasma VTG elevation at two urban sites, suggesting that these juveniles may be exposed to environmental estrogens at an early life stage. Also, wild fish tended to have higher plasma VTG levels than hatchery fish collected in the field. Elevation of mean VTG levels was similar to that previously reported in male English sole from the same area, where both males and females exhibited alterations in timing of spawning.

Comparative toxicity and bioconcentration of nonylphenol in freshwater organisms

Degradation of alkylphenol ethoxylates to more persistent alkylphenols such as nonylphenol occurs in wastewater treatment plants where nonylphenol is released to aquatic systems. In this study, acute and chronic tests were conducted to determine the toxicity and bioconcentration of nonylphenol to freshwater organisms for use in deriving national water quality criteria. Acute median effect concentrations (EC50s) based on loss of equilibrium, immobility, and lethality for species representing several taxonomic groups ranged from 21 to 596 microg/L. The EC50s were up to a factor of 2 less than median lethal concentrations (LC50s) and decreased with time over the test periods of 24 to 96 h. In chronic tests, early life stages of rainbow trout were 14 times more sensitive to nonylphenol than in acute tests and approximately 20 times more sensitive than Daphnia magna exposed over their complete life cycle. Comparisons of chronic test endpoints showed that 20% effect concentrations (EC20s), determined by regression testing, and chronic values, determined by hypothesis testing, were similar for both the rainbow trout and Daphnia magna. The lowest mean tissue-effect concentrations of nonylphenol appeared to be greater for the fathead minnow than bluegill, and ranged from approximately 130 to 160 microg/g after 96-h exposure and from approximately 20 to 90 microg/g after 28-d exposure. Mean lipid normalized bioconcentration factors (BCFs) associated with no-effect concentrations were approximately 180 and 50 for the fathead minnow and bluegill, respectively. The present test results suggest that long-term exposures to nonylphenol at concentrations found in some surface waters could adversely impact sensitive components of freshwater communities.

The immune response of juvenile Atlantic cod (Gadus morhua L.) to chronic exposure to produced water

Produced water (PW) is the main discharge from the offshore oil industry and contains oil-derived compounds such as poly-aromatic hydrocarbons, phenols, alkylphenols, and heavy metals. Studies suggest that PW discharges may affect the biota over larger areas from the oil drilling sites at sea than originally predicted. We investigated the effects of chronic exposure to PW on some aspects of juvenile Atlantic cod immunity, stress response and growth by intermittently exposing fish to 0, 100 or 200 ppm of PW for 22 weeks. No significant effects of PW were observed on growth, hepatosomatic index, condition factor or plasma cortisol. The respiratory burst (RB) of circulating leukocytes was significantly elevated in the 100 ppm group only, while the RB of head-kidney leukocytes was significantly decreased in both the 100 and 200 ppm groups. Significant up-regulation of the mRNA expression of beta-2-microglobulin, immunoglobulin-M light chain and interleukins-1beta and -8 was observed in the 200 ppm group, while the down-regulation of interferon stimulated gene 15 was obvious for both the 100 and 200 ppm groups. The results suggest that chronic exposure to environmentally relevant concentrations of PW causes modulations of the immune system of juvenile Atlantic cod with most immune parameters being stimulated, potentially resulting in an energetic cost that may be detrimental to the fish.

Effects on guppy brain aromatase activity following short-term steroid and 4-nonylphenol exposures

Brain estrogen production, performed by the enzyme aromatase, can be disrupted/affected in teleost fish exposed to endocrine disruptors found in polluted aquatic environments. The guppy (Poecilia reticulata) was previously studied and confirmed to suffer negative effects on reproductive behaviors following inhibition of the brain aromatase reaction. Here adult guppies (Poecilia reticulata) of both genders were subjected to known endocrine disruptors: the androgen androstenedione (A), the synthetic estrogen 17alpha-ethinylestradiol (EE(2)), and the estrogenic surfactant 4-nonylphenol (NP), at high (50 microg/L) and at environmentally relevant concentrations (10 ng/L EE(2), 5 microg/L NP, and 0.7 microg/L A) for 2 weeks followed by measurements of brain aromatase activity (bAA). In the adult males, bAA was stimulated by A and EE(2) at 50 microg/L. Female activity was also stimulated by the higher estrogenic treatment. At environmentally relevant concentrations only the EE(2) treatment affected bAA, and only in males. The alkylphenolic substance NP produced no effect in either of the experiments, not on males nor females. The results indicate that short-term steroid treatments have stimulatory effects on guppy brain aromatase even at concentrations that can be found in the environment. We thus suggest bAA of adult guppies to be a suitable bioindicator of endocrine disruptors.

Effects of a weak oestrogenic active chemical (4-tert-pentylphenol) on pair-breeding and F1 development in the fathead minnow (Pimephales promelas)

A fish full life-cycle (FFLC) is the most comprehensive test to determine reproductive toxicity of chemicals to fish and this is likely to apply equally to endocrine active chemicals (EACs). However, FFLC tests use large numbers of animals, are expensive and time consuming. Alternative chronic tests, to the FFLC, potentially include sensitive life-stage windows of effect, such as sexual differentiation, early gonadal development and reproduction. In this paper, a fish pair-breeding study was applied to assess the biological effects of a weak environmental oestrogen, 4-tert-pentylphenol (4TPP), on reproduction and subsequent development of the F1 generation. The results of this study were then compared with the results for a published FFLC study, with this chemical. Fathead minnows (Pimephales promelas) were held in pairs and their reproductive performance assessed over two concurrent 21-day periods, the first without exposure to the test chemical, followed by the second with exposure to the test chemical, in a flow-through system at 25+/-1 degrees C. Embryos from two pairs, per treatment, were subsequently grown up in clean water until 90 days post-hatch to assess developmental effects of the parental exposure on the F1 generation. Nominal (measured geometric mean, time weighted) test concentrations of 4TPP were 56 (48), 180 (173) and 560 (570) microg l(-1). A significant decrease in fecundity was observed in all 4TPP exposed fish (mean number of eggs spawned per pair and number of spawns per pair) when compared to the solvent control. Vitellogenin (VTG) was significantly elevated in F0 males exposed to 560 microg 4TPPl(-1). Somatic endpoints, secondary sexual characteristics (SSC) and gonadosomatic index (GSI) were not affected by the 4TPP exposure. In the F1 generation, there were no treatment-related effects on hatching success, survival, growth, SSC or GSI. Histological examination of the gonads of the F1 fish revealed no treatment-related effects on sex ratio, sexual differentiation or sexual development. However, plasma VTG concentrations were significantly elevated in F1 male fish, derived from parents that had previously been exposed to 4TPP at concentrations of > or = 180 microg l(-1). These data show that the reproductive performance test is suitable for detecting weak environmental oestrogenic chemicals and that exposure of adult fish to oestrogens can result in altered biomarker expression (VTG) of the F1 generation. Our findings indicate that the reproductive performance test was as sensitive for detecting effects on reproduction when compared with a published FFLC test for 4TPP.

Elucidation of the dissociation pathways of electro-ionized estrone

With the future aim of using gas chromatography coupled with mass spectrometry to characterize the transformation products of estrone submitted to UV-photolysis or to waste water treatment plants, an interpretation of the electron impact mass spectrum of estrone is presented. Fragmentation mechanisms are proposed on the basis of high-resolution measurements performed with a magnetic sector analyzer. Multiple-stage mass spectrometry experiments were carried out using an ion trap mass spectrometer. The structures proposed for product ions were confirmed by the m/z shifts observed in the estrone-d(4) and estrone methyl ether electron ionization mass spectra. If the formation of some of the most abundant ions may easily be explained by alpha-cleavages and retro-Diels-Alder type rearrangements, complex mechanisms need to be considered to rationalize the formation of others. Isotope labelling allows discrimination of isobaric ions.

Biomarker candidate discovery in Atlantic cod (Gadus morhua) continuously exposed to North Sea produced water from egg to fry

In this study Atlantic cod (Gadus morhua) were exposed to different levels of North Sea produced water (PW) and 17beta-oestradiol (E(2)), a natural oestrogen, from egg to fry stage (90 days). By comparing changes in protein expression following E(2) exposure to changes induced by PW treatment, we were able to compare the induced changes by PW to the mode of action of oestrogens. Changes in the proteome in response to exposure in whole cod fry (approximately 80 days post-hatching, dph) were detected by two-dimensional gel electrophoresis and image analysis and identified by MALDI-ToF-ToF mass spectrometry, using a newly developed cod EST database and the NCBI database. Many of the protein changes occurred at low levels (0.01% and 0.1% PW) of exposure, indicating putative biological responses at lower levels than previously detected. Using discriminant analysis, we identified a set of protein changes that may be useful as biomarker candidates of produced water (PW) and oestradiol exposure in Atlantic cod fry. The biomarker candidates discovered in this study may, following validation, prove effective as diagnostic tools in monitoring exposure and effects of discharges from the petroleum industry offshore, aiding future environmental risk analysis and risk management.

The effects of contaminants in European eel: a review

European eel (Anguilla anguilla (L.)) stocks are in decline in most of their geographical distribution and their status is considered below safe biological limits. Recently, there is an increasing awareness that spawner quality might be an essential element in the decline of the species since pollution by bioaccumulating chemical substances may have a large impact on the reproduction success of the eel. This review gives an overview of the literature on the effects of contaminants on the European eel and on the consequences on the biology and fitness of the eel in order to document the role of pollution in its decline. A variety of contaminants have been found to affect the eel. These contaminants may cause disturbance of the immune system, the reproduction system, the nervous system and the endocrine system and effects were reported on several levels of biological organization, from subcellular, organ, individual up to even population level. More extensive research is needed in order to evaluate how pollutants are detrimental to eel populations. Getting a comprehensive overview of the quality (including contamination levels, biomarker responses, lipid content and condition) of the silver eel population all over Europe seems to be an essential and urgent objective for the European eel management.

Effects of chronic exposure to nonylphenol on locomotor activity and social behavior in zebrafish (Danio rerio)

Nonylphenol (NP), a xenoestrogen ubiquitously found in aquatic ecosystems, is of high environmental concern. The present work assessed the effects of exposure to NP on locomotor activity and social behavior in male and female zebrafish (Danio rerio), to evaluate the possible hazard of NP to fish behavior and to pursue a potential biomarker of NP contamination. Fish were randomly divided into six groups. Five groups were receiving 0.1, 1, 10, 50 and 100 microg/L nominal concentrations of NP for 60 days, respectively. A sixth control group was given the same treatment as the other five groups, but no NP. Locomotor activity, aggressive behavior, group preference and leaving shoal were examined. NP exposure showed marked influence on locomotor activity of the male zebrafish, whereas that of the female was not significantly affected by NP. Aggressive behavior and group preference were significantly affected by NP exposure in both male and female groups. Locomotor activity and aggressive behavior of the male and group preference of both male and female zebrafish were clearly inhibited at 100 microg/L NP. No significant alteration in leaving shoal was observed under NP exposure. The results suggested that changes in locomotor activity and aggressive behavior of the male and group preference of both male and female may be used as an ecologically relevant integrative biomarker of NP contamination.

Candidate biomarker discovery in plasma of juvenile cod (Gadus morhua) exposed to crude North Sea oil, alkyl phenols and polycyclic aromatic hydrocarbons (PAHs)

In this study we have investigated protein changes in plasma of juvenile Atlantic cod (Gadus morhua) induced by crude North Sea oil and North Sea oil spiked with alkyl phenols and polycyclic aromatic hydrocarbons, a surrogate produced water composition. Using a proteomic approach, we identified 137 differentially expressed proteins at different levels of crude oil exposure. Many of the induced protein changes occurred at low levels of exposure. The results obtained with protein expression profiles after exposure to oil and surrogate produced water indicate effects on fibrinolysis and the complement cascade, the immune system, fertility-linked proteins, bone resorption, fatty acid metabolism as well as increased oxidative stress, impaired cell mobility and increased levels of proteins associated with apoptosis. Although the number of individuals and samples in this study is limited within each treatment group, the protein changes observed in this study represent a first screening for potential biomarker candidates in cod plasma reflecting potential effects of crude oil and produced water exposure on fish.

Identification of estrogen-like effects and biologically active compounds in river water using bioassays and chemical analysis

The Nackdong River is the longest river in South Korea and passes through major cities that have several industrial complexes, including chemical, electric, and petrochemical complexes, and municipal characteristics such as apartment complexes. Along the river, the Gumi region has an electric industrial complex and an apartment complex that may be possible point sources of xenoestrogens such as phenolic compounds. To identify the causative chemicals for estrogenic activity in the river water of this region, bioassay-directed chemical analysis was performed. All samples from six sampling sites (an upstream point: S1; hot spot points: S2-1, S2-2, and S2-3; and downstream points: S3, and S4) showed estrogenic activity in the E-screen assay, with bio-EEQs (17beta-E(2)-equivalent quantities) ranging from 25.35-677.15 pg/L. Samples from S2-2, the sampling point downstream of the junction of stream water, and domestic and industrial wastewater, contained the highest estrogenic activity. Since the bio-EEQ of the organic acid fraction (F2) of the S2-2 sample had the highest activity (823.25 pg-EEQ/L) and F2 may contain phenolic compounds, GC-MS analyses for phenolic xenoestrogens were conducted with the organic acid fractions of the river water samples. Six estrogenic phenolic chemicals, 4-NP, BPA, 4-t-OP, 4-t-BP, 4-n-OP, and 4-n-HTP, were detected, with the highest concentrations (I-EEQ) found in S2-2 (231.80 pg/L). Among these phenolic chemicals, 4-NP was the most potent estrogen (bio-EEF; 8.12 x1 0(-5)) and acted as a full agonist. Furthermore, 4-NP was present at levels (2.0 microg/L in S2-2) that can induce VTG induction in fish (>1 microg/L). In addition, we confirmed that river water (S2-2) significantly increased serum VTG levels in crucian carp (Carassius auratus) in a fish exposure experiment under laboratory conditions. Therefore, phenolic xenoestrogens, especially 4-NP, may be the main causative compounds responsible for the estrogenic effect on the Nackdong River.

Determination of nonylphenol and short-chained nonylphenol ethoxylates in drain water from an agricultural area

Water samples from agricultural drains were tested for the presence of nonylphenol and nonylphenol mono- and diethoxylates. The analytes belong to biodegradation products of long-chained nonylphenol ethoxylates, which are used as additives in pesticide formulations. Quantification of these analytes was performed by HPLC with fluorescence detection after isolation by using multi-capillary polytetrafluoroethylene (PTFE) trap extraction. This newly developed technique allowed obtaining about 90% recovery of these analytes in synthetic samples and several percent lower recovery in real samples. Also, no additional sample cleaning was needed before chromatographic analysis. The limit of quantitation for all the analytes was 0.1 microg L(-1). The nonylphenol, nonylphenol mono- and diethoxylates were detected at the concentrations ranging from 0.5 to 6.0 microg L(-1), from 0.2 to 0.7 microg L(-1) and from below 0.02 to 0.4 microg L(-1), respectively. Concentrations of nonylphenol and its derivatives were higher in samples taken in spring than in summer.

Extraction and purification procedures for simultaneous quantification of phenolic xenoestrogens and steroid estrogens in river sediment by gas chromatography/ion trap mass spectrometry

A sensitive and simple method based on ultrasonication extraction with a hexane/acetone (2:1, v/v) mixture, followed by clean up of the extract by solid-phase extraction (SPE) and gas chromatography/mass spectrometry (GC/MS) detection, has been developed and validated for the analysis of 20 estrogenic endocrine-disrupting chemicals (EEDCs) including phenolic xenoestrogens, synthetic and natural estrogens in river sediment. After extraction and purification, analytes are derivatised with a BSTFA/TMCS/pyridine (49:1:50, v/v/v) mixture and quantified by GC/MS. The GC/MS method involves switching between electron ionisation (EI) and chemical ionisation (CI); it also switches between selected ion storage and tandem mass spectrometry detection. The applicability of the method has been demonstrated by analysing extracts of French river sediments for which bioanalytical tests (in vitro) had already shown that they were impacted by estrogenic endocrine disrupters. The biological contribution of all the products detected in each sediment extract was compared to the estrogenic activity measured by bioassays.

Sensitivity of brown trout reproduction to long-term estrogenic exposure

A decline in brown trout (Salmo trutta fario) catches has been reported in Switzerland, but at present the causative factors have not been clearly identified. Estrogen-active endocrine disrupters (EEDs) have been suggested as one possible explanation, since they are widespread in the aquatic environment and often found at elevated concentrations. In the present study the effects of long-term estrogenic exposure on the reproductive capability of brown trout were investigated. Adult fish were continuously exposed to an environmentally relevant mixture of the natural estrogens estrone (E1), 17beta-estradiol (E2) and the xenoestrogen 4-nonylphenol (NP); the average measured concentrations over the entire exposure time (n=9) were 14.0 ng/l (Min 8.1 and Max 20.6) for E1, 2.1 ng/l (Min 1.3 and Max 4.1) for E2 and 111.0 ng/l (Min 106.7 and Max 115.9) for NP. A solvent control served as negative control, and up to 10-fold higher mixture concentration than the environmentally relevant concentration served as positive control. The fish were exposed for 150 days from the onset of gonadal recrudescence until sexual maturation. Plasma vitellogenin (Vtg) was significantly induced by both concentrations of the estrogenic mixture, whereas effects on growth and fertility were only observed in fish exposed to the high mixture treatment. Fertilization success and offspring hatchability in brown trout exposed to the high mixture treatment were significantly reduced to 9% and 6%, respectively. Developmental time from fertilization until hatching, the percentage of larvae with malformations and survival of larvae, however, were not affected. The results suggest that a combination of estrogen-active compounds at environmentally relevant concentrations would not adversely affect those parameters of brown trout reproductive capability measured in this study. Plasma Vtg in male brown trout appeared to be more sensitive to (xeno)estrogen exposure than the measured reproductive effects.

Sexually disrupting effects of nonylphenol and diethylstilbestrol on male silver carp (Carassius auratus) in aquatic microcosms

Based on detected nonylphenol (NP) levels in aquaculture water, this study investigated sexually disrupting effects in mature male silver carp (Carassius auratus) exposed to NP and a positive control diethylstilbestrol (DES). The combined evidences of steroid hormone (17beta-estradiol, estrone and testosterone) levels and hispathological pictures showed that NP (10 microg/L) and DES could exert estrogenic effects through indirect mechanisms [i.e. increased estrogens levels (up to two times) and decreased androgen level in serum (down to 20-30%)], which might subsequently induce vitellogenin synthesis in liver. Environmental realistic concentrations of NP might be on the verge of inducing significant estrogenic effects in male silver carps. High amounts of NP and DES might be accumulated in fish serum, and the uptake by fish was possibly responsible for their quick attenuation in experimental tank water. NP and DES might have different metabolic mechanisms, the estrogenic effects of DES were more significant than those of NP.

Multigeneration assessment of nonylphenol and endosulfan using a model Australian freshwater fish, Melanotaenia fluviatilis

Changes over two generations in offspring and reproductive ability were recorded in crimson-spotted rainbowfish (Melanotaenia fluviatilis), a model Australasian freshwater fish, following a 24 h exposure to nominal nonylphenol concentrations of 50, 100, 500, 1000, 2250, and 5000 microg/L and following a 4 h exposure to nominal endosulfan concentrations of 1.0, 5.0, 10, 22, 33, and 50 microg/L. There were also four replicated control treatments: control 1 and 2 and solvent control 1 and 2, as well as "positive" female and male controls: 1 microg/L estradiol 1 and 2 and 1 microg/L testosterone 1 and 2. Results suggested that there may be some parental transfer of toxicants to embryos even over this short exposure period. Fertility of M. fluviatilis was reduced by a 24 h pulse exposure of adults to 100 microg/L nonylphenol and a 4 h exposure to 1.0 microg/L endosulfan. Hatch rates were significantly reduced after exposure to nonylphenol, endosulfan, and estradiol control but not in solvent controls and testosterone control. Significant correlations were found between reproductive and physiological parameters for nonylphenol and endosulfan exposed F0 adult rainbowfish. The major reproductive effects were on hatchability of the F1 generation and the gonadosomatic indices of male F1. The respective nominal NOEC and LOEC's for nonylphenol were 50 and 100 microg/L, and for endosulfan were <1.0 and 1 microg/L. These observed effects have the potential to significantly impact exposed rainbowfish populations through the observed approximately 45% reduction of hatchability and thus larval production.

Distribution characteristics of nonylphenol in Jiaozhou Bay of Qingdao and its adjacent rivers

Nonylphenol (NP) is an endocrine disruptor and causes harmful effects including feminization and carcinogenesis to various organisms. Consequently, its contamination in natural waters has received wide concerns. This study aims to investigate the seasonal variation and contamination level of nonylphenol in Jiaozhou Bay of Qingdao and its adjacent rivers. A total of 10 phenolic compounds including alkylphenol, chlorophenol and bisphenol A were measured in water, suspended solids and sediments in winter (January), spring (April) and summer (July) of 2005. The results showed that nonylphenol accounted for the majority of phenolic compounds and that its concentrations in Jiaozhou Bay ranged between 20.2-269 ng l(-1), 17.1-77.5 ng l(-1) and 3.6-299 ng g(-1)dw in surface water, suspended solids and surface sediment, respectively. There existed a significant correlation between nonylphenol in water and in suspended solids. The concentration of nonylphenol in water varied with seasons and generally showed a decreasing order of July>April>January. The concentrations of nonylphenol in the adjacent rivers were much higher with the maximum of 28600 ng l(-1) in surface water. The spatial distribution of nonylphenol in Jiaozhou Bay was influenced by freshwater discharge from the adjacent rivers as well as current circulation system within the bay. The pollution level of nonylphenol in Jiaozhou Bay was comparable to other highly polluted areas of the world and its possible effects on local organisms were discussed.

Concentration- and time-dependent effects of the synthetic estrogen, 17alpha-ethinylestradiol, on reproductive capabilities of the zebrafish, Danio rerio

Partial or full life-cycle tests are needed to assess the potential of endocrine-disrupting compounds (EDCs) to adversely affect development and reproduction of fish. Small fish species such as zebrafish, Danio rerio, are under consideration as model organisms for appropriate test protocols. The present study examines how reproductive effects resulting from exposure of zebrafish to the synthetic estrogen 17alpha-ethinylestradiol (EE2) vary with concentration (0.05 to 10 ng EE2 L(-1), nominal), and with timing/duration of exposure (partial life-cycle, full life-cycle, and two-generation exposure). Partial life-cycle exposure of the parental (F1) generation until completion of gonad differentiation (0-75 d postfertilization, dpf) impaired juvenile growth, time to sexual maturity, adult fecundity (egg production/female/day), and adult fertilization success at 1.1 ng EE2 L(-1) and higher. Lifelong exposure of the F1 generation until 177 dpf resulted in lowest observed effect concentrations (LOECs) for time to sexual maturity, fecundity, and fertilization success identical to those of the developmental test (0-75 dpf), but the slope of the concentration-response curve was steeper. Reproduction of zebrafish was completely inhibited at 9.3 ng EE2 L(-1), and this was essentially irreversible as a 3-mo depuration restored fertilization success to only a very low rate. Accordingly, elevated endogenous vitellogenin (VTG) synthesis and degenerative changes in gonad morphology persisted in depurated zebrafish. Full life-cycle exposure of the filial (F2) generation until 162 dpf impaired growth, delayed onset of spawning and reduced fecundity and fertilization success at 2.0 ng EE2 L(-1). In conclusion, results show that the impact of estrogenic agents on zebrafish sexual development and reproductive functions as well as the reversibility of effects, varies with exposure concentration (reversibility at < or = 1.1 ng EE2 L(-1) and irreversibility at 9.3 ng EE2 L(-1)), and between partial and full life-cycle exposure (exposure to 10 ng EE2 L(-1) during critical period exerted no permanent effect on sexual differentiation, but life-cycle exposure did).