Endocrine-disrupting effects of compounds in Danish streams

Monitoring of emerging contaminants of concern in the aquatic environment: a review of studies showing the application of effect-based measures

Water scarcity is increasingly a global cause of concern mainly due to widespread changes in climate conditions and increased consumptive water use driven by the exponential increase in population growth. In addition, increased pollution of fresh water sources due to rising production and consumption of pharmaceuticals and organic chemicals will further exacerbate this concern. Although surface water contamination by individual chemicals is often at very low concentration, pharmaceuticals for instance are designed to be efficacious at low concentrations, creating genuine concern for their presence in freshwater sources. Furthermore, the additive impact of multiple compounds may result in toxic or other biological effects that otherwise will not be induced by individual chemicals. Globally, different legislative frameworks have led to pre-emptive efforts which aim to ensure good water ecological status. Reports detailing the use and types of effect-based measures covering specific bioassay batteries that can identify specific mode of actions of chemical pollutants in the aquatic ecosystem to evaluate the real threat of pollutants to aquatic lives and ultimately human lives have recently emerged from monitoring networks such as the NORMAN network. In this review, we critically evaluate some studies within the last decade that have implemented effect-based monitoring of pharmaceuticals and organic chemicals in aquatic fauna, evaluating the occurrence of different chemical pollutants and the impact of these pollutants on aquatic fauna with special focus on pollutants that are contaminants of emerging concern (CEC) in urban wastewater. A critical discussion on studies that have used effect-based measures to assess biological impact of pharmaceutical/organic compound in the aquatic ecosystem and the endpoints measurements employed is presented. The application of effect-based monitoring of chemicals other than assessment of water quality status is also discussed.

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.

A field study of hemolymph yolk protein levels in a bivalve (Unio tumidus) and future considerations for bivalve yolk protein as endocrine biomarker

Induction of yolk protein in male fish is a recognized biomarker for estrogenic exposure because the estrogen-dependent induction mechanism is well investigated and there is a clear difference in yolk protein levels of unexposed males and females. Attempts have been made to use induction of bivalve yolk protein as biomarker for estrogenic exposure. However, several biomarker validation criteria have not yet been investigated e.g. an in-depth understanding of the induction mechanism and background variability is needed and reliable detection assays are yet to be developed. To obtain background knowledge about yolk protein levels freshwater bivalves (Unio tumidus) were collected in an uncontaminated Danish lake over the course of a year (33 collection dates). The hemolymph yolk protein concentration of 569 individuals was determined by a species specific enzyme-linked immunosorbent assay (ELISA) and male and female gonadal development cycles were established. The average yolk protein levels of males and females collected at each sampling date overlapped in some periods; the male and female range was 66,946 - 169,692 ng/mL and 88,731 - 681,667 ng/mL, respectively. Because male and female hemolymph yolk protein levels overlap, great care should be taken if yolk protein induction in bivalve hemolymph is considered as endocrine biomarker.

Enhanced degradation of BDE209 in spiked soil by ferrous-activated persulfate process with chelating agents

In order to maintain the quantity of ferrous ions, two eco-friendly chelating agents (CAs), i.e., sodium citrate (Citrate) and sodium gluconate (Glu), have been introduced into a traditional iron activated sodium persulfate (PS) system (Fe²⁺/PS). The results indicated that the PS/CA/Fe²⁺ oxidation could be an effective method for BDE209 removal. Effects of the chelating agents, reagents dosage, and pH were evaluated in batch experiments. Glu was observed to be more effective than citrate. In addition, the rate constants (k ₁) of BDE209 removal indicated a quadratic curve relationship with initial persulfate concentrations (k ₁ = -0.019 × [PS]₀² + 0.031 × [PS]₀ + 0.007, R ² = 0.933, [PS]₀ = 0.1-1.0 M) and a good linear relationship with initial ferrous contents (k ₁ = 0.109 × [Fe²⁺]₀ + 0.002, R ² = 0.943). Furthermore, as a reducing agent, ascorbic acid (H₂A) could enhance the degradation rate of BDE209, which might be because H₂A accelerated the transformation process from Fe³⁺- to Fe²⁺-gluconate complexes.

Novel associations between contaminant body burdens and biomarkers of reproductive condition in male Common Carp along multiple gradients of contaminant exposure in Lake Mead National Recreation Area, USA

Adult male Common Carp were sampled in 2007/08 over a full reproductive cycle at Lake Mead National Recreation Area. Sites sampled included a stream dominated by treated wastewater effluent, a lake basin receiving the streamflow, an upstream lake basin (reference), and a site below Hoover Dam. Individual body burdens for 252 contaminants were measured, and biological variables assessed included physiological [plasma vitellogenin (VTG), estradiol-17β (E2), 11-ketotestosterone (11KT)] and organ [gonadosomatic index (GSI)] endpoints. Patterns in contaminant composition and biological condition were determined by Principal Component Analysis, and their associations modeled by Principal Component Regression. Three spatially distinct but temporally stable gradients of contaminant distribution were recognized: a contaminant mixture typical of wastewaters (PBDEs, methyl triclosan, galaxolide), PCBs, and DDTs. Two spatiotemporally variable patterns of biological condition were recognized: a primary pattern consisting of reproductive condition variables (11KT, E2, GSI), and a secondary pattern including general condition traits (condition factor, hematocrit, fork length). VTG was low in all fish, indicating low estrogenic activity of water at all sites. Wastewater contaminants associated negatively with GSI, 11KT and E2; PCBs associated negatively with GSI and 11KT; and DDTs associated positively with GSI and 11KT. Regression of GSI on sex steroids revealed a novel, nonlinear association between these variables. Inclusion of sex steroids in the GSI regression on contaminants rendered wastewater contaminants nonsignificant in the model and reduced the influence of PCBs and DDTs. Thus, the influence of contaminants on GSI may have been partially driven by organismal modes-of-action that include changes in sex steroid production. The positive association of DDTs with 11KT and GSI suggests that lifetime, sub-lethal exposures to DDTs have effects on male carp opposite of those reported by studies where exposure concentrations were relatively high. Lastly, this study highlighted advantages of multivariate/multiple regression approaches for exploring associations between complex contaminant mixtures and gradients and reproductive condition in wild fishes.

Adsorption Removal of Environmental Hormones of Dimethyl Phthalate Using Novel Magnetic Adsorbent

Magnetic polyvinyl alcohol adsorbent M-PVAL was employed to remove and concentrate dimethyl phthalate DMP. The M-PVAL was prepared after sequential syntheses of magnetic Fe₃O₄ (M) and polyvinyl acetate (M-PVAC). The saturated magnetizations of M, M-PVAC, and M-PVAL are 57.2, 26.0, and 43.2 emu g⁻¹ with superparamagnetism, respectively. The average size of M-PVAL by number is 0.75 μm in micro size. Adsorption experiments include three cases: (1) adjustment of initial pH (pH₀) of solution to 5, (2) no adjustment of pH₀ with value in 6.04–6.64, and (3) adjusted pH₀ = 7. The corresponding saturated amounts of adsorption of unimolecular layer of Langmuir isotherm are 4.01, 5.21, and 4.22 mg g⁻¹, respectively. Values of heterogeneity factor of Freundlich isotherm are 2.59, 2.19, and 2.59 which are greater than 1, revealing the favorable adsorption of DMP/M-PVAL system. Values of adsorption activation energy per mole of Dubinin-Radushkevich isotherm are, respectively, of low values of 7.04, 6.48, and 7.19 kJ mol⁻¹, indicating the natural occurring of the adsorption process studied. The tiny size of adsorbent makes the adsorption take place easily while its superparamagnetism is beneficial for the separation and recovery of micro adsorbent from liquid by applying magnetic field after completion of adsorption.

A review of the effects of azole compounds in fish and their possible involvement in masculinization of wild fish populations

Endocrine-mediated effects in fish populations have been widely documented. Most attention has been focused on feminization caused by estrogenic substances, but this paper reviews evidence for the effects of a group of fungicides and pharmaceuticals, the azoles, which have been reported to cause masculinization in fish. The paper considers information from laboratory studies on the effects of azole compounds on fish endocrinology, and on the potential existence of such effects in wild fish. The occurrence of some azoles in effluents and surface waters has also been briefly reviewed. Under laboratory conditions, many azoles are able to cause masculinization or defeminization in fish by inhibition of the P450 enzyme aromatase (CYP19). However, in no case where such effects have been observed in the field has a link been established with this group of substances. In most instances, other more convincing explanations have been proposed. Peak concentrations of some azoles in surface waters can approach those which, under continuous long-term exposure in the laboratory, might lead to some aromatase inhibition. However, available data on exposure and effects provide reassurance that the concentrations of azoles found in surface waters are too low to cause adverse effects in fish by interference with their endocrine system. Compared to the widespread observations of feminization and estrogenic effects in (male) fish, there are relatively few papers describing masculinization or defeminization in (female) wild fish populations, suggesting that this is quite a rare phenomenon. The significance of this result is emphasized by the fact that fish are among the best studied organisms in the environment.

Evaluation of yolk protein levels as estrogenic biomarker in bivalves; comparison of the alkali-labile phosphate method (ALP) and a species-specific immunoassay (ELISA)

Altered concentration of the vertebrate yolk protein precursor vitellogenin is a recognized biomarker for endocrine disruption in fish, and within recent years yolk protein alteration has also been associated with endocrine disruption in bivalves. Species-specific, direct and sensitive methods for quantification of vitellogenin in fish have been available for years whereas bivalve yolk protein levels have been estimated indirectly by alkali-labile phosphate (ALP) liberated from high molecular weight proteins because the sequence and biochemical structure of most bivalve yolk proteins are unknown. By applying a species-specific enzyme-linked immunosorbent assay (ELISA) for accurate determination of yolk protein level the impact of 17β-estradiol (57, 164 and 512 ng/L) on the freshwater bivalve Unio tumidus was investigated and compared with ALP estimations. Seven weeks of exposure during the pre-spawning and spawning period had no consistent effect on yolk protein concentration in hemolymph, and ALP levels in hemolymph also remained unchanged in both males and females. Further, basal male and female ALP levels were indistinguishable whereas the ELISA demonstrated that yolk protein levels of females exceeded male levels at the time of sampling, although male basal levels were high compared to fish. Altogether it is shown that individual ALP levels do not reflect yolk protein levels and hence hemolymph ALP levels cannot serve as biomarker for estrogenic exposure during the pre-spawning and spawning period in U. tumidus. The necessity of sensitive and validated biomarkers for reliable interpretation of data and the utility of ALP and yolk protein levels as biomarkers in bivalves are discussed.