In Search of Mercury Lost from Sediments in a Previously Contaminated Coastal Area, Harboøre Tange, Denmark

Concentrations of mercury in sediment and benthic invertebrate fauna of Nissum Broad, North-western Jutland, Denmark were investigated. The western coast of Nissum Broad is Harboøre Tange, along which heavy mercury contamination - caused by discharge from production of mercury containing seed dressers in the 1950 and 1960s - was documented in the 1980s. Recent investigations showed marked decreases in mercury contamination in the near shore sediments along Harboøre Tange since the 1980s and the present investigation was initiated to learn if the loss of mercury from Harboøre Tange had led to an increased mercury contamination in the neighbouring marine area, Nissum Broad. Mercury concentrations in the surface sediment correlated with the content of organic matter and the slope of the regression is a good indicator for the degree of mercury contamination. Average mercury concentrations in the upper 5 cm of the sediments ranged between 0.9 and 71 ng g- 1 dry weight (dw) with only 1 station exceeding the Background Assessment Concentration of 70 ng g- 1 dw. Average mercury concentrations in blue mussels Mytilus edulis (169-260 ng g- 1 dw) and periwinkles Littorina littorea (66-203 ng g- 1 dw) exceeded those in uncontaminated areas and the Environmental Quality Standard of approximately 100 ng g- 1 dw. Present sediment mercury concentrations in Nissum Broad are approximately half of what they were in the 1980s, rendering it unlikely that mercury lost from Harboøre Tange has been deposited there. Sediment and organism concentrations did not show any correlation.

Effect of size on concentrations and cadmium inducibility of metallothionein in the shore crab Carcinus maenas

Metallothionein (MT) plays an important role in protecting organisms from the adverse effects of Cd, Hg, Zn and Cu. Investigations on mammals show variations in metallothionein concentrations and inducibility with age. This has never been investigated in invertebrates, and we determined the concentrations and inducibility of metallothionein in gills and midgut gland of different size classes of shore crabs from uncontaminated areas. Metallothionein concentrations in gills and midgut gland ranged between 30 and 40 μg g^-1 dry weight with no differences among the different size classes. Concentrations of cadmium, copper and zinc in the midgut gland increased with increasing size of the crabs when the concentrations were expressed on a dry weight basis; water content in the midgut gland increased with the size and only the cadmium concentration increased with size when concentrations were expressed on wet weight basis. There was an inverse relationship between metallothionein and both copper and cadmium concentrations. Smaller crabs exposed to 1 mg Cd L^-1 accumulated higher concentrations of cadmium in midgut gland and gills than larger ones and metallothionein concentrations in the midgut gland were higher in the smaller crabs. However, the increase in metallothionein concentration per accumulated unit of cadmium showed a linear increase with the size of the crabs. The ratio [Cd]_midgut/[Cd]_gills decreased with the size of the crabs. The overall conclusion is that baseline metallothionein concentrations do not change with age in shore crabs, but that the inducibility of metallothionein upon cadmium challenge does.

Mercury levels in humpback whales, and other Southern Ocean marine megafauna

Mercury is a known potent neurotoxin. The biogeochemical cycle of mercury in the remote Antarctic region is still poorly understood, with Polar climate change contributing added complexity. Longitudinal biomonitoring of mercury accumulation in Antarctic marine megafauna can contribute top-down insight into the bio-physical drivers of wildlife exposure. The bioaccumulative nature of organic mercury renders high trophic predators at the greatest risk of elevated exposure. Humpback whales represent secondary consumers of the Antarctic sea-ice ecosystem and an ideal biomonitoring species for persistent and bioaccumulative compounds due to their extended life-spans. This study provides the first results of mercury accumulation in humpback whales, and places findings within the context of mercury accumulation in both prey, as well as six other species of Antarctic marine megafauna. Combined, these findings contribute new baseline information regarding mercury exposure to Antarctic wildlife, and highlights methodological prerequisites for routine mercury biomonitoring in wildlife via non-lethally biopsied superficial tissues.

Exposure to methylmercury and inorganic mercury in the food does not lead to trophic magnification in the sea star Asterias rubens

Methylmercury accumulated at the top of aquatic food chains constitutes a toxicological risk to humans and other top predators. Biomagnification of methylmercury takes place among vertebrates at the higher trophic levels, but this process is less elucidated in benthic invertebrates at the lower trophic levels. Therefore, we investigated the accumulation from food and elimination of methylmercury and inorganic mercury in the benthic sea star Asterias rubens (L.) - a representative of trophic level ~3 - in laboratory experiments. Sea stars fed over 49 days with contaminated mussels (Mytilus edulis) accumulate methylmercury and inorganic mercury to the highest concentrations in the digestive glands, the pyloric caeca, less in stomach, gonad, tube feet, aboral body wall and not to detectable levels in the coelomic fluid. Concerning whole body contents, steady states were reached for both methylmercury and inorganic mercury during the 7-week feeding period and the sea stars reached approximately ½ and ¼ of the concentrations in the mussel food for the two mercury forms, respectively. Half-lives for the elimination of the two mercury forms varied between 45 and 173 days in a 140-d elimination period following the feeding period; inorganic mercury was eliminated faster than methylmercury. Examination of total mercury concentrations in field-collected sea stars confirmed this lack of trophic magnification in relation to the major food items, soft parts of molluscs. We suggest that mercury is not trophically magnified in sea stars 1) because they eliminate methylmercury faster than larger fish and decapod crustaceans and 2) maybe more importantly, because inorganic mercury with its faster elimination constitutes a larger fraction of the total mercury in the food at the lower trophic levels - as opposed to methylmercury which dominates at the higher trophic levels.

Investigation of the in vivo estrogenicity of the UV-filters 4-methylbenzylidene camphor and octyl methoxy cinnamate in rainbow trout (Oncorhynchus mykiss)

The estrogenic activity of the chemical UV-filters, 4-methylbenzylidene camphor (4-MBC) and octyl methoxy cinnamate (OMC) was investigated in an in vivo rainbow trout (Oncorhynchus mykiss) assay. Plasma vitellogenin concentrations were quantified by means of an Enzyme Linked Immuno Sorbent Assay (ELISA) in juvenile rainbow trout before and after intraperitoneal injection of the test compounds. Injection of 4-MBC on day 0, 3, 6 and 10 in the exposure period caused dose and time dependent increases in the concentration of plasma vitellogenin. Significant elevation of vitellogenin concentrations in plasma was demonstrated from 151 mg 4-MBC kg-1 injection-1. Logistic regression analysis relating the percentage of responding fish to the injected dose of 4-MBC resulted in ED10, ED50 and ED90 values of 37, 115 and 194 mg kg-1 injection-1, respectively, after 14 days of exposure (4 injections). Injections with OMC (up to 202 mg kg-1 injection-1) did not result in a statistically significant response in groups of exposed fish, although some individual fish showed elevated concentrations of vitellogenin in plasma. The results confirm that 4-MBC is estrogenic in fish in vivo.

Mercury (Hg2+) interferes with physiological adaptations to freezing in the arctic earthworm Enchytraeus albidus

Freezing temperatures is an important stressor in the arctic regions and has a significant influence on the population dynamics and geographic distribution of terrestrial invertebrates. Toxic metals in the environment can interfere with protective cold-acclimation responses of organisms. It is therefore important to evaluate the combined effects of cold stress and environmental contaminants. Here, we aimed to investigate the effects of Hg (HgCl₂) on various physiological aspects of freeze-tolerance in the earthworm (Enchytraeus albidus). We measured the levels of the cryoprotectant glucose, the glycogen content (source of glucose molecules for cryoprotection and fuel for metabolism), and changes in the composition of membrane phospholipid fatty acids (PLFA) as an indicator of lipid peroxidation. Freezing at -6 °C had no effect on survival in uncontaminated soil, however, survival of freezing in Hg contaminated soil was clearly reduced, especially at extended exposure times. Thus, the LC₅₀ value in frozen soil decreased from 8.3 mg Hg kg^-1 (when exposed for 17 days) to only 4.2 mg Hg kg^-1 after 36 days' exposure indicating that combined effects of Hg and freezing became larger at prolonged exposure times. Hg caused a depletion of glycogen reserves (almost 50% at 12 mg kg^-1 dry soil), but despite this effect worms were able to maintain a constant cryoprotectant level (about 0.12 mg glucose mg^-1 dry weight) at all Hg concentrations. Hg had clear negative effects on the proportion of unsaturated PLFAs, which could be an indication of lipid peroxidation. Since a high proportion of unsaturated fatty acids in the membrane is important for invertebrate freeze-tolerance, our results suggest that the negative effect of Hg on freeze-tolerance in E. albidus is related to degraded membrane functionality at low temperature.

Elevated mercury concentrations in biota despite reduced sediment concentrations in a contaminated coastal area, Harboøre Tange, Denmark

Metals sequestered in coastal sediments are normally considered to be stable, but this investigation shows - somewhat surprisingly - that mercury concentrations in a previously contaminated area, Harboøre Tange, Denmark, have decreased since the 1980s. Mercury concentrations were determined in sediment and benthic biota and present values were compared to values in the 1980s and values from areas without known; history of mercury contamination. Concentrations in both the upper 20 cm of the sediments and; biota are considerably lower now compared to latest monitoring (1980s). Sediment. concentrations at most locations have decreased from the 100-300 ng Hg g^-1 dry weight (dw) level to levels below the Background Concentration (BC) of 50 ng Hg g^-1 dw defined by Oslo-Paris Convention for the Protection of the Marine Environment of the North-East Atlantic; some stations are at the 2-10 ng Hg g^-1 dw level characteristic of Danish coastal sediments with no known history of mercury contamination. Concentrations of mercury in the benthic biota along Harboøre Tange have also decreased since the 1980s but despite the lowered mercury concentrations in the sediments, concentrations in most samples of benthic invertebrate fauna still exceed those in uncontaminated coastal areas and also the Environmental Quality Standard (EQS) of 20 ng Hg g^-1 wet weight (≈100 ng Hg g^-1 dry weight) defined by the European Union's Water Framework Directive. Concentration ranges in selected organisms are: (Harboøre Tange l980s/Harboøre Tange now/uncontaminated areas - given in ng Hg g^-1 dw): Periwinkles Littorina littorea 9000/150-450/55-77, blue mussels Mytilus edulis up to 9000/300-500/40-170, cockles Cerastoderma edule up to 8000/400-1200/200, brown shrimp Crangon crangon 700-2200/150-450/47, eelgrass Zostera marina up to 330/25-70/12. The present results - together with a literature review - show that a simple and straight forward relationship between the concentrations of mercury in sediment and benthic organisms does not necessarily exist.

Investigation of the potential endocrine effect of nitrate in zebrafish Danio rerio and brown trout Salmo trutta

Nitrate has the potential to affect steroid production. Nitrate concentrations in streams in agricultural areas may exceed concentrations showing effects in laboratory studies. The effects of nitrate and/or nitrite on endocrine relevant endpoints were tested in zebrafish and brown trout. Zebrafish were exposed in two experiments to nitrate (8.8 to 89 mg NO₃^-/L) and nitrite (3.6 to 19 mg NO₂^-/L) during the period of sexual differentiation and sex ratios were determined. Vitellogenin concentrations were determined in the second experiment. The sex ratio was unaffected by the exposure to nitrate and nitrite. Vitellogenin concentrations were slightly elevated in males (but not females) in all of the groups exposed to nitrate. Juvenile brown trout were exposed to 5.7, 14, and 31 mg NO₃^-/L for 8 days and vitellogenin levels in liver were determined. Vitellogenin concentrations in the females were not affected by exposure, but in the males, there was an overall statistically significant effect of exposure to nitrate with the group exposed to 5.7 mg NO₃^-/L showing a trend of higher vitellogenin concentrations than the control group; levels in the males of the groups exposed to 14 and 31 mg NO₃^-/L were not statistically different from those of the control group. In conclusion, some marginal effect of nitrate in male fish on endocrine activity was observed but the present results for zebrafish, using environmentally relevant concentrations, do not define nitrate and nitrite as endocrine disrupting chemicals according to the generally accepted WHO/IPCS definition because no adverse effects (altered sex ratios) were demonstrated.

Retention and distribution of methylmercury administered in the food in marine invertebrates: Effect of dietary selenium

Methylmercury is transported along aquatic food chains from the lower trophic levels and selenium modulates the biokinetics of mercury in organisms in complex ways. We investigated the retention of orally administered methylmercury in various marine invertebrates and the effect of selenium hereon. Shrimps (Palaemon adpersus and P. elegans), blue mussels (Mytilus edulis), shore crabs (Carcinus maenas) and sea stars (Asterias rubens) eliminated methylmercury slowly (t_½ = ½ to >1 year) and the copepod (Acartia tonsa) faster (t_½ ∼ 12-24 h). Orally administered selenite augmented elimination of methylmercury in the copepod (in one of two experiments) and blue mussels, but not in shrimps, crabs and sea stars. Selenium generally alters the distribution of the body burden of mercury, leaving more mercury in muscle and less mercury in digestive glands or rest of the body - also in the species where total body retention is not affected.

Vitellogenin concentrations in feral Danish brown trout have decreased: An effect of improved sewage treatment in rural areas?

Feminization of male and juvenile fish because of exposure to estrogens or estrogenic chemicals in effluents from central wastewater treatment plants (WWTPs) is a worldwide issue of concern. Intersex and induction of the female yolk protein, vitellogenin, in male and juvenile fish are robust biomarkers for estrogenic exposure, and feminized fish have been observed downstream of WWTP outlets in many countries. Danish central WWTPs reduce effluent estrogenicity effectively by advanced sewage treatment, and feminizations have not been observed downstream of central WWTP outlets. However, between 2000 and 2004, investigations of Danish streams not receiving sewage from central WWTPs revealed a high variation in vitellogenin concentrations of male juvenile brown trout (Salmo trutta); some individuals had high concentrations, probably as a result of estrogenic point sources, and the plasma concentration was >50 ng mL^-1 in 79% of the juvenile males. The streams were reinvestigated in 2010 to 2016, and the average male level had decreased to a hitherto unseen baseline level; in 2010 only 0.7% (one individual) of the males had a vitellogenin concentration >50 ng mL^-1 , which could indicate that the estrogenicity of the streams decreased after 2004. We examined possible estrogenic sources in streams unaffected by central WWTP effluents, and found that the reduced vitellogenin levels are most likely explained by a national effort to improve on-site wastewater treatment in scattered houses not connected to central WWTPs. Environ Toxicol Chem 2018;37:839-845. © 2017 SETAC.

Two common mild analgesics have no effect on general endocrine mediated endpoints in zebrafish (Danio rerio)

Mild analgesics such as acetylsalicylic acid (ASA) and acetaminophen (APAP) exert their pain-relieving effect in humans by inhibition of prostaglandin synthesis. Prostaglandins play key roles in developmental and reproductive processes in vertebrates, and in recent years, it has been suggested that weak analgesics might also act as endocrine disrupters. In a set of experiments we investigated if ASA and APAP affect well-established endocrine endpoints in zebrafish (Danio rerio), which is a commonly used model organism in the investigation of endocrine disrupting chemicals. Zebrafish were exposed to APAP (0.22, 2.3, and 30mgL^-1) or ASA (0.2, 0.5, 1.7, and 8.2mgL^-1) from hatch to sexual maturity in a test design resembling the OECD Fish Sexual Development Test. No effects on sex ratio and vitellogenin levels were observed. Adult zebrafish were exposed to high concentrations (mgL^-1) of ASA or APAP for eight or 14days. ASA reduced the levels of prostaglandin E₂, but had no effect on the concentration of 11-ketotestosterone and vitellogenin. Overall, ASA decrease prostaglandin E₂ concentrations, but well-established endpoints for endocrine disruption in zebrafish are generally not affected by aquatic exposure neither during development nor adulthood. According to the WHO/IPCS definition of an endocrine disrupter, the present results do not define APAP and ASA as endocrine disrupters.

Uncertainties in biological responses that influence hazard and risk approaches to the regulation of endocrine active substances

Endocrine-disrupting substances (EDS) may have certain biological effects including delayed effects, multigenerational effects, and may display nonmonotonic dose-response (NMDR) relationships that require careful consideration when determining environmental hazards. Endocrine disrupting substances can have specific and profound effects when exposure occurs during sensitive windows of the life cycle (development, reproduction). This creates the potential for delayed effects that manifest when exposure has ceased, possibly in a different life stage. This potential underscores the need for testing in appropriate (sensitive) life stages and full life cycle designs. Such tests are available in the Organisation for Economic Co-operation and Development (OECD) tool box and should be used to derive endpoints that can be considered protective of all life stages. Similarly, the potential for effects to be manifest in subsequent generations (multigenerational effects) has also been raised as a potential issue in the derivation of appropriate endpoints for EDS. However, multigenerational studies showing increasing sensitivity of successive generations are uncommon. Indeed this is reflected in the design of new higher tier tests to assess endocrine active substances (EAS) that move to extended one-generation designs and away from multi-generational studies. The occurrence of NMDRs is also considered a limiting factor for reliable risk assessment of EDS. Evidence to date indicates NMDRs are more prevalent in in vitro and mechanistic data, not often translating to adverse apical endpoints that would be used in risk assessment. A series of steps to evaluate NMDRs in the context of endocrine hazard and risk assessment procedures is presented. If careful consideration of delayed, multigenerational effects and NMDRs is made, it is feasible to assess environmental endocrine hazards and derive robust apical endpoints for risk assessment procedures ensuring a high level of environmental protection. Integr Environ Assess Manag 2017;13:293-301. © 2016 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Recommended approaches to the scientific evaluation of ecotoxicological hazards and risks of endocrine-active substances

A SETAC Pellston Workshop® "Environmental Hazard and Risk Assessment Approaches for Endocrine-Active Substances (EHRA)" was held in February 2016 in Pensacola, Florida, USA. The primary objective of the workshop was to provide advice, based on current scientific understanding, to regulators and policy makers; the aim being to make considered, informed decisions on whether to select an ecotoxicological hazard- or a risk-based approach for regulating a given endocrine-disrupting substance (EDS) under review. The workshop additionally considered recent developments in the identification of EDS. Case studies were undertaken on 6 endocrine-active substances (EAS-not necessarily proven EDS, but substances known to interact directly with the endocrine system) that are representative of a range of perturbations of the endocrine system and considered to be data rich in relevant information at multiple biological levels of organization for 1 or more ecologically relevant taxa. The substances selected were 17α-ethinylestradiol, perchlorate, propiconazole, 17β-trenbolone, tributyltin, and vinclozolin. The 6 case studies were not comprehensive safety evaluations but provided foundations for clarifying key issues and procedures that should be considered when assessing the ecotoxicological hazards and risks of EAS and EDS. The workshop also highlighted areas of scientific uncertainty, and made specific recommendations for research and methods-development to resolve some of the identified issues. The present paper provides broad guidance for scientists in regulatory authorities, industry, and academia on issues likely to arise during the ecotoxicological hazard and risk assessment of EAS and EDS. The primary conclusion of this paper, and of the SETAC Pellston Workshop on which it is based, is that if data on environmental exposure, effects on sensitive species and life-stages, delayed effects, and effects at low concentrations are robust, initiating environmental risk assessment of EDS is scientifically sound and sufficiently reliable and protective of the environment. In the absence of such data, assessment on the basis of hazard is scientifically justified until such time as relevant new information is available. Integr Environ Assess Manag 2017;13:267-279. © 2017 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Parkinson’s disease among Inuit in Greenland: organochlorines as risk factors

OBJECTIVES

In the present study we investigate organochlorines as possible risk factors for Parkinson's disease (PD) in an arctic population. This has never been done before.

STUDY DESIGN

Case-control study of Inuit in Greenland.

MATERIALS AND METHODS

Plasma from 31 PD (20 males and 11 females) (mean age 69 yr) and 122 controls (57 males and 65 females) (mean age 61 yr) was analysed for 31 PCBs and pesticides by dual-column GC-ECD and GC-NCI/MS.

RESULTS

Plasma concentrations of PCBs and pesticides were markedly increased in both PD and controls. The concentrations did not differ between the PD cases and controls. However, the mean DDE concentration was higher in PD than in controls (42.1 and 15.0 microg/l, respectively, and with a wide range among the PD cases). The difference was significant for log transformed DDE values after control for age and sex (p=0.005).

CONCLUSION

A few epidemiological studies indicate a possible connection between exposure to pesticides and PD. The idea that exposure to organochlorines may be an important risk factor for PD among the Inuit in Greenland requires more investigations.

Trends in the dietary patterns and prevalence of obesity among Greenlandic school children

OBJECTIVE

The aim of the study was to examine the trends in the dietary patterns of selected food items and in the prevalence of self-perceived obesity in a population of Greenlandic schoolchildren.

STUDY DESIGN

The study is based on three school surveys among Greenlandic schoolchildren, class 6 to 11 in public schools, and contributing to the Health Behaviour in School-aged Children (HBSC) Study. Data are collected through self-completed questionnaires administered in the classroom. Three surveys have been carried out in Greenland in 1994, 1998 and 2002 with the participation of 2,999, 3,057 and 2,010 pupils, respectively.

RESULTS

The intake of vegetables has increased significantly since 1994, and the intake of fruits, sweets and soft drink has decreased significantly at a 5% level. An unchanged high proportion of schoolchildren report to be on a diet or consider themselves obese.

CONCLUSION

Most of the observed trends are positive, with regard to intake of vegetables and sweets and consumption of soft drinks. The fact that a high proportion of schoolchildren consider themselves to be obese must be assumed to have a negative impact on the psychological well-being of this population. The results of the survey can reveal changes which have occurred over time for the specified population. This knowledge can be used in public health work and planning.

Mental health, violence, sexual abuse, tobacco and alcohol Acculturation and mental health — empirical verification of J.W. Berry’s model of acculturative stress

OBJECTIVES

Many studies concerning mental health among ethnic minorities have used the concept of acculturation as a model of explanation, in particular J.W. Berry's model of acculturative stress. But Berry's theory has only been empirically verified few times. The aims of the study were to examine whether Berry's hypothesis about the connection between acculturation and mental health can be empirically verified for Greenlanders living in Denmark and to analyse whether acculturation plays a significant role for mental health among Greenlanders living in Denmark.

STUDY DESIGN AND METHODS

The study used data from the 1999 Health Profile for Greenlanders in Denmark. As measure of mental health we applied the General Health Questionnaire (GHQ-12). Acculturation was assessed from answers to questions about how the respondents value the fact that children maintain their traditional cultural identity as Greenlander and how well the respondents speak Greenlandic and Danish. The statistical methods included binary logistic regression.

RESULTS

We found no connection between Berry's definition of acculturation and mental health among Greenlanders in Denmark. On the other hand, our findings showed a significant relation between mental health and gender, age, marital position, occupation and long-term illness.

CONCLUSION

The findings indicate that acculturation in the way Berry defines it plays a lesser role for mental health among Greenlanders in Denmark than socio-demographic and socio-economic factors. Therefore we cannot empirically verify Berry's hypothesis.

Severe malformations of eelpout (Zoarces viviparus) fry are induced by maternal estrogenic exposure during early embryogenesis

Pregnant eelpout were exposed via the water to known endocrine disrupting compounds (EDCs) to clarify if EDCs could be causing the increased eelpout fry malformation frequencies observed in coastal areas receiving high anthropogenic input. The presence of a teratogenic window for estrogen-induced malformations was also investigated by starting the exposure at different times during eelpout pregnancy. Both 17α-ethinylestradiol (EE2) (17.8 ng/L) and pyrene (0.5 μg/L) significantly increased fry malformation frequency whereas 4-t-octylphenol (4-t-OP) up to 14.3 μg/L did not. Vitellogenin was significantly induced by EE2 (5.7 and 17.8 ng/L) but not by 4-t-OP and pyrene. A critical period for estrogen-induced fry malformations was identified and closed between 14 and 22 days post fertilization (dpf). Exposure to 17β-estradiol (E2) between 0 and 14 dpf caused severe malformations and severity increased the closer exposure start was to fertilization, whereas malformations were absent by exposure starting later than 14 dpf. Data on ovarian fluid volume and larval length supported the suggested teratogenic window. Larval mortality also increased when exposure started right after fertilization.

Endocrine-disrupting effect of the ultraviolet filter benzophenone-3 in zebrafish, Danio rerio

The chemical ultraviolet (UV) filter benzophenone-3 (BP-3) is suspected to be an endocrine disruptor based on results from in vitro and in vivo testing. However, studies including endpoints of endocrine adversity are lacking. The present study investigated the potential endocrine-disrupting effects of BP-3 in zebrafish (Danio rerio) in the Fish Sexual Development Test (Organisation for Economic Co-operation and Development TG 234) and a 12-d adult male zebrafish study. In TG 234, exposure from 0 d to 60 d posthatch caused a monotone dose-dependent skewing of the phenotypic sex ratio toward fewer males and more female zebrafish (no observed effect concentration [NOEC]: 191 μg/L, lowest observed effect concentration [LOEC]: 388 μg/L). Besides, gonad maturation was affected in both female fish (NOEC 191 μg/L, LOEC 388 μg/L) and male fish (NOEC 388 μg/L, LOEC 470 μg/L). Exposure to BP-3 did not affect the vitellogenin concentration in TG 234. After 12 d exposure of adult male zebrafish, a slight yet significant increase in the vitellogenin concentration was observed at 268 μg/L but not at 63 μg/L and 437 μg/L BP-3. Skewing of the sex ratio is a marker of an endocrine-mediated mechanism as well as a marker of adversity, and therefore the conclusion of the present study is that BP-3 is an endocrine-disrupting chemical in accordance with the World Health Organization's definition.

A path forward in the debate over health impacts of endocrine disrupting chemicals

Several recent publications reflect debate on the issue of "endocrine disrupting chemicals" (EDCs), indicating that two seemingly mutually exclusive perspectives are being articulated separately and independently. Considering this, a group of scientists with expertise in basic science, medicine and risk assessment reviewed the various aspects of the debate to identify the most significant areas of dispute and to propose a path forward. We identified four areas of debate. The first is about the definitions for terms such as "endocrine disrupting chemical", "adverse effects", and "endocrine system". The second is focused on elements of hormone action including "potency", "endpoints", "timing", "dose" and "thresholds". The third addresses the information needed to establish sufficient evidence of harm. Finally, the fourth focuses on the need to develop and the characteristics of transparent, systematic methods to review the EDC literature. Herein we identify areas of general consensus and propose resolutions for these four areas that would allow the field to move beyond the current and, in our opinion, ineffective debate.

17β-estradiol causes abnormal development in embryos of the viviparous eelpout

Elevated frequencies of malformations among the offspring of Baltic eelpout (Zoarces viviparus) have been observed in aquatic environments receiving high anthropogenic input suggesting that manmade chemicals could be the causative agent. However, causal links between exposure to chemicals and abnormal development have never been confirmed in laboratory experiments. The purpose of this study was to investigate if exposure to 17β-estradiol (E2) causes abnormal development in larvae of the viviparous eelpout. Wild female eelpout were collected immediately after fertilization and exposed to E2 concentrations ranging from 5.7 to 133 ng L(-1) for 6 weeks in a flow through test system. The experiment shows that E2 concentrations of 53.6 and 133 ng L(-1) cause severe abnormal development among eelpout embryos. Reduced amount of ovarian fluid and increased weight of the ovarian sac indicate disturbance of ovarian function. Female plasma concentrations of E2 and vitellogenin increase in a monotonic concentration-response relationship with significant induction in the low concentration range. Our findings support the plausibility that the abnormal development among eelpout embryos encountered in monitoring programs may actually be caused by exposure to chemicals 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.

Amount and metal composition of midgut gland metallothionein in shore crabs (Carcinus maenas) after exposure to cadmium in the food

Accumulation of cadmium in aquatic invertebrates may compromise human food safety and anthropogenic additions of cadmium to coastal areas cause concern. Induction of crustacean metallothionein has been suggested as a useful biomarker for contamination of the aquatic environment with cadmium. We investigated how exposure to low concentrations of cadmium in the food affects the subcellular binding of cadmium with the shore crab Carcinus maenas as model organism. Approximately 80% of the assimilated cadmium was bound in the soluble fraction of the midgut gland and of this, 82% was found in the metallothionein fraction. Metallothionein synthesis was only induced at the highest exposure level. However, the number of cadmium atoms bound per molecule of metallothionein increased linearly with exposure, from approximately 0.18 in the control group to 1.4 in a group administered food containing 5.1 μg Cd g(-1). We noted a marked interaction between the presence of copper and zinc in the midgut gland and the binding of cadmium. The usefulness of crustacean midgut gland metallothionein as a biomarker for cadmium exposure at modest levels was questioned since exposures at levels producing significant increases in the tissue contents of the metal did not result in elevated concentrations of metallothionein in the midgut gland.

Abnormalities in eelpout Zoarces viviparus upon chemical exposure

Elevated frequencies of abnormal embryos in female eelpout Zoarces viviparus have been demonstrated in Danish, Swedish and German monitoring programmes at certain geographic locations with high levels of anthropogenic input. Pollutants present in areas with high malformation frequencies were selected and tested in a controlled laboratory experiment for their potential to induce abnormalities among eelpout embryos upon injection into pregnant eelpout. Tributyltin, 2,3,7,8-tetrachlorodibenzo-p-dioxin, pyrene, nonylphenol, 2,2',4,4'-tetrabromophenylether and heptadecafluorooctanesulfonic acid were tested, either individually or combined. Generally, the chemicals were transferred to eggs and/or embryos. Some of the exposures increased the proportion of broods with more than 10% abnormal or 5% malformed embryos, although the average percentages of abnormal development were not affected. Spinal, cranial and eye deformities were evident, similarly to what is seen in nature. Some of the exposures resulted in increased percentages of females with as well a low reproductive capacity as embryos with a low condition index.

Vitellogenin as biomarker for estrogenicity in flounder Platichthys flesus in the field and exposed to 17α-ethinylestradiol via food and water in the laboratory

The ability of 17α-ethinylestradiol (EE2) to elevate vitellogenin levels were investigated in male flounder Platichthys flesus and vitellogenin concentrations in flounders from the Danish coastal environment were determined. Male flounders were exposed to 17α-ethinylestradiol (EE2) via food or water. Average vitellogenin concentrations in the control fish ranged between 25 and 100 ng mL(-)(1). Exposure to 5.1, 8.1 and 16.8 ng EE2 L(-)(1) in water and 500 and 5000 ng EE2 kg(-)(1) body weight (bw) every second day in the food increased the plasma vitellogenin concentration in a concentration and time dependent manner, whereas exposure to 2.7 ng EE2 L(-)(1) in water for 21 d and 5 and 50 ng EE2 kg(-)(1) bw for 12 days in the food did not. EE2 could be detected in liver and testes (but not in muscle) after exposure to 8.1 and 16.8 ng EE2 L(-)(1) in the water and 5000 ng EE2 kg(-)(1) bw in the food; the highest concentration was 6 ng g(-)(1) wet weight in liver. The majority of the male flounders collected from nine coastal Danish sites from 1999 to 2004 had vitellogenin concentrations below 100 ng mL(-)(1), and only at two sites moderate estrogenic inputs were indicated.

Estrogenic effect of the phytoestrogen biochanin A in zebrafish, Danio rerio, and brown trout, Salmo trutta

Isoflavones with estrogenic activity produced in Fabaceae plants are known to leach from agricultural areas to freshwater systems, but the effect of waterborne isoflavones in fish has not been thoroughly characterized. Therefore, the estrogenic effect of waterborne biochanin A was investigated in zebrafish (Danio rerio) and juvenile brown trout (Salmo trutta). Exposure of juvenile brown trout to 10 μg biochanin AL(-1) or higher caused marked vitellogenin induction after 9-10 days of exposure and so did exposure to 186 μg biochanin AL(-1) for 6h. Following 8d of exposure, a NOEC for induction of vitellogenin production in male zebrafish was 70 and LOEC 114 μg biochanin AL(-1). Exposure to 209 μg biochanin AL(-1) from hatch to 60 days post hatch (dph) caused a skewing of the sex ratio toward more phenotypic female zebrafish, but did not cause induction of vitellogenin in male and undifferentiated fish.

IN CONCLUSION

(1) biochanin A elicits estrogenic effects in trout at environmentally realistic concentrations, (2) brown trout plasma vitellogenin concentrations respond to lower biochanin A exposure concentrations than vitellogenin concentrations in zebrafish homogenates and (3) concerning vitellogenin induction, the hypothesis should be tested if short term tests with zebrafish may show a higher sensitivity than partial life cycle tests.

Science and policy on endocrine disrupters must not be mixed: a reply to a "common sense" intervention by toxicology journal editors

The "common sense" intervention by toxicology journal editors regarding proposed European Union endocrine disrupter regulations ignores scientific evidence and well-established principles of chemical risk assessment. In this commentary, endocrine disrupter experts express their concerns about a recently published, and is in our considered opinion inaccurate and factually incorrect, editorial that has appeared in several journals in toxicology. Some of the shortcomings of the editorial are discussed in detail. We call for a better founded scientific debate which may help to overcome a polarisation of views detrimental to reaching a consensus about scientific foundations for endocrine disrupter regulation in the EU.

Evidence of small modulation of ethinylestradiol induced effects by concurrent exposure to trenbolone in male eelpout Zoarces viviparus

The interaction of xenobiotics is common in aquatic ecosystems; therefore, we wanted to evaluate if trenbolone (TB) modulates the effects of 17α-ethinylestradiol (EE2). Male eelpout (Zoarces viviparus) were exposed to 5 ng L(-1) EE2 continuously for 19 d (EE2-C) or discontinuously (11 d, EE2-D) alone or in combination with low (50 ng L(-1), TBL) or high (500 ng L(-1), TBH) concentrations of TB (19 d). Exposure to EE2 caused reduced gonadosomatic index, increased plasma vitellogenin concentrations, up-regulated vtg and era mRNA expression and severe alterations in gonadal histology. TBL and TBH did not affect plasma vitellogenin, era or vtg mRNA expression. TBL and TBH did not counteract the EE2-induced increase in plasma vitellogenin and reduction in 11-ketotestosterone whereas TBH counteracted the EE2 induced increase in vtg and era mRNA expression. Exposure to TBH and EE2-C + TBH lead to severe gonadal histology alterations. TBL and EE2-D + TBH exposed fish showed less histopathological alterations.

Ibuprofen reduces zebrafish PGE(2) levels but steroid hormone levels and reproductive parameters are not affected

Prostaglandins are important regulators of reproductive function in fish. Analgesics like aspirin and ibuprofen are prostaglandin inhibitors and have been detected in freshwater systems at ng/L-μg/L levels. We investigated whether ibuprofen would affect prostaglandin and sex steroid hormone levels in adult zebrafish (Danio rerio) and if expression levels of genes involved in steroidogenesis and prostaglandin synthesis were affected. Zebrafish were exposed to moderate concentrations of ibuprofen (21, 201 or 506 μg/L) for 7 days in a semi-static test system. Ibuprofen concentrations were close to nominal levels and decreased by a maximum of 12-13% over 24 h. Prostaglandin E(2) (PGE(2)) levels in whole body homogenates of males and ovaries of females decreased in a monotonic dose-response relationship whereas male 11-ketotestosterone levels and ovarian 17β-estradiol levels remained unchanged. Ibuprofen did not have an influence on vitellogenin levels, female gonadosomatic index or cumulative egg production and no dose-response relationship in ovarian and testicular expression levels of the investigated genes was observed. This study shows that ibuprofen reduces PGE(2) levels in male and female zebrafish but has no consistent effects on other investigated reproductive parameters.

Selenium reduces the retention of methyl mercury in the brown shrimp Crangon crangon

Methyl mercury accumulated at the top of aquatic food chains constitutes a toxicological risk to humans and other top predators. Because the methyl mercury enters the aquatic food chains at the lower trophic levels, uptake and elimination processes at these levels affect the methyl mercury content at the higher levels. Selenium modulates the biokinetics of mercury in aquatic organisms in fairly complex ways, increasing mercury retention in some aquatic mammals, but decreasing methyl mercury retention in fish. However, it is not known if selenium modulates methyl mercury accumulation at lower trophic levels in aquatic food chains. Here, we show that selenium administered via the food augments the elimination of methyl mercury from marine shrimp and that the effect is dose-dependent, demonstrable down to natural selenium concentrations in aquatic food items. Selenite, seleno-cystine, and seleno-methionine exert this effect but selenate does not. Our results suggest that the selenium naturally present at the lower trophic levels in marine food chains may play an essential role as a modifier of methyl mercury accumulation at these levels, thereby potentially also affecting biomagnification of methyl mercury toward the higher trophic levels in the aquatic food chains.

Diabetes in Greenland and its relationship with urbanization

BACKGROUND AND AIM

Most studies show that diabetes increases with migration and urbanization. Previous studies from Greenland have shown inconsistent associations between cardiovascular risk and urbanization. Thus, the aim was to study the association between diabetes and urbanization among Greenland Inuit.

METHODS

A total of 3089 adult Inuit aged 18 years and older participated in a geographically representative, population-based study 'Inuit Health in Transition Study'. The examination included a 75 g oral glucose tolerance test and anthropometric measurements. Information on socio-demographic characteristic and health behaviour was obtained by interview or questionnaire. The participants were categorized according to degree of urbanization into three groups based on current place of residence: (1) participants living in towns (> 2000 inhabitants), (2) participants living in small towns (< 2000 inhabitants) and (3) participants living in villages (< 500 inhabitants).

RESULTS

The total prevalence of diabetes was 9% of which 79% were previously unknown. Nine per cent had impaired glucose tolerance and 19% had impaired fasting glycaemia (IFG). Compared with towns, odds rations (ORs) for diabetes and impaired fasting glycaemia were higher in small towns [OR(diabetes) = 1.5 (1.0-2.3), OR(IFG) = 1.9 (1.2-2.3)] and villages [OR(diabetes) = 1.2 (0.8-1.9), OR(IFG) = 1.3 (0.9-2.0)], whereas no association was seen for impaired glucose tolerance. The inverse association between urbanization and diabetes and impaired fasting glycaemia persisted after adjustment for relevant confounders.

CONCLUSION

Diabetes and impaired fasting glycaemia decreased with urbanization contrary to the results of most studies. It appears that Greenland Inuit follow the pattern usually observed in industrialized countries with the highest risk of diabetes in the lower socio-economic groups.

Comparison of zebrafish (Danio rerio) and fathead minnow (Pimephales promelas) as test species in the Fish Sexual Development Test (FSDT)

Results are presented from a validation (with 5 laboratories) of the Fish Sexual Development Test (FSDT) developed to detect endocrine disrupters (EDs) and included in the OECD (Organisation for Economic Co-operation and Development) working program. The aromatase-inhibiting fungicide prochloraz was tested in zebrafish (Danio rerio) and fathead minnow (Pimephales promelas). The fish were exposed during sexual differentiation and development from 0 to 60 days post hatch (dph). After exposure, the vitellogenin (VTG) concentrations were quantified in head/tail homogenate and the sex ratio was determined (defined as female, male, intersex or undifferentiated). NOEC/LOEC and EC(x) designs were compared to optimize the test approach. Results show that both species are highly sensitive to prochloraz during sexual development. They respond by skewing of the sex ratio towards male phenotype and by a VTG decline in females. The NOEC/LOEC approach is preferred because sex ratio is difficult to analyze with a regression model. The mean NOEC/LOEC for prochloraz on the sex ratio was 43.3/134 μg/L and 101/293 μg/L for zebrafish and fathead minnow, respectively. The mean NOEC/LOEC on the decline in female VTG concentration was 65/110 μg/L and ~30/68 μg/L respectively. In conclusion, zebrafish and fathead minnow are suitable species in the FSDT and their sexual differentiation is equally labile to EDs.

Uptake of 17β-estradiol and biomarker responses in brown trout (Salmo trutta) exposed to pulses

In streams, chemicals such as 17β-estradiol (E2) are likely to occur in pulses. We investigated uptake and biomarker responses in juvenile brown trout (Salmo trutta) of 3- or 6-h pulses of concentrations up to 370 ng E2 L(-1). Uptake by the fish was estimated from disappearance of E2 from tank water. A single 6-h pulse of 370 ng E2 L(-1) increased the plasma vitellogenin concentration, liver Erα- and vitellogenin-mRNA. Exposure to 150-160 ng E2 L(-1) for 6 h increased vitellogenin in one experiment but not in another. Two 6-h pulses had a larger effect one pulse. Brown trout in the size range 24-74 g took up E2 linearly with time and exposure concentration with a concentration ratio rate of 20.2 h(-1). In conclusion, the threshold for induction of estrogenic effects in juvenile brown trout at short term pulse exposure appears to be in the range 150-200 ng E2 L(-1).

Dietary selenium reduces retention of methyl mercury in freshwater fish

Adverse effects from organic mercury transported along aquatic food chains are health issues in humans and other top predators. Methyl mercury in organisms at the lower food chain levels is eliminated slowly, and laboratory studies have not clarified the role of selenium in the retention of methyl mercury in fish. Here, we investigated the effects of dietary selenium on the retention of organic and inorganic mercury in freshwater fish. Addition of selenite to the food augmented elimination of methyl mercury (but not inorganic mercury) from goldfish Carassius auratus in a dose dependent manner; selenite caused methyl mercury to be lost from the general body rather than from any specific organ. Seleno-cystine and seleno-methionine (but not selenate) likewise promoted elimination of methyl mercury from goldfish. The threshold for the augmenting effect of selenite on the elimination of methyl mercury in the zebra fish Danio rerio was 0.95 μg Se g(-1) food; higher concentrations reduced retention of methyl mercury in a dose dependent manner. Selenium concentrations in the food approaching natural background levels increase the elimination of methyl mercury from fish. Thus, selenium levels in a given aquatic food chain may affect mercury contamination along the food chain.

Bezafibrate, a lipid-lowering pharmaceutical, as a potential endocrine disruptor in male zebrafish (Danio rerio)

Fibrates are pharmaceuticals commonly used to control hypercholesterolemia in humans and they are frequently detected in the freshwater environment. Since cholesterol is the precursor of all steroid hormones, it is suspected that low cholesterol levels will impact steroidogenesis. However, the effect of fibrates on fish reproductive endocrinology is not clear; therefore the aim of the present study was to evaluate the effect of bezafibrate (BZF) on gonadal steroidogenesis and spermatogenesis of zebrafish (Danio rerio). For this purpose, adult males were exposed orally to 1.7, 33 and 70 mg BZF/g food for 21 days. Blood and gonads were collected after 48 h, 7 days and 21 days to evaluate plasma cholesterol and plasma 11-ketotestosterone (11-KT). The expression of gonadal genes involved in the steroidogenesis was quantified to determine a potential mechanism of action, likewise the effect on spermatogenesis was evaluated by examining gonadal histopathology. A time dependent monotonic decrease in the plasma cholesterol concentration was observed in fish exposed to BZF. Plasma 11-KT decreased significantly after 21 days of exposure in fish exposed to the high concentration of BZF. Different gene expression patterns were observed: down-regulation in ppara and pparg mRNA levels was observed in fish exposed to the higher concentrations after 48 h; however, the expression of pparg increased after 21 days. After 21 days an increase in the star and cyp17a1 mRNA expression was observed in fish exposed to 70 mg BZF/g food. Sampling time and bezafibrate concentration explained 52.4% and 20%, respectively, of the gene expression variability. Gonadal histology revealed the presence of germ cell syncytia in the tubular lumen of fish exposed to bezafibrate and also an increased number of cysts containing spermatocytes, which indicate testicular degeneration. The study shows that bezafibrate exerts a hypocholesterolemic effect in adult male zebrafish and its potential as an endocrine disruptor due to its effect on the gonadal steroidogenesis and spermatogenesis.

Behavioural changes in three species of freshwater macroinvertebrates exposed to the pyrethroid lambda-cyhalothrin: laboratory and stream microcosm studies

Pesticides are transported from crop fields to adjacent streams via surface run-off, drains, groundwater, wind drift and atmospheric deposition and give rise to transient pulse contamination. Although the concentrations observed, typically <10 microg L(-1), cannot be expected to be acutely lethal, effects in streams at the population and ecosystem level have been reported. One of the most conspicuous phenomena associated with these transient pesticide pulses is drift, where large numbers of freshwater invertebrates are carried along by the current and disappear from the contaminated stretch of the stream. The aim of the present study was to evaluate the feasibility of linking laboratory studies of the sublethal effects of pulse exposure to the pyrethroid lambda-cyhalothrin on the locomotory behaviour of stream invertebrates with effects on drift behaviour under more environmentally realistic conditions in stream microcosms. In the laboratory as well as in the microcosms, the order of sensitivities of the three species tested was (with Leuctra nigra being the most sensitive): L. nigra>Gammarus pulex>Heptagenia sulphurea. The LOECs determined for L. nigra (1 ng L(-1)), G. pulex (10 ng L(-1)) and H. sulphurea (100 ng L(-1)) are all within expected environmental concentrations. For the species of invertebrates investigated, it was possible to extrapolate directly from pyrethroid-induced behavioural changes observed in the laboratory to drift under more realistic conditions in stream microcosms. Consequently, the fast and cost-effective video tracking methodology may be applied for screening for potential effects of a wider range of pesticides and other stressors on the locomotory behaviour of freshwater invertebrates. The results indicate that such behavioural changes may be predictive of effects at the ecosystem level.

Trenbolone causes irreversible masculinization of zebrafish at environmentally relevant concentrations

Feminization of fish caused by certain estrogenic compounds e.g. 17 alpha-ethinylestradiol (EE2) has been shown to be partly reversible. So far it has not been studied if this applies for androgenic compounds too. The androgenic steroid trenbolone acetate (TbA) is used as growth promoter in beef cattle in the United States, South America, and Australia. TbA metabolites are stable in animal waste and have been detected in surface waters associated with feedlot areas and studies on both fish and mammals have demonstrated a strong androgenic effect of those metabolites. Zebrafish (Danio rerio) were exposed to environmentally relevant concentrations of the TbA metabolite 17beta-trenbolone from 0 to 60 days post-hatch (dph) and either sacrificed at 60 dph, transferred to clean water for 170 days or kept in exposure for 170 days. At 60 dph gonadal histology and vitellogenin analyses revealed all-male populations in groups exposed to 15.5 and 26.2 ng/L, and at 9.2 ng/L a skewed sex ratio towards males was observed. After the depuration period no sign of reversibility was observed. Environmentally relevant concentrations of 17beta-trenbolone cause a strong and irreversible masculinization of zebrafish and that raises concern about the effects of androgenic discharges in the aquatic environment. In addition this study also aids in understanding of the so far unknown sex determination process in zebrafish.

Childhood conditions and education as determinants of adult height and obesity among Greenland Inuit

Height and obesity are risk factors for cardiovascular disease and other physical and mental health conditions. Their association with childhood socioeconomic position has been demonstrated in studies among European and a few third world populations. In a random sample of adult Greenland Inuit (N = 2302) we studied the association between childhood socioeconomic conditions and height as well as prevalence of obesity (BMI > or = 30) in a cross sectional design. In block recursive graphical independence models, height was associated with mother's place of birth, birth cohort, childhood residence, alcohol problems in childhood home, and education among both men and women. Obesity was associated with mother's place of birth (for men) and with alcohol problems (for women). In General Linear Models, men with an all rural background and no education beyond primary school measured on average 165.1 cm compared with 172.1 cm for men with an all urban background (P < 0.001); women measured 153.9 and 161.1 cm (P < 0.001). Rural-urban differences in prevalence of obesity were not statistically significant. The height differences were considerably larger than between educational groups in European countries and of the same order of magnitude as those reported between men from the 17th century and men from 400 BC in the European and Mediterranean region. The rural-urban gradient in height follows the socioeconomic gradient and may negatively affect cardiovascular risk among the rural Greenlanders, while their physically active lifestyle and high consumption of n-3 fatty acids may counteract this.

Multi-criteria decision analysis of test endpoints for detecting the effects of endocrine active substances in fish full life cycle tests

Fish full life cycle (FFLC) tests are increasingly required in the ecotoxicological assessment of endocrine active substances. However, FFLC tests have not been internationally standardized or validated, and it is currently unclear how such tests should best be designed to provide statistically sound and ecologically relevant results. This study describes how the technique of multi-criteria decision analysis (MCDA) was used to elicit the views of fish ecologists, aquatic ecotoxicologists and statisticians on optimal experimental designs for assessing the effects of endocrine active chemicals on fish. In MCDA qualitative criteria (that can be valued, but not quantified) and quantitative criteria can be used in a structured decision-making process. The aim of the present application of MCDA is to present a logical means of collating both data and expert opinions on the best way to focus FFLC tests on endocrine active substances. The analyses are presented to demonstrate how MCDA can be used in this context. Each of 3 workgroups focused on 1 of 3 species: fathead minnow (Pimephales promelas), Japanese medaka (Oryzias latipes), and zebrafish (Danio rerio). Test endpoints (e.g., fecundity, growth, gonadal histopathology) were scored for each species for various desirable features such as statistical power and ecological relevance, with the importance of these features determined by assigning weights to them, using a swing weighting procedure. The endpoint F1 fertilization success consistently emerged as a preferred option for all species. In addition, some endpoints scored highly in particular species, such as development of secondary sexual characteristics (fathead minnow) and sex ratio (zebrafish). Other endpoints such as hatching success ranked relatively highly and should be considered as useful endpoints to measure in tests with any of the fish species. MCDA also indicated relatively less preferred endpoints in fish life cycle tests. For example, intensive histopathology consistently ranked low, as did measurement of diagnostic biomarkers, such as vitellogenin, most likely due to the high costs of these methods or their limited ecological relevance. Life cycle tests typically do not focus on identifying toxic modes and/or mechanisms of action, but rather, single chemical concentration-response relationships for endpoints (e.g., survival, growth, reproduction) that can be translated into evaluation of risk. It is, therefore, likely to be an inefficient use of limited resources to measure these mechanism-specific endpoints in life cycle tests, unless the value of such endpoints for answering particular questions justifies their integration in specific case studies.

Expression of prostaglandin synthases (pgds and pges) during zebrafish gonadal differentiation

The present study aimed at elucidating whether the expression pattern of the membrane bound form of prostaglandin E2 synthase (pges) and especially the lipocalin-type prostaglandin D2 synthase (pgds) indicates involvement in gonadal sex differentiation in zebrafish as has previously been found in other species. In mice and chicken, the lipocalin-type Pgds is specifically expressed in pre-Sertoli cells just after Sry and Sox9 and is involved in masculinisation of the developing testis. Furthermore, Pges are implicated in female reproduction including follicular development and ovulation. In this study, a sexually dimorphic expression of pgds was found in gonads of adult zebrafish with expression in testis but not in ovaries. To determine whether the sex-specific expression pattern of pgds was present in gonads of juvenile zebrafish and therefore could be an early marker of sex in zebrafish, we microdissected gonads from four randomly selected individual zebrafish for every second day in the period 2-20 days post hatch (dph) and 0-1 dph. The temporal expression of pgds and pges was investigated in the microdissected gonads, however, no differential expression that could indicate sex-specific difference between individual juvenile zebrafish was observed.

Gonadal alterations in male eelpout (Zoarces viviparus) exposed to ethinylestradiol and trenbolone separately or in combination

To evaluate the interaction between 17β-trenbolone (TB) and 17α-ethinylestradiol (EE2) in relevant environmental concentrations, male eelpout Zoarces viviparus were exposed in a flow-through seawater-system for 21 days to 5 ng l⁻¹ EE2, 5 ng l⁻¹ or 20 ng l⁻¹ TB or to combinations of both compounds. The effects on hepatosomatic index (HSI), gonadosomatic index (GSI) and gonadal histology were studied. No significant effects on HSI were observed in any treatment; in contrast, decreased GSI was observed in males exposed to EE2 alone or in combination with TB compared to controls (p<0.05). The histology revealed that the males were in the beginning of spermatogenesis. Males from the control group and some from the TB groups showed tubules with cysts containing spermatogonia, spermatocytes and spermatids; however, some testes of males exposed to TB showed slight to moderate interstitial fibrosis. Nevertheless, the most severely affected were males exposed to EE2 showing marked interstitial fibrosis, necrosis of germinal cells and reduced number of spermatocytes and spermatogonia in the cyst. Likewise, increased tubule number and proportionally decreased tubule diameter were observed in the testis of all EE2 exposed groups (p<0.05). Finally, a similar tubule number was observed in males exposed to EE2+20 ng l⁻¹ TB compared to control (p>0.05). This study shows that EE2 dramatically disrupts the spermatogenesis and low doses of 17β-trenbolone are unable to effectively counteract the morphological effects of EE2.

Laser capture microdissection of gonads from juvenile zebrafish

BACKGROUND

Investigating gonadal gene expression is important in attempting to elucidate the molecular mechanism of sex determination and differentiation in the model species zebrafish. However, the small size of juvenile zebrafish and correspondingly their gonads complicates this type of investigation. Furthermore, the lack of a genetic sex marker in juvenile zebrafish prevents pooling gonads from several individuals. The aim of this study was to establish a method to isolate the gonads from individual juvenile zebrafish allowing future investigations of gonadal gene expression during sex determination and differentiation.

METHODS

The laser capture microdissection technique enables isolation of specific cells and tissues and thereby removes the noise of gene expression from other cells or tissues in the gene expression profile. A protocol developed for laser microdissection of human gonocytes was adjusted and optimised to isolate juvenile zebrafish gonads.

RESULTS

The juvenile zebrafish gonad is not morphologically distinguishable when using dehydrated cryosections on membrane slides and a specific staining method is necessary to identify the gonads. The protocol setup in this study allows staining, identification, isolation and subsequent RNA purification and amplification of gonads from individual juvenile zebrafish thereby enabling gonadal gene expression profiling.

CONCLUSION

The study presents a protocol for isolation of individual juvenile zebrafish gonads, which will enable future investigations of gonadal gene expression during the critical period of sex differentiation. Furthermore, the presented staining method is applicable to other species as it is directed towards alkaline phosphatase that is expressed in gonocytes and embryonic stem cells, which is conserved among vertebrate species.

Amiodarone for refractory supraventricular tachycardias

Amiodarone was administered to 53 patients with otherwise drug-refractory supraventricular tachycardias. Therapy was effective in 35 patients and partially effective in nine patients for a median duration of 35 months. The median maintenance dose was 200 mg/day in both groups, whereas the median serum amiodarone concentrations were 1.1 mg/l and 0.7 mg/l, respectively. Amiodarone was ineffective in nine patients despite higher dosage (median 400 mg/day) and insignificantly higher serum concentrations (median 2.0 mg/l). Neither the age of the patients, the duration or type of arrhythmia, the cardio-thoracic index, nor the type of underlying heart disease were predictive of the efficacy of amiodarone. Side-effects occurred in 28 patients, leading to withdrawal of therapy in 12 patients. Side-effects were not associated with higher serum amiodarone concentrations. Despite its efficacy, amiodarone should be reserved for otherwise drug-resistant supraventricular tachyarrhythmias.

Deceleration-dependent shortening of the QT interval: a new electrocardiographic phenomenon?

In clinical cardiology, deceleration-dependent QT interval shortening is considered to be an extraordinary electrocardiographic phenomenon. We present an early premature born 4-year-old African-American girl with complications related to her premature birth, developmental delay, and several episodes of cardiac arrest. An episode of severe transient bradyarrhythmia was documented on Holter monitoring. The unique feature of the rhythm strips was paradoxical gradual shortening of the QT interval to 216 ms with accompanying transient T-waves abnormalities. The activation of the Ik, ACh due to an unusually high vagal discharge to the heart is proposed as a possible mechanism responsible for both slowing of the heart rate and shortening of the QT interval.