Psychoactive pharmaceuticals induce fish gene expression profiles associated with human idiopathic autism

Antidepressants - The new endocrine disruptors? The case of crustaceans

Antidepressants are high-volume pharmaceuticals that accumulate to concentrations in the μg·L-1 range in surface waters. The release of peptide hormones via neurosecretory cells appears as a natural target for antidepressants. Here I review research that suggests that antidepressants indeed disrupt endocrine signalling in crustaceans, by acting on the synthesis and release of neurohormones, such as crustacean hyperglycaemic hormone, moult inhibiting hormone and pigment dispersing hormone in decapods, as well as methyl farnesoate in Daphnids. Hence, antidepressants can affect hormonal regulation of physiological functions: increase in energy metabolism and activity, lowered ecdysteroid levels, potentially disrupting moult and somatic growth, reducing colour change capacity and compromising camouflage, as well as induction of male sex determination. Several studies further suggest effects of antidepressants on crustacean reproduction, but the hormonal regulation of these effects remains elusive. All things considered, a body of evidence strongly suggests that antidepressants are endocrine disrupting compounds in crustaceans.

Prescribed aggression of fishes: Pharmaceuticals modify aggression in environmentally relevant concentrations

Traces of psychoactive substances have been found in freshwaters globally. Fish are chronically exposed to pollution at low concentrations. The changes of aggressive behaviour of chub (Squalius cephalus) were determined under the exposure to four psychoactive compounds (sertraline, citalopram, tramadol, methamphetamine) at environmentally relevant concentrations of 1 μg/L for 42 days. We tested whether (A) the behavioural effect of compounds varies within a single species; (B) there is a correlation between the individual brain concentration of the tested pollutants and fish aggression using the novel analysis of pollutants in brain; and (C) there is detectable threshold to effective pollutant concentration in brain. Behaviour and pollutant concentrations in brain were determined repeatedly (1st, 7th, 21st, 42nd and 56th days), including a two-week-long depuration period. The effect of particular compounds varied. Citalopram and methamphetamine generally increased the fish aggression, while no such effect was found after exposure to tramadol or sertraline. The longitudinal analysis showed an aggression increase after depuration, indicating the presence of withdrawal effects in methamphetamine- and tramadol-exposed fish. The analysis of pollutant concentration in brain revealed a positive linear relationship of citalopram concentration and aggression, while no such effect was detected for other compounds and/or their metabolites. Structural break analyses detected concentration thresholds of citalopram (1 and 3 ng/g) and sertraline (1000 ng/g) in brain tissue, from which a significant effect on behaviour was manifested. While the effect of sertraline was not detected using traditional approaches, there was a reduction in aggression after considering its threshold concentration in the brain. Our results suggest that pursuing the concentration threshold of psychoactive compounds can help to reduce false negative results and provide more realistic predictions on behavioural outcomes in freshwater environments, especially in the case of compounds with bioaccumulation potential such as sertraline.

Developmental Neurotoxicity of Environmentally Relevant Pharmaceuticals and Mixtures Thereof in a Zebrafish Embryo Behavioural Test

Humans are exposed daily to complex mixtures of chemical substances via food intake, inhalation, and dermal contact. Developmental neurotoxicity is an understudied area and entails one of the most complex areas in toxicology. Animal studies for developmental neurotoxicity (DNT) are hardly performed in the context of regular hazard studies, as they are costly and time consuming and provide only limited information as to human relevance. There is a need for a combination of in vitro and in silico tests for the assessment of chemically induced DNT in humans. The zebrafish (Danio rerio) embryo (ZFE) provides a powerful model to study DNT because it shows fast neurodevelopment with a large resemblance to the higher vertebrate, including the human system. One of the suitable readouts for DNT testing in the zebrafish is neurobehaviour (stimulus-provoked locomotion) since this provides integrated information on the functionality and status of the entire nervous system of the embryo. In the current study, environmentally relevant pharmaceuticals and their mixtures were investigated using the zebrafish light-dark transition test. Zebrafish embryos were exposed to three neuroactive compounds of concern, carbamazepine (CBZ), fluoxetine (FLX), and venlafaxine (VNX), as well as their main metabolites, carbamazepine 10,11-epoxide (CBZ 10,11E), norfluoxetine (norFLX), and desvenlafaxine (desVNX). All the studied compounds, except CBZ 10,11E, dose-dependently inhibited zebrafish locomotor activity, providing a distinct behavioural phenotype. Mixture experiments with these pharmaceuticals identified that dose addition was confirmed for all the studied binary mixtures (CBZ-FLX, CBZ-VNX, and VNX-FLX), thereby supporting the zebrafish embryo as a model for studying the cumulative effect of chemical mixtures in DNT. This study shows that pharmaceuticals and a mixture thereof affect locomotor activity in zebrafish. The test is directly applicable in environmental risk assessment; however, further studies are required to assess the relevance of these findings for developmental neurotoxicity in humans.

Removal of Carbamazepine onto Modified Zeolitic Tuff in Different Water Matrices: Batch and Continuous Flow Experiments

Carbamazepine (CBZ) is the most frequently detected pharmaceutical residues in aquatic environments effluent by wastewater treatment plants. Batch and column experiments were conducted to evaluate the removal of CBZ from ultra-pure water and wastewater treatment plant (WWTP) effluent using raw zeolitic tuff (RZT) and surfactant modified zeolite (SMZ). Point zero net charge (pHpzc), X-ray diffraction (XRD), X-ray fluorescence (XRF), and Fourier Transform Infrared (FTIR) were investigated for adsorbents to evaluate the physiochemical changes resulted from the modification process using Hexadecyltrimethylammonium bromide (HDTMA-Br). XRD and FTIR showed that the surfactant modification of RZT has created an amorphous surface with new alkyl groups on the surface. The pHpzc was determined to be approximately 7.9 for RZT and SMZ. The results indicated that the CBZ uptake by SMZ is higher than RZT in all sorption tests (>8 fold). Batch results showed that the sorption capacity of RZT and SMZ in WWTP effluent (0.029 and 0.25 mg/g) is higher than RZT and SMZ (0.018 and 0.14 mg/g) in ultrapure water (1.6–1.8 fold). Batch tests showed that the equilibrium time of CBZ removal in the WWTP matrix (47 h) is much longer than CBZ removal in ultrapure water. The sorption capacity of RZT & SMZ in WWTP effluent (0.03, 0.33 mg/g) is higher than RZT and SMZ (0.02 and 0.17 mg/g) in ultrapure water (1.5–2 fold) using column test. This study has clearly demonstrated that the performance of RZT and SMZ is more efficient for the removal of CBZ from realistic wastewater than ultrapure water. It is evident that the surfactant modification of RZT has enhanced the CBZ removal in both matrices.

The potential association of psychoactive pharmaceuticals in the environment with human neurological disorders

Psychoactive pharmaceuticals release into the environment and reach humans through a variety of routes, including sewage, drinking water, contaminated irrigation water, biosolids, soil and food. It was assumed that these compounds via the environment could induce genetic effects in the etiology of human neurological disorders. With the help of in vitro, in vivo and in silico approaches, we demonstrated that psychoactive pharmaceuticals in drinking water can cross maternal biological barriers and alter in vitro molecular and genetic mechanisms that potentially have a key role in the development, growth and regulation of neuronal systems during embryonic brain development.

Contamination profiles, mass loadings, and sewage epidemiology of neuropsychiatric and illicit drugs in wastewater and river waters from a community in the Midwestern United States

In this study, residues of the neuropsychiatric and illicit drugs including stimulants, opioids, hallucinogens, antischizophrenics, sedatives, and antidepressants were determined in influent and effluent samples from a small wastewater treatment plant, a receiving creek, and river waters in the Four Rivers region of the Midwestern United States. Nineteen neuropsychiatric drugs, eight illicit drugs, and three metabolites of illicit drugs were detected and quantitated in the water samples using HPLC-MS/MS. Residual concentrations of the drugs varied from below the detection limit to sub-μg/L levels. The source of residual cocaine and benzoylecgonine in wastewater is primarily from human consumption of cocaine rather than direct disposal. Wastewater based epidemiology is utilized to estimate the community usage of drugs based on the concentration of drug residues in wastewater, wastewater inflow, and the population served by the centralized wastewater treatment plant. The per-capita consumption rate of methamphetamine (1740 mg/d/1000 people) and amphetamine (970 mg/d/1000 people) found in this study were the highest reported per-capita consumption rates in the USA. Antidepressant venlafaxine found to have the highest environmental emission from the WWTP (333 ± 160 mg/d/1000 people) followed by citalopram (132 ± 60.2 mg/d/1000 people), methamphetamine (111 ± 43.6 mg/d/1000 people), and hydrocodone (108 ± 90.1 mg/d/1000 people). Bee Creek, an immediate receiving water body, is found to be a source of several neuropsychiatric and illicit drugs including methamphetamine, methadone, alprazolam, oxazepam, temazepam, carbamazepine, venlafaxine, citalopram, sertraline, oxycodone, and hydrocodone (p < 0.036) in the Clarks River.

Pesticides exposure through environment and risk of pre-term birth: a study from Agra city

Pre-term birth is an increasingly prevalent complex condition with multiple risk factors including environmental pollutants. Evidences linking organochlorine pesticides with adverse pregnancy outcomes are inconsistent for link between organochlorine pesticides and adverse pregnancy outcomes. We performed a case-control study of 50 cases of full-term births and 40 cases of pre-term births in this study. Placental organochlorine pesticides like metabolites of dichlorodiphenyltrichloroethane that is, (p,p-DDE, p,p-DDT and o,p-DDD) and isomers of hexachlorocyclohexane (α, β, γ and δ HCH) were analyzed by gas chromatography. Although the mean levels of pesticide were found higher in the placenta of the women with pre-term delivery cases placentas, but only α-HCH, total-HCH, p,p-DDE and total-DDT were found statistically significant. It was observed that pesticide exposed women were approximately 1.7 times more likely to deliver pre-term baby as compare to pregnant women that were not exposed to any pesticides. We also observed that increasing maternal age reduced the risk of having pre-term birth (OR = 0.99). Among all pesticides, α-HCH was found to be strongest isomer to induce premature baby birth (p < 0.001). This study found that pregnant women's age and chronic disease, baby's weight at the time of birth and α-HCH were important risk factors for pre-term births.

Toxicokinetics, disposition and metabolism of fluoxetine in crabs

The disposition and metabolism of fluoxetine in the European shore crab and the Dungeness crab were assessed. Crabs received intracardiac doses of either 0.13 μg/kg or 0.5 mg/kg fluoxetine, respectively. In addition, fluoxetine was administered to Metacarcinus cancer by oral gavage at 7.8 mg/kg. The distribution of fluoxetine was quantified in haemolymph and digestive gland for both crabs, as well as brain, muscle, and testis of Carcinus maenas, over 12 days. The metabolite norfluoxetine, was also measured in C. maenas. Fluoxetine was mainly found in lipid rich tissues. Distribution coefficients increased for digestive gland until three days after fluoxetine administration and then decreased until the end of the observations. The highest distribution coefficients were obtained for brain. Norfluoxetine displayed continuously high levels in digestive gland and brain. The strong decrease in fluoxetine and the concomitant increase in norfluoxetine demonstrates that decapod crustaceans metabolise fluoxetine into the more biologically active norfluoxetine. Fluoxetine levels in the haemolymph of M. cancer declined within 20 h, but showed a second peak 25 h later, suggesting remobilisation from tissues sequestering the compound. The steady state volume distribution and the total body clearance of fluoxetine were high, consistent with high diffusion of fluoxetine into the peripheral tissues and biotransformation as an important elimination pathway. Oral administration of fluoxetine prolonged its half-life in M. cancer, but bioavailability was low. These results confirm the high distribution into nervous tissue, extensive biotransformation into the highly active norfluoxetine and a half-life similar to that observed in vertebrates.

Dysregulation of autism-associated synaptic proteins by psychoactive pharmaceuticals at environmental concentrations

Autism Spectrum Disorders (ASD) are complex neurological disorders for which the prevalence in the U.S. is currently estimated to be 1 in 50 children. A majority of cases of idiopathic autism in children likely result from unknown environmental triggers in genetically susceptible individuals. These triggers may include maternal exposure of a developing embryo to environmentally relevant minute concentrations of psychoactive pharmaceuticals through ineffectively purified drinking water. Previous studies in our lab examined the extent to which gene sets associated with neuronal development were up- and down-regulated (enriched) in the brains of fathead minnows treated with psychoactive pharmaceuticals at environmental concentrations. The aim of this study was to determine whether similar treatments would alter in vitro expression of ASD-associated synaptic proteins on differentiated human neuronal cells. Human SK-N-SH neuroblastoma cells were differentiated for two weeks with 10μM retinoic acid (RA) and treated with environmentally relevant concentrations of fluoxetine, carbamazepine or venlafaxine, and flow cytometry technique was used to analyze expression of ASD-associated synaptic proteins. Data showed that carbamazepine individually, venlafaxine individually and mixture treatment at environmental concentrations significantly altered the expression of key synaptic proteins (NMDAR1, PSD95, SV2A, HTR1B, HTR2C and OXTR). Data indicated that psychoactive pharmaceuticals at extremely low concentrations altered the in vitro expression of key synaptic proteins that may potentially contribute to neurological disorders like ASD by disrupting neuronal development.

Psychoactive pharmaceuticals at environmental concentrations induce in vitro gene expression associated with neurological disorders

Background

A number of researchers have speculated that neurological disorders are mostly due to the interaction of common susceptibility genes with environmental, epigenetic and stochastic factors. Genetic factors such as mutations, insertions, deletions and copy number variations (CNVs) are responsible for only a small subset of cases, suggesting unknown environmental contaminants play a role in triggering neurological disorders like idiopathic autism. Psychoactive pharmaceuticals have been considered as potential environmental contaminants as they are detected in the drinking water at very low concentrations. Preliminary studies in our laboratory identified gene sets associated with neuronal systems and human neurological disorders that were significantly enriched after treating fish brains with psychoactive pharmaceuticals at environmental concentrations. These gene expression inductions were associated with changes in fish behavior. Here, we tested the hypothesis that similar treatments would alter in vitro gene expression associated with neurological disorders (including autism) in human neuronal cells. We differentiated and treated human SK-N-SH neuroblastoma cells with a mixture (fluoxetine, carbamazepine and venlafaxine) and valproate (used as a positive control to induce autism-associated profiles), followed by transcriptome analysis with RNA-Seq approach.

Results

We found that psychoactive pharmaceuticals and valproate significantly altered neuronal gene sets associated with human neurological disorders (including autism-associated sets). Moreover, we observed that altered expression profiles in human cells were similar to gene expression profiles previously identified in fish brains.

Conclusions

Psychoactive pharmaceuticals at environmental concentrations altered in vitro gene expression profiles of neuronal growth, development and regulation. These expression patterns were associated with potential neurological disorders including autism, suggested psychoactive pharmaceuticals at environmental concentrations might mimic, aggravate, or induce neurological disorders.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-016-2784-1) contains supplementary material, which is available to authorized users.

Maternal exposure to carbamazepine at environmental concentrations can cross intestinal and placental barriers

Psychoactive pharmaceuticals have been found as teratogens at clinical dosage during pregnancy. These pharmaceuticals have also been detected in minute (ppb) concentrations in drinking water in the US, and are environmental contaminants that may be complicit in triggering neurological disorders in genetically susceptible individuals. Previous studies have determined that psychoactive pharmaceuticals (fluoxetine, venlafaxine and carbamazepine) at environmentally relevant concentrations enriched sets of genes regulating development and function of the nervous system in fathead minnows. Altered gene sets were also associated with potential neurological disorders, including autism spectrum disorders (ASD). Subsequent in vitro studies indicated that psychoactive pharmaceuticals altered ASD-associated synaptic protein expression and gene expression in human neuronal cells. However, it is unknown if environmentally relevant concentrations of these pharmaceuticals are able to cross biological barriers from mother to fetus, thus potentially posing risks to nervous system development. The main objective of this study was to test whether psychoactive pharmaceuticals (fluoxetine, venlafaxine, and carbamazepine) administered through the drinking water at environmental concentrations to pregnant mice could reach the brain of the developing embryo by crossing intestinal and placental barriers. We addressed this question by adding (2)H-isotope labeled pharmaceuticals to the drinking water of female mice for 20 days (10 pre-and 10 post-conception days), and quantifying (2)H-isotope enrichment signals in the dam liver and brain of developing embryos using isotope ratio mass spectrometry. Significant levels of (2)H enrichment was detected in the brain of embryos and livers of carbamazepine-treated mice but not in those of control dams, or for fluoxetine or venlafaxine application. These results provide the first evidence that carbamazepine in drinking water and at typical environmental concentrations is transmitted from mother to embryo. Our results, combined with previous evidence that carbamazepine may be associated with ASD in infants, warrant the closer examination of psychoactive pharmaceuticals in drinking water and their potential association with neurodevelopmental disorders.

Leveraging existing data for prioritization of the ecological risks of human and veterinary pharmaceuticals to aquatic organisms

Medicinal innovation has led to the discovery and use of thousands of human and veterinary drugs. With this comes the potential for unintended effects on non-target organisms exposed to pharmaceuticals inevitably entering the environment. The impracticality of generating whole-organism chronic toxicity data representative of all species in the environment has necessitated prioritization of drugs for focused empirical testing as well as field monitoring. Current prioritization strategies typically emphasize likelihood for exposure (i.e. predicted/measured environmental concentrations), while incorporating only rather limited consideration of potential effects of the drug to non-target organisms. However, substantial mammalian pharmacokinetic and mechanism/mode of action (MOA) data are produced during drug development to understand drug target specificity and efficacy for intended consumers. An integrated prioritization strategy for assessing risks of human and veterinary drugs would leverage available pharmacokinetic and toxicokinetic data for evaluation of the potential for adverse effects to non-target organisms. In this reiview, we demonstrate the utility of read-across approaches to leverage mammalian absorption, distribution, metabolism and elimination data; analyse cross-species molecular target conservation and translate therapeutic MOA to an adverse outcome pathway(s) relevant to aquatic organisms as a means to inform prioritization of drugs for focused toxicity testing and environmental monitoring.

Occurrence and fate of select psychoactive pharmaceuticals and antihypertensives in two wastewater treatment plants in New York State, USA

The fates of psychoactive pharmaceuticals, including two antischizophrenics, six sedative-hypnotic-anxiolytics, four antidepressants, four antihypertensives, and their select metabolites, were determined in two wastewater treatment plants (WWTPs) in the Albany area of New York. All target psychoactive pharmaceuticals and their metabolites were found at a mean concentration that ranged from 0.98 (quetiapine) to 1220 ng/L (atenolol) in wastewater and from 0.26 (lorazepam) to 1490 ng/g dry weight (sertraline) in sludge. In this study, the fraction of psychoactive pharmaceuticals that was sorbed to suspended particulate matter (SPM) was calculated for the first time. Over 50% of the total mass of aripiprazole, norquetiapine, norsertraline, citalopram, desmethyl citalopram, propranolol, verapamil, and norverapamil was found sorbed to SPM in the influent. The mass loadings, i.e., influx, of target psychoactive pharmaceuticals in WWTPs ranged from 0.91 (diazepam) to 347 mg/d/1000 inhabitants (atenolol), whereas the environmental emissions ranged from 0.01 (dehydro-aripiprazole) to 316 mg/d/1000 inhabitants (atenolol). The highest calculated removal efficiencies were found for antischizophrenics (quetiapine=88%; aripiprazole=71%). However, the removal of some psychoactive pharmaceuticals through adsorption onto sludge was minimal (<1% of the initial mass load), which suggests that bio-degradation and/or chemical-transformation are the dominant mechanisms of removal of these pharmaceuticals in WWTPs.

Psychoactive pharmaceuticals as environmental contaminants may disrupt highly inter-connected nodes in an Autism-associated protein-protein interaction network

Background

Most cases of idiopathic autism spectrum disorder (ASD) likely result from unknown environmental triggers in genetically susceptible individuals. These triggers may include maternal exposure of a fetus to minute concentrations of pharmaceuticals, such as carbamazepine (CBZ), venlafaxine (VNX) and fluoxetine (FLX). Unmetabolized pharmaceuticals reach drinking water through a variety of routes, including ineffectively treated sewage. Previous studies in our laboratory examined the extent to which gene sets were enriched in minnow brains treated with pharmaceuticals. Here, we tested the hypothesis that genes in fish brains and human cell cultures, significantly enriched by pharmaceuticals, would have distinct characteristics in an ASD-associated protein interaction network. We accomplished this by comparing these groups using 10 network indices.

Results

A network of 7212 proteins and 33,461 interactions was generated. We found that network characteristics for enriched gene sets for particular pharmaceuticals were distinct from each other, and were different from non-enriched ASD gene sets. In particular, genes in fish brains, enriched by CBZ and VNX 1) had higher network importance than that in the overall network, and those enriched by FLX, and 2) were distinct from FLX and non-enriched ASD genes in multivariate network space. Similarly, genes in human cell cultures enriched by pharmaceutical mixtures (at environmental concentrations) and valproate (at clinical dosages) had similar network signatures, and had greater network importance than genes in the overall ASD network.

Conclusions

The results indicate that important gene sets in the ASD network are particularly susceptible to perturbation by pharmaceuticals at environmental concentrations.

The Matthew Effect and widely prescribed pharmaceuticals lacking environmental monitoring: case study of an exposure-assessment vulnerability

Assessing ambient exposure to chemical stressors often begins with time-consuming and costly monitoring studies to establish environmental occurrence. Both human and ecological toxicology are currently challenged by the unknowns surrounding low-dose exposure/effects, compounded by the reality that exposure undoubtedly involves mixtures of multiple stressors whose identities and levels can vary over time. Long absent from the assessment process, however, is whether the full scope of the identities of the stressors is sufficiently known. The Matthew Effect (a psychosocial phenomenon sometimes informally called the "bandwagon effect" or "iceberg effect," among others) may adversely bias or corrupt the exposure assessment process. The Matthew Effect is evidenced by decisions that base the selection of stressors to target in environmental monitoring surveys on whether they have been identified in prior studies, rather than considering the possibility that additional, but previously unreported, stressors might also play important roles in an exposure scenario. The possibility that the Matthew Effect might influence the scope of environmental stressor research is explored for the first time in a comprehensive case study that examines the preponderance of "absence of data" (in contrast to positive data and "data of absence") for the environmental occurrence of a very large class of potential chemical stressors associated with ubiquitous consumer use - active pharmaceutical ingredients (APIs). Comprehensive examination of the published data for an array of several hundred of the most frequently used drugs for whether their APIs are environmental contaminants provides a prototype example to catalyze discussion among the many disciplines involved with assessing risk. The findings could help guide the selection of those APIs that might merit targeting for environmental monitoring (based on the absence of data for environmental occurrence) as well as the prescribing of those medications that might have minimal environmental impact (based on data of absence for environmental occurrence).

Uptake of human pharmaceuticals in bull sharks (Carcharhinus leucas) inhabiting a wastewater-impacted river

The presence of human pharmaceuticals in sewage-impacted ecosystems is a growing concern that poses health risks to aquatic wildlife. Despite this, few studies have investigated the uptake of active pharmaceutical ingredients (APIs) in aquatic organisms. In this study, the uptake of 9 APIs from human drugs was examined and compared in neonate bull sharks (Carcharhinus leucas) residing in pristine (Myakka River) and wastewater-impacted (Caloosahatchee River) tributaries of Florida's Charlotte Harbor estuary. The synthetic estrogen used in human contraceptives (17α-ethynylestradiol) and 6 of the selective serotonin/norepinephrine reuptake inhibitors (citalopram, fluoxetine, fluvoxamine, paroxetine, sertraline, venlafaxine) used in human antidepressants were observed at detectable and, in some cases, quantifiable levels in plasma of Caloosahatchee River sharks. Comparatively, only venlafaxine was detected in the plasma of a single Myakka River shark at a level below the limit of quantitation. These results suggest that sharks residing in wastewater-impacted habitats accumulate APIs, a factor that may pose special risks to C. leucas since it is one of few shark species to regularly occupy freshwater systems. Further research is needed to determine if the low levels of API uptake observed in Caloosahatchee River bull sharks pose health risks to these animals.

Estrogen-like effects in male goldfish co-exposed to fluoxetine and 17 alpha-ethinylestradiol

The antidepressant fluoxetine (FLX) and the synthetic estrogen, 17 alpha-ethinylestradiol (EE2), are present in municipal sewage discharges. To better understand possible interactions between them, male goldfish were exposed to an ethanol control or to nominal concentrations of FLX (0.54 μg/L) and EE2 (5 ng/L) alone and in combination for 14 days. Real-time reverse-transcription polymerase chain reaction was used to assess effects on hepatic gene expression and liquid chromatography tandem mass spectrometry to analyze the plasma proteome. The results showed an increase in estrogen receptor alpha (esr1) and vitellogenin (vtg) gene expression by 1.9-2.4-fold in the FLX and EE2 groups, but this did not reach statistical significance. In contrast, co-exposure up regulated esr1 and vtg gene expression by 5.5- and 5.3-fold, respectively. Fluoxetine and EE2 alone did not affect estrogen receptor beta (esr2), but the co-exposure down regulated esr2 expression by 50%. There was a significant increase in the number of plasma proteins that were related to endocrine system disorders in the FLX and FLX plus EE2 groups. The level of VTG protein was increased in the plasma from goldfish exposed to EE2, FLX, and FLX plus EE2. Our study demonstrates that low concentrations of FLX and EE2 in a simple mixture produce strong estrogen-like effects in the male goldfish.

An ecological study on childhood autism

BACKGROUND AND METHODS

Idiopathic autism, suspected to be caused by exposure of genetically susceptible individuals to unknown environmental triggers, has increased dramatically in the past 25 years. The objectives of our study were to determine, using a linear regression model, whether the county prevalence of autism in the Pacific Northwest of the United States was associated with the source of drinking water for that county and whether this relationship was dependent on the level of environmental pollutants and meteorological factors in the county.

RESULTS

We found the previously reported relationship between precipitation and autism in a county was dependent on the amount of drinking water derived from surface sources in the county. We also found a positive association between the EPA's risk of neurological disease and autism, but this relationship was only present in warm areas.

CONCLUSIONS

Our study provides evidence for the hypothesis that environmental factors are associated with autism and that meteorological factors play a role in this relationship.