Oxidative potential of size-fractionated atmospheric aerosol in urban and rural sites across Europe.

In this study we applied several assays, an in vitro rat alveolar macrophage model, a chemical ROS probe (DTT, dithiothreitol), and cytokine induction (TNFα) to examine relationships between PM-induced generation of reactive oxygen species (ROS) and PM composition, using a unique set of size-resolved PM samples obtained from urban and rural environments across Europe. From April-July 2012, we collected PM from roadside canyon, roadside motorway, and background urban sites in each of six European cities and from three rural sites spanning the continent. A Hi-Vol sampler was used to collect PM in three size classes (PM>7, PM7-3, PM3) and PM was characterized for total elements, and oxidative activity quantified in unfiltered and filtered PM extracts. We measured a remarkable uniformity in air concentrations of ROS and especially DTT activity across the continent. Only a 4-fold difference was documented for DTT across the urban sites and a similar variance was documented for ROS, implying that chemical drivers of oxidative activity are relatively similar between sites. The ROS and DTT specific activity was greater at urban background sites (and also rural sites) than at urban canyon locations. PM3 dominated the size distribution of both ROS activity (86% of total) and DTT activity (76% of total), reflecting both the large contribution of PM3 to total PM mass levels and importantly the higher specific oxidative activity of the PM3 in comparison with the larger particles. The soluble fraction of total activity was very high for DTT (94%) as well as for ROS (64%) in the PM3. However in the larger PM size fractions the contributions of the insoluble components became increasingly significant. The dominance of the insoluble PM drivers of activity was particularly evident in the TNFα data, where the insoluble contribution to cytokine production could be 100-fold greater than that from soluble components. ROS and DTT activity were strongly correlated in the PM3 (r = 0.93), however oxidative activity was not correlated with any measured inorganic element in this size cut. In contrast, significant correlations of both ROS and DTT oxidative activity with specific groups of chemical elements were documented in the larger PM size fractions.

Influence of Acidification on the Partitioning of Steroid Hormones among Filtrate, Filter Media, and Retained Particulate Matter.

Hormone contamination of aquatic systems has been shown to have deleterious effects on aquatic biota. However, the assessment of hormone contamination of aquatic environments requires a quantitative evaluation of the potential effects of sample preservation on hormone concentrations. This study investigated the influence of acidification (pH 2) of surface water samples on the partitioning of hormones among filtrate, filter media, and filter-retained particulate matter. Hormones were spiked into unpreserved and sulfuric acid-preserved ultrapure water and surface water runoff samples. The samples were filtered, and hormones were extracted from the filter and filtrate and analyzed by high-performance liquid chromatography. Acidification did not influence the partitioning of hormones onto the filter media. For the majority of the hormones investigated in this study, the partitioning of hormones to the filter-retained particulate matter was not influenced by acidification. Acidification increased the partitioning of progesterone and melengestrol acetate onto the retained particulate matter (about 25% for both analytes). Incorporation of an isotopically labeled internal standard (ISTD) for progesterone accounted for the loss of progesterone to the filter-retained particulates and resulted in accurate concentrations of progesterone in the filtrate. The incorporation of an ISTD for melengestrol acetate, however, was unable to account for the loss of melengestrol acetate to the retained particulates and resulted in underestimations of melengestrol acetate in the filtrate. Our results indicate that the analysis of melengestrol acetate in acid preserved surface runoff samples should be conducted on the filter-retained particulates as well as the filtrate.

Circulating serum xenoestrogens and mammographic breast density.

INTRODUCTION: Humans are widely exposed to estrogenically active phthalates, parabens, and phenols, raising concerns about potential effects on breast tissue and breast cancer risk. We sought to determine the association of circulating serum levels of these chemicals (reflecting recent exposure) with mammographic breast density (a marker of breast cancer risk). METHODS: We recruited postmenopausal women aged 55 to 70 years from mammography clinics in Madison, Wisconsin (N = 264). Subjects completed a questionnaire and provided a blood sample that was analyzed for mono-ethyl phthalate, mono-butyl phthalate, mono-benzyl phthalate, butyl paraben, propyl paraben, octylphenol, nonylphenol, and bisphenol A (BPA). Percentage breast density was measured from mammograms by using a computer-assisted thresholding method. RESULTS: Serum BPA was positively associated with mammographic breast density after adjusting for age, body mass index, and other potentially confounding factors. Mean percentage density was 12.6% (95% confidence interval (CI), 11.4 to 14.0) among the 193 women with nondetectable BPA levels, 13.7% (95% CI, 10.7 to 17.1) among the 35 women with detectable levels below the median (<0.55 ng/ml), and 17.6% (95% CI, 14.1 to 21.5) among the 34 women with detectable levels above the median (>0.55 ng/ml; Ptrend = 0.01). Percentage breast density was also elevated (18.2%; 95% CI, 13.4 to 23.7) among the 18 women with serum mono-ethyl phthalate above the median detected level (>3.77 ng/ml) compared with women with nondetectable BPA levels (13.1%; 95% CI, 11.9 to 14.3; Ptrend = 0.07). No other chemicals demonstrated associations with percentage breast density. CONCLUSIONS: Postmenopausal women with high serum levels of BPA and mono-ethyl phthalate had elevated breast density. Further investigation of the impact of BPA and mono-ethyl phthalate on breast cancer risk by using repeated serum measurements or other markers of xenoestrogen exposure are needed.

Mammographic breast density and serum phytoestrogen levels.

Some forms of estrogen are associated with breast cancer risk as well as with mammographic density (MD), a strong marker of breast cancer risk. Whether phytoestrogen intake affects breast density, however, remains unclear. We evaluated the association between serum levels of phytoestrogens and MD in postmenopausal women. We enrolled 269 women, ages 55-70 yr, who received a screening mammogram and had no history of postmenopausal hormone use. Subjects completed a survey on diet and factors related to MD and provided a blood sample for analysis of 3 phytoestrogens: genistein, daidzein, and coumestrol. We examined whether mean percent MD was related to serum level of phytoestrogens, adjusting for age and body mass index. Genistein and daidzein levels correlated with self-reported soy consumption. Mean percent MD did not differ across women with different phytoestrogen levels. For example, women with nondetectable genistein levels had mean density of 11.0% [95% confidence intervals (CI) = 9.9-12.4], compared to 10.5% (95% CI = 8.0-13.7) and 11.2% (95% CI = 8.7-14.6) for < and ≥ median detectable levels, respectively. In a population with relatively low soy intake, serum phytoestrogens were not associated with mammographic density. Additional studies are needed to determine effects of higher levels, particularly given patterns of increasing phytoestrogen intake.

Occurrence of estrogens, androgens and progestogens and estrogenic activity in surface water runoff from beef and dairy manure amended crop fields.

Hormone contamination of aquatic systems has been shown to cause reproductive impairment of aquatic organisms. To assess to what extent beef and dairy farms represent a source of hormones to the aquatic environment, surface water runoff samples from three beef and dairy farms that utilize best manure management practices were evaluated for hormone concentrations (estrogens, androgens, progestogens) and estrogenic activity. Runoff was collected from weirs at the edge of each of six study fields from March 2008 to March 2010 and was analyzed for hormone concentrations using liquid chromatography with tandem mass spectrometry and for estrogenic activity using the E-screen bioassay. The majority of runoff events occurred in February and March when the soil was frozen. Progesterone and 4-androstenedione were the most frequently detected hormones (63% and 50%, respectively) and occurred at event loads up to 49,000 µg/ha and 26,000 µg/ha, respectively. Progesterone, 4-androstenedione, 17α-estradiol had the highest event load concentrations and were found at the field that sustained dairy cattle grazing during the winter and were likely due to application of excreta on frozen soil. The high progesterone event loads could lead to concentrations in receiving streams that exceed the lowest observable effects concentrations for fish. There was a consistent association with the elevated zearalenone presence and corn production. The synthetic hormones, 17α-trenbolone and 17ß-trenbolone, were not detected in runoff from the beef farm that utilized trenbolone acetate implants, which is likely due to their short half lives. Estrogenic activity in runoff samples ranged from 0.09 to 133 ng/L estradiol equivalents, with 39% of runoff events exceeding the 2 ng/L predicted-no-effect-concentration for fish. These results indicate that grazing cattle and application of manure to frozen fields present the greatest risk to elevated hormones in runoff and that progesterone is the primary hormone of concern from beef and dairy operations.

Removal of organic wastewater contaminants in septic systems using advanced treatment technologies.

The detection of pharmaceuticals and other organic wastewater contaminants (OWCs) in ground water and surface-water bodies has raised concerns about the possible ecological impacts of these compounds on nontarget organisms. On-site wastewater treatment systems represent a potentially significant route of entry for organic contaminants to the environment. In this study, effluent samples were collected and analyzed from conventional septic systems and from systems using advanced treatment technologies. Six of 13 target compounds were detected in effluent from at least one septic system. Caffeine, paraxanthine, and acetaminophen were the most frequently detected compounds, and estrogenic activity was detected in 14 of 15 systems. The OWC concentrations were significantly lower in effluent after sand filtration (p < 0.01) or aerobic treatment (p < 0.05) as compared with effluent that had not undergone advanced treatment. In general, concentrations in conventional systems were comparable to those measured in previous studies of municipal wastewater treatment plant (WWTP) influent, and concentrations in systems after advanced treatment were comparable to previously measured concentrations in WWTP effluent. These data indicate that septic systems using advanced treatment can reduce OWCs in treated effluent to similar concentrations as municipal WWTPs.

Application of the direct peptide reactivity assay (DPRA) to inorganic compounds: a case study of platinum species.

The in chemico Direct Peptide Reactivity Assay (DPRA) was developed as a non-animal, relatively high throughput, screening tool for skin sensitization potential. Although the Adverse Outcome Pathway (AOP) for respiratory sensitization remains to be fully elucidated, it is recognized that the molecular initiation event for both skin and respiratory sensitization to low molecular weight chemicals involves haptenation with proteins. The DPRA examines the reactivity of a test compound to two model peptides (containing either cysteine or lysine) and consequently is able to screen for both skin and respiratory sensitization potential. The DPRA was primarily developed for and validated with organic compounds and assessment of the applicability of the assay to metal compounds has received only limited attention. This paper reports the successful application of the DPRA to a series of platinum compounds, including hexachloroplatinate and tetrachloroplatinate salts, which are some of the most potent chemical respiratory sensitizers known. Eleven platinum compounds were evaluated using the DPRA protocol as detailed by Lalko et al., with only minor modification. Two palladium compounds with structures similar to that of the platinum species studied and cobalt chloride were additionally tested for comparison. The hexachloroplatinate and tetrachloroplatinate salts showed exceptionally high reactivity with the cysteine peptide (EC15 values of 1.4 and 14 µM, respectively). However, for platinum compounds (e.g. hydrogen hexahydroxyplatinate and tetraammineplatinum) where clinical and epidemiological evidence indicates limited sensitization potential, the cysteine DPRA showed only minor or no reactivity (EC15 values of 24 600 and >30 000 µM, respectively). The outcomes of the lysine peptide assays were less robust and where EC15 was measurable, values were substantially higher than the corresponding results from the cysteine assay. This work supports the value of in chemico peptide reactivity as a metric for assessment of platinum sensitization potential and therefore in screening of new platinum compounds for low or absent sensitization potential. Additional studies are required to determine whether the DPRA may be successfully applied to other metals. We provide details on method modifications and precautions important to the success of the DPRA in the assessment of metal reactivity.

Emissions from a flex fuel GDI vehicle operating on ethanol fuels show marked contrasts in chemical, physical and toxicological characteristics as a function of ethanol content.

This study assessed the gaseous and particulate emissions, as well as the toxicological properties of particulate matter (PM) from a flex fuel vehicle equipped with a wall-guided gasoline direct injection engine over triplicates cold-start and hot-start LA92 cycles. The vehicle was operated on a Tier 3 E10 fuel, an E10 fuel with higher levels of aromatics than the Tier 3 E10, an E30, and an E78 blend. Total hydrocarbon (THC), non-methane hydrocarbon (NMHC), carbon monoxide (CO), particulate emissions, and gaseous toxics (of benzene, toluene, ethylbenzene, xylenes (BTEX), and 1,3-butadiene) reduced for E30 and E78 blends compared to both E10 fuels. Formaldehyde and acetaldehyde emissions substantially increased with the higher ethanol blends. The high aromatic E10 fuel increased the emissions of THC, NMHC, particulates, and BTEX compared to the Tier 3 E10 fuel and the higher ethanol blends, as well as showed higher concentrations of accumulation mode particles. The GDI PM did not exhibit any measurable mutagenicity at the PM concentrations tested. Cytotoxicity varied only within a small range and concentrations of PM, eliciting a cytotoxic response similar to those by ambient aerosol. The outcomes of our two measures of PM oxidative potential (macrophage ROS and DTT) were significantly correlated, with the E78 blend exhibiting the least oxidative potential and the E30 the greatest. Gene expression analysis at both the mRNA and protein level indicates that there is the potential for GDI PM emissions to contribute to inflammation and etiology of disease such as asthma, and in contrast to the ROS and DTT outcomes, the E78 fuel PM exhibited the greatest potential to elicit pro-inflammatory cytokine (TNFα) production. Overall, the trends in toxicity emission rates (activity/mi) across the ethanol blends was driven primarily by PM mass emission rate contrasts and only secondarily by the differences in intrinsic toxicity of the PM.

Seasonal variations in the oxidative stress and inflammatory potential of PM2.5 in Tehran using an alveolar macrophage model; The role of chemical composition and sources.

The current study was designed to assess the association between temporal variations in urban PM2.5 chemical composition, sources, and the oxidative stress and inflammatory response in an alveolar macrophage (AM) model. A year-long sampling campaign collected PM2.5 samples at the Sharif University in Tehran, Iran. PM-induced reactive oxygen species (ROS) production was measured both with an acellular dithiothreitol consumption assay (DTT-ROS; ranged from 2.1 to 9.3 nmoles min-1 m-3) and an in vitro macrophage-mediated ROS production assay (AM-ROS; ranged from 125 to 1213 µg Zymosan equivalents m-3). The production of tumor necrosis factor alpha (TNF-α; ranged from ~60 to 518 pg TNF-α m-3) was quantified as a marker of the inflammatory potential of the PM. PM-induced DTT-ROS and AM-ROS were substantially higher for the colder months' PM (1.5-fold & 3-fold, respectively) compared with warm season. Vehicular emission tracers, aliphatic diacids, and hopanes exhibited moderate correlation with ROS measures. TNF-α secretion exhibited a markedly different pattern than ROS activity with a 2-fold increase in the warm months compared to the rest of the year. Gasoline vehicles and residual oil combustion were moderately associated with both ROS measures (R ≥ 0.67, p < 0.05), while diesel vehicles exhibited a strong correlation with secreted TNF-α in the cold season (R = 0.89, p < 0.05). mRNA expression of fourteen genes including antioxidant response and pro-inflammatory markers were found to be differentially modulated in our AM model. HMOX1, an antioxidant response gene, was up-regulated throughout the year. Pro-inflammatory genes (e.g. TNF-α and IL1ß) were down-regulated in the cold season and displayed moderate to weak correlation with crustal elements (R > 0.5, p < 0.05). AM-ROS activity showed an inverse relationship with genes including SOD2, TNF, IL1ß and IL6 (R ≥ -0.66, p < 0.01). Our findings indicate that Tehran's PM2.5 has the potential to induce oxidative stress and inflammation responses in vitro. In the current study, these responses included NRF2, NF-κB and MAPK pathways.

Analysis of glutathione endpoints for measuring copper stress in Chlamydomonas reinhardtii.

Glutathione (GSH) is the most abundant nonprotein thiol in eukaryotic cells and it protects cells by functioning as an antioxidant and a metal-binding ligand. Because glutathione readily undergoes oxidation-reduction reactions to combat oxidative stress, intracellular ratios of the reduced (GSH) to the oxidized (GSSG) forms of glutathione may serve as an important biomarker of exposure and effect of trace metals in eukaryotic cells. We compared sensitivity of glutathione ratios in the freshwater alga Chlamydomonas reinhardtii to the traditional endpoints of cell growth rates and chlorophyll a following exposure to Cu for periods of 6 and 24 h. A response of the GSH:GSSG ratio to Cu concentration was observed at Cu levels of 40 and 80 nM after exposure for both 6 and 24 h. The concentration of total GSH at 24 h was roughly half the value at 6 h after exposure to either 40 or 80 nM Cu. A response for cell growth rate was observed only at 24 h, whereby the average specific growth rate decreased from about 1.1 to 0.4 d(-1). The total Cu concentrations eliciting a cell response of 50%, effect concentrations (EC50s), after 24 h of exposure were similar (49.2, 49.8, and 38.2 nM Cu) and not significantly different for GSH:GSSG ratio, GSH levels, and specific growth, respectively. Total cell-associated Cu concentrations after exposure for 24 h were calculated from the EC50 endpoints and ranged from 13.3 to 17.0 fg/cell. Overall, thiol ratios were indicative of toxicity resulting from exposure to Cu, but precision may be greater for the cell growth rate endpoints.

An algal probe for copper speciation in marine waters: laboratory method development.

Laboratory-based algal assays were developed to explore the bioavailability of copper to the marine alga Thalassiosira weissflogii. A calibration strategy was developed that avoided use of the synthetic ligand ethylenediaminetetraacetic acid (EDTA) in the Aquil growth medium, thereby allowing ambient metal speciation. In a comparison of T. weissflogii cells grown in Aquil medium with EDTA to medium containing no added copper, zinc, and less than 0.003 nM of EDTA, no significant growth differences were observed after 8 d, indicating adequate stored nutrients. A 30-h assay was selected as the optimal time frame after examination of data from concentration-response experiments. Using 65Cu stable isotope additions, parameters examined included growth, chlorophyll a, copper uptake, phytochelatin production, and dissolved organic carbon excretion. The T. weissflogii specific growth rates decreased from 1.36 d(-1)( at pCu (i.e., the negative logarithmic concentration of free Cu) = 8.8 to 0.56 d(-1) at pCu = 7.8, whereas intercellular copper concentrations increased from 13.6 to 70.1 fg/cell, respectively. Calculated values of the copper concentration that caused a 50% reduction in algal growth of pCu = 7.7 and copper per algal mass of 625 microg/g were established. Using an algal assay based on EDTA-free culture medium, along with trace-metal clean techniques, the effect of copper on T. weissflogii and the speciation of copper in marine waters can be studied.

An assessment of endocrine disrupting activity changes during wastewater treatment through the use of bioassays and chemical measurements.

The objective of this study was to assess the removal efficiencies of secondary wastewater treatment processes for compounds causing endocrine disrupting activity. The study used bioassays and chemical measurements, such as gas chromatography with mass spectrometry and enzyme immunosorbent assays. A total of seven full-scale water reclamation facilities using different unit operations and two pilot-scale membrane bioreactors were examined. Findings of this study imply that estrogenic disrupting activity in primary effluent is mainly caused by two steroidal hormones (17beta-estradiol and estriol) and, to a lesser extent, by synthetic chemicals, such as bisphenol A, 4-nonylphenol, and 4-tert-octylphenol. During secondary treatment, steroidal hormones were removed to a higher degree than nonylphenol and bisphenol A. The total estrogenic activity was removed by an average of 96%. The remaining concentrations of targeted steroids in secondary effluents, except for estriol, still had the potential to elicit a positive response in the human breast cell cancer assay. For the majority of facilities, the remaining activity was likely attributed to residual concentrations of two steroidal hormones (17beta-estradiol and estriol).

Effects of androstenedione exposure on fathead minnow (Pimephales promelas) reproduction and embryonic development.

High concentrations (300 ng/L) of androstenedione (A4) were identified in snowmelt runoff from fields fertilized with manure from livestock feeding operations in Wisconsin, USA. In fishes, A4 is an active androgen and substrate for biosynthesis of functional androgens (e.g., testosterone and 11-ketotestosterone) and estrogens (e.g., estradiol-17ß). Thus, A4 has the potential to be a powerful endocrine disruptor. This hypothesis was tested by exposing reproductively mature fathead minnows to 0.0 ng/L, 4.5 ng/L, 74 ng/L, and 700 ng/L A4 for 26 d in a flow-through system. Various reproductive endpoints were measured including fecundity, fertilization success, secondary sexual characteristics, gonadosomatic index (GSI), and hepatic vitellogenin messenger RNA (mRNA) expression. In addition, fertilized embryos from the reproduction assay were used in an embryonic development assay to assess A4 effects on development and hatchability. In males, A4 significantly increased Vtg mRNA expression (estrogenic effect), significantly reduced GSI, and had no effect on tubercle expression (p = 0.067). In females, A4 induced tubercle development (androgenic effect) with no effects on GSI. Fecundity was not significantly impacted. Exposure to A4 had no effect on fertilization, embryonic development, or hatchability. These data indicate that exogenous A4, at environmentally relevant concentrations, can significantly modulate the reproductive physiology of the fathead minnows in a sex-specific manner and that A4 should be monitored as an endocrine disruptor.

Potential estrogenic effects of wastewaters on gene expression in Pimephales promelas and fish assemblages in streams of southeastern New York.

Direct linkages between endocrine-disrupting compounds (EDCs) from municipal and industrial wastewaters and impacts on wild fish assemblages are rare. The levels of plasma vitellogenin (Vtg) and Vtg messenger ribonucleic acid (mRNA) in male fathead minnows (Pimephales promelas) exposed to wastewater effluents and dilutions of 17α-ethinylestradiol (EE2), estrogen activity, and fish assemblages in 10 receiving streams were assessed to improve understanding of important interrelations. Results from 4-d laboratory assays indicate that EE2, plasma Vtg concentration, and Vtg gene expression in fathead minnows, and 17ß-estradiol equivalents (E2Eq values) were highly related to each other (R(2) = 0.98-1.00). Concentrations of E2Eq in most effluents did not exceed 2.0 ng/L, which was possibly a short-term exposure threshold for Vtg gene expression in male fathead minnows. Plasma Vtg in fathead minnows only increased significantly (up to 1136 µg/mL) in 2 wastewater effluents. Fish assemblages were generally unaffected at 8 of 10 study sites, yet the density and biomass of 79% to 89% of species populations were reduced (63-68% were reduced significantly) in the downstream reach of 1 receiving stream. These results, and moderate to high E2Eq concentrations (up to 16.1 ng/L) observed in effluents during a companion study, suggest that estrogenic wastewaters can potentially affect individual fish, their populations, and entire fish communities in comparable systems across New York, USA.

Intraspecific variation in aspen phytochemistry: effects on performance of gypsy moths and forest tent caterpillars.

Individual quaking aspen trees vary greatly in foliar chemistry and susceptibility to defoliation by gypsy moths and forest tent caterpillars. To relate performance of these insects to differences in foliar chemistry, we reared larvac from egg hatch to pupation on leaves from different aspen trees and analyzed leaf samples for water, nitrogen, total nonstructural carbohydrates, phenolic glycosides, and condensed tannins. Larval performance varied markedly among trees. Pupal weights of both species were strongly and inversely related to phenolic glycoside concentrations. In addition, gypsy moth performance was positively related to condensed tannin concentrations, whereas forest tent caterpillar pupal weights were positively associated with leaf nitrogen concentrations. A subsequent study with larvae fed aspen leaves supplemented with the phenolic glycoside tremulacin confirmed that the compound reduces larval performance. Larvae exhibited increased stadium durations and decreased relative growth rates and food conversion efficiencies as dietary levels of tremulacin increased. Differences in performance were more pronounced for gypsy moths than for forest tent caterpillars. These results suggest that intraspecific variation in defensive chemistry may strongly mediate interactions between aspen, gypsy moths and forest tent caterpillars in the Great Lakes region, and may account for differential defoliation of aspen by these two insect species.

Toxicity of ambient atmospheric particulate matter from the Lake Michigan (USA) airshed to aquatic organisms.

Short-term chronic and acute aquatic bioassays are valuable tools in screening a variety of environmental samples. However, only a limited number of studies have used these methods for testing the toxicity of atmospheric particulate matter samples. Previous studies have shown that compounds known to have adverse biological effects, such as polycyclic aromatic hydrocarbons, are deposited in significant quantities into Lake Michigan (USA); however, these compounds comprise a small portion of the total particulate matter deposition. In the present study, a method is described for using Ceriodaphnia dubia, Selenastrum capricornutum (green algae), and MitoScan bioassays to compare the toxicities of reconstituted hard freshwater and methylene chloride extracts of atmospheric particulate matter collected at three locations around the southern shore of Lake Michigan in August 2000. The locations include an urban/industrial site in Milwaukee (WI, USA), an urban-impacted/industrial site in Porter (IN, USA), and a rural site in Bridgman (MI, USA). The bulk chemistry, including organic and elemental carbon, sulfate, nitrate, ammonium, and chloride, shows regional similarities over the sampling event, but the toxicities vary spatially by site, by extraction solvent, and by bioassay. Thus, the bioassays are sufficiently sensitive to show differences in toxicity among the atmospheric particulate matter extracts and have significantly different responses to the samples to enable an initial comparison of toxicity from the different sites.

Serum factors and clinical characteristics associated with serum E-screen activity.

BACKGROUND: The E-Screen bioassay can measure the mitogenicity of human serum and thus may be useful as a biomarker in epidemiologic studies of breast cancer. While the assay's MCF-7 cells are known to proliferate in response to estrogen, the specific determinants of variation in E-Screen activity in human serum samples are poorly understood. We sought to identify serum molecules and patient characteristics associated with serum E-Screen activity among postmenopausal women. METHODS: Postmenopausal women (N = 219) aged 55 to 70 years with no history of postmenopausal hormone use or breast cancer completed a questionnaire and provided a blood sample. Serum was analyzed for E-Screen activity and a variety of molecules including sex hormones, growth factors, and environmental chemicals. Stepwise selection procedures were used to identify correlates of E-Screen activity. RESULTS: Serum samples from all women had detectable E-Screen activity, with a median estradiol equivalents value of 0.027 ng/mL and interquartile range of 0.018-0.036 ng/mL. In the final multivariable-adjusted model, serum E-Screen activity was positively associated with serum estradiol, estrone, insulin-like growth factor-binding protein (IGFBP)-3, and testosterone levels (all P < 0.05), as well as body mass index (P = 0.03). Serum E-Screen activity was lower among women with higher SHBG (P < 0.0001) and progesterone levels (P = 0.03). CONCLUSION: Serum E-Screen activity varies according to levels of endogenous estrogens and other serum molecules. Obesity appears to confer additional serum mitogenicity beyond its impact on the measured hormones and growth factors. IMPACT: By capturing mitogenicity due to a variety of patient and serum factors, the E-Screen may provide advantages for use as a biomarker in breast cancer studies.

Effects of progesterone on reproduction and embryonic development in the fathead minnow (Pimephales promelas).

High concentrations (375 ng/L) of the steroid hormone progesterone (P4) were measured in snowmelt runoff associated with large livestock-feeding operations in Wisconsin. To gain insight into the potential endocrine-disrupting effects of P4 in fish, experiments were conducted to evaluate the effects of short-term exposure to environmentally relevant concentrations of P4 on reproduction and embryonic development in the fathead minnow (Pimephales promelas). For the reproduction assay, groups of reproductively mature fish were exposed for 21 d to nominal concentrations of 0, 10, 100, and 1,000 ng/L P4 in a flow-through system, and various key reproductive endpoints (e.g., egg number, fertilization success) were quantified throughout the exposure period. The embryonic development assay consisted of incubating fathead minnow eggs in static culture to quantify the effects of P4 on early development and hatching success. Progesterone caused dose-dependent decreases in fecundity and fertility and significantly reduced gonadosomatic index and vitellogenin gene expression in females. There were no effects of P4 on early embryonic development or hatching success. Progesterone may be a significant endocrine-disrupting chemical in fish.