AbstractBACKGROUNDThe development of novel highly efficacious fungicides that lack cross‐resistance is extremely desirable. Fenpicoxamid (Inatreq™ active) possesses these characteristics and is a member of a novel picolinamide class of fungicides derived from the antifungal natural product UK‐2A.RESULTSFenpicoxamid strongly inhibited in vitro growth of several ascomycete fungi, including Zymoseptoria tritici (EC50, 0.051 mg L−1). Fenpicoxamid is converted by Z. tritici to UK‐2A, a 15‐fold stronger inhibitor of Z. tritici growth (EC50, 0.0033 mg L−1). Strong fungicidal activity of fenpicoxamid against driver cereal diseases was confirmed in greenhouse tests, where activity on Z. tritici and Puccinia triticina matched that of fluxapyroxad. Due to its novel target site (Qi site of the respiratory cyt bc1 complex) for the cereals market, fenpicoxamid is not cross‐resistant to Z. tritici isolates resistant to strobilurin and/or azole fungicides. Across multiple European field trials Z. tritici was strongly controlled (mean, 82%) by 100 g as ha−1 applications of fenpicoxamid, which demonstrated excellent residual activity.CONCLUSIONSThe novel chemistry and biochemical target site of fenpicoxamid as well as its lack of cross‐resistance and strong efficacy against Z. tritici and other pathogens highlight the importance of fenpicoxamid as a new tool for controlling plant pathogenic fungi. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Maintaining the viability of populations of plants and animals is a key focus for environmental regulation Population level responses integrate the cumulative effects of chemical stressors on individuals as those individuals interact with and are affected by their conspecifics, competitors predators, prey habitat and other biotic and abiotic factors Models of population level effects of contaminants can integrate information from lower levels of biological organization and feed that information into higher level community and ecosystem models As individual level endpoints are used to predict population responses this requires that biological responses at lower levels of organization be translated Into a form that is usable by the population modeler In the current study we describe how mechanistic data as captured in adverse outcome pathways (AOPs) can be translated Into modeling focused on population level risk assessments First we describe the regulatory context surrounding population modeling, risk assessment and the emerging role of AOPs Then we present a succinct overview of different approaches to population modeling and discuss the types of data needed for these models We describe how different key biological processes measured at the level of the individual serve as the linkage or bridge between AOPs and predictions of population status including consideration of community level interactions and genetic adaptation Several case examples illustrate the potential for use of AOPs in population modeling and predictive ecotoxicology Finally we make recommendations for focusing toxicity studies to produce the quantitative data needed to define AOPs and to facilitate their incorporation into population modeling Environ Toxicol Chem 2011 30 64-76 (C) 2010 SETAC

Aultfathead minnows ( Pimophales promelas ) were exposed to waterborne concentrations of 4‐nonylphenol (NP) ranging from 0.05 to 3.4 μg NP/L for 42 d. Results were similar, but slightly different, for two experiments conducted during July and August, near the beginning of the breeding season, and a second experiment conducted during September and October, at the end of the breeding season, during which the adults were maintained continuously in breeding condition. Inverted U–type dose‐response relationships were observed for egg production and for concentrations of vitellogenin (Vtg) and 17β‐estradiol (E 2 ) in blood plasma. Concentrations of plasma Vtg were significantly different between males and females, with plasma concentrations in females ranging from 20 to 110 μg Vtg/ml. Both experiments had no statistically significant, dose‐dependent effect of NP on plasma Vtg in males but significant effects of NP on Vtg concentrations in females. In the first experiment, Vtg concentration generally increased with NP concentration, whereas the second experiment showed a negative correlation. Plasma E 2 concentrations in both males and females were significantly affected by NP. The concentration of total estrogen equivalents in the plasma increased 900% because of exposure to NP. Most of this increase resulted from increased plasma E 2 concentrations, with only a 4% increase resulting from the estrogen agonist activity of NP. The effects of NP on adult fathead minnows seem not to result from a direct‐acting estrogen agonist mechanism but rather from changes in the endogenous concentrations of E 2 through an indirect activation mechanism of action.

Environmental contaminants with estrogenic activity have recently received attention because of their potential effects on the reproductive efficiency of humans and wildlife. This study was conducted with the endogenous estrogen, 17 β-estradiol (E2), to establish the histologic response of the fathead minnow (Pimephales promelas) as a model organism. Sexually mature fathead minnows were exposed for 14 days to waterborne concentrations of 1000, 100, 10, 2, 1, 0.5, 0.25, 0.125, 0.1 or 0.0625 nM E2. Exposure to E2 caused a reduction in size of the prominent male secondary sex characteristics, the fatpads and nuptial breeding tubercles. Histological lesions observed in the testes included proliferation of Sertoli cells and degenerative changes. Electron microscopy of seminiferous tubules and their Sertoli cells revealed large phagolysosomes filled with degenerating spermatozoa and other cellular debris. Females had ovaries in which most of the follicles were in the primary stage of development. There were also more atretic follicles and fewer secondary and Graafian follicles than in unexposed females. These findings demonstrate components of sexually mature fish which may be altered by compounds that mimic E2. To determine if lesions observed in males were permanent, 50 sexually mature males and females were exposed to a single concentration of 10 nM E2 for 10 days. Samples were collected from males on the final day of E2 exposure and over a period of 16 weeks after the exposure was stopped. No E2-induced lesions were observed beyond 16 weeks post E2 exposure. Results of these studies suggest that histological lesions could occur at ecologically-relevant exposures to ‘estrogenic’ compounds. However, certain lesions caused by exposure of adult fathead minnows are not permanent.

The objectives of this research were: (1) to survey a wide variety of structurally diverse (and mostly chlorinated) aromatic chemicals for specific binding to the calf uterine estrogen receptor; (2) to develop a quantitative structure-binding relationship (QSBR) for hydroxylated polychlorinated biphenyls (OH-PCBs). This report specifically includes data on substances that did not exhibit specific binding to ER thereby exploring the structural requirements for specific binding to the estrogen receptor. Although several other QSBRs for OH-PCBs have been reported, this study presents data on a larger, environmentally relevant set of OH-PCBs than previously reported. Fifty three chemicals were tested for the ability to bind specifically to calf uterine estrogen receptor. All but three OH-PCBs bound specifically to calf uterine ER. For DDT compounds, receptor binding affinity followed the pattern: o,p'-DDT>o,p'-DDE>o,p'-DDD (Not active). Also exhibiting measurable affinity were 17ß-estradiol (a positive control and the native ligand of the estrogen receptor), 2,4,6-trichlorobiphenyl and 4-chloro-2-isopropyl-5-methyl-phenol. Substances that did not bind to calf uterine estrogen receptor comprised several individual PCB congeners, chlorinated naphthalenes and naphthalenols, chlorinated bibenzyls, chlorinated phenols, and 9-chloro-retene. For 25 hydroxylated PCBs, a five parameter QSBR was developed using multiple linear regression and selection of the most parsimonius model from a total of seven molecular modeling parameters examined. The QSBR model predicted the ER binding log (IC50) to within one log unit.

Fathead minnows were exposed to 4-nonylphenol (NP) or nonylphenol ethoxylate (NPEO) to determine the effects of these weak estrogen agonists on secondary sex characteristics and gonads of sexually mature males and females during 42-day continuous-flow exposures. Neither NP nor NPEO caused statistically significant effects on tubercles or fatpad size at the concentrations tested. Exposure to 1. 1 or 3.4 micrograms NP/L caused changes in the number and size of Sertoli cells and germ cell syncytia. Necrotic aggregates of various stages of germ cells in the spermatogenic sequence were observed in the testes of males exposed to NP. Electron microscopy of the testes of NP-exposed males revealed the presence of phagocytic cells in the lumina of seminiferous tubules. The cytoplasm of some Sertoli cells was distended with myelin figures and necrotic spermatozoa. No significant effects on the stages of follicular development were observed in females exposed to NP. There were no differences in the gonads or secondary sex characteristics of males or females exposed to 5.5 micrograms NPEO/L, the greatest concentration studied. The histologic responses observed are sensitive indicators of waterborne exposure to NP at environmentally relevant concentrations, but not as sensitive as induction of plasma vitellogenin. The secondary sex characteristics were not affected by concentrations of NP or NPEO as great as 3.4 or 5.5 micrograms/L, respectively. Histologic responses occurred at concentrations that were less than the final chronic value based on survival and approximately the same as those required to cause effects on egg production. The histologic effects caused by NP were similar to, but not exactly the same as those caused by exposure of fathead minnows to 17 beta-estradiol.

The U.S. Congress has passed legislation requiring the U.S. Environmental Protection Agency (U.S. EPA) to develop, validate, and implement screening tests for identifying potential endocrine-disrupting chemicals within 3 years. To aid in the identification of methods suitable for this purpose, the U.S. EPA, the Chemical Manufacturers Association, and the World Wildlife Fund sponsored several workshops, including the present one, which dealt with wildlife species. This workshop was convened with 30 international scientists representing multiple disciplines in March 1997 in Kansas City, Missouri, USA. Participants at the meeting identified methods in terms of their ability to indicate (anti-) estrogenic/androgenic effects, particularly in the context of developmental and reproductive processes. Data derived from structure-activity relationship models and in vitro test systems, although useful in certain contexts, cannot at present replace in vivo tests as the sole basis for screening. A consensus was reached that existing mammalian test methods (e.g., with rats or mice) generally are suitable as screens for assessing potential (anti-) estrogenic/ androgenic effects in mammalian wildlife. However, due to factors such as among-class variation in receptor structure and endocrine function, it is uncertain if these mammalian assays would be of broad utility as screens for other classes of vertebrate wildlife. Existing full and partial life-cycle tests with some avian and fish species could successfully identify chemicals causing endocrine disruption; however, these long-term tests are not suitable for routine screening. However, a number of short-term tests with species from these two classes exist that could serve as effective screening tools for chemicals inducing (anti-) estrogenic/androgenic effects. Existing methods suitable for identifying chemicals with these mechanisms of action in reptiles and amphibians are limited, but in the future, tests with species from these classes may prove highly effective as screens. In the case of invertebrate species, too little is known at present about the biological role of estrogens and androgens in reproduction and development to recommend specific assays.

The objectives of this research were: (1) to assess the effects of waterborne 17β-estradiol [E2; (17β)-estra-1,3,5(10)-triene-3,17-diol; CAS RN 50-28-2] on the reproduction of fathead minnows (Pimephales promelas) as a benchmark to which xeno-estrogens can be compared, and (2) to correlate the effects on reproductive function with plasma vitellogenin expression, measured as alkaline-labile phosphorous. Histopathological changes were also noted but are reported elsewhere. Duplicate groups of six fish (3 male and 3 female) were exposed to waterborne E2 at nominal concentrations of 10, 1, and 0.1 nM (2724, 272.4, and 27.24 ng l−1) administered via a flow-through proportional diluter apparatus for 19 days. An ethanol carrier solvent was used at a final tank concentration of 1 ppm v/v in the treated tanks and in the solvent control tanks; the latter did not receive E2. Duplicate control tanks received neither ethanol nor E2. Dissolved E2 concentrations, measured throughout the exposure period using an ELISA, averaged 79% of nominal concentrations in the treated tanks. ELISA-detectable concentrations of E2 were found in all tanks (ranging from 3.5 to 15 ng E2 l−1), including the control and solvent control tanks, which indicated that fish in the untreated tanks may have been the source of some E2. The EC50 (concentration expected to cause 50% effect), based on measured E2 concentrations, for inhibition of egg production was 120 ng E2 l−1 (log10EC50=2.08±1.22, ±S.E.). The EC50 for induction of vitellogenin (measured as plasma alkaline-labile phosphate) in males was 251 ng E2 l−1 (log10EC50=2.40±0.33, ±S.E.). No vitellogenin induction plateau was observed in females, therefore no EC50 could be calculated. Egg production, expressed as eggs laid per female, was significantly correlated with plasma vitellogenin in both males (linear r2=0.46, P<0.03) and females (linear r2=0.81, P<0.0004), though the relationship was stronger with female plasma vitellogenin expression than with males. The primary effect of E2 exposure on female fathead minnows appeared to be alteration of the timing of recrudescence including vitellogenin production. Spawning was inhibited in a way that indicated that exposure to waterborne E2 may have `reset' the cycle of recrudescence toward the beginning of the oogenic cycle. Vitellogenin induction in male fathead minnows was strongly correlated with E2 exposure, but less so with egg production. The results of this experiment link a biochemical indicator of waterborne estrogen exposure, vitellogenin, with a reproductive performance indicator, egg production, an important parameter affecting fish populations in the environment.

Hydroxylated metabolites of polychlorinated biphenyls (OHCBs) have been identified in blood of marine mammals, fish-eating birds, and humans at concentrations in some cases exceeding those of the unmetabolized polychlorinated biphenyls (PCBs). OHCBs have been associated with inhibition of vitamin A and thyroxin transport, estrogenicity in a mouse uterotrophic assay, and feminization of male turtle sexual development. OHCBs, representing both environmentally derived and laboratory exposure-derived metabolites, were tested in an in vitro bioassay utilizing an estrogen-responsive human breast adenocarcinoma cell line (MCF7-LUC) stably transfected with a luciferase reporter gene linked to estrogen responsive elements. OHCB activity was tested at three different media concentrations of 17beta-estradiol (E2), comparing the concentration-response curves using charcoal-stripped medium (0.0009 nM E2), and two physiologically relevant E2 concentrations (0.1 and 1.0 nM E2). Eleven of 13 OHCBs tested were anti-estrogenic. Evidence for an estrogen receptor mediated mechanism of action was apparent for only two OHCBs-4-OH-2',3,3',4',5,5'-Cl6-biphenyl and 4,4'-(OH)2-3,3',5,5'-Cl4-biphenyl. These two have not been identified in environmental samples. The remaining OHCBs exhibited "anti-estrogenicity" that was related to their effect on cell viability and, therefore, cannot be described as exhibiting "hormone disruption" solely by an estrogen receptor mediated mechanism. OHCB anti-estrogenic activity was eliminated in the presence of E2 concentrations normally found in humans, except for 4,4'(OH)2-3,3',5,5'-Cl4-biphenyl. 4-OH-2',3',4',5'-Cl4-biphenyl and 4-OH-2',4',6'-Cl3-biphenyl were partial estrogen agonists, exhibiting weak estrogenicity in the presence of 0.0009 nM E2 and weak anti-estrogenicity in the presence of 0.1 and 1 nM E2. Human metabolites of PCBs were not estrogenic in MCF7 cells.