Effects of Copper on the Neuromasts of Xenopus Laevis.

Fish and aquatic amphibians possess neuromasts on the surface of their body that constitute the lateral line, a sensory system used to detect water displacement. Copper is known to inactivate the neuromast organs of this system. Copper-induced neuromast loss in African clawed frogs, Xenopus laevis, was examined by exposing Nieuwkoop-Faber stage 54-55 larvae to copper concentrations of 0, 100, 200, 300, and 400 µg/L for 96 h, followed by an examination of neuromast counts, staining intensity, and behavioral responses. Neuromasts were counted using a novel imaging method across four different body regions: the whole body, partial body, head, and tail. Neuromast counts showed a decreasing, but nonsignificant, trend across increasing levels of copper exposure. Intensity of neuromast staining showed a stronger concentration-dependent decrease in all four body regions. The decrease in staining intensity, but not neuromast number, may indicate that although neuromasts are still functioning, they have a decreased number of viable hair cells. Potential loss of responsiveness related to neuromast damage was examined via sensitivity to puffs of air at varying distances. We detected little to no difference in response to the air puff stimulus between control tadpoles and tadpoles exposed to 400 µg/L of copper. Neuromasts of X. laevis may be more resistant to copper than those of North American tadpole species, possibly suggesting greater tolerance of the lateral line to environmental stressors in species that maintain this sensory system throughout their lifespan as compared with species that only have the lateral line during the larval period.

Effects of sublethal application of Deepwater Horizon oil to bird eggs on embryonic heart and metabolic rate.

Following large crude oil spills, oil from feathers of brooding birds and oiled nesting material can transfer to eggs, resulting in reduced embryonic viability for heavily oiled eggs. Eggs may also be subjected to trace or light oiling, but functional teratogenic effects from sublethal crude oil exposure have not been examined. We assessed whether sublethal application of weathered Deepwater Horizon crude oil to the eggshell surface alters heart rate and metabolic rate in Zebra Finch (Taeniopygia guttata) embryos. We first determined sublethal applications with a dosing experiment. Embryo viability for eggs exposed to 5 µL or more of crude oil decreased significantly. We conducted a second experiment to measure heart rate and metabolic rate (CO2 production) 5 and 9 d after 1 sublethal application of crude oil to eggshells on day 3 of incubation. One application of 1.0 or 2.5 µL of crude oil reduced embryonic heart rate and metabolic rate on day 12 of incubation. Using unfertilized eggs, we measured the transfer of polycyclic aromatic hydrocarbons (PAHs) from the eggshell surface to egg contents 9 d after a single application of sublethal crude oil. Our results suggest avian eggs externally exposed to small amounts of crude oil may exhibit protracted embryonic development and impaired postnatal cardiac performance.

Aplicaciones Subletales de Petróleo de la Plataforma Deepwater Horizon en los Huevos de Aves y sus Efectos sobre la Frecuencia Cardíaca y la Tasa Metabólica de Embriones Resumen Después de grandes derrames de crudo, el petróleo que se encuentra en las plumas de las aves incubadoras y el petróleo adherido al material para nidos puede transferirse a los huevos, lo que resulta en la reducción de la viabilidad embrionaria en el caso de los huevos con un contacto alto con el petróleo. Los huevos también pueden estar sujetos a manchas de petróleo ligeras o por contacto, pero no se han examinado los efectos teratogénicos funcionales de la exposición subletal al crudo. Evaluamos si la aplicación subletal de petróleo crudo desgastado del derrame de la plataforma Deepwater Horizon a la superficie de los cascarones altera la frecuencia cardíaca y la tasa metabólica de los embriones de gorrión cebra (Taeniopygia guttata). Primero determinamos las aplicaciones subletales con un experimento de dosificación. La viabilidad de los embriones en huevos expuestos a 5 µL o más de crudo disminuyó significativamente. Realizamos un segundo experimento para medir la frecuencia cardíaca y la tasa metabólica (producción de CO2 ) cinco y nueve días después de una aplicación subletal de crudo a los cascarones durante el tercer día de incubación. La aplicación de 1.0 o de 2.5 µL de crudo redujo la frecuencia cardíaca y la tasa metabólica al décimo segundo día de incubación. También medimos la transferencia de hidrocarburos aromáticos policíclicos (PAHs) en huevos sin fertilizar desde la superficie del cascarón hasta el contenido del huevo nueve días después de una aplicación subletal única de crudo. Nuestros resultados sugieren que los huevos de aves expuestos externamente a pequeñas cantidades de crudo pueden tener un desarrollo embrionario prolongado y un desempeño cardíaco postnatal deteriorado.

Distribution and Bioavailability of Trace Metals in Shallow Sediments from Grand Lake, Oklahoma.

The Tri-State Mining District (TSMD) is a historic mining area containing the Tar Creek superfund site and is the source for sediment-bound metals in Grand Lake. Despite elevated concentrations of cadmium, lead, and zinc, no evidence of sediment toxicity has been observed during previous investigations; however, these studies were limited to lake transects with mostly deep-water sediments. The purpose of this study was to assess whether TSMD-specific sediment toxicity thresholds (STTs), developed for small streams and tributaries draining the TSMD, are predictive of biological effects within the greater lake body. Investigations focused on determining trace metal distribution within the northern reaches of Grand Lake, emphasizing shallow water areas (≤ 6-m depth), and the effects of sediment disturbance on trace metal bioavailability and toxicity to two freshwater invertebrates. No significant mortality or differences in growth occurred under natural or disturbed sediment conditions for either aquatic invertebrate despite using some sediments that exceeded both McDonald general sediment quality guidelines (SQGs) and TSMD-specific STTs. Although the simulated disturbance event (i.e., vigorously aerating sediments for 30 days before toxicity tests) was sufficient to increase trace metal water concentrations and detection frequencies, no changes in overall sediment load, bioavailability, or toxicity were observed following a 10-day exposure duration. These results suggest that TSMD-specific STTs could be used to evaluate Grand Lake sediments that could potentially be disturbed by boat traffic, wave action, and dredging associated with dock construction as opposed to the more conservative general-SQGs.

Investigation of polar organic chemical integrative sampler (POCIS) flow rate dependence for munition constituents in underwater environments.

Munition constituents (MC) are present in aquatic environments throughout the world. Potential for fluctuating release with low residence times may cause concentrations of MC to vary widely over time at contaminated sites. Recently, polar organic chemical integrative samplers (POCIS) have been demonstrated to be valuable tools for the environmental exposure assessment of MC in water. Flow rate is known to influence sampling by POCIS. Because POCIS sampling rates (Rs) for MC have only been determined under quasi-static conditions, the present study evaluated the uptake of 2,4,6-trinitrotoluene (TNT), RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine), and 2,4- and 2,6-dinitrotoluenes (DNT), by POCIS in a controlled water flume at 7, 15, and 30 cm/s in 10-day experiments using samplers both within and without a protective cage. Sampling rate increased with flow rate for all MC investigated, but flow rate had the strongest impact on TNT and the weakest impact on RDX. For uncaged POCIS, mean Rs for 30 cm/s was significantly higher than that for 7 cm by 2.7, 1.9, 1.9, and 1.3 folds for TNT, 2,4-DNT, 2,6-DNT, and RDX, respectively. For all MC except RDX, mean Rs for caged POCIS at 7 cm/s were significantly lower than for uncaged samplers and similar to those measured at quasi-static condition, but except for 2,6-DNT, no caging effect was measured at the highest flow rate, indicating that the impact of caging on Rs is flow rate-dependent. When flow rates are known, flow rate-specific Rs should be used for generating POCIS-derived time-averaged concentrations of MC at contaminated sites.

Atrazine reduces the transmission of an amphibian trematode by altering snail and ostracod host-parasite interactions.

Trematodes are ubiquitous members of aquatic environments, have many functional roles in ecosystems, and can cause diseases in humans, livestock, and wild animals. Despite their importance and reports of parasite population declines, few studies have concurrently assessed the effects of aquatic contaminants on multiple hosts, multiple parasite life cycle stages, and on transmission-related host-parasite interactions. Here, we test the effects of environmentally relevant concentrations of the herbicide atrazine (0, 3, 30 µg/L) on the establishment and development of an amphibian trematode (Halipegus eccentricus) in a first-intermediate snail host (Physa acuta) and in a second-intermediate ostracod host (Cypridopsis sp.). Additionally, we test the interactive effects of atrazine and parasitism on snail and ostracod survival. Our results indicate that atrazine negatively affects trematode transmission by altering snail and ostracod host-parasite interactions. Although atrazine did not affect the survival of uninfected snails alone, atrazine acted synergistically with parasitism to reduce the longevity of infected snails. As a result, the number of cercariae (i.e., larval trematodes) produced by snails was 50.7 % (3 µg/L) and 14.9 % (30 µg/L) relative to controls. Atrazine exhibited direct negative effects on ostracod survival at 30 µg/L. However, when ostracods were also exposed to trematodes, the negative effects of atrazine on survival were diminished. Although infected ostracod survival remained high, trematode development was significantly reduced, resulting in reduced infectivity of metacercariae (i.e., nongravid adult cysts infective to definite host) to 32.2 % (3 µg/L) and 28.6 % (30 µg/L) relative to the controls. The combination of reduced cercaria production and reduced metacercarial infectivity in the 3 and 30 µg/L atrazine treatment groups reduced the net number of infective worms produced to 16.4 and 4.3 % (respectively) relative to the control. These results demonstrate the complex nature of pesticide effects on trematode infections and indicate that trematodes can affect their first- and second-intermediate hosts differently under different pesticide concentrations. Our work has broad implications for parasite transmission and conservation and provides a testable mechanism for understanding trematode population declines in contaminated wetlands.

Acute toxicity of Headline® fungicide to Blanchard's cricket frogs (Acris blanchardi).

Previous laboratory studies have suggested that pyraclostrobin-containing fungicide formulations are toxic to amphibians at environmentally relevant concentrations. However, it is unknown if all pyraclostrobin formulations have similar toxicity and if toxicity occurs in different amphibian species. We investigated the acute toxicity of two formulations, Headline(®) fungicide and Headline AMP(®) fungicide, to Blanchard's cricket frogs (Acris blanchardi) based on a direct overspray scenario. In addition, we examined body residues of fungicide active ingredients in A. blanchardi following direct exposure to Headline AMP fungicide. Headline fungicide and Headline AMP fungicide had similar toxicity to A. blanchardi with calculated median lethal doses of 2.1 and 1.7 µg pyraclostrobin/cm(2), respectively, which are similar to the suggested maximum label rate in North American corn (2.2 and 1.52 µg pyraclostrobin/cm(2), respectively). Tissue concentrations of pyraclostrobin were lower than predicted based on full uptake of a direct dose, and did not drop during the first 24 h after exposure. Headline fungicides at corn application rates are acutely toxic to cricket frogs, but acute toxicity in the field will depend on worst-case exposure.

Variation in toxicity of a current-use insecticide among resurrected Daphnia pulicaria genotypes.

This study examined how genotypes of Daphnia pulicaria from a single population, separated by thousands of generations of evolution in the wild, differ in their sensitivity to a novel anthropogenic stressor. These genotypes were resurrected from preserved resting eggs isolated from sediments belonging to three time periods: 2002-2008, 1967-1977, and 1301-1646 A.D. Toxicity of the organophosphate insecticide chlorpyrifos was determined through a series of acute toxicity tests. There was a significant dose-response effect in all genotypes studied. Moreover, significant variation in toxicity among genotypes within each time period was detected. Importantly, a significant effect of time period on sensitivity to chlorpyrifos was found. Analysis of the median effect concentrations (EC50s) for genotypes within each time period indicated that the 1301-1646 genotypes were 2.7 times more sensitive than the 1967-1977 genotypes. This trend may be partially explained by microevolutionary shifts in response to cultural eutrophication.

The effects of the herbicide atrazine on freshwater snails.

Atrazine has been shown to affect freshwater snails from the subcellular to community level. However, most studies have used different snail species, methods, endpoints, and atrazine exposure concentrations, resulting in some conflicting results and limiting our understanding. The goal of this study was to address these concerns by (1) investigating the acute and chronic effects of atrazine on four species of freshwater snails (Biomphalaria glabrata, Helisoma trivolvis, Physa acuta, and Stagnicola elodes) using the same methods, endpoints, and concentrations, and (2) summarizing the current literature pertaining to the effects of atrazine on freshwater snails. We conducted a 48 h acute toxicity test with an atrazine concentration higher than what typically occurs in aquatic environments (1000 µg/L). Additionally, we exposed snails to environmentally relevant atrazine concentrations (0, 0.3, 3, and 30 µg/L) for 28 days and assessed snail survival, growth, and reproduction. We also summarized all known literature pertaining to atrazine effects on freshwater snails. The literature summary suggests snails are often affected by environmentally relevant atrazine concentrations at the subcellular and cellular levels. These effects are typically not transitive to effects on survival, growth, or reproduction at the same concentrations. Our acute exposures corroborate the general trend of no direct effect on snail populations as atrazine did not directly affect the survival of any of the four snail species. Similarly, environmentally relevant concentrations did not significantly affect the survival, growth, or reproduction of any snail species. These results indicate that, in the absence of other possible stressors, the direct effects of environmentally relevant atrazine concentrations may not be realized at the snail population level.

Terrestrial exposure and effects of Headline AMP(®) Fungicide on amphibians.

Recent studies have demonstrated that a pyraclostrobin-containing fungicide (Headline(®) Fungicide--Headline(®) Fungicide and Headline AMP(®) Fungicide are registered trademarks of BASF) is toxic to amphibians at environmentally relevant concentrations. However, these studies were performed in a laboratory setting of a worst-case direct exposure in clean media. Interception of spray by the crop canopy and ground cover used by animals for security cover will influence exposure. Thus, risk to amphibians is unclear in an environmentally realistic field environment. We tested exposure and toxicity of Headline AMP(®) Fungicide to amphibians in multiple agricultural habitat scenarios (e.g., within treated crop vs. grassy areas adjacent to crop) and at two rates during routine aerial application. Specifically, we placed Woodhouse's toads (Bufo woodhousii) and Blanchard's cricket frogs (Acris blanchardi) in enclosures located within treated and untreated corn (VT stage, approximate height = 3 m), and in the potential drift area (adjacent to treated corn) during aerial application of Headline AMP Fungicide at either 731 or 1052 ml/ha (70 and 100 % the maximum application rate in corn, respectively). Mean concentrations of pyraclostrobin measured at ground level were ≤19 % of nominal application rate in all areas. Overall, mean mortality of recovered individuals of both species was ≤15 %, and mortality within Headline AMP Fungicide-treated corn (where risk was anticipated to be highest) was <10 %. It is important to understand that application timing, interception by the crop canopy (which varies both within and between crop systems), and timing of amphibian presence in the crop field influences risk of exposure and effects; however, our results demonstrate that amphibians inhabiting VT stage corn during routine aerial application of Headline AMP Fungicide are at low risk for acute mortality, matching existing laboratory results from acute toxicity studies of Headline Fungicide.

Chronic effects of strobilurin fungicides on development, growth, and mortality of larval Great Plains toads (Bufo cognatus).

Agricultural fungicide application has increased tenfold since 2005 in the United States. Active ingredients and formulations of strobilurin fungicides at environmentally relevant concentrations cause mortality to larval and metamorph amphibians; however, little is known about chronic exposure effects in amphibians. We exposed larval amphibians (Bufo cognatus) throughout metamorphosis to the common fungicide formulations Headline(®), Stratego(®), Quilt(®), and a control to determine effects on development and growth. Formulations were tested at 1.7, 50, and 400 µg/L of the active strobilurin ingredient for Headline(®), Stratego(®), and Quilt(®), respectively. Fungicide exposure did not affect body mass or snout-vent length at metamorphosis. However, exposure to Headline(®) at 1.7 µg/L increased the development rate of tadpoles by approximately 5 days compared to the control, an effect not observed for Stratego(®) and Quilt(®). Stratego(®) also caused approximately 35 % cumulative mortality. Results from the experiment suggest that chronic effects of strobilurin fungicides on development, growth, and mortality to B. cognatus are apparent at environmentally relevant concentrations.

Interactive Effects of Copper-Silver Mixtures at the Intestinal Epithelium of Rainbow Trout: An In Vitro Approach.

While metals are present in mixture in the environment, metal toxicity studies are usually conducted on an individual metal basis. There is a paucity of data in the existing literature regarding specific metal-metal interactions and their effect on metal toxicity and bioavailability. We studied interactions of a silver (Ag)-copper (Cu) mixture at the intestinal epithelium using an intestinal cell line derived from rainbow trout (Oncorhynchus mykiss), the RTgutGC. Exposures were conducted in media containing different chloride concentrations (low chloride, 1 mM; high chloride, 146 mM), thus resulting in different metal speciation. Cytotoxicity was evaluated based on two endpoints, cell metabolic activity and cell membrane integrity. The Ag-Cu mixture toxicity was assessed using two designs: independent action and concentration addition. Metal mixture bioavailability was studied by exposing cells to 500 nM of Ag or Cu as a single metal or a mixture (i.e., 500 nM of Cu plus 500 nM of Ag). We found an antagonistic effect in the low-chloride medium and an additive/synergistic effect in the high-chloride medium. We found that Cu dominates over Ag toxicity and bioavailability, indicating a competitive inhibition when both metals are present as free metal ions in the exposure media, which supports our hypothesis. Our study also suggests different mechanisms of uptake of free metal ions and metal complexes. The study adds valuable information to our understanding of the role of metal speciation on metal mixture toxicity and bioavailability. Environ Toxicol Chem 2024;43:105-114. © 2023 SETAC.

Assessment of the effects of farming and conservation programs on pesticide deposition in high plains wetlands.

We examined pesticide contamination in sediments from depressional playa wetlands embedded in the three dominant land-use types in the western High Plains and Rainwater Basin of the United States including cropland, perennial grassland enrolled in conservation programs (e.g., Conservation Reserve Program [CRP]), and native grassland or reference condition. Two hundred and sixty four playas, selected from the three land-use types, were sampled from Nebraska and Colorado in the north to Texas and New Mexico in the south. Sediments were examined for most of the commonly used agricultural pesticides. Atrazine, acetochlor, metolachlor, and trifluralin were the most commonly detected pesticides in the northern High Plains and Rainwater Basin. Atrazine, metolachlor, trifluralin, and pendimethalin were the most commonly detected pesticides in the southern High Plains. The top 5-10% of playas contained herbicide concentrations that are high enough to pose a hazard for plants. However, insecticides and fungicides were rarely detected. Pesticide occurrence and concentrations were higher in wetlands surrounded by cropland as compared to native grassland and CRP perennial grasses. The CRP, which is the largest conservation program in the U.S., was protective and had lower pesticide concentrations compared to cropland.

Acute toxicity of three strobilurin fungicide formulations and their active ingredients to tadpoles.

Fungicide applications in the United States have increased tenfold in the last 5 years. Formulations and active ingredients (AIs) have been demonstrated to cause acute mortality to amphibian life stages. However, there has been little to no discrimination between the toxicity of fungicide formulations and their AIs. Therefore, we compared the acute toxicity of the active ingredients and formulations of the fungicides Headline®, Stratego®, and Quilt® using Bufo cognatus tadpoles exposed to four concentrations and a control. All fungicides, including AIs and formulations, demonstrated toxicity to tadpoles, with Headline® and Stratego® causing 100 % mortality at the highest concentrations. Exposure to Quilt® formulation and its AIs resulted in 50-60 % tadpole mortality. Overall, toxicity was comparable between AIs and formulations for all fungicides and concentrations, with the exception of Headline® at 5 µg/L, where formulation exposure resulted in 79 % mortality versus no mortality from exposure to the AI. Results suggest the AIs are responsible for most mortality for Quilt® and Stratego®. Results for Headline® however suggest that although the AI is toxic to tadpoles at environmentally relevant concentrations, adjuvant(s) in the Headline® formulation also contribute to mortality, making it the most toxic of the fungicides studied.

The acute toxicity of pesticide mixtures to honeybees.

Honeybees (Apis mellifera) frequently live in complex environments where exposure to mixtures of pesticides is possible. Although several studies have expressed concern regarding the combined effects of pesticide mixtures, other studies did not find increased toxicity. Thus, the primary objective of this study was to identify peer-reviewed literature measuring the toxicity of pesticide mixtures to honeybees and determine how frequently synergistic interactions occur. Many experiments (258) were identified that met the criteria for inclusion. When considering all experiments, 34% of experiments had model deviation ratios (MDR; expected toxicity/observed toxicity) greater than 2, suggesting greater-than-additive toxicity. Twelve percent of experiments had MDR values greater than 5, with several studies exceeding 100. However, most experiments that had higher MDRs included azole fungicides or acaricides as a component of the mixture. After removal of these groups, only 8% of experiments exceeded an MDR of 2, and no experiments exceeded 5. Moreover, the influence of the azole fungicides was dose dependent. If only experiments that used azole exposure at environmentally relevant concentrations were considered, azole fungicides had limited impact on neonicotinoid insecticides. However, pyrethroid insecticides still had greater than expected toxicity with 80% of experiments having MDR values greater than 2. Acaricides also had greater than expected incidence of synergy with approximately 30% of studies reporting MDR values greater than 2. It should be noted that even the azole studies considered environmentally relevant frequently used maximum exposure rates and worst-case exposure scenarios. The primary finding is that synergy is uncommon except for a few cases where known synergists (azole fungicides) and pesticides with variable metabolism potential, such as some pyrethroids, are in combination. Future work is still needed to refine the relevance of azole fungicides at commonly occurring environmental concentrations. Integr Environ Assess Manag 2022;18:1694-1704. © 2022 SETAC.

Environmental Characterization of Underwater Munitions Constituents at a Former Military Training Range.

As a result of military activities, unexploded ordnance and discarded military munitions are present in underwater environments, which has resulted in the release of munitions constituents including the high explosives 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), along with their primary degradation products, to the water column and adjacent sediments. The present study focused on the characterization of underwater exposure and concentrations of energetics such as TNT and RDX at the former Vieques Naval Training Range at Bahia Salina del Sur (Vieques, Puerto Rico, USA), a bay with documented high incidence of munitions. In situ passive sampling using polar organic chemical integrative samplers (POCIS) was used for the detection and quantification of constituents in water at target locations approximately 15 to 30 cm from 15 individual potentially leaking munitions, and also at 15 unbiased locations approximately evenly spaced across the Bay. For comparison with POCIS-derived concentrations, grab samples were taken at the POCIS target locations. The POCIS-derived and averaged grab samples agreed within a factor of 3. When detected, munitions constituent concentrations (primarily TNT and RDX) were observed at ultratrace concentrations (as low as 4 ng/L for RDX), except 30 cm from one General Purpose bomb where the TNT concentration was 5.3 µg/L, indicating that low-level contamination exists at Bahia Salina del Sur on a very localized scale despite the relatively high density of munitions, similar to previously reported results for other munitions sites around the world. Sediment and porewater sampled at 4 stations where munitions constituents were detected in the water column had concentrations below detection (approximately 5 µg/kg and 5 ng/L, respectively), suggesting that the sediment was not a sink for these constituents at those locations. Environ Toxicol Chem 2022;41:275-286. © 2021 SETAC. This article has been contributed to by US Government employees and their work is in the public domain in the USA.

Atrazine and estradiol effects on development of Acris blanchardi (Blanchard's cricket frog) exposed in outdoor enclosures.

BACKGROUND: The herbicide atrazine has been proposed as a potential endocrine disrupting compound (EDC) for amphibians. Using atrazine concentrations below or at those typically found in surface waters (0.5, 5.0, 50 µg/L), we exposed Acris blanchardi (Blanchard's cricket frog) larvae throughout development until metamorphosis (i.e. Gosner stages 26-45). An additional 50 µg/L treatment (50s µg/L) was utilized where supplemented algae was added to control for indirect atrazine effects from reduced food sources. In addition to atrazine, experimental groups also included a negative control and two positive controls, 17ß-estradiol (E2) at 2.3 and 25 µg/L. At 60 days post-metamorphosis, A. blanchardi metamorphs were euthanized for analysis of gross and histopathological development. RESULTS: Atrazine did not significantly influence mortality (mean recovery of 54% across treatments), sex ratio, body mass (BM), snout-vent length (SVL), gonad size, nor gonad development of A. blanchardi. Females exposed to 50s µg/L atrazine had 29% less mass, were 10% shorter, and had a 29% lower mean ovary area (mm2 ) as compared to negative controls, suggesting algae enrichment had a significant negative effect. Males exposed to estradiol (25 µg/L) showed an increased level of oviduct development. Ovary area was also significantly influenced by estradiol treatment at 2.3 and 25 µg/L. CONCLUSION: Overall, estradiol had much less effect than predicted based on other model species (e.g. Xenopus laevis). Development of A. blanchardi, overall, was not affected by long-term exposure to environmentally relevant concentrations of atrazine. However, this species also was largely insensitive to exogenous estradiol in this test system. © 2022 Society of Chemical Industry.

Parenting, Pesticides and Adolescent Psychological Adjustment: A Brief Report.

Pesticides used to control insects, such as pyrethroids, are neurotoxicants, yet adolescent researchers often overlook their potential role in adolescent psychological adjustment. This brief report is guided by bioecological theory and considers the possible independent and interactive effects of environmental pyrethroid pesticide exposure for adolescent depressive symptoms. Self-reported adolescent appraisals of the parent-child relationship and depressive symptoms were obtained from a convenience sample of impoverished, predominantly Latino urban youth (n = 44). Exposure to environmental pyrethroids was obtained from wipe samples using a standardized protocol. Parent-adolescent conflict was higher in households with bifenthrin than those without, and adolescent depressive symptoms were elevated in homes where cypermethrin was detected. In addition, the presence of bifenthrin in the home attenuated the protective effects of parental involvement on adolescent depressive symptoms. The current results suggest that adolescent mental health researchers must consider the synergistic combinations of adolescents' environments' physical and social features. Given the endemic presence of pesticides and their neurotoxic function, pesticide exposure may demand specific attention.

Applications of the RTgill-W1 Cell Line for Acute Whole-Effluent Toxicity Testing: In Vitro-In Vivo Correlation and Optimization of Exposure Conditions.

The cell line RTgill-W1 was evaluated as an in vitro alternative model for acute fish whole-effluent toxicity (WET) testing. We determined the 50% effective concentration (EC50) that reduces the viability of RTgill-W1 cells for selected toxicants commonly found in effluent samples and correlated those values with the respective 50% lethal concentration (LC50) of freshwater (fathead minnow, Pimephales promelas) and marine (sheepshead minnow, Cyprinodon variegatus) fish species obtained from the literature. Excluding low water-soluble organics and the volatile sodium hypochlorite, significant correlations were measured for metal, metalloids, ammonia, and higher water-soluble organics between in vitro EC50 values and in vivo LC50 values for both species. Typically, toxicity studies with RTgill-W1 cells are conducted by adding salts to the exposure medium, which may affect the bioavailability of toxicants. Osmotic tolerance of RTgill-W1 cells was found between 150 and 450 mOsm/kg, which were set as the hypoosmotic and hyperosmotic limits. A subset of the toxicants were then reexamined in hypoosmotic and hyperosmotic media. Copper toxicity decreased in hyperosmotic medium, and nickel toxicity increased in hypoosmotic and hyperosmotic media. Linear alkylbenzene sulfonate toxicity was not affected by the medium osmolality. Overall, RTgill-W1 cells have shown potential for applications in measuring metal, metalloids, ammonia, and water-soluble organic chemicals in acute WET tests, as well as complementing current toxicity identification and reduction evaluation strategies. In the present study, RTgill-W1 cells have been established as a valid animal alternative for WET testing, and we show that through manipulation of medium osmotic ranges, sensitivity to nickel was enhanced. Environ Toxicol Chem 2021;40:1050-1061. © 2020 SETAC.

Evaluating a developmental endocrine toxicity assay for Blanchard's cricket frog (Acris blanchardi) in outdoor enclosures.

A developmental toxicity testing design was evaluated for larval and post-metamorphic Blanchard's cricket frogs (Acris blanchardi) raised in outdoor enclosures. Larvae were chronically exposed to 17ß-estradiol (0.0-2.3 µg/L E2) from free swimming (Gosner stage 26) until metamorphosis. Juvenile frogs were allowed to mature within the enclosures for 60 days to assess effects of larval exposure on development, including body mass, snout-vent length (SVL), sex ratio, gonad size, and gonadal histopathology. Forty-eight percent of the initial 600 animals were recovered at the end of the study. Recovery was not influenced by E2 exposure, but larval losses were negatively impacted by unusually high spring rain events that flooded some larval tanks, and heat-related mortality of late stage larvae during summer. All surviving larvae completed metamorphosis within an average of 47 days. Overall, E2 exposure did not influence sex ratio, or the body mass, SVL, or gonad size of either males or females. Development of testes was not influenced by E2 exposure, but oviduct development in males was 4.5-fold greater in the highest treatment. Oviduct and ovary development in females exposed to the two highest E2 treatments were half that of control females. Although not treatment related and despite ad-lib feeding, variation in terminal body mass and SVL within enclosures was pronounced, with minimum - maximum differences ranging from 207 to 1442 mg for body mass and 1 mm to 15 mm for SVL. This design allowed us to assess the effects of larval exposure to a contaminant on post-metamorphic development of a native amphibian in a semirealistic field environment. With modifications to decrease flooding or overheating, this enclosure design and species is a good test system for assessing contaminant effects on development of an amphibian from early larval stages through reproductive maturity.

Field studies of pollutant removal from nursery and greenhouse runoff by constructed wetlands.

Plant nursery runoff commonly contains pesticides and nutrients that often threaten aquatic ecosystems. Constructed wetlands could be a tool to remove pesticides and nutrients from nursery runoff but have not been extensively studied in this setting. Two field-scale constructed wetlands (one subsurface-flow constructed wetland [SFCW] and one free-surface constructed wetland [FSCW]) were implemented and monitored for water quality improvement. The SFCW demonstrated significant mass reduction of 78% or greater for nitrate, orthophosphate, total nitrogen, total phosphorus, and total suspended solids. The SFCW also demonstrated significant mass reduction of 79% or greater for 10 of the 12 pesticide compounds detected in over half of the collected samples. The FSCW demonstrated significant mass reduction of 46% or greater for all nonpesticide analytes except total nitrogen. Loading rate and actual storage volume compared with inflow volume likely affected performance. Reduced size and increased loading rate of the FSCW likely reduced its ability to effectively reduce pesticides. Results from this study indicate that constructed wetlands are likely an effective tool for nursery runoff management. When designing and implementing constructed wetlands, it is important for practitioners to consider the tradeoff between system size (additional cost and land otherwise dedicated to production) and performance.