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At least 415 records · Page 23Linked to original sources
USGS2005

Toxicity to amphibians of environmental extracts from natural waters in National Parks and Fish and Wildlife Refuges

Amphibian population declines are not limited to overtly degraded habitats, but often occur in relatively pristine environments such as national parks or wildlife refuges, thus forcing biologists to examine less obvious causes for declines such as the presence of contaminants. The objective of our study was to extract naturally-occurring compounds from amphibian habitats (using semipermeable membrane devices) in three national parks or wildlife refuges (two sites within Sequoia Kings Canyon National Park, Big Bend National Park, and Kenai National Wildlife Refuge), and assess their toxicity to developing larvae using bioassays. Extracts did not cause mortality, so all effects observed were sublethal, influencing life history characteristics. In all three areas studied, amphibians reared in extracts from at least one of the two sites exhibited either a lengthened larval period or reduced mass at metamorphosis. Extracts from both the air and water at one site in Sequoia Kings Canyon National Park lengthened the larval period, which is in agreement with studies showing elevated levels of aerially transported contaminants at sites such as this within the park. Ultraviolet radiation, which is also suspected of having caused amphibian declines and was included as a factor in our study, did not act alone or alter the toxicity of the extracts. ?? ISSCA 2005.

Conference Paper↗
USGS2013

Arsenic induced toxicity in broiler chicks and its alleviation with ascorbic acid: a toxico-patho-biochemical study

To find out toxico-pathological effects of arsenic (As) and ameliorating effect of ascorbic acid (Vit C), broilers birds were administered 50 and 250 mg/kg arsenic and Vit C, respectively alone/in combination. As-treated birds exhibited severe signs of toxicity such as dullness, depression, increased thirst, open mouth breathing and watery diarrhea. All these signs were partially ameliorated with the treatment of Vit C. As-treated birds showed a significant decrease in serum total proteins while serum enzymes, urea and creatinine were significantly increased. Alkaline phosphatase and lactate dehydrogenase completely whereas proteins, aspartate aminotransferase (AST), alanine aminotransferase (ALT), urea and creatinine were partial ameliorated in birds treated with As+Vit C as compared to As-treated and control birds. Pale and hemorrhagic liver and swollen kidneys were observed in As-treated birds. Histopathologically, liver exhibited congestion and cytoplasmic vacuolation while in kidneys, condensation of tubular epithelium nuclei, epithelial necrosis, increased urinary spaces, sloughing of tubules from basement membrane and cast deposition were observed in As-treated birds. Pathological lesions were partially ameliorated with the treatment of Vit C. It can be concluded that arsenic induces biochemical and histopathological alterations in broiler birds; however, these toxic effects can be partially attenuated by Vit C.

International Journal of Agriculture & Biology↗
USGS2003

Pharmaceuticals, hormones, personal-care products, and other organic wastewater contaminants in water resources: Recent research activities of the U.S. Geological Survey's toxic substances hydrology program

Recent decades have brought increasing concerns for potential contamination of water resources that could inadvertently result during production, use, and disposal of the numerous chemicals offering improvements in industry, agriculture, medical treatment, and even common household products. Increasing knowledge of the environmental occurrence or toxicological behavior of these contaminants from various studies in Europe, United States, and elsewhere has resulted in increased concern for potential adverse environmental and human health effects (Daughton and Ternes, 1999). Ecologists and public health experts often have incomplete understandings of the toxicological significance of many of these contaminants, particularly long-term, low-level exposure and when they occur in mixtures with other contaminants (Daughton and Ternes, 1999; Kümmerer, 2001). In addition, these ‘emerging contaminants’ are not typically monitored or assessed in ambient water resources. The need to understand the processes controlling the transport and fate of these contaminants in the environment, and the lack of knowledge of the significance of long-term exposures have increased the need to study environmental occurrence down to trace (nanogram per liter) levels. Furthermore, the possibility that mixtures of environmental contaminants may interact synergistically or antagonistically has increased the need to characterize the types of mixtures that are found in our waters. The U.S. Geological Survey’s Toxic Substances Hydrology Program (Toxics Program) is developing information and tools on emerging water-quality issues that will be used to design and improve water-quality monitoring and assessment programs of the USGS and others, and for proactive decision-making by industry, regulators, the research community, and the public (http://toxics.usgs.gov/regional/emc.html). This research on emerging water-quality issues includes a combination of laboratory work to develop new analytical capabilities as well as field work on the occurrence, fate, and effects of these contaminants.

Geohealth News↗
USGS2005

Toxicity to amphibians of environmental extracts from natural waters in National Parks and Fish and Wildlife Refuges

Amphibian population declines are not limited to overly degraded habitats, but often occur in relatively pristine environments such as national parks or wildlife refuges, thus forcing biologists to examine less obvious causes for declines such as the presence of contaminants. The objective of our study was to extract naturally-occurring compounds from amphibian habitats (using semipermeable membrane devices) in three national parks or wildlife refuges (two sites within Sequoia Kings Canyon National Park, Big Bend National Park, and Kenai National Wildlife Refuge), and assess their toxicity to developing larvae using bioassays. Extracts did not cause mortality, so all effects observed were sublethal, influencing life history characteristics. In all three areas studied, amphibians reared in extracts from at least one of the two sites exhibited either a lengthened larval period or reduced mass at metamorphosis. Extracts from both the air and water at one site in Sequoia Kings Canyon National Park lengthened the larval period, which is in agreement with studies showing elevated levels of aerially transported contaminants at sites such as this within the park. Ultraviolet radiation, which is also suspected of having caused amphibian declines and was included as a factor in our study, did not act alone or alter the toxicity of the extracts.

Alytes↗
USGS1996

Measures of fish behavior as indicators of sublethal toxicosis during standard toxicity tests

Behavioral functions essential for growth and survival can be dramatically altered by sublethal exposure to toxicants. Measures of these behavioral responses are effective in detecting adverse effects of sublethal contaminant exposure. Behavioral responses of fishes can be qualitatively and quantitatively evaluated during routine toxicity tests. At selected intervals of exposure, qualitative evaluations are accomplished through direct observations, whereas video recordings are used for quantitative evaluations. Standardized procedures for behavioral evaluation are readily applicable to different fish species and provide rapid, sensitive, and ecologically relevant assessments of sublethal exposure. The methods are readily applied to standardized test protocols.

Book chapter↗
USGS2019

Comparison of continuous and interrupted lampricide block toxicity to sea lamprey and lake sturgeon

Lake Sturgeon ( Acipenser fulvescens , LST) is a state, provincial, and tribal species of special concern that is sensitive to lampricides used in sea lamprey control. As such, there is significant interest in the Great Lakes fisheries community to develop alternative sea lamprey ( Petromyzon marinus , SL) control approaches to minimize impacts on LST for applicable LST producing streams. Currently, lampricides are applied continuously to streams for 10 to 14 hours to achieve at least a 9-hour lampricide block at or above the SL minimum lethal concentration (MLC). Once the application of lampricides are initiated it usually takes 1-4 hours for the lampricide concentration to build to the target concentration during treatments depending on the flow dynamics of the stream. An interrupted lampricide block, wherein the treatment consists of two lampricide blocks (cumulative MLC of at least 9 hours) with a break in the middle, has been shown to decrease burrowing mayfly ( Hexagenia limbata ) mortality and resulted in no change to MLC when interruptions were up to 12 hours in duration. This study compared mortality of LST and SL during continuous and interrupted lampricide blocks with the goal of establishing whether an interrupted lampricide block treatment could be used to protect LST while maintaining treatment efficacy. Results show that there was no difference in toxicity to larval SL or LST between the interrupted block and continuous exposures. No differences were detected among calculated LC25s andLC50s for LST in the interrupted block tests compared to the continuous block tests during laboratory and streamside bioassays. An interrupted block field trial on Eliza Creek resulted in high mortality among caged larval SL (99.5%); however, posttreatment surveys estimated the treatment kill at 83.5% compared to >99% from the two previous continuous block treatments (2007, 2001). This suggests a substantial decrease in treatment effectiveness when using the interrupted block strategy. The lack of separation in toxicity between LST and SL under continuous interrupted block treatment and the reduced efficacy of the interrupted treatment block combine to make this treatment method a less desirable option.

Report↗
USGS2017

Have mummichog (Fundulus heteroclitus) from the lower Penobscot River, Maine, developed tolerance to the toxic effects of mercury?

Fish populations that are chronically exposed to mercury (Hg) can develop resistance to the toxic effects of this metal, including mummichog (Fundulus heteroclitus; Weis 2002). Such resistance allows them to potentially accumulate very high levels of this contaminant (Stefansson et al. 2013). Mercury is a neurotoxin that affects behavior in fish, including swimming and the ability to capture prey (Samson et al. 2001, Zhou et al. 2001), and behavior, reproduction and immune function in birds (Evers et al. 2008, Hawley et al. 2009). Ingestion of mercury-contaminated prey could have significant, and severe, effects on migratory fish and piscivorous birds, including loons (Evers et al. 2008). We found that mercury concentrations in resident mummichog collected from sites in the lower Penobscot River in 2011 were 9 to 16 times higher than Hg levels in mummichog from a control site in Wells, Maine (Elskus 2012). For part one of this study, reproductively mature male and female mummichog were collected in Fall 2015 from two sites in Maine: Bald Hill Cove, a mercury-contaminated site along the mercury gradient of the Penobscot River, and Drake, a reference site at the Wells National Estuarine Research Reserve. These parental fish were housed at the US EPA laboratory (Narragansett, RI). Beginning in Spring 2016, these fish were fed diets containing either low or high concentrations of mercury for 28 days. Embryos were collected from these parents and divided into subsets. One subset was used to measure the mercury concentrations in the embryos, the second subset was shipped to the University of Maine where they were hatched, and the larval fish evaluated for behavioral effects. For part two of this study, adult mummichog were collected from Hg-contaminated Bald Hill Cove and from a reference site, Wells, in the Wells National Estuarine Reserve and evaluated for mercury body burdens and behavior. In Study 1, mercury was maternally transferred to the progeny demonstrating this is one pathway of generational exposure to mercury. Unfortunately, all larvae from the mercury-contaminated Bald Hill Cove population died before behavioral analysis could be done. Behavioral studies of the reference Drake population, however, demonstrated no significant differences between offspring of parents fed high mercury diets and offspring of parents fed low mercury diets. In Study 2, adult fish from the mercury contaminated BHC population had mercury body burdens that were four times higher than those in the reference Wells population, but while fewer BHC adults performed prey strikes than the Wells adults, there were no other significant behavioral differences between the two populations. In conclusion, the main hypothesis, that fish from the site receiving chronic mercury exposure had developed resistance to mercury toxicity, could not be definitively determined due to the death of embryos from the chronically exposed population. However, the present study did reveal some behavioral effects associated with mercury exposure that warrant further study. Behavioral approaches are important because they address some of the basic and difficult questions surrounding contaminant exposures; namely that sub-lethal effects are important to evaluate because they may have consequences for individual and perhaps population survival.

Maine↗
USGS2014

In situ and laboratory toxicity of coalbed natural gas produced waters with elevated sodium bicarbonate

Some tributaries in the Powder River Structural Basin, USA, were historically ephemeral, but now contain water year round as a result of discharge of coalbed natural gas (CBNG)-produced waters. This presented the opportunity to study field sites with 100% effluent water with elevated concentrations of sodium bicarbonate. In situ experiments, static renewal experiments performed simultaneously with in situ experiments, and static renewal experiments performed with site water in the laboratory demonstrated that CBNG-produced water reduces survival of fathead minnow ( Pimephales promelas ) and pallid sturgeon ( Scaphirhynchus albus ). Age affected survival of fathead minnow, where fish 2 d posthatch (dph) were more sensitive than 6 dph fish, but pallid sturgeon survival was adversely affected at both 4 and 6 dph. This may have implications for acute assays that allow for the use of fish up to 14 dph. The survival of early lifestage fish is reduced significantly in the field when concentrations of NaHCO 3 rise to more than 1500 mg/L (also expressed as >1245 mg HCO 3 (-) /L). Treatment with the Higgin's Loop technology and dilution of untreated water increased survival in the laboratory. The mixing zones of the 3 outfalls studied ranged from approximately 800 m to 1200 m below the confluence. These experiments addressed the acute toxicity of effluent waters but did not address issues related to the volumes of water that may be added to the watershed.

Environmental Toxicology and Chemistry↗
USGS2017

A comparison of four porewater sampling methods for metal mixtures and dissolved organic carbon and the implications for sediment toxicity evaluations

Evaluations of sediment quality conditions are commonly conducted using whole-sediment chemistry analyses but can be enhanced by evaluating multiple lines of evidence, including measures of the bioavailable forms of contaminants. In particular, porewater chemistry data provide information that is directly relevant for interpreting sediment toxicity data. Various methods for sampling porewater for trace metals and dissolved organic carbon (DOC), which is an important moderator of metal bioavailability, have been employed. The present study compares the peeper, push point, centrifugation, and diffusive gradients in thin films (DGT) methods for the quantification of 6 metals and DOC. The methods were evaluated at low and high concentrations of metals in 3 sediments having different concentrations of total organic carbon and acid volatile sulfide and different particle-size distributions. At low metal concentrations, centrifugation and push point sampling resulted in up to 100 times higher concentrations of metals and DOC in porewater compared with peepers and DGTs. At elevated metal levels, the measured concentrations were in better agreement among the 4 sampling techniques. The results indicate that there can be marked differences among operationally different porewater sampling methods, and it is unclear if there is a definitive best method for sampling metals and DOC in porewater.

Environmental Toxicology and Chemistry↗
USGS2019

Brodifacoum toxicity in American Kestrels (Falco sparverius) with evidence of increased hazard upon subsequent anticoagulant rodenticide exposure

A seminal question in ecotoxicology is the extent to which contaminant exposure evokes prolonged effects on physiological function and fitness. A series of studies were undertaken with American kestrels ingesting environmentally realistic concentrations of the second-generation anticoagulant rodenticide (SGAR) brodifacoum (BROD). Kestrels fed BROD at 0.3, 1.0 or 3.0 µg/g diet wet wt for 7 d exhibited dose-dependent hemorrhage, histopathological lesions and coagulopathy (prolonged prothrombin and Russell’s viper venom times). Following termination of a 7 d exposure to 0.5 µg BROD/g diet, prolonged blood clotting time returned to baseline values within a week, but BROD residues in liver and kidney (terminal half-life estimates >50 d) persisted during the 28 d recovery period. In order to examine the hazard of sequential AR exposure, kestrels were exposed to either the firstgeneration AR chlorophacinone (CPN; 1.5 µg/g diet) or the SGAR BROD (0.5 µg/g diet) for 7 d, and following a recovery period, were challenged with a low dose of CPN (0.75 µg/g diet) for 7 d. In BROD-exposed kestrels, the challenge exposure clearly prolonged prothrombin time compared to naïve controls and kestrels previously exposed to CPN. These data provide evidence that the SGAR BROD may have prolonged effects that increase toxicity of subsequent AR exposure. As free-ranging predatory and scavenging wildlife are often repeatedly exposed to ARs, such protracted toxicological effects need to be considered in hazard and risk assessments.

Environmental Toxicology and Chemistry↗
USGS2020

Bioaccumulation and toxicity of cadmium, copper, nickel, and zinc and their mixtures to aquatic insect communities

We describe 2 artificial stream experiments that exposed aquatic insect communities to zinc (Zn), copper (Cu), and cadmium (year 2014) and to Zn, Cu, and nickel (year 2015). The testing strategy was to concurrently expose insect communities to single metals and mixtures. Single-metal tests were repeated to evaluate the reproducibility of the methods and year-to-year variability. Metals were strongly accumulated in sediments, periphyton, and insect (caddisfly) tissues, with the highest concentrations occurring in periphyton. Sensitive mayflies declined in metal treatments, and effect concentrations could be predicted effectively from metal concentrations in either periphyton or water. Most responses were similar in the replicated tests, but median effect concentration values for the mayfly Rhithrogena sp. varied 20-fold between the tests, emphasizing the difficulty comparing sensitivities across studies and the value of repeated testing. Relative to the single-metal responses, the toxicity of the mixtures was either approximately additive or less than additive when calculated as the product of individual responses (response addition). However, even less-than-additive relative responses were sometimes greater than responses to similar concentrations tested singly. The ternary mixtures resulted in mayfly declines at concentrations that caused no declines in the concurrent single-metal tests. When updating species-sensitivity distributions (SSDs) with these results, the mayfly responses were among the most sensitive 10th percentile of available data for all 4 metals, refuting older literature placing mayflies in the insensitive portion of metal SSDs. Testing translocated aquatic insect communities in 30-d artificial streams is an efficient approach to generate multiple species effect values under quasi-natural conditions that are relevant to natural streams.

Environmental Toxicology and Chemistry↗
USGS2011

Toxic effects of dietary methylmercury on immune system development in nestling American kestrels ( Falco sparverius )

This study evaluated the effects of dietary methylmercury (MeHg) on immune system development in captive-reared nestling American kestrels ( Falco sparverius ) to determine whether T cell–mediated and antibody-mediated adaptive immunity are targets for MeHg toxicity at environmentally relevant concentrations. Nestlings received various diets, including 0 (control), 0.6, and 3.9 μg/g (dry wt) MeHg for up to 18 d posthatch. Immunotoxicity endpoints included cell-mediated immunity (CMI) using the phytohemagglutinin (PHA) skin-swelling assay and antibody-mediated immune response via the sheep red blood cell (SRBC) hemagglutination assay. T cell– and B cell–dependent histological parameters in the spleen, thymus, and bursa of Fabricius were correlated with the functional assays. For nestlings in the 0.6 and 3.9 μg/g MeHg groups, CMI was suppressed by 73 and 62%, respectively, at 11 d of age. Results of this functional assay were correlated with T cell–dependent components of the spleen and thymus. Dose-dependent lymphoid depletion in spleen tissue directly affected the proliferation of T-lymphocyte populations, insofar as lower stimulation indexes from the PHA assay occurred in nestlings with lower proportions of splenic white pulp and higher THg concentrations. Nestlings in the 3.9 μg/g group also exhibited lymphoid depletion and a lack of macrophage activity in the thymus. Methylmercury did not have a noticeable effect on antibody-mediated immune function or B cell–dependent histological correlates. We conclude that T cell–mediated immunosuppression is the primary target of MeHg toward adaptive immunity in developing kestrels. This study provides evidence that environmentally relevant concentrations of MeHg may compromise immunocompetence in a developing terrestrial predator and raises concern regarding the long-term health effects of kestrels that were exposed to dietary MeHg during early avian development.

Environmental Toxicology and Chemistry↗
USGS2021

Method development for a short-term 7-day toxicity test with unionid mussels

The US Environmental Protection Agency's short-term freshwater effluent test methods include a fish ( Pimephales promelas ), a cladoceran ( Ceriodaphnia dubia ), and a green alga ( Raphidocelis subcapitata ). There is a recognized need for additional taxa to accompany the three standard species for effluent testing. An appropriate additional taxon is unionid mussels because mussels are widely distributed, live burrowed in sediment and filter particles from the water column for food, and exhibit high sensitivity to a variety of contaminants. Multiple studies were conducted to develop a relevant and robust short-term test method for mussels. We first evaluated the comparative sensitivity of two mussel species ( Villosa constricta and Lampsilis siliquoidea ) and two standard species ( P. promelas and C. dubia ) using two mock effluents prepared by mixing ammonia and five metals (cadmium, copper, nickel, lead, and zinc) or a field-collected effluent in 7-day exposures. Both mussel species were equally or more sensitive (more than two-fold) to effluents compared with the standard species. Next, we refined the mussel test method by first determining the best feeding rate of a commercial algal mixture for three age groups (1, 2, and 3 weeks old) of L. siliquoidea in a 7-day feeding experiment, and then used the derived optimal feeding rates to assess the sensitivity of the three ages of juveniles in a 7-day reference toxicant (sodium chloride [NaCl]) test. Juvenile mussels grew substantially (30%–52% length increase) when the 1- or 2-week-old mussels were fed 2 ml twice daily and the 3-week-old mussels were fed 3 ml twice daily. The 25% inhibition concentrations (IC25s) for NaCl were similar (314–520 mg Cl/L) among the three age groups, indicating that an age range of 1- to 3-week-old mussels can be used for a 7-day test. Finally, using the refined test method, we conducted an interlaboratory study among 13 laboratories to evaluate the performance of a 7-day NaCl test with L. siliquoidea . Eleven laboratories successfully completed the test, with more than 80% control survival and reliable growth data. The IC25s ranged from 296 to 1076 mg Cl/L, with a low (34%) coefficient of variation, indicating that the proposed method for L. siliquoidea has acceptable precision. Environ Toxicol Chem 2021;40:3392–3409. © 2021 SETAC

Environmental Toxicology and Chemistry↗
USGS2022

Comparative toxicity of aquatic per- and polyfluoroalkyl substance exposure in three species of amphibians

Per- and polyfluoroalkyl substances (PFAS) are contaminants of concern due to their widespread occurrence in the environment, persistence, and potential to elicit a range of negative health effects. Per- and polyfluoroalkyl substances are regularly detected in surface waters, but their effects on many aquatic organisms are still poorly understood. Species with thyroid-dependent development, like amphibians, can be especially susceptible to PFAS effects on thyroid hormone regulation. We examined sublethal effects of aquatic exposure to four commonly detected PFAS on larval northern leopard frogs ( Rana [Lithobates] pipiens ), American toads ( Anaxyrus americanus ), and eastern tiger salamanders ( Ambystoma tigrinum ). Animals were exposed for 30 days (frogs and salamanders) or until metamorphosis (toads) to 10, 100, or 1000 μg/L of perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonate (PFHxS), or 6:2 fluorotelomer sulfonate (6:2 FTS). We determined that chronic exposure to common PFAS can negatively affect amphibian body condition and development at concentrations as low as 10 µg/L. These effects were highly species dependent, with species having prolonged larval development (frogs and salamanders) being more sensitive to PFAS than more rapidly developing species (toads). Our results demonstrate that some species could experience sublethal effects at sites with surface waters highly affected by PFAS. Our results also indicate that evaluating PFAS toxicity using a single species may not be sufficient for accurate amphibian risk assessment. Future studies are needed to determine whether these differences in susceptibility can be predicted from species' life histories and whether more commonly occurring environmental levels of PFAS could affect amphibians.

Environmental Toxicology and Chemistry↗
USGS1985

Toxicity of abate® 4E (temephos) in mallard ducklings and the influence of cold

Diets mixed to contain 0, 0.1, 1.0, 10 and 100 ppm temephos (determined chemically to contain less than 0.5, less than 0.5, 0.89, 6.0 and 59 ppm temephos, respectively) in an Abate® 4E formulation, were fed to mallard (Anas platyrhynchos) ducklings for 7 d. During this period, half of the ducklings in each dietary treatment group were housed in a heated brooder (39 to 41 °C) and half were housed in an unheated brooder (10 to 18°C). Mortality in all dietary groups in the unheated brooder was higher than in the heated brooder. High temephos-related mortality occurred in the 100 ppm group in the unheated brooder but not in any other diet-temperature groups. Ingestion of the 100 ppm temephos diet inhibited plasma Cholinesterase (ChE) activity and elevated plasma corticosterone concentration and creatine phosphokinase activity, but other selected plasma chemistries were not affected in a dose-related manner. Brain ChE activity was depressed only in the 100 ppm dietary groups; maximum inhibition of brain ChE activity was 48%. These findings suggest that diets containing up to 10 ppm temephos do not directly affect duckling survival during the first week of life and that the toxicity of 100 ppm temephos is markedly enhanced by cold.

Environmental Toxicology and Chemistry↗
USGS1987

Orthene® toxicity to little brown bats (Myotis lucifugus): Acetylcholinesterase inhibition, coordination loss, and mortality

The 24-h LD50 of Orthener̀ (active ingredient acephate, acetylphosphoramidothioic acid o,s -dimethyl ester, CAS 30560-19–1) to little brown bats (Myotis lucifugus) was high (> 1,500 mg acephate/kg) and at least several times greater than the LD50 for mice (Mus musculus) (720 mg/kg). Twenty-four hours after dosing, all surviving mice appeared behaviorally normal, but 9 of 30 surviving bats could not right themselves when placed on their backs. When dead and incapacitated bats were combined to calculate an ED50 (median effective dose), the resultant estimate (687 mg/kg) did not differ ( p > 0.05) from the LD50 for mice. Serum cholinesterase (ChE) activity in control bats was 3.2 times greater than in mice. The relationship between this naturally high level of ChE and the relative tolerance of bats to organophosphorus insecticides is unexplained. Toxicity of Orthene was clearly less than that reported elsewhere for methyl parathion (phosphorothioic acid o,o -dimethyl o-[4-nitrophenyl] ester, CAS 298–00-0). This finding may be useful in selection of a chemical for agricultural use, but conclusions about the safety of Orthene to this bat species, or to others, must remain tentative until confirmed by studies under field conditions. Because bats are long-lived with low reproductive rates and slow recruitment, any additional mortality in the wild could be critical to population survival.

Environmental Toxicology and Chemistry↗
USGS1988

Influence of the method of fluoride administration on toxicity and fluoride concentrations in Japanese quail

Young Japanese quail ( Coturnix japonica ) were administered NaF for 16 d either in their diet or by esophageal intubation. Based on the total fluoride ion (Σmg F − ) intake over the 16-d experimental period, fluoride administered by intubation was at least six times more toxic than that fed in the diet. Dietary concentrations of 1,000 ppm F − (Σmg F − for 16 d = approx. 144) produced no mortality, whereas intubated doses produced 73% or greater mortality in all groups administered 54 mg F − /kg/d or more (Σmg F − for 16 d ≥ approx. 23 mg). Graphic comparison of the regression of log F − ppm in femurs/mg F − intake showed that fluoride levels in the femurs of quail administered fluoride by intubation were higher than in those administered fluoride in the diet.

Environmental Toxicology and Chemistry↗
USGS1989

Toxic effects of boron on mallard reproduction

Boron, a naturally occurring trace element generally considered environmentally innocuous, was documented to severely impair mallard reproduction. Boron is leached from irrigated agricultural soils and transported in drainage water that contaminates wetlands. Until now, only the selenium accumulated in aquatic food chains has been documented to pose a toxic hazard to wildlife in drainage water wetlands. Adult mallard ( Anas platyrhynchos ) ducks were fed diets supplemented with 0, 30, 300 or 1,000 ppm boron (fresh weight; diets contained about 10% moisture). The hatching success of fertile eggs was significantly reduced by 1,000 ppm boron, less than one-third the highest boron concentrations found in plants in California's San Joaquin Valley. Hatching weights, duckling survival and duckling weight gain were also reduced by 1,000 ppm boron. Boron concentrations in mallard egg, liver and brain tissues were dose-related. Boron did not affect adult survival or egg fertility. Management of drainage water-contaminated environments must now also consider the adverse effects of boron, as well as the possible interactions of drainage water contaminants.

Environmental Toxicology and Chemistry↗