Sensitive Measure Of Effects Research Articles

Guns Are Not Faster to Enter Awareness After Seeing a Black Face: Absence of Race-Priming in a Gun/Tool Task During Continuous Flash Suppression.

In the Weapon Identification Task (WIT), Black faces prime the identification of guns compared with tools. We measured race-induced changes in visual awareness of guns and tools using continuous flash suppression (CFS). Eighty-four participants, primed with Black or Asian faces, indicated the location of a gun or tool target that was temporarily rendered invisible through CFS, which provides a sensitive measure of effects on early visual processing. The same participants also completed a standard (non-CFS) WIT. We replicated the standard race-priming effect in the WIT. In the CFS task, Black and Asian primes did not affect the time guns and tools needed to enter awareness. Thus, race priming does not alter early visual processing but does change the identification of guns and tools. This confirms that race-priming originates from later post-perceptual memory- or response-related processing.

Ecotoxicological assessments of biochar additions to soil employing earthworm species Eisenia fetida and Lumbricus terrestris

Biochar is the degradation-resistant product generated by the pyrolysis of organic materials and is produced for the intended use of land application in order to promote carbon sequestration and soil improvement. However, despite the many potential benefits biochar application offers, it is important to quantify any ecological impacts that may result from soil amendment in order to avoid potentially causing negative effects upon soil biota which are crucial in the many ecosystem services provided by soil. Any impacts on earthworms in particular are important to evaluate because of their pivotal role in organic matter breakdown, nutrient cycling and soil formation. In this study, we conducted a series of ecotoxicological assays to determine lethal and sublethal (avoidance, mass change and moisture content) effects of heavy biochar applications that reflect levels that may be used in soil restoration efforts. Two earthworm species, Eisenia fetida, an epigeic species, and Lumbricus terrestris, an anecic species, were utilised as test organisms. Two types of biochar, produced from wheat straw and rice husk feedstocks, respectively, were applied to OECD artificial soil and to a natural soil (Kettering loam) at rates of up to 20% w/w. The influence of biochar application on soil porewater chloride, fluoride and phosphate concentrations was also assessed. The biochar applications induced only a subtle level of avoidance behaviour while effects on survival over a 4-week exposure period were inconsistent. However, death and physical damage to some individual earthworms at high biochar application rates were observed, the mechanisms and processes leading to which should be investigated further. Earthworm development (mean mass change over time) proved to be a more sensitive measure, revealing negative effects on L. terrestris at 10% and 20% (w/w) wheat biochar applications in OECD soil and at 20% (w/w) applications of both biochars in Kettering loam. The moisture content of E. fetida remained remarkably consistent across all treatments (~ 82%), indicating that this is not a sensitive measure of effects. The high rates of biochar application resulted in increased chloride (2 to 3-fold) and phosphate (100-fold) concentrations in simulated soil porewaters, which has important implications for soil fertility and production but also for environmental management.

Investigations on the dose\u2013response relationship of combined exposure to low doses of three anti-androgens in Wistar rats

The current investigation examines whether combined exposure to three anti-androgens (flutamide, prochloraz, vinclozolin) result in interference with endocrine homeostasis when applied at very low dose levels, and whether the results of combined exposure are more pronounced than to the individual compounds. A pre–post-natal in vivo study design was chosen with more parameters than regulatory testing protocols require (additional endpoints addressing hormone levels, morphology and histopathological examinations). Dose levels were chosen to represent the lowest observed adverse effect level (LOAEL), the no observed adverse effect level (NOAEL), and the acceptable daily intake for each individual substance. Anti-androgenic changes were observable at the effect level (LOAEL) but not at lower exposures. Nipple/areola counts appeared to be a sensitive measure of effect, in addition to male sex organ weights at sexual maturation, and finally gross findings. The results indicate the absence of evidence for effects at low or very low dose levels. No (adverse) effects were seen at the NOAEL dose. A non-monotonic dose–response relationship was not evident. Combined exposure at LOAEL level resulted in enhanced responses for anogenital index, number of areolas/nipples, delayed preputial separation and reduced ventral prostate weight in comparison to the individual compounds.

Investigations of putative reproductive toxicity of low-dose exposures to vinclozolin in Wistar rats.

The current investigation examines whether the fungicide vinclozolin, which has an anti-androgenic mode of action, is capable of disrupting endocrine homeostasis at very low doses. The data generated clarify whether a non-monotonic dose-response relationship exists to enhance the current debate about the regulation of endocrine disruptors. Moreover, it is part of a series of investigations assessing the dose-response relationship of single and combined administration of anti-androgenic substances. A pre-postnatal in vivo study design was chosen which was compliant with regulatory testing protocols. The test design was improved by additional endpoints addressing hormone levels, morphology and histopathological examinations. Doses were chosen to represent an effect level (20mg/kg bw/d), the current NOAEL (4mg/kg bw/d), and a dose close to the "ADI" (0.005mg/kg bw/d) for the detection of a possible non-monotonic dose-response curve. Anti-androgenic changes were observable at the effect level but not at lower exposures. Nipple/areola counts appeared to be the most sensitive measure of effect, followed by male sex organ weights at sexual maturation, and finally gross and histopathological findings. The results indicate the absence of evidence for effects at low or very low dose levels. A non-monotonic dose-response relationship was not evident.

Sublethal effects of copper on some biological traits of the amphipod Gammarus aequicauda reared under laboratory conditions

The common and widespread copper contamination in marine coastal environments make toxicity data necessary to assess the aquatic hazard and risk of this metal.In the present study, the sublethal effects of copper on survival, growth and reproduction of Gammarus aequicauda were investigated. Amphipods were exposed for 77d to 2 nominal copper concentrations (50, 100μgL−1).Survival was the most sensitive measure of effect and was significantly reduced, especially during early life stage (juveniles). Growth of amphipods was also negatively affected by copper and the growth impairment in G. aequicauda increases with increasing metal concentration. The reproductive traits were impaired by each of the copper concentrations, even if there were not any significant differences between control and copper treatments. The size at maturity increased with increasing copper, so the smallest ovigerous females in the control and copper treatments were 0.83mm and 1.35mm head length, respectively. There was a positive correlation between the brood size and the body size of the female in all treatments, whilst the fecundity (n°juveniles/female) decreased in the order control, 50 and 100μgCuL−1.Copper demonstrates chronic toxicity to G. aequicauda at realistic environmental concentrations. The results of this study entail that the understanding of chronic toxicity of a substance, especially on population level effects, is crucial to assess the long-term effect of the substance in the ecosystem.

Accumulation of tributyltin in Hyalella azteca as an indicator of chronic toxicity: Survival, growth, and reproduction

The chronic toxicity of tributyltin (TBT) was examined by exposing two successive generations of the freshwater amphipod, Hyalella azteca, to sediments spiked with TBT. Survival was the most sensitive measure of effect, with lethal concentration resulting in 50% mortality (LC50) values on a water and body concentration basis ranging from 76 to 145 ng Sn/L and 2,790 to 4,300 ng Sn/g, respectively. Individual growth of amphipods was not negatively affected by TBT, and although reproduction might be more sensitive than survival, the data were too variable to use on a routine basis. There were no detectable TBT-induced differences in the response between first- and second-generation animals. The relationship between toxicity and bioaccumulation of TBT in H. azteca was determined and can be used as a tool to predict the toxicity of TBT in environmental samples. Body concentrations exceeding 2,000 ng Sn/g in H. azteca exposed to field-collected samples would indicate that chronic toxicity due to TBT is likely occurring in amphipod populations at those sites.

A simplified procedure for conducting small scale short‐term embryo toxicity tests with salmonids

A method for conducting short-term (7 day) embryo toxicity tests with rainbow trout is described. The test uses an easily recognizable endpoint that incorporates fertilization success, embryo mortality, and morphogenesis. Method validation included 26 tests on pulp and paper mill effluents and 10 tests with the reference toxicant sodium dodecyl sulphate. The results demonstrate that the method is sensitive and reproducible. Sensitivity, as measured by the minimum statistically significant response, averaged 15.5% of the control performance. Control embryo viability averaged 90% over 36 tests, indicating that the test procedures are robust with low probability of failure. Reference toxicant test results suggested that the short-term embryo toxicity tests were appreciably more sensitive than 96 h acute tests with juvenile rainbow trout and 7 day fathead minnow larval survival and growth tests. This test offers the potential for conducting routine toxicity tests where cold water salmonids are the species of interest and it is desirable to use a more sensitive measure of effects than a 96 h LC50 acute toxicity test with juvenile fish. ©1999 John Wiley & Sons, Inc. Environ Toxicol 14: 301–307, 1999

A simplified procedure for conducting small scale short-term embryo toxicity tests with salmonids

A method for conducting short-term (7 day) embryo toxicity tests with rainbow trout is described. The test uses an easily recognizable endpoint that incorporates fertilization success, embryo mortality, and morphogenesis. Method validation included 26 tests on pulp and paper mill effluents and 10 tests with the reference toxicant sodium dodecyl sulphate. The results demonstrate that the method is sensitive and reproducible. Sensitivity, as measured by the minimum statistically significant response, averaged 15.5% of the control performance. Control embryo viability averaged 90% over 36 tests, indicating that the test procedures are robust with low probability of failure. Reference toxicant test results suggested that the short-term embryo toxicity tests were appreciably more sensitive than 96 h acute tests with juvenile rainbow trout and 7 day fathead minnow larval survival and growth tests. This test offers the potential for conducting routine toxicity tests where cold water salmonids are the species of interest and it is desirable to use a more sensitive measure of effects than a 96 h LC50 acute toxicity test with juvenile fish. ©1999 John Wiley & Sons, Inc. Environ Toxicol 14: 301–307, 1999

The influence of worm age, duration of exposure and endpoint selection on bioassay sensitivity for Neanthes arenaceodentata (Annelida: Polychaeta)

AbstractThe influence of worm age, duration of exposure, and endpoint selection on bioassay sensitivity were evaluated for Neanthes arenaceodentata. Worms were exposed to contaminated sediment collected from Black Rock Harbor (BRH) near Bridgeport, Connecticut, USA. This sediment was diluted with clean control sediment to result in five experimental treatments: 0, 25, 50, 75, and 100% BRH. Three exposure scenarios were employed: (1) a 4‐week exposure beginning with newly emerged juveniles (EJ–4w), (2) a 7‐week exposure beginning with newly emerged juveniles (EJ–7w), and (3) a 4‐week exposure beginning with 3‐week‐old juveniles (3WO–4w). Six measures of worm size were recorded at the conclusion of each exposure to evaluate differences among measurement endpoints. Survival was significantly reduced at the 25% BRH level for the EJ–7w scenario and at the 100% BRH level for the EJ–4w and 3WO–4w scenarios. Growth was significantly reduced at the 25% BRH level in each exposure scenario. Estimates based on the calculated minimum detectable difference indicated that considerably lower concentrations of BRH (6–10%) should be distinguishable by measuring effects on Neanthes growth. Worm size measured in terms of projected area, dry weight, and ash‐free dry weight provided the most sensitive measures of effects. Increasing the length of exposure from 4 to 7 weeks and initiating exposures with emergent juveniles rather than 3‐week‐old worms increased the sensitivity of the bioassay. The results of this study demonstrate that N. arenaceodentata is sensitive to the presence of sediment‐associated contaminants and that test animal age, duration of exposure, and choice of endpoint can have a large effect on the magnitude of the toxic response observed.

The DC-ERG as a highly sensitive measure of effects of prostaglandins.

A few microliters of a prostaglandin preparation (PGE2 or PGF2 alpha) were injected via the ora serrata into the posterior vitreous of one of the eyes in albino rabbits. The fellow eye received an equal volume of saline intravitreally and served as control. The DC electroretinogram (ERG) and the standing potential of the eye (SP) were recorded directly with corneal contact lenses, very stable calomel electrodes, and under very constant anesthesia. The b- and c-wave amplitudes increased in response to 0.1 and 1.0 microgram of PGE2 and PGF2 alpha, respectively. At medium doses there was an increase in the b- and c-wave amplitudes followed by a long-lasting reduction. At very high, nonphysiological doses of PGE2, b- and c-wave amplitudes decreased as compared with the control eye. Prostaglandins modify inflammatory reactions, influence ion transport across membranes, modulate synaptic transmission, and regulate blood flow to various organs. Effects of extremely low doses on the retina and pigment epithelium might indicate a transmitter-like nature of prostaglandins. The present experimental model might be of use in studies of inflammatory eye disease, prostaglandin inhibitors, and characteristics of the pigment epithelial membranes.

The c-wave of the electroretinogram and the standing potential of the eye as highly sensitive measures of effects of low doses of trichloroethylene, methylchloroform, and halothane.

Low and moderate intravenous doses of trichloroethylene, methylchloroform, and halothane dissolved in a lipid emulsion (Intralipid) were given to cynomolgus monkeys. The DC electroretinogram (ERG) and the standing potential of the eye (SP) were recorded directly with corneal contact lenses, very stable calomel electrodes, and under very constant general anesthesia. Even low doses of the substances (close to the hygienic threshold limit values in Sweden) clearly provoked slow variations with time in the amplitude of the c-wave of the ERG and in the SP level. Both potentials are generated mainly in the pigment epithelium. It is suggested that the effects reflect a direct influence of the chemicals upon the metabolism of the pigment epithelium or on the cell membrane. Thus the method used is a highly sensitive measure of effects of certain halogenated hydrocarbons on structures belonging to the central nervous system.

Toxicity of the synthetic pyrethroids, permethrin and AC 222, 705 and their accumulation in early life stages of fathead minnows and snails

Early life stages of fathead minnows ( Pimephales promelas) were exposed to permethrin and AC 222, 705 and snails ( Helisoma trivolvis) were exposed to permethrin in continuous flow-through exposures for approximately 30 days. Saturated solutions of each pesticide were used to avoid the use of solvents. Survival of newly hatched larvae and early juveniles was found to be the most sensitive measure of effect on fathead minnows of both pesticides. AC 222, 705 was approximately 20 times more toxic to fathead minnows than permethrin by the end of the test period. Based on the chronic limits, as defined in these tests, the predicted chronic no-effect concentrations for fathead minnows were between 0.66 and 1.4 μ/l for permethrin and 0.03 and 0.07 μ/l for AC 222, 705. The no-effect concentration for permethrin and snails was ≥ 0.33 μg/l. The chronic values for these compounds were approximately one-sixteenth and one-fourth of the corresponding 96-h LC 50 values, respectively, for fathead minnows in Lake Superior water. The mean bioconcentration factors (BCFs) for permethrin were 2800 for fathead minnows and 800 for snails. The mean BCF for AC 222, 705 and fathead minnows was 4000. Residue concentrations for both pesticides increased with increased water concentrations.