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Archives of Environmental Contamination and Toxicology (v.60, #4)

Dynamics of Reactive Sulfide and its Control on Metal Bioavailability and Toxicity in Metal-Polluted Sediments from Lake Taihu, China by Hongbin Yin; Chengxin Fan (pp. 565-575).

This study was conducted to elucidate the vertical and seasonal distribution of acid-volatile sulfide (AVS) and simultaneously extracted metals (SEM) in sediment cores of metal-polluted areas of Lake Taihu, China. The concentrations of AVS in sediments were more dynamic than the SEM values, which were higher in warmer seasons. Two types of AVS profiles were identified in the studied area. Generally, the AVS levels increased at a certain depth (6–18 cm), below which they decreased, except for two sites during summer. Very high concentrations of AVS were observed at these two sites during summer, and its concentrations decreased almost exponentially with increased depth. The higher content of AVS near surface sediments in summer at these two sites was attributed to a high input of organic matter resulting from dead algal deposits. The SEM contents decreased with depth and remained almost constant with season. Metal toxicity in the sediment cores was assessed on the basis of three models: ΣSEM − AVS, ΣSEM/AVS, and ΣSEM − AVS/f _OC, and the results showed that toxicity occurred in the surface sediment interval (0–1 cm) at one site during winter.

Source Identification of Atmospheric Polycyclic Aromatic Hydrocarbons in Industrial Complex Using Diagnostic Ratios and Multivariate Factor Analysis by Seok-Un Park; Jong-Guk Kim; Mi-Jeong Jeong; Byoung-Ju Song (pp. 576-589).

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants worldwide; currently, they are being described as potential persistent organic pollutants (POPs). This study is aimed to identify sources of PAHs in the atmosphere around the Sihwa and Banwol industrial area by using diagnostic ratios and multivariate factor analysis such as principal component analysis/absolute principal component score (PCA/APCS) and positive matrix factorization (PMF). The atmospheric PAHs level was 8.07–177 ng/m³ (gaseous phase: 5.93–68.4 ng/m³; particulate phase: 1.85–128 ng/m³) and PAHs concentration in the warm period was lower than the cold period. As a result of the examination of relative BaP concentration, photodecomposition was found not to be an important factor in the seasonal difference of PAHs concentration in this study. Source identification was first carried out through a double ratio plot. As a result of double ratio plots, atmospheric PAHs in this study were found to stem from the combination of vehicular emission, combustion (coal or biomass–wood or grass), and petroleum. Moreover, PCA/APCS and PMF showed that the main sources were vehicular emission and coal combustion and and incineration-related source with a summed contribution of about 72.6–86.7%. Finally, the fitness of the two models was very good; the estimated values were highly correlated with the measured values (R ² = 0.991–0.999, p < 0.05).

Screening Level of PAHs in Sediment Core from Lake Hongfeng, Southwest China by Jian-Yang Guo; Feng-Chang Wu; Liang Zhang; Hai-Qing Liao; Run-Yu Zhang; Wei Li; Xiao-Li Zhao; She-Jun Chen; Bi-Xian Mai (pp. 590-596).

Using data from a 25-year retrospective of polycyclic aromatic hydrocarbons (PAHs) in sediment core from Lake Hongfeng, Southwest China, their possible sources and potential toxicologic significance were investigated. The total PAH concentrations (16 priority PAHs as proposed by the United States Environmental Protection Agency) in sediments ranged from 2936.1 to 5282.3 ng/g and gradually increased from the analyzed deeper sediments to surface sediments. PAHs were dominated by low molecular-weight components, especially phenanthrene (PHEN) and fluorene (FLU). However, a significantly increased number of high molecular-weight (HMW) PAHs was found in upper segments. The temporal trends of individual PAH species suggest that there may have been a change in energy use from low- to high-temperature combustion, especially after approximately 2001. PAH input to Lake Hongfeng originated mainly from domestic coal combustion and biomass burning, whereas fuel combustion characteristics have also been found in recent years. Sediment-quality assessment implied that potential adverse biologic impact could be a probability for most low-ring PAHs (including naphthalene, acenaphthylene, acenaphthylene, FLU, PHEN, and anthracene). Nevertheless, more concern should be paid to HMW PAHs in the future due to their rapidly increasing trends in upper sediments. Because only one core was analyzed in this study, more work is needed to confirm the sources and toxicity of PAHs in Lake Hongfeng.

Distribution of Organophosphorus Pesticides in the Bed Sediments of a Backwater System Located in an Agricultural Watershed: Influence of Seasonal Intrusion of Seawater by V. Babu; P. Unnikrishnan; G. Anu; S. M. Nair (pp. 597-609).

This article focuses on the temporal and spatial distribution of three organophosphorous pesticides―malathion, methyl parathion, and chlorpyrifos―in the sedimentary environment of a backwater ecosystem, Kuttanad backwaters, situated in Kerala, India. Based on salinity distribution, geographic characteristics, and human activities prevailing in the area, the study area was divided into three zones: zone 1 with riverine characteristics, zone 2 with freshwater characteristics during and after the monsoon season and estuarine characteristics during the premonsoon season, and zone 3 with estuarine characteristics. The organophosphorus pesticides in the study area showed the order of enrichment as chlorpyrifos >malathion >methyl parathion. While studying the variations in pesticide concentrations seasonally, higher concentrations were observed during the premonsoon monsoon season, with the concentrations being lower than the detectable level. Sediment characteristics, such as pH, texture, organic carbon, moisture content, etc., had reflective effect on the degradation rates of pesticides. The runoff water from the paddy fields made a larger contribution of pesticide pollution to the study area.

Toxicity of Cadmium, Anthracene, and Their Mixture to Desmodesmus subspicatus Estimated by Algal Growth-Inhibition ISO Standard Test by Agnieszka Baścik-Remisiewicz; Anna Aksmann; Adam Żak; Maja Kowalska; Zbigniew Tukaj (pp. 610-617).

Cells of Desmodesmus subspicatus 86.81 were used to examine the toxicity of cadmium chloride (CdCl₂) and anthracene (ANT) applied individually and in combination. The experiments were performed according to standardized ISO (International Organization for Standardization) 8692 protocol (2004). Parameters measured were the number of cells and chlorophyll a fluorescence parameters. E_rC₁₀ and E_rC₅₀ values (growth rate [r] inhibition by 10% and 50%, respectively) for single toxicants were determined separately. The effect of mixtures of the substances (Cd + ANT) at concentrations corresponding to E_rC₁₀ (E_rC₁₀ + E_rC₁₀) and E_rC₅₀ (E_rC₅₀ + E_rC₅₀) values was characterized. The toxicity of individual chemicals after a 72-h exposure was as follows: ANT (E_rC₁₀ = 0.06; E_rC₅₀ = 0.26 mg l⁻¹) and CdCl₂ (E_rC₁₀ = 0.12; E_rC₅₀ = 0.30 mg l⁻¹). The combination Cd + ANT decreased the population growth rate more strongly than the substances applied individually. Cadmium at a concentration corresponding to E_rC₁₀ slightly influenced the parameters of chlorophyll a fluorescence as measured by the OJIP test (O, J, I, and P are the different steps of fluorescence induction curve), whereas the influence of ANT was not statistically significant. In Cd + ANT–treated samples, the photosynthetic “vitality” (PI), the maximum quantum yield of primary photochemistry (φ_Po), and the fraction of active PS II reaction centre (RC) decreased, but the values of ABS/RC, TR₀/RC, and DI₀/RC increased. The type of interaction between Cd and ANT depended on the concentration of chemicals used. When the substances were applied at concentrations of E_rC₁₀, synergistic effects were observed, whereas the mixture of chemicals used at an E_rC₅₀ concentration showed an antagonistic interaction.

High Mercury Concentrations Reflect Trophic Ecology of Three Deep-Water Chondrichthyans by Michael C. Newman; Xiaoyu Xu; Charles F. Cotton; Kyle R. Tom (pp. 618-625).

The relative contributions of proximity to mercury sources and trophic ecology to realized axial muscle mercury concentrations were explored for three deep-water chondrichthyans (Etmopterus princeps, Centroscymnus coelolepis, and Hydrolagus affinis), two species of which are harvested for human consumption. Samples were taken at three North Atlantic Ocean locations: the Azores, the Charlie Gibbs Fracture Zone, and the Bear Seamount. Despite the long distances between anthropogenic sources and the sampling locations, all species from all locations had muscle mercury concentrations exceeding the United States human health screening value of 0.3 mg/kg wet weight. Proximity to anthropogenic sources was not an obvious determinant of these elevated concentrations. Generally, mercury concentrations appeared to increase with increased dependence on benthic versus pelagic food sources (as indicated by interspecies differences in δ¹³C), and with higher position in the trophic web (as indicated by differences in δ¹⁵N).

The Effect of Organism Density on Bioaccumulation of Contaminants from Sediment in Three Aquatic Test Species: A Case for Standardizing to Sediment Organic Carbon by J. L. Van Geest; D. G. Poirier; K. R. Solomon; P. K. Sibley (pp. 626-635).

Laboratory methods for measuring bioaccumulation of organic contaminants from sediment into aquatic organisms continue to improve, but some aspects are still in need of standardization. From a review of published methods, we noted that the loading density of organisms was determined inconsistently and was primarily based on either sediment volume or total organic carbon (TOC). The rationale mainly expressed for standardizing to TOC was to minimize the depletion of sediment contaminants. However, even when density was standardized to TOC, the relative amount of TOC provided (i.e., ratio of TOC to organism dry weight [dw]) was highly variable. In this study, we examined the effect of organism density (standardized to sediment TOC or volume) on bioaccumulation in three freshwater organisms. The oligochaete Lumbriculus variegatus, mayfly nymph Hexagenia spp., and fathead minnow Pimephales promelas were exposed for 28 days to two field-contaminated sediments that varied in concentration of PCBs and TOC. Densities tested were 50:1 and 27:1 ratios of TOC to organism dw and 140 ml sediment/g wet weight (ww) biomass, yielding low to high organism densities. Bioaccumulation in Hexagenia spp. was significantly higher at the lowest organism density compared with the highest organism density when exposed to site 2 sediment (1.1% TOC) but only with tissue concentrations expressed on a ww basis. Otherwise, there was no significant effect of density on bioaccumulation in organisms exposed to sediments from site 1 (12% TOC) or site 2. Survival of Hexagenia spp. was adversely affected at the highest organism density when the relative amount of TOC was low. The results of this study support the recommendation of standardizing organism density relative to a particular amount of TOC for invertebrate species. A 27:1 ratio of TOC:organism dw was selected as a standard organism density for a new bioaccumulation method because survival, growth, and bioaccumulation were not impacted relative to a 50:1 ratio, and less sediment was required. This density is recommended as an appropriate ratio for sediment bioaccumulation assessments in general.

Polybrominated Diphenyl Ethers in Three Commercially Important Fish from the Northwestern Arabian Gulf: Occurrence, Concentration, and Profiles by Bondi Gevao; Foday M. Jaward; Majed Al-Bahloul; Saif Uddin; Mirza U. Beg; Jamal Zafar (pp. 636-642).

Polybrominated diphenyl ethers (PBDEs) were measured in three species of fish (yellowfin seabream [Acanthopagrus latus, a predatory fish]; Klunzinger’s mullet [Liza klunzingeri, a pelagic fish]; and large-scaled tonguesole [Cynoglossus arel, a demersal fish]) collected from two sites in the northwestern part of the Arabian Gulf, a marginal sea of the tropical Indo-Pacific Ocean. Concentrations of ΣPBDEs ranged from 11 to 57 ng g⁻¹ lipid weight (lw) for mullet, 5.0–38 ng g⁻¹ lw for tonguesole, and 2.8–48 ng g⁻¹ lw for seabream in Kuwait Bay, whereas in the open gulf, concentrations ranged from 6.0 to 160 lw for mullet, 8.3–190 lw for tonguesole, and 7.1–62 for lw for seabream. The congener composition in all species from both sites was dominated by BDEs 47, 99, and 100, which together constituted approximately 90% of the congeners detected. Although no statistically significant intersite differences were found, ΣPBDEs concentrations in mullet were significantly higher than those in seabream (p = 0.01). However, no significant differences existed between mullet and tonguesole (p = 0.28) or between tonguesole and seabream (p = 0.06). ΣPBDE concentrations were negatively correlated with fish mass for all species; however, the correlations were statistically insignificant, suggesting a growth dilution effect.

Study on the Accumulation of Heavy Metals in Shallow-Water and Deep-Sea Hagfishes by Kuo-Hsun Chiu; Hin-Kiu Mok (pp. 643-653).

Hagfish, the plesiomorphic sister group of all vertebrates, are scavengers, and many of them live at depths reaching thousands of meters. They are caught for use as food and serve as a substitute for leather in crafts in Asian hagfisheries. At present, the amount of various pollutants present in hagfishes from bioaccumulation through the food chain is unknown. To understand the bioaccumulation characteristics of heavy metals in deep-sea scavengers, selected heavy metals, including iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), arsenic (As), selenium (Se), cadmium (Cd), mercury (Hg), and lead (Pb), were analyzed and compared in two hagfish species, Paramyxine nelsoni (Pn) (found at approximately 200 m) and Myxine formosana (Mf) (found at approximately 850 m) caught in southwestern Taiwanese waters. Hagfish muscle (PnM and MfM) and liver (PnL and MfL) samples were lyophilized, and their metal levels were then analyzed using an inductively coupled plasma mass spectrometer. The metals with the highest levels in Pn tissues included Cu and As (PnL > MfL and PnM > MfM); in contrast, those that were higher in Mf tissues were Cd, Hg (both MfL > PnL and MfM > PnM), and Zn (MfM > PnM). Multivariate analyses, i.e., principle component analysis and partial least squares for discriminant analysis of metal levels were able to clearly separate these four tissue types into two groups corresponding to the two species: Pn and Mf. The present data also show differences in the levels of certain heavy metals in these tissues of the two hagfish species. These differences might have resulted not only from depth-related environmental factors but also from different species’ accumulation characteristics. Fe, Cu, and Hg concentrations were much higher in hagfish muscle than have been found in other fishes from adjacent polluted regions, and Hg was approximately 10- to 100-fold higher in hagfish muscles. Public health issues related to the consumption of hagfish are also discussed.

Disposition Kinetics of Caffeine and Paraxanthine in Nile Tilapia (Oreochromis niloticus): Characterization of the Main Metabolites by Lisbeth E. Gómez-Martínez (pp. 654-664).

The reproductive and developmental toxicities of caffeine (CA) reported in mammals have been linked with the characteristics of its kinetic disposition. Because undesirable reproductive effects in fish have also been reported, and considering that CA has been found worldwide at relatively high concentrations in most bodies of waters, this study evaluated the disposition kinetics of CA and its main metabolite paraxanthine (1,7-dimethylxanthine; PX) in Nile tilapia after a single intraperitoneal administration (4 mg/kg). CA showed rapid absorption, first-order elimination with biexponential decay, rapid intercompartmental transfer, wide distribution in almost the entire body water (apparent volume of distribution [Vd_ss] 0.45 l/kg), terminal elimination half-life (t_1/2 _β) 4.08 h, and systemic clearance (Cl) 0.75 ml/min/kg; there were no important differences between parameters determined in plasma or in other organs (liver and gills). PX was rapidly formed in liver, showing saturable-kinetic properties in this organ, with V_max 8.11 μg/g h and K_m 12.58 μg/g. The terminal elimination linear process was similar between matrices, with a half-life (t_{1/2 el}) 2.12 h, Vd_ss 0.35 l/kg, and Cl 1.24 ml/min/kg. CA in tilapia was extensively metabolized to 1-methyl-uric acid and 1-methyl-xanthine in all of the organs studied. Metabolic and kinetic patterns were comparable with those reported for mammals. The observation of a concentration-dependent kinetic of PX is an important finding. Thus, toxicities of CA in fish would appear to be similar to those in mammals and should be considered in the risk assessments for this species, especially during the early stages of development.

Roundup Effects on Oxidative Stress Parameters and Recovery Pattern of Rhamdia quelen by Charlene Cavalheiro de Menezes; Milene Braga da Fonseca; Vânia Lúcia Loro; Adriana Santi; Roberta Cattaneo; Bárbara Clasen; Alexandra Pretto; Vera Maria Morsch (pp. 665-671).

Antioxidant enzymes and oxidative stress indicators were evaluated in fish exposed to different concentrations of the herbicide Roundup 48% (Monsanto, St. Louis, MO): control (none), 0.45, or 0.95 mg/l. After exposure for 8 days to herbicide, fish were transferred to clean water for a recovery response period (also 8 days). Herbicide increased thiobarbituric acid reactive species in liver and muscle at the higher concentration and in the brain at both concentrations. Protein carbonyl in liver increased after exposure. Catalase (CAT) and superoxide dismutase (SOD) activities and ascorbic acid levels in liver did not change in fish exposed to both concentrations. Glutathione S-transferase (GST) levels decreased at both concentrations. The nonprotein thiol levels decreased at the 0.95 mg/l concentration. During the recovery period, some of the parameters that had altered, such as protein carbonyl content, later recovered. However, some enzymes reacted during this period, e.g., GST increased its activity, possibly indicating a compensatory response against the toxic conditions. In contrast, CAT and SOD activities decreased during the recovery period, indicating herbicide toxicity. Oxidative stress that occurred during the exposure period was likely due to the increased lipid peroxidation and protein carbonyl content. The results concerning oxidative and antioxidant profiles indicate that short-term exposure to herbicide is capable of causing oxidative stress in fish tissues.

Influence of a Combination of Agricultural Chemicals on Embryos of the Endangered Gold-Striped Salamander (Chioglossa lusitanica) by M. E. Ortiz-Santaliestra; M. J. Fernández-Benéitez; M. Lizana; A. Marco (pp. 672-680).

Pollution from agrochemicals may be contributing to the global decline of amphibian populations. Environmentally relevant concentrations of a fertiliser, ammonium nitrate, and a commercial formulation of the herbicide glyphosate Roundup Plus were tested on the embryonic development of Chioglossa lusitanica. This study introduces new data at three different levels. First, we provide previously unknown information about hatchling traits of C. lusitanica. Second, we present the first ecotoxicological study of this endangered species, to which environmental pollution is considered a major threat. Third, we conduct the first experiment with an amphibian species exposed to a mixture of a glyphosate-based herbicide and a nitrogenous fertiliser. Control individuals hatched with an average (±SD) total length of 18.77 (±2.02) mm and at an average Harrison’s developmental stage of 44.58 (±1.24). Mean hatching time among controls was 11.52 (±1.29) weeks. None of the chemicals or their interaction produced lethal effects; however, a significant interaction was found when analysing total length at hatching. Individuals exposed to the herbicide hatched at a larger size than controls, and this effect was especially clear when the fertiliser was added to the water. The absence of pollutant-related mortality or severe sublethal effects is in agreement with most studies indicating a high tolerance of amphibian embryos to agrochemicals. However, further research considering other life stages and additional natural factors (i.e., predators, food availability) is needed to estimate the ecological impact of chemical mixtures on C. lusitanica.

Toxicity of Four Herbicide Formulations with Glyphosate on Rhinella arenarum (Anura: Bufonidae) Tadpoles: B-esterases and Glutathione S-transferase Inhibitors by Rafael C. Lajmanovich; Andrés M. Attademo; Paola M. Peltzer; Celina M. Junges; Mariana C. Cabagna (pp. 681-689).

In this study, amphibian tadpoles Rhinella arenarum were exposed to different concentrations of Roundup Ultra-Max (ULT), Infosato (INF), Glifoglex, and C-K YUYOS FAV. Tadpoles were exposed to these commercial formulations with glyphosate (CF-GLY) at the following concentrations (acid equivalent [ae]): 0 (control), 1.85, 3.75, 7.5, 15, 30, 60, 120, and 240 mg ae/L for 6–48 h (short-term). Acetylcholinesterase (AChE), butyrylcholinesterase (BChE), carboxylesterase (CbE), and glutathione S-transferase (GST) activities were measured among tadpoles sampled from those treatments that displayed survival rates >85%. Forty-eight-hour LC₅₀ for R. arenarum tadpoles exposed to CF-GLY in the static tests ranged from ULT = 2.42 to FAV = 77.52 mg ae/L. For all CF-GLY, the LC₅₀ values stabilized at 24 h of exposure. Tadpoles exposed to all CF-GLY concentrations at 48 h showed decreases in the activities of AChE (control = 17.50 ± 2.23 nmol/min/mg/protein; maximum inhibition INF 30 mg ae/L, 71.52%), BChE (control = 6.31 ± 0.86 nmol/min/mg/protein; maximum inhibition INF 15 mg ae/L, 78.84%), CbE (control = 4.39 ± 0.46 nmol/min/mg/protein; maximum inhibition INF 15 mg ae/L, 81.18%), and GST (control = 4.86 ± 0.49 nmol/min/mg/protein; maximum inhibition INF 1.87 mg ae/L, 86.12%). These results indicate that CF-GLY produce a wide range of toxicities and that all enzymatic parameters tested may be good early indicators of herbicide contamination in R. arenarum tadpoles.

Chlorpyrifos-Induced Toxicity in Duttaphrynus melanostictus (Schneider 1799) Larvae by M. R. Wijesinghe; M. G. D. K. Bandara; W. D. Ratnasooriya; G. P. Lakraj (pp. 690-696).

This study investigates the effects of continuous exposure to a widely used organophosphate pesticide, chlorpyrifos, on survival, growth, development, and activity of larvae of the Asian common toad, Duttaphrynus melanostictus Schneider 1799. Larvae were continuously exposed to six different concentrations (1–1,500 μg l⁻¹) of commercial-grade chlorpyrifos for 14 days and monitored for 1 additional week. Chlorpyrifos at ≥1,000 μg l⁻¹ caused significantly high and dose-dependent mortality, and the weekly LC50_{7 day–21 day} values ranged from 3,003 to 462 μg l⁻¹. Larvae surviving exposure to ≥500 μg l⁻¹ chlorpyrifos showed significant growth impairment, delays in metamorphosis, and decreased swimming activity. Tail abnormalities were the most common morphologic deformity at concentrations of 1,000 and 1,500 μg l⁻¹ chlorpyrifos. The findings of the present study highlight the need to recognize the potential risk that agrochemicals pose to amphibians inhabiting agricultural landscapes in Sri Lanka and other Asian countries.

In Vivo and In Vitro Effects of Metals in Reactive Oxygen Species Production, Protein Carbonylation, and DNA Damage in Land Snails Eobania vermiculata by A. Itziou; M. Kaloyianni; V. K. Dimitriadis (pp. 697-707).

Heavy metals are known to induce oxidative damage by way of enhancement of intracellular reactive oxygen species (ROS) production, which often preludes the onset of alterations, such as protein carbonylation and DNA damage. In this study, our aim was to examine the early responses of land snails Eobania vermiculata to environmental contaminants by investigating the use of a modified enzyme-linked immunosorbent assay (ELISA) assay for the measurement of protein carbonylation as a new biomarker of terrestrial pollution as well as by measuring ROS production and DNA damage. Land snails were treated with heavy metals―cadmium, lead, or copper―in vivo (15 or 40 ppm) for 25 days or in vitro (0.5, 5, 50 or 500 μM) for 30 min in the laboratory, and the previously mentioned biomarkers were determined in digestive gland and haemolymph of the treated animals. A statistically significant increase in ROS production, protein carbonylation, and DNA damage was shown in the snails treated with pollutants compared with the untreated snails. The results indicate the effectiveness of measuring ROS production and DNA damage, as well as using the present ELISA method, as sensitive tools of terrestrial pollution biomonitoring studies. Statistically significant correlations among the previously mentioned techniques further enhance their role as promising biomarkers in terrestrial pollution studies.

Variability in the Dynamics of Mortality and Immobility Responses of Freshwater Arthropods Exposed to Chlorpyrifos by Mascha N. Rubach; Steven J. H. Crum; Paul J. Van den Brink (pp. 708-721).

The species sensitivity distribution (SSD) concept is an important probabilistic tool for environmental risk assessment (ERA) and accounts for differences in species sensitivity to different chemicals. The SSD model assumes that the sensitivity of the species included is randomly distributed. If this assumption is violated, indicator values, such as the 50% hazardous concentration, can potentially change dramatically. Fundamental research, however, has discovered and described specific mechanisms and factors influencing toxicity and sensitivity for several model species and chemical combinations. Further knowledge on how these mechanisms and factors relate to toxicologic standard end points would be beneficial for ERA. For instance, little is known about how the processes of toxicity relate to the dynamics of standard toxicity end points and how these may vary across species. In this article, we discuss the relevance of immobilization and mortality as end points for effects of the organophosphate insecticide chlorpyrifos on 14 freshwater arthropods in the context of ERA. For this, we compared the differences in response dynamics during 96 h of exposure with the two end points across species using dose response models and SSDs. The investigated freshwater arthropods vary less in their immobility than in their mortality response. However, differences in observed immobility and mortality were surprisingly large for some species even after 96 h of exposure. As expected immobility was consistently the more sensitive end point and less variable across the tested species and may therefore be considered as the relevant end point for population of SSDs and ERA, although an immobile animal may still potentially recover. This is even more relevant because an immobile animal is unlikely to survive for long periods under field conditions. This and other such considerations relevant to the decision-making process for a particular end point are discussed.

Two-Phase Uptake of Nickel in the Ground Beetle Pterostichus oblongopunctatus (Coleoptera: Carabidae): Implications for Invertebrate Metal Kinetics by Agnieszka J. Bednarska; Anna Brzeska; Ryszard Laskowski (pp. 722-733).

We studied nickel (Ni) kinetics in the ground beetle Pterostichus oblongopunctatus exposed to different, potentially stressful, temperatures. We found unexpected Ni kinetics in metal-exposed adult and larval beetles. Instead of the pattern observed commonly for other metals, i.e., an increase in metal concentration followed by stabilisation in the uptake phase and a decrease after transfer to uncontaminated food, the Ni-fed beetles apparently switched to decontamination soon after the start of Ni exposure while they were still being fed Ni-spiked food. In addition, internal body Ni concentrations showed high variance. The traditional first-order, one-compartment model with the switch to decontamination set to the last day of the uptake phase appeared inadequate and in most cases was nonsignificant. Instead, the model with a regression-estimated point of switching to decontamination fit the data better, explaining 57.2–91.5% of the temporal variability of mean Ni body concentrations (weighted regression) in adult beetles and 44.1–62.3% in larvae. Temperature did not affect Ni toxicokinetics in adults, but in larvae there were some temperature-dependent differences in kinetic parameters.

The Effect of Cadmium on Steroid Hormones and Their Receptors in Women with Uterine Myomas by Marzenna Nasiadek; Ewa Swiatkowska; Anna Nowinska; Tomasz Krawczyk; Jacek R. Wilczynski; Andrzej Sapota (pp. 734-741).

Cadmium (Cd) is one of the environmental metalloestrogens, and its role in uterine tissues has not yet been fully elucidated. The aim of the study was to investigate estrogenic properties of Cd in uterine tissues by analyzing the expression of estrogen receptor (ER) and progesterone receptor (PR) as well as estrogen and progesterone levels in serum and Cd concentrations in blood and tissues. The samples of tissues (leiomyoma and surrounding myometrium) collected intrasurgically and blood samples drawn from 53 women (age 39 to 52 years) with uterine myomas were thoroughly analyzed. In the study group, blood Cd concentration ranged from 0.33 to 3.5 μg/L. Cd concentration in leiomyoma tissues was twice as high as that in surrounding myometrium (0.48 and 0.75 μg Cd/g wet tissue, respectively), albeit the difference was not statistically significant. Cd concentrations in blood significantly correlated with Cd concentrations in tissues (leiomyoma and surrounding myometrium). The measurement of ER expression showed no difference between leiomyoma tissues and surrounding myometrium. The statistical analysis showed a significant correlation between ER expression and Cd concentration in both tissues under study. An additional statistical analysis (path analysis) demonstrated the correlation of uterine tissue levels of Cd and ER expression. However, there was no association between ER expression in both tissues and E₂ level in serum. Our results suggest a metalloestrogenic effect of Cd by way of ER stimulation in the uterus.

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Archives of Environmental Contamination and Toxicology (v.60, #4)