Helicid snails appear to regulate Pb more closely than other toxic metals, though it is reported as the least toxic. No regulatory mechanism has been described in animals, and the possible role of Mg in limiting Pb assimilation is examined here for the first time. Three populations of Cantareus aspersus were fed Pb and Ca with three levels of Mg for up to 64 days. Metal assimilation and production efficiency was calculated for each of 108 snails. Populations differed in their pattern of uptake but soft tissue Pb was unaffected by dietary Mg. The proportion of Pb assimilated did not change as soft tissue concentrations increased, indicating no specific regulatory mechanism. The daily addition of Pb to the soft tissues increases with growth rate suggesting uptake is instead some function of growth or cell turnover. Bioconcentration factors varied with time and are unreliable indicators of an evolved regulatory mechanism for Pb.

Agricultural wastes are a source of steroid estrogens and, if present, conjugated estrogens may add to the estrogen load released to soil and aquatic environments. Dairy shed effluent samples were collected from 18 farms for analysis of steroid estrogens by GC–MS, conjugated estrogens by LC–MS–MS, and estrogenic activity by E-screen in vitro bioassay. 17α-estradiol was found at highest concentrations (median 730 ng l−1), followed by estrone (100 ng l−1) and 17β-estradiol (24 ng l−1). Conjugated estrogens (estrone-3-sulfate, 17α-estradiol-3-sulfate and 17β-estradiol-3,17-disulfate) were measured in most samples (12–320 ng l−1). Median estrogenic activity was 46 ng l−1 17β-estradiol equivalents. Conjugated estrogens contributed up to 22% of the total estrogen load from dairy farming, demonstrating their significance. Steroid estrogens dominated overall estrogenic activity measured in the samples. Significantly, 17α-estradiol contributed 25% of overall activity, despite potency 2% that of 17β-estradiol, highlighting the importance in environmental risk assessments of this previously neglected compound. In rural ecosystems, 17α-estradiol and conjugated estrogens are significant sources of environmental estrogens from agricultural wastes.

An inexpensive sensitive gas-phase chemiluminescence (GPCL) based analyzer for arsenic is described; this device utilizes manual fluid dispensing operations to reduce size, weight and cost. The analyzer in its present form has a limit of detection (LOD, S/N = 3) of 1.0 μg/L total inorganic As (peak heightbased, 3 mL sample). The system was used to measure low level arsenic in tap water samples from Texas and New Mexico and compared with results obtained by inductively coupled plasma-mass spectrometry (ICP-MS) as well as those from an automated GPCL analyzer. Good correlations were observed. Higher levels of As (50–500 μg/L, As(III), As(V) and mixtures thereof) were spiked into local tap water; the recoveries ranged from 95 ± 2% to 101 ± 1%. A single instrument weighs less than 3 kg, consumes <25 W in power, can be incorporated in a briefcase and constructed for <$US $1000. It is easily usable in the field. An inexpensive instrument capable of measuring down to 1 μg/L As is reported.

Malondialdehyde (MDA), a product of lipid peroxidation and biomarker of oxidative stress, is measured over the long term in spruce Picea abies needles under real conditions in three Czech mountain border areas. The trends presented collate the MDA content in spruce needles with ambient ozone, temperature and precipitation as casual, and defoliation as a subsequent factor for the period 1994-2006. We have found the overall decreasing trends in MDA and defoliation. The highest MDA and defoliation are recorded in the Jizerske, the lowest in the Krusne hory Mts. Out of the examined variables the MDA is predicted best by mean temperature in vegetation season, median of O3 concentrations and AOT40; these three variables account for 34% of MDA1 and 36% of MDA2 variability. Our hypothesis that higher ambient O3 exposure results in higher MDA contents in P. abies needles under real conditions has not been approved.

Assessment of wildlife exposure to organophosphorus (OP) pesticides generally involves the measurement of cholinesterase (ChE) inhibition, and complementary biomarkers (or related endpoints) are rarely included. Herein, we investigated the time course inhibition and recovery of ChE and carboxylesterase (CE) activities in the earthworm Lumbricus terrestris exposed to chlorpyrifos, and the ability of oximes to reactivate the phosphorylated ChE activity. Results indicated that these esterase activities are a suitable multibiomarker scheme for monitoring OP exposure due to their high sensitivity to OP inhibition and slow recovery to full activity levels following pesticide exposure. Moreover, oximes reactivated the inhibited ChE activity of the earthworms exposed to 12 and 48 mg kg-1 chlorpyrifos during the first week following pesticide exposure. This methodology is useful for providing evidence for OP-mediated ChE inhibition in individuals with a short history of OP exposure (≤1 week); resulting a valuable approach for assessing multiple OP exposure episodes in the field.

There is strong interest in developing tools to link chemical concentrations of contaminants to the potential for observing sediment toxicity that can be used in initial screening-level sediment quality assessments. This paper presents new approaches for predicting toxicity in sediments, based on 10-day survival tests with marine amphipods, from sediment chemistry, by means of the application of Partial Least Squares-Discriminant Analysis (PLS-DA) and Counter-propagation Artificial Neural Networks (CP-ANNs) to large historical databases of chemical and toxicity data. The exploration of the internal structure of the developed models revealed inherent limitations of predicting toxicity from common chemical analyses of bulk contaminant concentrations. However, the results obtained in the validation of these models combined relevant values of non-error classification rate, sensitivity and specificity of, respectively, 76, 87 and 73% with PLS-DA and 92, 75 and 97% with CP-ANNs, outperforming the results reported for previous approaches. Models for predicting toxicity based on amphipod tests, derived using PLS-DA and CP-ANN, can be useful aids for screening-level sediment quality assessment.

The impact of residual PAHs (2250 ± 71 μg total PAHs g−1) following enhanced natural attenuation (ENA) of creosote-contaminated soil (7767 ± 1286 μg total PAHs g−1) was assessed using a variety of ecological assays. Microtox™ results for aqueous soil extracts indicated that there was no significant difference in EC50 values for uncontaminated, pre- and post-remediated soil. However, in studies conducted with Eisenia fetida, PAH bioaccumulation was reduced by up to 6.5-fold as a result of ENA. Similarly, Beta vulgaris L. biomass yields were increased 2.1-fold following ENA of creosote-contaminated soil. While earthworm and plant assays indicated that PAH bioavailability was reduced following ENA, the residual PAH fraction still exerted toxicological impacts on both receptors. Results from this study highlight that residual PAHs following ENA (presumably non-bioavailable to bioremediation) may still be bioavailable to important receptor organisms such as earthworms and plants. Residual PAHs in creosote-contaminated soil following enhanced natural attenuation impacted negatively on ecological receptors.

Current European Union regulation regarding polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) in food and feed is based on Toxic Equivalent Quotient (TEQ) concept. For confirmatory purpose, the isotope-dilution method associated to a measurement by gas chromatography coupled with high resolution mass spectrometry is usually the method of choice for precisely measuring the 29 target congeners in three separated fractions. Time and cost related to these analyses are very significant. Various kinds of screening concepts can be considered. In the present study, we elaborated and validated a prediction model for the 2005 World Health Organization TEQ in fish, based on the measurement of 4 PCDD/F and 2 non-ortho dl-PCB congeners, potentially analyzable in a single extracted fraction by gas chromatography coupled with mass spectrometry. Large independent datasets have been used for model elaboration (n = 108) and validation (n = 363, n = 357 and n = 6). This study describes a statistical regression model approach for screening PCDD/Fs and dl-PCBs in fish.

A Pb-mine site situated on acidic soil, but comprising of Ca-enriched islands around derelict buildings was used to study the spatial pattern of genetic diversity in Lumbricus rubellus. Two distinct genetic lineages (‘A’ and ‘B’), differentiated at both the mitochondrial (mtDNA COII) and nuclear level (AFLPs) were revealed with a mean inter-lineage mtDNA sequence divergence of approximately 13%, indicative of a cryptic species complex. AFLP analysis indicates that lineage A individuals within one central ‘ecological island’ site are uniquely clustered, with little genetic overlap with lineage A individuals at the two peripheral sites. FTIR microspectroscopy of Pb-sequestering chloragocytes revealed different phosphate profiles in residents of adjacent acidic and calcareous islands. Bioinformatics found over-representation of Ca pathway genes in ESTPb libraries. Subsequent sequencing of a Ca-transport gene, SERCA, revealed mutations in the protein's cytosolic domain. We recommend the mandatory genotyping of all individuals prior to field-based ecotoxicological assays, particularly those using discriminating genomic technologies. Landscapes punctuated by Pb-polluted islands have engendered local genetic differentiation in resident earthworms.

We evaluated whether life-time exposure to PFOS affects egg development, hatching, larval development, survival, metamorphosis and body mass of Enallagma cyathigerum (Insecta: Odonata). Eggs and larvae were exposed to five concentrations ranging from 0 to 10 000 μg/L. Our results show reduced egg hatching success, slower larval development, greater larval mortality, and decreased metamorphosis success with increasing PFOS concentration. PFOS had no effect on egg developmental time and hatching or on mass of adults. Eggs were the least sensitive stage (NOEC = 10 000 μg/L). Larval NOEC values were 1000 times smaller (10 μg/L). Successful metamorphosis was the most sensitive response trait studied (NOEC < 10 μg/L). The NOEC value suggests that E. cyathigerum is amongst the most sensitive freshwater organisms tested. NOEC for metamorphosis is less than 10-times greater than the ordinary reported environmental concentrations in freshwater, but is more than 200-times smaller than the greatest concentrations measured after accidental releases. Long-term laboratory exposure to perfluorooctane sulfonic acid reduces survival and interferes with metamorphosis of Enallagma cyathigerum (Insecta: Odonata).