C60 fullerene: a powerful antioxidant or a damaging agent? The importance of an in-depth material characterization prior to toxicity assays

Since the discovery of fullerenes in 1985, these carbon nanospheres have attracted attention regarding their physico/chemical properties. Despite little knowledge about their impact on the environment and human health, the production of fullerenes has already reached an industrial scale. However, the toxicity of C₆₀ is still controversially discussed.The aim of this study was to clarify the biological effects of tetrahydrofuran (THF) suspended C₆₀ fullerene in comparison to water stirred C₆₀ fullerene suspensions. Beyond that, we analyzed the effects on the Crustacea Daphnia magna an indicator for ecotoxicological effects and the human lung epithelial cell line A549 as a simplified model for the respiratory tract.We could demonstrate that water-soluble side products which were formed in THF nC₆₀ suspension were responsible for the observed acute toxic effects, whereas fullerenes themselves had no negative effect regardless of the preparative route on either A549 cell in vitro or D. magna in vivo.     

Identifying natural and anthropogenic sources of metals in urban and rural soils using GIS-based data,PCA, and spatial interpolation

Determining sources of neurotoxic metals in rural and urban soils is important for mitigating human exposure. Surface soil from four areas with significant clusters of mental retardation and developmental delay (MR/DD) in children, and one control site were analyzed for nine metals and characterized by soil type, climate, ecological region, land use and industrial facilities using readily available GIS-based data. Kriging, principal component analysis (PCA) and cluster analysis (CA) were used to identify commonalities of metal distribution. Three MR/DD areas (one rural and two urban) had similar soil types and significantly higher soil metal concentrations. PCA and CA results suggested that Ba, Be and Mn were consistently from natural sources; Pb and Hg from anthropogenic sources; and As, Cr, Cu, and Ni from both sources. Arsenic had low commonality estimates, was highly associated with a third PCA factor, and had a complex distribution, complicating mitigation strategies to minimize concentrations and exposures.     

New best estimates for radionuclide solid–liquid distribution coefficients in soils. Part 3: miscellany of radionuclides (Cd,Co, Ni,Zn, I,Se, Sb,Pu, Am,and others)

New best estimates for the solid–liquid distribution coefficient (K_d) for a set of radionuclides are proposed, based on a selective data search and subsequent calculation of geometric means. The K_d best estimates are calculated for soils grouped according to the texture and organic matter content. For a limited number of radionuclides this is extended to consider soil cofactors affecting soil–radionuclide interaction, such as pH, organic matter content, and radionuclide chemical speciation. Correlations between main soil properties and radionuclide K_d are examined to complete the information derived from the best estimates with a rough prediction of K_d based on soil parameters. Although there are still gaps for many radionuclides, new data from recent studies improve the calculation of K_d best estimates for a number of radionuclides, such as selenium, antimony, and iodine.     

Review of Russian language studies on radionuclide behaviour in agricultural animals: 3. Transfer to muscle

Over 150 publications reporting studies conducted in the former USSR were reviewed to provide transfer coefficients (F_f) to the muscle of domestic animals from experiments using chronic administration, often for long timescales in large scale experiments. Only a few of these studies were made available in the English language literature or taken into account in international reviews. The values derived have been compared with expected values reported by the IAEA's Handbook of parameter values for the prediction of radionuclide transfer in temperate environments (TRS 364) where possible. The information presented here has been used in the current updating of parameters recommended for environmental assessments by the IAEA. Many of the reported values are for Sr due to the Mayak accident and Cs due to the Chernobyl accident. Nevertheless, the reported data for a wide range of radionuclides, in particular for Ru, Sb, and Zn markedly improve the extent of available data.     

Modeling of Cs migration in soils using an 80-year soil archive: role of fertilizers and agricultural amendments

An 80-year soil archive, the 42-plot experimental design at the INRA in Versailles (France), is used here to study long-term contamination by ¹³⁷Cs atmospheric deposition and the fate of this radioisotope when associated with various agricultural practices: fallow land, KCl, NH₄(NO₃), superphosphate fertilizers, horse manure and lime amendments. The pertinence of a simple box model, where radiocaesium is supposed to move downward by convectional mechanisms, is checked using samples from control plots which had been neither amended, nor cultivated since 1928. This simple model presents the advantage of depending on only two parameters: α, a proportional factor allowing the historical atmospheric ¹³⁷Cs fluxes to be reconstructed locally, and k, an annual loss coefficient from the plow horizon. Another pseudo-unknown is however necessary to run the model: the shape of historical ¹³⁷Cs deposition, but this function can be easily computed by merging several curves previously established by other surveys. A loss of ∼1.5% per year from the plow horizon, combined with appropriate fluxes, provides good concordance between simulated and measured values. In the 0–25 cm horizon, the residence half time is found to be ∼18 yr (including both migration and radioactive decay). Migration rate constants are also calculated for some plots receiving continuous long-term agricultural treatments. Comparison with the control plots reveals significant influence of amendments on ¹³⁷Cs mobility in these soils developed from a unique genoform.     

Review of Russian-language studies on radionuclide behaviour in agricultural animals: part 4. Transfer to poultry

Data on radionuclide transfer to domestic chickens and ducks obtained from research performed in the former Soviet Union were reviewed to provide transfer coefficient values (Ff) to poultry and edible egg contents. The majority of the data are from experiments with ⁹⁰Sr and ¹³⁷Cs, reflecting the importance of these radionuclides after global fallout and major radiation accidents. Data for ³H, ⁵⁴Mn, ⁵⁹Fe, ⁶⁰Co, ²²Na ⁶⁵Zn, ¹³¹I and U are also given. The values derived have been compared with those in the current IAEA Handbook of parameter values for the prediction of radionuclide transfer in temperate environments (TRS 364) and the recent revision which incorporates the values from this paper. The Russian-language data give improved estimates for many radionuclides and the revised handbook is now based on the better quality data given for chronic administration.     

Use and knowledge of fuelwood in three rural caatinga (dryland) communities in NE Brazil

The woody species known, used, and preferred as fuelwood were examined in three rural communities within the county of Soledade, Paraíba State, NE Brazil. Ethnobotanical information was collected using semi-structured interviews with more than 90% of the local households (55 adult residents; 31 women, and 24 males). The interviewees cited 36 plant species as fuelwoods, distributed among 30 genera and 15 families, in addition to two unidentified plants. The plant families represented by the largest numbers of species were Euphorbiaceae, Anacardiaceae, Mimosaceae, Caesalpiniaceae, Sapotaceae, and Fabaceae. The species Caesalpinia pyramidalis Tul. (“catingueira”) was cited with the greatest frequency in all three communities. Within the communities we found significant differences on the number of plants cited and actually used (p < 0.05), indicating that the residents knew more fuelwood species than they effectively harvest. The different distances from the communities to the urban centers were not related to differences on the use or the size of the stocks of fuelwood. Additionally, the study revealed that the communities examined still maintain a significant knowledge of the use of energy-providing plants in spite of the widespread use of liquefied petroleum gas (LPG). Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.     

A detailed field-based evaluation of naphthenic acid mobility in groundwater

An anaerobic plume of process-affected groundwater was characterized in a shallow sand aquifer adjacent to an oil sands tailings impoundment. Based on biological oxygen demand measurements, the reductive capacity of the plume is considered minimal. Major dissolved components associated with the plume include HCO₃, Na, Cl, SO₄, and naphthenic acids (NAs). Quantitative and qualitative NA analyses were performed on groundwater samples to investigate NA fate and transport in the subsurface. Despite subsurface residence times exceeding 20 years, significant attenuation of NAs by biodegradation was not observed based on screening techniques developed at the time of the investigation. Relative to conservative tracers (i.e., Cl), overall NA attenuation in the subsurface is limited, which is consistent with batch sorption and microcosm studies performed by other authors. Insignificant biological oxygen demand and low concentrations of dissolved As (< 10 µg L^− 1) in the plume suggest that the potential for secondary trace metal release, specifically As, via reductive dissolution reactions driven by ingress of process-affected water is minimal. It is also possible that readily leachable As is not present in significant quantities within the sediments of the study area. Thus, for similar plumes of process-affected groundwater in shallow sand aquifers which may occur as oil sands mining expands, a reasonable expectation is for NA persistence, but minimal trace metal mobilization.     

Arsenic species in ecosystems affected by arsenic-rich spring water near an abandoned mine in Korea

The objectives of this study were to quantitatively estimate the distribution of arsenic with its speciation and to identify potential pathways for transformation of arsenic species from samples of water, sediments, and plants in the ecosystem affected by the Cheongog Spring, where As(V) concentration reached levels up to 0.270 mg L⁻¹. After flowing about 100 m downstream, the arsenic level showed a marked reduction to 0.044 mg L⁻¹ (about 84% removal) without noticeable changes in major water chemistry. The field study and laboratory hydroponic experiments with the dominant emergent plants along the creek (water dropwort and thunbergian smartweed) indicated that arsenic distribution, reduction, and speciation appear to be controlled by, (i) sorption onto stream sediments in exchangeable fractions, (ii) bioaccumulation by and possible release from emergent plants, and (iii) transformation of As(V) to As(III) and organic species through biological activities.     

Histopathological effects of chronic aqueous exposure to bis(tri-n-butyltin)oxide (TBTO) to environmentally relevant concentrations reveal thymus atrophy in European flounder (Platichthys flesus)

Although the use of tributyltin in antifouling paints has been banned, this compound is still a serious pollutant of the marine environment. This paper describes a unique study in which European flounder (Platichthys flesus) were chronically (8 months) exposed to bis(tri-n-butyltin)oxide (TBTO) in the water under controlled laboratory conditions. Residue levels in selected tissues (liver, muscle) and general health status indices were measured and the effects on several organs (gills, liver, mesonephros, ovary/testis, spleen, and gastrointestinal tract) were examined histopathologically. Additionally, morphometric analysis of the thymus was performed. The major finding is that exposure of flounder to 5 μg TBTO/l over a period of 8 months, resulting in body burdens comparable to high field levels, induced significant reduction of thymus volume, possibly affecting immunocompetence of the animals. Chronic exposure of European flounder to tributyltin is therefore likely to affect the general health status of this species in heavily polluted aquatic environments.