The influence of salinity on the effects of Multi-walled carbon nanotubes on polychaetes

Salinity shifts in estuarine and coastal areas are becoming a topic of concern and are one of the main factors influencing nanoparticles behaviour in the environment. For this reason, the impacts of multiwalled carbon nanotubes (MWCNTs) under different seawater salinity conditions were evaluated on the common ragworm Hediste diversicolor, a polychaete species widely used as bioindicator of estuarine environmental quality. An innovative method to assess the presence of MWCNT aggregates in the sediments was used for the first time. Biomarkers approach was used to evaluate the metabolic capacity, oxidative status and neurotoxicity of polychaetes after long-term exposure. The results revealed an alteration of energy-related responses in contaminated polychaetes under both salinity conditions, resulting in an increase of metabolism and expenditure of their energy reserves (lower glycogen and protein contents). Moreover, a concentration-dependent toxicity (higher lipid peroxidation, lower ratio between reduced and oxidized glutathione and activation of antioxidant defences and biotransformation mechanisms) was observed in H. diversicolor, especially when exposed to low salinity. Additionally, neurotoxicity was observed by inhibition of Cholinesterases activity in organisms exposed to MWCNTs at both salinities.publishe

Bioaccumulation and ecotoxicity of carbon nanotubes

Carbon nanotubes (CNT) have numerous industrial applications and may be released to the environment. In the aquatic environment, pristine or functionalized CNT have different dispersion behavior, potentially leading to different risks of exposure along the water column. Data included in this review indicate that CNT do not cross biological barriers readily. When internalized, only a minimal fraction of CNT translocate into organism body compartments. The reported CNT toxicity depends on exposure conditions, model organism, CNT-type, dispersion state and concentration. In the ecotoxicological tests, the aquatic organisms were generally found to be more sensitive than terrestrial organisms. Invertebrates were more sensitive than vertebrates. Single-walled CNT were found to be more toxic than double-/multi-walled CNT. Generally, the effect concentrations documented in literature were above current modeled average environmental concentrations. Measurement data are needed for estimation of environmental no-effect concentrations. Future studies with benchmark materials are needed to generate comparable results. Studies have to include better characterization of the starting materials, of the dispersions and of the biological fate, to obtain better knowledge of the exposure/effect relationships

Depressive symptoms during adolescence:comparison between epidemiological and high risk sampling

PURPOSE: Both epidemiological (unselected) and high risk (screening on known risk criteria) samplings have been used to investigate the course of affective disorders. Selecting individuals on multiple risk criteria may create a sample not comparable to individuals with similar risk criteria within the general population. This study compared depressive symptoms across the two sampling methods to test this possibility. METHODS: The high risk Cambridge Hormones and Moods Project (CHAMP) screened and recruited adolescents aged 12 to 16. A total of 905 (710 high risk) individuals participated and were reassessed at three follow-ups. The ROOTS epidemiological sample consisted of 1,208 14-year-olds reassessed at 15.5 and 17 years. The risk profile for CHAMP was recreated in the ROOTS study. Both samples completed the Moods and Feelings Questionnaire, a self-report measure of current depressive symptoms. RESULTS: Comparing individuals with the same high risk profiles across the CHAMP and ROOTS studies revealed no significant differences in mean depression scores. Combining the samples revealed that for females, mean depression scores were maintained from 12 to 15 years then declined by 17 years. For males, scores declined from 12 throughout adolescence. High risk status led to consistently higher levels of depressive symptoms in female adolescents but result in little change within male adolescents. CONCLUSIONS: The high risk design recruited adolescents with a depression symptoms profile comparable to the general population for both sexes. High risk status may alter the trajectory of depressive symptoms in female adolescents only. Males may be less sensitive to recent adversity