Ana Rita R. Silva

Toxicity of tributyltin (TBT) to terrestrial organisms and its species sensitivity distribution

The contamination of the terrestrial environment by disposal of tributyltin (TBT) by contaminated harbour sediments, sewage sludge and/or biocide products has been raising concerns and it may pose a risk to soil invertebrates and plants. This study aimed to improve the amount and quality of data for TBT toxicity in soils in order to assess the ecological risk of TBT to the terrestrial ecosystems. For this, bioassays were performed with the species Porcellionides pruinosus, Folsomia candida, Brassica rapa and Triticum aestivum to evaluate the toxic effects of TBT (as chloride) on these species. Additionally, this study contributed to increase the amount of data concerning TBT toxicity on soil dwelling organisms. The results showed a dose-response relationship between TBT concentration and the increase of toxicity in all species tested. These results were collated with results from literature to construct species sensitivity distributions (SSDs) and to calculate the hazardous concentration at 5% (HC₅) for all data, for each type of soil and TBT formulation used. The HC₅ value for TBT in soil was 2.06 mg TBT/kg soil dw. Little information is available concerning the concentrations of TBT in soils. In addition the predicted no-effect concentration (PNEC) value was determined to be 30 μg/kg soil. Only one study was found referring to TBT contaminated soils, and where TBT concentrations were lower than 0.024 μg TBT/kg for the wetland soil. Therefore it can be concluded that the real TBT concentrations determined represent low risk for environmental effects. In conclusion, the construction of SSDs and the calculation of HC5 using all the data available showed to be a more suitable method rather than the construction of several SSDs for each soil and TBT types. Further investigations concerning TBT concentrations and toxicity on soil organisms need to be performed to increase data and improve risk calculations.

Ecotoxicity and genotoxicity of a binary combination of triclosan and carbendazim to Daphnia magna

In the environment, chemical substances appear as complex mixtures and consequently organisms are exposed to a variety of chemicals from different sources (e.g. wastewater treatment plants, agriculture runoffs). When studying chemical mixtures, there are two conceptual models usually used to predict toxicity: the Independent Action (IA) and Concentration Addition (CA) models. However, deviations from these reference models can occur as synergism or antagonism, dose ratio or dose level dependency. The aim of the present study was to investigate the effects of triclosan and carbendazim, and their binary mixture to Daphnia magna. With this purpose, immobilisation, feeding inhibition, and reproduction were assessed as main ecotoxicity endpoints. In addition, in vivo genotoxicity of both chemicals was investigated using the comet assay. In the single exposure, carbendazim was more toxic to D. magna than triclosan. When daphnids were exposed to both single compounds, DNA damage was observed. Concerning mixture exposures, different endpoints followed different patterns of response, from additivity: IA model (feeding inhibition and reproduction data), to deviations that indicate interaction between chemicals inside the organism: dose level dependency (immobilisation data) and dose ratio dependency (DNA damage). This study showed that additivity does not rule the dose-effect relation in chemical mixtures of carbendazim and triclosan and interactions between both chemicals might induce generally higher toxicity than predicted based on single chemical exposures.

Ecotoxicity and genotoxicity of cadmium in different marine trophic levels

Cadmium ecotoxicity and genotoxicity was assessed in three representative species of different trophic levels of marine ecosystems - the calanoid copepod Acartia tonsa, the decapod shrimp, Palaemon varians and the pleuronectiform fish Solea senegalensis. Ecotoxicity endpoints assessed in this study were adult survival, hatching success and larval development ratio (LDR) for A. tonsa, survival of the first larval stage (zoea I) and post-larvae of P. varians, egg and larvae survival, as well as the presence of malformations in the larval stage of S. senegalensis. Inxa0vivo genotoxicity was assessed on adult A. tonsa, the larval and postlarval stage of P. varians and newly hatched larvae of S. senegalensis using the comet assay. Results showed that the highest sensitivity to cadmium is displayed by A. tonsa, with the most sensitive endpoint being the LDR of nauplii to copepodites. Sole eggs displayed the highest tolerance to cadmium compared to the other endpoints evaluated for all tested species. Recorded cadmium toxicity was (by increasing order): S. senegalensis eggsxa0<xa0P. varians post-larvaexa0<xa0P. varians zoea Ixa0<xa0S. senegalensis larvaexa0<xa0A. tonsa eggsxa0<xa0A. tonsa LDR. DNA damage to all species exposed to cadmium increased with increasing concentrations. Overall, understanding cadmium chemical speciation is paramount to reliably evaluate the effects of this metal in marine ecosystems. Cadmium is genotoxic to all three species tested and therefore may differentially impact individuals and populations of marine taxa. As A. tonsa was the most sensitive species and occupies a lower trophic level, it is likely that cadmium contamination may trigger bottom-up cascading effects in marine trophic interactions.

The family inheritance process: motivations and patterns of interaction

Material inheritance constitutes a challenge for families in later life. Yet inheritance decisions, the underlying reasons and motivations and patterns of family interaction have barely been studied. Research suggests that motivations fluctuate on a continuum between unconditional donation (altruism, normative obligation) and conditional donation (strategic exchange, reciprocity). However, the literature emphasises the need for further research into the motivations that constitute this continuum and on the patterns of family interaction attached to them. This exploratory study therefore sets out to examine the motivations and patterns of family interaction in the process of transmitting material inheritances. Using the critical incidents technique (CIT) 55 usable incidents were collected from 43 participants (7 donors, 16 heirs and 20 professionals). Results of this study suggest four motivations: (i) altruism driven by family solidarity; (ii) equity centred on the equal division of possessions in order to maintain family unity; (iii) strategy focused on reciprocity (I give you if you give me); (iv) egoism based on self-interest. Findings contribute to a better knowledge of the factors that promote and prevent family problems over inheritance.

Construindo a integridade familiar no fim da vida

A integridade familiar constitui um desafio normal no desenvolvimento das pessoas idosas, fortemente influenciado por factores do sistema familiar. Este estudo pretende aprofundar o conhecimento sobre o que contribui para o desenvolvimento do sentimento de integridade familiar em pessoas idosas. A recolha de dados efectuou-se com a aplicacao de uma entrevista semi-estruturada (baseada em King & Wynne, 2004), administrada a 8 individuos com idade superior a 64 anos (5 mulheres e 3 homens), que vivem em contexto familiar. Os principais resultados sugerem que o sentido de integridade familiar na pessoa idosa e influenciado por: i) redefinicao da identidade pessoal sustentada por uma filosofia de vida; ii) existencia de proximidade afectiva nas relacoes; iii) aceitacao de conflitos; iv) satisfacao com a transmissao de legado; v) continuidade das relacoes familiares; vi) existencia de projectos de vida futuros. A integridade nao exclui contrariedades e amarguras, mas envolve-as num significado de paz com a vida. Na intervencao as pessoas idosas devem ser apoiadas no processo de aceitacao de si e do outro, pois este e um mecanismo facilitador da integridade familiar.

Multigenerational effects of carbendazim in Daphnia magna.

Carbendazim is a fungicide largely used in agriculture as a plant protection product. As a result of agricultural runoffs, drainage, and leaching, it reaches surface waters at concentrations possibly hazardous to aquatic communities. Because of potential and continuous release of carbendazim to aquatic systems, long-term exposure to aquatic organisms should be addressed. To fill the knowledge gap, the present study evaluated the responses of multiple generations of Daphnia magna (clone K6) to an environmentally relevant concentration of carbendazim (5u2009μg/L). Twelve successive generations were evaluated, and the effects in these offspring were compared with those from a control population. Neonates fitness was assessed through immobilization, reproduction, and feeding activity tests, along with the comet assay for in vivo DNA damage evaluation. Recovery from long-term exposure was also assessed. In the F5 generation, the results revealed that when daphnids were re-exposed to carbendazim, DNA damage was higher in daphnids continuously exposed to carbendazim than those from clean medium. After daphnids were moved to a clean medium, a low recovery potential was observed for DNA damage. Daphnids exposed continuously for 6 generations (F6) to carbendazim displayed an increase in feeding rates when re-exposed to carbendazim compared with F6 daphnids reared in clean medium. Continuous exposure of daphnids to carbendazim induced a significant increase in DNA damage from the F0 to the F12 generation. Deleterious effects of the multigenerational exposure to carbendazim were more prominent at a subcellular level (DNA damage) compared with the individual level. Environ Toxicol Chem 2017;36:383-394.

The comet assay in Folsomia candida: A suitable approach to assess genotoxicity in collembolans

The present study shows the comet assay technique being successfully applied for the first time to one of the most widely used soil organisms in standardized ecotoxicological tests, Folsomia candida, providing a step forward in assessing the genotoxicity induced by xenobiotics. Because collembolans have a high content of chitin, a new methodology was developed in which the heads of the collembolans were separated from the rest of the body, allowing the hemolymph to leak out. This procedure allows the cells to be released, and after lysis the genetic material is available for the comet assay. Among other key procedures, the use of 30 organisms (20- to 22-d-old adults) per replicate and the correct amount of cells with genetic material (translated as 10u2009μL of suspension) applied on the agarose gel were determinants for the success of the results obtained. The methodology was validated by exposing F. candida to a representative metallic element (cadmium) and a representative of organophosphates, the insecticide dimethoate, for a shorter time period of 10 d, compared with the 28 d for the International Organization for Standardization 11267 method. Within this method, the relatively low percentage of DNA damage (30%) observed in controls and the significant increase in terms of percentage of DNA damage for almost all the concentrations of dimethoate and Cd (reaching 52% and 56% of damage in the highest concentrations, respectively) confirmed the genotoxic effect of both compounds and validated this technique. The comet assay proved to be a sensitive technique to detect DNA strand breaks in collembolans cells. Environ Toxicol Chem 2017;36:2514-2520.