Browsing by Issue Date, starting with "2017-06-23"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
- Evaluating the cytotoxic potential of a panel of manufactured nanomaterials using the plating efficiency assayPublication . Pinhão, Mariana; Louro, Henriqueta; Silva, Maria JoãoStatement of the Problem: The emergence of newly developed nanomaterials (NMs), with physicochemical features useful for innovative applications in consumer products and medicine, generated the need of fast- and cost-effective toxicology screening strategies for safety assessment. Overall toxicity can be evaluated using survival or cell death as an endpoint. However, in view of the NMs’ specificities, many methods are vulnerable to interference of the NMs with the detection process. We analyzed the cytotoxic effects of a panel of 10 benchmark NMs in respiratory cells (A549) using plating efficiency (PE) assay, and compared with a spectrophotometric method. Methodology: The NMs were used for PE assay in cells exposed for 7 days to silicon dioxide (NM-200 and NM-203), titanium dioxide(NM-100, NM-101, NM-103), silver (NM-300 k, NM-302), cerium oxide (NM-212), barium sulphate (NM-220), zinc oxide (NM-110) nanomaterials or carbon nanotubes (NM-401). For a core group of NMs, NM-212, NM-100, NM-101, NM- 103 and NM-220, the MTT assay was also performed in 24 h exposed cells. In addition, the batch dispersions and their dilutions in the cell medium were analyzed by dynamic light scattering (DLS). Findings: The size distribution of the dispersions showed that in general the NMs showed peaks around 100 nm, but a multimodal size-distribution was observed for NM-103, NM-200, NM-302 and NM-401. Considering the PE assay, NM-212, NM-101, NM-110, silicon dioxides and both silver NMs were cytotoxic. On the contrary, NM-100, NM-103 and NM-220 were not cytotoxic. In the MTT assay following 24h- exposure to the core NMs, no significant cytotoxicity was observed. Conclusion & Significance: Overall, cytotoxicity determined in PE assay yielded positive results in the majority of the NMs, suggesting that this methodology may be more sensitive than MTT to NMs’ induced toxicity. Furthermore, long-term exposure to NMs is possibly more relevant to address health impact of NMs.
- Can human biomonitoring studies contribute to improve public health decisions?Publication . Silva, Maria João; Louro, HenriquetaStatement of the Problem: Our previous work has shown the presence of the hazardous chemicals within a complex mixture of contaminants (e.g., metals, pesticides, polycyclic aromatic hydrocarbons) trapped in sediments of a Portuguese estuary. In that case-study, an epidemiological survey confirmed the exposure of the local population mainly through food chain, suggesting the need of a biomonitoring study that includes the quantification of contaminants in biological fluids as well as biomarkers of early biological effects (e.g., biochemical, genetic and omics-based endpoints) in the target population. Recognizing the knowledge gap between exposure to hazardous substances and health outcomes, not only in Portuguese population, but also throughout Europe, the project European Human Biomonitoring Initiative (HBM4EU) has just started, with the overarching goal of generating knowledge towards the safe management of chemicals. Methodology & Theoretical Orientation: Human biomonitoring will be used to understand the human exposure to chemicals and resulting health impacts. The first steps rely on harmonizing procedures for human biomonitoring across countries, to provide policy makers with comparable data on human internal exposure to chemicals and mixtures of chemicals at EU level. Then, linking data on internal exposure with the hazardous chemicals, will allow to aggregate external exposure and identifying exposure pathways and upstream sources. Conclusion & Significance: By generating scientific evidence on the causal links between human exposure to chemicals and negative health outcomes, an evidence-base will be established to allow the use of human biomonitoring in chemical risk assessment methodologies to data. The risk management and communication with stakeholders and policy makers will ensure that results are applied in the design of new regulations for chemicals and for supporting public health protection policies.