Repository logo

Browsing by Issue Date, starting with "2014-07-29"

Filter results by year or month
Now showing 1 - 3 of 3
  • Amianto: ação de sensibilização (jornalistas)
    Publication . Proença, Carmo; Neves, Maria Manuela
    Tópicos: - Amianto: propriedades, aplicações e efeitos na saúde - Legislação aplicável: profissionais em riscos - Tipos de exposição - Metodologia de análise: materiais e ar ambiente. - Fibrocimento: Resultados de estudo
    2014-07-29Lecture Restricted access Show more
  • Modeling of human exposure to benzene in urban environments
    Publication . Tchepel, O.; Dias, D.; Costa, C.; Santos, B.F.; Teixeira, João Paulo
    Urban areas characterized by high spatial and temporal variability in air pollution levels require implementation of comprehensive approaches to address exposure of individuals. The main objective of this study was to implement a quantitative assessment of individual exposure to benzene in urban environments. For this purpose, ExPOSITION model based on a global positioning system (GPS) tracking approach was applied to estimate individual exposure in different microenvironments. The current investigation provides an application example and validation of the modeling approach against personal and biological exposure measurements collected during the measurements campaign. The probabilistic approach using the Johnson system of distributions was implemented to characterize variability of indoor concentrations. The results obtained for daily average individual exposure to benzene corresponded to mean levels of 1.6 and 0.8–2.7 μg/m3 in terms of 5th–95th percentiles. Validation of the model results against several personal exposure samples collected for the selected individuals revealed a Pearson’s correlation coefficient of .66. This modeling approach explicitly addressed the temporal and spatial variability in the exposure and established a source–receptor relationship.
    2014-07-29Journal article Restricted access Show more
  • Applicability of In Vitro Methods to Study Patulin Bioaccessibility and Its Effects on Intestinal Membrane Integrity
    Publication . Assunção, Ricardo; Ferreira, Mariana; Martins, Carla; Diaz, Irene; Padilla, Beatriz; Dupond, Didier; Bragança, Mauro; Alvito, Paula
    In human health risk assessment, ingestion of food is considered a major route of exposure to many contaminants, although the total amount of an ingested contaminant (external dose) does not always reflect the quantity available for the body (internal dose). In this study, two in vitro methods were applied to study bioaccessibility and intestinal membrane integrity of cells exposed to patulin, a mycotoxin with significant public health risk. Seven artificially contaminated fruit juices were assayed in the presence or absence of a standard meal, showing a significant difference for bioaccessibility values between contaminated samples alone (mean 27.65 ± 13.50%) and combinations with a standard meal (mean 7.89 ± 4.03%). Different concentrations of patulin (PAT) and cysteine (CYS) (protector agent) were assayed in Caco-2 cells monolayers. At 95 μM, PAT produced a marked decrease in transepithelial electrical resistance (TEER). This effect was significantly reduced when 400 μM and 4000 μM CYS was added to the cells. Combined use of in vitro digestion models with other techniques using intestinal cell lines, such as in vitro intestinal absorption models that use Caco-2 cells, may offer a more comprehensive model of what is occurring during digestion and absorption processes. The study of beneficial effects of protective agents would also be enhanced.
    2014-07-29Journal article Restricted access Show more