México es el principal consumidor mundial de agua embotellada en envases de Tereftalatode Polietileno (PET), por lo que es importante que el envase garantice la salud del consumidor. El PET es el polímero más usado como envase para bebidas no alcohólicas. El PET libera una sustancia conocida como Bisfenol A (BPA). Se ha encontrado que esta sustancia afecta la actividad hormonal de los seres vivos, lo cual, aumenta el riesgo de obesidad, diabetes o paro cardiacos. En los últimos años, se han investigado los distintos factores que contribuyen a que la sustancia migre al agua durante su tiempo de almacenamiento. Sin embargo, se han presentado contradicciones en cuanto a los factores que contribuyen a la liberaciónde la molécula. En esta investigación se analizaron tres tipos de agua embotellada, de las cuales los factores a evaluar fueron: la marca, tiempo, temperatura de almacenado, volumen y peso de la botella. Los efectos de los factores fueron analizados con ANOVA. Solo latemperaturay el tiempo de almacenado contribuyen a que el BPA migre a el agua. Los dos factores, tuvieron una relaciónpositiva con la concentraciónde BPA en el agua.Posteriormente se hizo una investigación en situación de la vida real donde dos tipos de envases fueron colocados en un auto durante una semana para comprobar el efecto de las variablessignificativas mencionadas, las mediciones se hicieron diariamente. La temperatura resulto no ser un factor importanteya que no llego a ser tan altacomo en la investigaciónprevia. Sin embargo, se detectó que el compuesto continúamigrando a travésdel tiempo.Los resultados sugieren que la investigación acerca del tema debe continuar para poder definir las condiciones de almacenamiento de los productos almacenados en PET o cualquier otro polímeropara alargar su periodo de vida de útil. | Mexico is the main consumer of polyethylene terephthalate’s bottled water, worldwide, therefore, containers shall warrant the client ́s health. PET is known to release Bisphenol A (BPA). BPA is reported to have effects on the hormonal activity of living beings, that increases the risks of obesity, diabetes and heart attack. Shelf life impact of BPA released in bottled water remains a research subject. Its importance has increased during the last years, where, some contradictions have been found in regards to factors of the molecule migration. In this research three brands of bottled water were analyzed, where the factors toevaluate were: brand, time & temperature of storage and volume & weight of the bottle. The effect of the factors was analyzed with ANOVA. The results showed that only the temperature and the time were significant factors for the BPA migration. Both have apositive relationship with the concentration of the molecule in the water, i. e., the higher is the temperature and time, the quantity of the molecule will be higher in the product.Later these two factors were analyzed on a real-life situation by storingtwo types of bottled water on a car during one week, the measurements were done daily. The temperature was not significant in this casebecause it was not high enough to influence the migration of the molecule, as the previous investigation. Nevertheless,the concentration of the BPA increased through the time.The results suggest to continue the investigation about the subjectto define the best storage conditionsfor food products in PET or any other polymer in order to prolong as much as possible its useful life

For a long time it has been accepted that tropical soils, specially oxisols, have excellent physical characteristics, that they are permeables, with high infiltration and drainage rates. However, we have to accept today that tropical soils are very susceptible to degradation by human intervention, especially by the use of intensive and tillage and by rainfall erosivity. Knowing by experience, that soils of the Eastern plains of Colombia are very susceptible to physical degradation, a study to identify the properties that are more vulnerable to use of machinery has been started to try to establish some indicators of degradation. One of the parameters that reflect the actual condition of soils and that is sensible to changes is infiltration, which is really low in the soils that have been studied even under native savanna. This means that they have a low rainfall acceptance capacity and that could behave as "dry soils" under wet clime. The values of infiltration rate found varied from 3 to 15 mm/h for different conditions of use and management systems when it was determined even at different depths | Edgar Amézquita Collazos, H Londoño, 'La infiltración del agua en algunos suelos de los Llanos Orientales y sus implicaciones en su uso y manejo', Centro Internacional de Agricultura Tropical (CIAT), 2016