Showing papers by "M. Glória Pereira published in 2016"

Risk assessment of environmental mixture effects

Abstract: In the environment, organisms are exposed to a diverse array of chemicals in complex mixtures. The majority of approaches that aim to assess the risk of environmental chemical mixtures, including those used by regulatory bodies, use toxicity data generated from the individual component chemicals to predict the overall mixture toxicity. It is assumed that the behaviour of chemicals in a mixture can be predicted using the concepts of concentration or dose addition for chemicals with similar mechanisms of action or response addition for dissimilarly acting chemicals. Based on empirical evidence, most traditional risk assessment methods, such as toxic equivalency factors and the hazard index, make the assumption that the components of a mixture adhere to the concentration addition model. Thus, mixture toxicity can be predicted by the summation of the individual component toxicities. However in some mixtures, interactions can occur between chemicals or at target sites that alter the toxicity so that it is more or less than expected from the constituents. Many regulatory and experimental methods for predicting mixture toxicity rely on the use of a concentration addition model so that if interactions occur in mixtures, the risk posed may have been significantly underestimated. This is particularly concerning when considering environmental mixtures which are often highly complex and composed of indeterminate chemicals. Failure to accurately predict the effects chemicals will have if released into the environment, where they can form mixtures, can lead to unexpected detrimental effects on wildlife and ecosystems. The number of confounding factors that may alter the ecotoxicity of a mixture and the accuracy of predictive methods makes risk assessment of environmental mixtures a complex and intimidating task. With this in mind, this review aims show why accurate risk assessment of mixtures is vital by demonstrating the effect they can have on organisms in the environment. Furthermore, it also aims to look at the current challenges facing the assessment of mixture effects and examines future areas of focus that seek to develop methodologies more suitable for environmental mixtures.

Ingestion of microplastics by the chironomid Chironomus sancticaroli and effects on the microbiome in the presence of PBDEs

Abstract: Microplastic particles in the environment can associate with persistent organic pollutants (POPs) due to the hydrophobic nature of plastics and organic chemicals. PBDEs (polybrominated diphenyl ethers) are widely used as flame-retardants in products such as textiles and soft furnishings, with the potential to leach into the environment and be associated with microplastics. If ingested, the gut environment of an organism may favour desorption of adsorbed chemicals due to gut condition. Therefore the ingestion of microplastic particles has implications for uptake and bioaccumulation of these chemicals. Furthermore the presence of microplastics and chemicals in the gut of an organism can also influence the gut environment itself. Gut microbiomes are known to hold a vital role in host metabolism, nutrition and immunity and as such understanding the influence of chemicals and microplastics on the gut microbiota is key.