Vous joueriez vos seins à la loterie?

Faire confiance à la mammographie ou pas?

Vidéo publiée le 27 septembre 2016 par Tech Box.

Quelle est la réelle efficacité du dépistage organisé?

En savoir plus

VEGA computer modelling tool to identify persistent chemicals

Chemicals that persist in the environment can harm humans and wildlife

Persistent chemicals (which remain unchanged in the environment for a long time) can accumulate in ecosystems and inside wildlife where they can have damaging effects. People and habitats can remain at risk from these chemicals, even when they are no longer produced, and the substances can also be transported far from their original source.

Under the EU chemicals legislation REACH, all chemicals manufactured or imported above 10 tonnes per year must be assessed for persistent, bioaccumulative and toxic (PBT) properties. Substances are generally assessed based on how easily they biodegrade; chemicals that readily degrade in an experimental test system are considered not persistent. Increasingly sophisticated modelling systems are being developed which can predict the activity of a chemical based on its structure, such as quantitative structure-activity relationship (QSAR) models. These may be particularly efficient when experimental data are not available.

A new integrated in silico strategy for the assessment and prioritization of persistence of chemicals under REACH, science direct, pii/S0160412015301240, 2013.

In this study, collaborators from Germany and Italy describe a novel, integrated approach to assess the persistence of chemicals. The software system, combines multiple computational models to predict persistence in several environmental compartments (e.g. water, soil).

To create the VEGA system, the researchers first used thresholds for ‘persistent’ and ‘very persistent’ substances as defined by REACH, and applied them to the experimental data on the half-life (the time needed to remove half of the starting amount of a substance from the environment) of 12 chemicals in sediment, water and soil. If the half-life of a substance was below the criteria for ‘persistent’ then it was considered ‘not persistent’. A range of sources, including the US Geological Survey, Netherlands National Institute for Public Health and the Environment, the European Chemicals Agency and studies published in journals were used to compile the database of substances with experimental values of persistency.

New computer modelling tool to identify persistent chemicals, Science for Environment Policy, Issue 470, 16 September 2016.

VEGA system is tiered, and involves multiple stages of checks before a prediction is made. First of all, the system checks whether an experimental value (a level of persistence established in previous research) is available for the chemical, as this is generally more reliable than a predicted value. If no experimental value is available, the system checks if the compound is perfluorinated (as these compounds are known to be persistent in the environment). If it is, the chemical is automatically classified as ‘persistent’. If not, the biodegradability of the compound is evaluated using a model. If readily biodegradable, the chemical is classified as ‘not persistent’.

If none of these checks can be carried out, three software models are run on the compound, which predict its persistence in sediment, water and soil: IstKNN, machine learning software, which estimates the activity of chemicals based on similar compounds; SARpy, which automatically identifies structural features of chemicals (‘structural alerts’) that are linked to persistence; and IstCHEMfeat, which separates chemicals into classes based on particular features and chemical groups.

The final assessment is made based on a combination of the predictions and their reliability, and is always conservative (e.g. if a chemical is assessed as ‘very persistent’ in water with medium reliability, but ‘not persistent’ in soil with high reliability, the final outcome will be ‘very persistent’).

After ‘training’ the software using chemicals with known properties, the researchers tested its ability to recognise harmful substances from a set of compounds in the Candidate List of substances of very high concern maintained by the European Chemicals Agency. Of 12 compounds, the persistence of 11 were correctly predicted (the remaining compound could not be assessed as it was too dissimilar to the chemicals used during the training phase). These results suggest this tool could be used to prioritise chemicals for regulatory purposes, such as REACH. It may be a more affordable and speedier alternative to experiments for classifying compounds as ‘persistent’.

 

Le Distilbène en 2016 (3/4)

Conséquences pour les petits-enfants DES

Vidéo publiée le 1er septembre 2016 par l’ Association Réseau DES FRANCE DISTILBENE.

En 2016, quelles sont les conséquences du DES pour la troisième génération?

Guide Pratique

Suite à l’étude Distilbène 3 générations qu’elle a initiée en 2013, l’association Réseau D.E.S. France a publié, fin 2015, un guide pratique pour les professionnels de la santé, synthétisant les données actuelles de la science. Deux versions sont à télécharger:

Le Distilbène DES, en savoir plus

Environmental influences on reproductive health: the importance of chemical exposures

Environmental exposures: pregnancy, placenta, and miscarriage

Abstract

Chemical exposures during pregnancy can have a profound and life-long impact on human health.

Because of the omnipresence of chemicals in our daily life, there is continuous contact with chemicals in food, water, air, and consumer products.

Consequently, human biomonitoring studies show that pregnant women around the globe are exposed to a variety of chemicals.

In this review we provide a summary of current data on maternal and fetal exposure, as well as health consequences from these exposures.

Environmental influences on reproductive health: the importance of chemical exposures, Fertility and Sterility, Volume 106, Issue 4, Pages 905–929, September 15, 2016.

Pregnancy image: Stefan Pasch.

We review several chemical classes, including polychlorinated biphenyls, perfluoroalkyl substances, polybrominated diphenyl ethers, phenols, phthalates, pesticides, and metals.

Additionally, we discuss environmental disparities and vulnerable populations, and future research directions.

We conclude by providing some recommendations for prevention of chemical exposure and its adverse reproductive health consequences.

Very clear evidence that testosterone does not help men’s health

Treatment of Men for “Low Testosterone”: No Benefits…

A group of researchers have announced that they have established testosterone treatments benefits: none.

Abstract

Testosterone products are recommended by some prescribers in response to a diagnosis or presumption of “low testosterone” (low-T) for cardiovascular health, sexual function, muscle weakness or wasting, mood and behavior, and cognition.

We performed a systematic review of 156 eligible randomized controlled trials in which testosterone was compared to placebo for one or more of these conditions. We included studies in bibliographic databases between January 1, 1950 and April 9, 2016, and excluded studies involving bodybuilding, contraceptive effectiveness, or treatment of any condition in women or children. Studies with multiple relevant endpoints were included in all relevant tables.

Treatment of Men for “Low Testosterone”: A Systematic Review, PLOS one, September 21, 2016.

*Testosterone, Baby! marshallsegal.

Testosterone supplementation did not show consistent benefit for cardiovascular risk, sexual function, mood and behavior, or cognition. Studies that examined clinical cardiovascular endpoints have not favored testosterone therapy over placebo. Testosterone is ineffective in treating erectile dysfunction and controlled trials did not show a consistent effect on libido. Testosterone supplementation consistently increased muscle strength but did not have beneficial effects on physical function. Most studies on mood-related endpoints found no beneficial effect of testosterone treatment on personality, psychological well-being, or mood.

Researchers say there are no benefits of testosterone treatments for men, the guardian, 21 September 2016.

The prescription of testosterone supplementation for low-T for cardiovascular health, sexual function, physical function, mood, or cognitive function is without support from randomized clinical trials.