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May

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Harmful chemicals and fire in space

 
In this month's research column, we take a look at a banned chemical that is still making kids fat, and experiments on flammability in zero gravity

You know how sometimes mistakes from the past can keep popping up and sully the present? Well, researchers from Aarhus University and Aarhus University Hospital have given us one more mistake to add to that uncomfortably long list. Together with an international team, the researchers have found that an old ingredient in 3M’s stain repellent Scotchguard is causing disproportionate amounts of stomach fat in children whose mothers were exposed to the chemical during pregnancy.

The chemical is  perfluorooctane sulfonate – or PFOS – is a man-made chemical that was created to bond surfaces together. It was used mostly in Scotchguard as well as some stain repellents and fire fighting equipment such as extinguishing foams. PFOS was first introduced in 1949, and by 1976 it had already been suggested that the presence of PFOS in products was detrimental to consumers’ health. However, it was not until 2000 that 3M started phasing out the chemical from its production. It was not banned in the EU until 2006.

Though the pollutant is now defunct, it has long lasting characteristics. The chemical degrades very slowly and is still present in some furniture, fabrics and fire fighting equipment. An amendment to the EU’s ban also allows its continued use in hydraulic fluid for commercial airplanes, and China continues to produce and export products with PFOS.  Traces of the compound can be found in Danish  groundwater.

A recent study has confirmed what many have long suspected, that PFOS acts as an endocrine disruptor. The study followed over 1,000 children between the ages of 5 and 9 whose mothers were especially exposed to PFOS during their pregnancies. It found that these children had an increased risk of excess abdominal fat during childhood – a type of fat that is related to obesity, cardiovascular diseases and Type 2 diabetes –  children of the same age whose mothers were exposed to lower levels of the chemical.

PFOS is could therefore responsible for a share of the 16% of Danish boys and 20% of Danish girls who, according to the OECD, suffer from obesity. So despite being long banned, PFOS continues to impact our individual and communal health system for some time. At least we don’t have to blame ourselves entirely for that midsection pudge.

Mission Inflammable

Grunde Jomaas, Associate Professor of Civil Engineering at the Technical University of Denmark (DTU), is coordinating a team skilled at understanding how fire and flames behave – in space.

Jomaas, a fire safety expert, wants to better understand how flames behave in weightless environments. All space-borne crafts require ventilation systems to control the flow of breathable air, but this very same air can allow flames to spread quickly and unpredictably. The project is entitled the ‘Safe Cosmos’ project and is housed in the European Space Agency and is partnered with NASA.

To eliminate this risk on rockets bound for the great beyond, Jomaas and his team are conducting experiments on so-called ‘vomit comets’. These are planes that fly in a series of parabolas, climbing and diving steeply, and in such a way that creates the sensation of weightlessness for around 22 seconds at a time. This is long enough to study the flammability of materials in zero gravity.

During the flights, the researchers ignite 30cm-by-5cm samples of material via a short circuit. If the sample does not create flames that spread further than 15cm over three different flight tests, it is deemed safe for use in space. This means that the progression of flames on this material is controllable enough in zero gravity.

Each flight is carefully designed beforehand and with extreme precaution, as the flights are both costly and risky. They also provide useful data for researchers as well as security for astronauts. It is important, interesting and risky work. It is also really, really cool.  M

 

Tech

By Nereya Otieno

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