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Wednesday, 12 February 2020


What are POPs?

There’s increasing concern about the growing mass of our discarded plastics – yet not because of their direct effects on wildlife (e.g. entanglement), but because plastics could be a crucial vector for the transport of key environmental contaminants: persistent organic pollutants, or POPs.

There are many thousands of POP chemicals, originating from agriculture, combustion processes, industrial syntheses, and products such as flame retardants, plasticisers and antimicrobials. In fact, our understanding and classification of them is ever evolving. They’re named not because of their chemical groups, but because of their behaviour. As the name “persistent organic pollutants” suggests, they’re long-lived and harmful.

Plastic debris on a beach. By (Flickr).


What chemicals are we talking about?

Mosquito – By Alvesgaspar via Wikipedia Commons.
Typical culprits include DDT, polynuclear aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), halogenated flame retardants, and polybrominated diphenyl ethers (PBDEs). Although DDT is now banned in most countries, it’s still permitted in some places with a high incidence of malaria to fight off mosquitoes[1].

POPs are polluting and persistent because of certain properties, such as their solubility, reactivity and volatility.

Thursday, 6 February 2020

Vitamins and Supplements (Things We Don’t Know about Pregnancy Series #13)

Is it a safe and good idea to take vitamins whilst pregnant? One thing’s for certain – it’s the norm.

Bacteria. Public Domain.
Whilst scientists have shown that taking certain specific vitamin supplements can protect you against diseases to which you are at risk, taking high, regular doses of multivitamins is actually proven to increase your risk of heart disease or cancer[1]. We don’t know why – it could be because of the fibre, or the various digestive pathways food goes through in your body – but swallowing a broccoli vitamins tablet just doesn’t do the same as eating a broccoli. It may also mean you are missing out on foods rich in other stuff your body needs, perhaps things we haven’t even discovered yet. Then there’s your microbiome: we still understand relatively little about this, but we know you can alter the microbial constitution of your gut through diet and use of supplements.

Overall, a varied diet is recommended as the most healthy one – supplementing where necessary.

Thursday, 30 January 2020

Determining the Sex of a Baby (Things We Don’t Know about Pregnancy Series #12)

“And do you know… what it is?” they ask.

They mean the sex of our unborn baby, of course.

There isn’t much you can find out about who your unborn baby is, but you can know their sex. Or can you?

Often misnamed as “gender”, sex primarily relates to the organs a person presents with, but we already know that it’s more complex than that.

Chromosomes via Wikipedia Commons.
For a long time, we believed that sex was determined by a single chromosomal pair: XX or XY, but recent research has shown that the expressions of a bunch load of other genes is important too. For example, genes known as “enhancers” regulate the expression of genes that drive the development of physical sex characteristics. This means you can develop testes if you have an extra copy of the enhancers, even if you have two X chromosomes, or develop ovaries if you’re missing them, even if you are XY. The enhancers were found amongst the set of DNA formally known as “junk DNA”. These findings imply that observed biological sex and genetic sex may actually be different in some cases.

Tuesday, 21 January 2020

Adipogenesis – the making of fat

How Are Fat Cells Formed?

Our entire bodies originate from a single cell. Once it starts dividing, it kick-starts a multiplication process that lasts our whole lives. This ‘starter’ cell is a stem cell; a biologically programmable template for any other cell. They are responsible for everything, including our hearts, minds and waistlines.

Wait, waistlines?

Yes, this is determined by adipocytes, or white fat cells, in a process known as adipogenesis. There are six roughly defined phases of adipogenesis, but within them are a multitude of molecular processes, and explaining how they work poses a considerable challenge to scientists.

Fat, by Bigplankton via Wikipedia Commons.

Sunday, 12 January 2020

Silent Miscarriage (Things We Don’t Know about Pregnancy Series #11)

Miscarriage is a common medical complication that leads to the loss of a pregnancy before 23 weeks, and affects 1 in 4 women during their reproductive lifetime. Depending on how early or late it happens, it can have bigger or smaller impacts on a woman’s physical and mental health.

But why does it happen? Is it mostly to do with lifestyle, or genetics? Is there something you can do to prevent it? And how can we get early warnings of silent miscarriages – the ones you never even knew had happened?

If you’ve ever been pregnant – miscarriage or not – you’ll probably have wondered about these things, and worried about them, as I have. Whilst the chance of miscarriage drops off rapidly with time, stillbirth and postnatal foetal death are still classed as late pregnancy losses, and do happen from time to time, meaning there is no good time to truly forget about it.

Chances of miscarriage drop as pregnancy progresses. © TWDK. Data from:

Saturday, 4 January 2020

The Thalidomide Scandal (Things We Don’t Know about Pregnancy Series #10)

In 1953, a new drug was made, and by 1957 it was on the market. In the six years that followed, over 10,000 children in 46 countries were born with congenital deformities[1]. The disaster was known as the thalidomide scandal, and led to serious reforms in drug regulation and monitoring worldwide.

What happened?

Thalidomide was prescribed for insomnia, anxiety, asthma, hypertension, migraine, and morning sickness. Doctors thought that it was very safe because taking an overdose simply cast the drinker into a prolonged sleep – and did not cause death. It was also non-addictive. Nobody tested it in pregnant women or animals.

Then, in 1961, two doctors independently called out statistically high numbers of congenital abnormalities in “thalidomide babies” – 20% where the normal rate is 1.5% (or a bit higher, depending on your source)[2].

Thalidomide babies. Image via Wikipedia Commons.

Friday, 27 December 2019

Alcohol and Caffeine (Things We Don’t Know about Pregnancy Series #9)

It’s the Christmas season and, for many people, time to get merry. But pregnant women can’t drink – alcohol or caffeine – or can they?

All things, wrote Paracelsus, are poison and nothing is without poison, only the dose permits something not to be poisonous.

And dose, apparently, works both ways. You may be able to have too much of a good thing, but you may also be able to have too little of a bad thing.

We often think that a drug does nothing to us until the point where it has an effect – the threshold dose. However, this describes a linear dose-response relationship… which doesn’t fit every drug. Researchers think that some substances follow a biphasic dose response: at some point they switch over from stimulating to inhibiting or from inhibiting to stimulating. Alcohol is one such drug.

This dose response phenomenon is known as hormesis, and is explained in more detail in this article.
The hormetic effect. © TWDK.

Wednesday, 18 December 2019

Biodiversity on Ice

Whilst 97% of water on earth is salty and 1% is freshwater, 2% is locked up in snow and ice – but never gets a mention in the national curriculum! However, as the planet warms due to climate change, the ice is melting, and this could have an unprecedented impact on habitats and biodiversity.

Interestingly, as more water becomes available and the climate becomes more temperate, what is observed is a loss of biodiversity. Specialist organisms designed for living in harsh, cold, wintry environments die or are out-competed by more common species already found in neighbouring environments. The conclusion is that the unforgiving glaciers provide pockets for more unusual lifeforms to flourish. These lifeforms are known as extremophiles.