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September 2014

Second-hand and chemical free

Ask for EvidenceA fortnight ago, when my wife mentioned we were planning on getting a second-hand pram, one of her colleagues firmly remarked: “You shouldn’t buy anything second-hand – why would you put your baby’s life at risk?”. As expectant parents you’re susceptible to the hard sell and bombarded with conflicting advice, but at times like this asking for evidence can help. Where did this second-hand claim originate? I decided to do a bit of digging.

Car seats and mattresses

The problem with second-hand things is you don’t always know their history – for a car seat that means you wouldn’t know if it was damaged as a result of a car accident.

It seems second-hand mattresses are similarly a bad idea, as soft mattresses have been linked to cot death. Seeing as a new mattress for our second-hand Moses basket is a little under £20, it’s a price worth paying.

It turns out my wife’s colleague vaguely remembered an article about the dangers of second-hand car seats – but she’d taken it further and decided against any second-hand items for her children. The original article seems to have come from a press release issued by the Baby Products Association which quite openly states it was “set up with the objectives of promoting the baby and nursery products sector in both the UK and Europe.” It’s always worth asking questions rather than just accept things at face value. “Who made the claim?” “Where did the information come from?”

Pure, safe and chemical-free

We have splashed out on a bedside crib which came with a brand new mattress proudly boasting to be ‘chemical-free’. Something that we at Sense About Science have already found is completely meaningless.

I asked Mothercare for evidence about this claim and they replied quickly saying “Chemical-free is a term used in marketing to imply that a product is safe, healthy or environmentally friendly because it only contains natural ingredients.” Mothercare accepts that the term is a ‘misnomer’ as “nothing that physically exists in Earth’s ecosystems is free of chemicals”.

But it’s a shame that Mothercare continues to misinform people by using the phrase ‘chemical-free’ in its marketing, as well as perpetuating the myth that natural is always better than synthetic. I’ve asked Mothercare to amend this claim and I’m waiting to hear back.

In the meantime it’s great to see Mumsnet championing the Ask for Evidence campaign by featuring it as this week’s ‘Campaign of the Week’. As a Voice of Young Science member put it:  "As father to a one year old I see this area as a minefield of misinformation so Mumsnet getting on board is excellent."


Mumsnet & Ask for Evidence

There are so many different arguments about what we should and shouldn't do... how to raise an autistic child, fight dementia, cut the environmental impact of waste collection, or reduce obesity. You should follow this diet, change school meals, limit phone use, avoid plastic. Or should you? Confused? Frustrated?

Some of these claims are based on reliable evidence and sound science, but many are not. None of us want to be exploited by misleading information or products that don't work. But there’s something you can do to protect yourself from misleading information – Ask for Evidence is helping thousands of people to find out more about the evidence behind claims they hear.

And that’s exactly why Mumsnet, the UK’s biggest network for parents, is featuring Ask for Evidence as its “Campaign of the Week” this week.

Justine Roberts, co-founder and Chief Executive, Mumsnet.com:

“Parents and those expecting are bombarded with often conflicting advice and product claims, at a time when hormones are raging and you're most susceptible to the hard sell. Likewise conception difficulties and sub-fertility can be heartbreaking for women and their partners, and it's understandable that some may be tempted to try unproven methods to help them conceive a much-wanted baby. The way to deal with the bombardment is to ask questions. This campaign epitomises the need to ask for evidence rather than just accept things at face value.”


Context is crucial

Guest post by Grace Gottlieb, Sense About Science volunteer (@Grace_Gottlieb)

“Lack of sleep linked with depression”

“Divorce linked to smoking” 

“Mother’s diet linked to childhood obesity”

Do these types of headlines look familiar to you? Newspapers, health websites and adverts for the latest ‘super foods’ regularly claim that a new ‘link’ has been discovered. But it’s important to look a little deeper when you see these sorts of headlines because with these ‘link’ stories, context is crucial.

The problem is that the word ‘link’ implies causation and assuming a ‘link’ is causal can lead you to the wrong conclusion. For example, a ‘link’ between sleeping with the light on and shortsightedness in young children made people think leaving a night light on makes you shortsighted. It turns out that the parents of shortsighted children are more likely to be shortsighted themselves (since shortsightedness is partly genetic), and this also means they are more likely to leave the light on in their children’s rooms. So night lights don’t cause shortsightedness. It is instead shortsightedness in parents that leads to both shortsightedness in their children and a night light being used.

It’s important to look at the context of a correlation to find out whether there really is a causal ‘link’. Try keeping in mind the principle that “correlation does not imply causation” to help weigh up whether a ‘link’ story is credible.

The dose makes the poison

It is becoming common knowledge that red wine and grapes contain a chemical called resveratrol which is ‘linked’ to longevity and cancer prevention. So will drinking lots of red wine make you live into your 90s and never get cancer? Unfortunately it probably won’t.

There’s some evidence from animal tests and experiments on cells grown in the lab that resveratrol may have an anti-cancer effect, but very little is known about its effects in humans. And many of the studies showing this anti-cancer effect have used doses of resveratrol that are far higher than the dose you could get in your diet. So drinking red wine will never be an effective way to prevent cancer.

Resveratrol is also marketed as an ‘anti-aging elixir’ in beauty products. Dr Cat Ball from the Biochemical Society decided to ask for evidence behind one of these products. She was sent a study which found that a resveratrol-containing solution increased lifespan – in mice, with the caveat that the researchers weren’t sure whether it was the resveratrol that was actually causing the effect.


Dose is just one part of the context behind a ‘link’ story. If you live in the UK and sit in the sun for just 10 minutes each day, your chances of developing skin cancer will be much lower than someone living in Australia who sunbathes daily for hours. And surely it’s obvious that putting a product containing a specific ingredient on your skin won't have the same effect as eating something with that ingredient? Unfortunately this is an assumption we see all too often. Mathilde Thomas, founder of beauty brand Caudalie, advised in a Daily Mirror article that you should eat grapes because they are “full of antioxidants, which help to give you really beautiful skin”. I asked Caudalie for evidence, and they got back to me explaining how antioxidants act by “inhibiting the oxidation of other molecules”. I was then told that: “Grapeseeds are very rich in polyphenols, such as [those in] our cosmetic range. This is why you can prevent oxidation by eating grapes and/or applying our creams and serums”. But there’s no reason to assume that applying something to your face will have the same effect as eating it. Caudalie failed to provide evidence that polyphenols, when consumed in grapes, either end up in your skin or can in any way work to make your skin “beautiful”.

Asking for Evidence can help

Next time you see a ‘link’ story or come across extraordinary claims like the one made by Caudalie, you can Ask for Evidence to find out the context, and see how robust the ‘link’ actually is – extraordinary claims need extraordinary evidence. 

Ask for Evidence