Richard Sharpe: Let common sense guide you in the saga of bisphenol A

I am not a die-hard 'chemicals are safe' man, by any means

Related Topics

The Independent has campaigned for restricted use of the chemical bisphenol A in the belief that it is likely to cause harm to humans, and babies in particular. Bisphenol A is used in the hard plastic of baby feeding bottles and small amounts can leach out into milk. Even after having spent around $50m on the question, scientists are split in their views on the health risks, and the Independent has challenged regulators and the UK Foods Standards Agency to explain why they continue to say that Bisphenol A is safe. To any sane reader this simply does not make sense; surely it's either safe or not? Perhaps after reading below, you may think, like me, that a lot of the $50m is money wasted because the original findings were deemed incorrect some time ago.

Let me start with a statement by one of the scientists (Fred vom Saal) who strongly advocates banning bisphenol A: "The science is clear and the findings are not just scary, they are horrific. Why [would] you feed a baby out of a clear, hard plastic bottle – it's like giving a baby a birth control pill?" Scary indeed, when you think how many mothers in Britain have done just this. Who would (knowingly) do such a thing and why on earth would the Food Standards Agency say this was OK? There is a simple explanation – this statement is not only wrong; it is a complete misrepresentation of what the scientific facts show.

Bisphenol A can act like an oestrogen, the primary female sex hormone. The contraceptive pill contains a very potent oestrogen, ethinyl oestradiol, and this is partly responsible for its effects (preventing ovulation). The difference between bisphenol A and ethinyl oestradiol is in their potency. You need at least 10,000 times as much bisphenol A as you do ethinyl oestradiol to have similar oestrogenic potency. There is accurate data on how much bisphenol A we ingest each day and it is at least 50,000 times less than the level needed to make this the equivalent of taking a contraceptive pill. In fact it is less still, because not much of the bisphenol A we ingest ever gets into the blood to cause any effect in the body.

So how can a sub-set of scientists make claims for bisphenol A being a dangerous oestrogen? The answer is that their own studies in laboratory animals showed it could cause potentially harmful effects. However, attempts to repeat these findings in much larger studies have failed. This is not unusual in scientific research. It is common for a small preliminary study to find something which cannot later be reproduced by another laboratory in a more detailed study. This is why one of the golden rules of scientific research is that results must be reproducible.

But once the results could not be reproduced, the authors of the original studies claimed this was because the follow-up studies had been paid for by the chemicals industry. But then, completely independent studies, by US and Japanese government laboratories, also failed to reproduce the original findings.

Most studies that reported finding effects of bisphenol A did not expose the animals to this chemical in the way that you and I are exposed (by mouth); they either injected it or used an implant under the skin. This effectively bypasses breakdown of bisphenol A in the gut and means that you get a much higher level of exposure than if the animals had been exposed orally. This may explain some of the differences in results from the contrasting studies.

End of story? No, the authors of the original studies assert these next studies did not use the right animal strain – it was not sensitive enough to oestrogens. But these differences are trivial and cannot rationally explain the difference in results. So on the one hand, small, preliminary studies; on the other, large, detailed studies designed explicitly to repeat the findings – which would you believe? To dismiss the more detailed studies in favour of the initial smaller studies not only defies common sense. It is bad science too.

So, can we all sleep free from worries about health risks of bisphenol A? Perhaps not quite yet. There is good evidence that obese people with heart and liver diseases also have higher levels of bisphenol A. This is probably because people with lots of bisphenol A are the ones drinking sugary drinks from cans – ie it is probably the diet causing the problem, not the chemical.

I should declare my credentials. I am funded by the UK Medical Research Council (an independent body). My research does not involve bisphenol A and I therefore have no vested interests in proving that bisphenol A is either safe or dangerous. From my research I do think that some environmental chemicals, to which we are exposed via our lifestyles and diets, probably do have harmful effects in the way claimed for bisphenol A. I am not a die-hard "chemicals are safe" man by any means, but I am convinced, based on present evidence, that bisphenol A poses minimal risk to people because of any oestrogenic effect. As to other possible effects, we will have to wait and see.

A final plea – use your common-sense when making your own decision about bisphenol A; in science, as in life, it is the most robust indicator of what is right and wrong.

Professor Richard Sharpe is a senior scientist at the Medical Research Council Human Reproductive Sciences Unit, Centre for Reproductive Biology, Edinburgh

React Now

Latest stories from i100
Have you tried new the Independent Digital Edition apps?
iJobs Job Widget
iJobs General

Recruitment Genius: Bookkeeper / Office Co-ordinator

£9 per hour: Recruitment Genius: This role is based within a small family run ...

Recruitment Genius: Designer - Print & Digital

£28000 - £32000 per annum: Recruitment Genius: This Design and marketing agenc...

Recruitment Genius: Quantity Surveyor

£46000 per annum: Recruitment Genius: This property investment firm are lookin...

Recruitment Genius: Telesales / Telemarketing Executive - OTE £30k / £35k plus

£18000 - £35000 per annum: Recruitment Genius: This company specialises provid...

Day In a Page

Read Next

Errors & Omissions: When is a baroness not a baroness? Titles still cause confusion

Guy Keleny

CPAC 2015: What I learnt from the US — and what the US could learn from Ukip

Nigel Farage
War with Isis: Fears that the looming battle for Mosul will unleash 'a million refugees'

The battle for Mosul will unleash 'a million refugees'

Aid agencies prepare for vast exodus following planned Iraqi offensive against the Isis-held city, reports Patrick Cockburn
Yvette Cooper: We can't lose the election. There's too much on the line

Yvette Cooper: We can't lose the election. There's too much on the line

The shadow Home Secretary on fighting radical Islam, protecting children, and why anyone in Labour who's thinking beyond May must 'sort themselves out'
A bad week for the Greens: Leader Natalie Bennett's 'car crash' radio interview is followed by Brighton council's failure to set a budget due to infighting

It's not easy being Green

After a bad week in which its leader had a public meltdown and its only city council couldn't agree on a budget vote, what next for the alternative party? It's over to Caroline Lucas to find out
Gorillas nearly missed: BBC producers didn't want to broadcast Sir David Attenborough's famed Rwandan encounter

Gorillas nearly missed

BBC producers didn't want to broadcast Sir David Attenborough's famed Rwandan encounter
Downton Abbey effect sees impoverished Italian nobles inspired to open their doors to paying guests for up to €650 a night

The Downton Abbey effect

Impoverished Italian nobles are opening their doors to paying guests, inspired by the TV drama
China's wild panda numbers have increased by 17% since 2003, new census reveals

China's wild panda numbers on the up

New census reveals 17% since 2003
Barbara Woodward: Britain's first female ambassador to China intends to forge strong links with the growing economic superpower

Our woman in Beijing builds a new relationship

Britain's first female ambassador to China intends to forge strong links with growing economic power
Courage is rare. True humility is even rarer. But the only British soldier to be awarded the Victoria Cross in Afghanistan has both

Courage is rare. True humility is even rarer

Beware of imitations, but the words of the soldier awarded the Victoria Cross were the real thing, says DJ Taylor
Alexander McQueen: The catwalk was a stage for the designer's astonishing and troubling vision

Alexander McQueen's astonishing vision

Ahead of a major retrospective, Alexander Fury talks to the collaborators who helped create the late designer's notorious spectacle
New BBC series savours half a century of food in Britain, from Vesta curries to nouvelle cuisine

Dinner through the decades

A new BBC series challenged Brandon Robshaw and his family to eat their way from the 1950s to the 1990s
Philippa Perry interview: The psychotherapist on McDonald's, fancy specs and meeting Grayson Perry on an evening course

Philippa Perry interview

The psychotherapist on McDonald's, fancy specs and meeting Grayson Perry on an evening course
Bill Granger recipes: Our chef recreates the exoticism of the Indonesian stir-fry

Bill Granger's Indonesian stir-fry recipes

Our chef was inspired by the south-east Asian cuisine he encountered as a teenager
Chelsea vs Tottenham: Harry Kane was at Wembley to see Spurs beat the Blues and win the Capital One Cup - now he's their great hope

Harry Kane interview

The striker was at Wembley to see Spurs beat the Blues and win the Capital One Cup - now he's their great hope
The Last Word: For the good of the game: why on earth don’t we leave Fifa?

Michael Calvin's Last Word

For the good of the game: why on earth don’t we leave Fifa?
HIV pill: Scientists hail discovery of 'game-changer' that cuts the risk of infection among gay men by 86%

Scientists hail daily pill that protects against HIV infection

Breakthrough in battle against global scourge – but will the NHS pay for it?