Endocrine Disruptors

endocrine disruptors

As I made clear in my post on cosmetic safety assessments, as a rule cosmetics are safe and there is a good procedure in place to make sure they stay that way.   What I didn’t say is that this is basically a scientific approach and one of the things about science is that even things you are really sure about can be changed if new evidence comes to light.  The history of science is basically the story of scientists realising what they had got wrong.  This means that even the best established scientific judgement can be overturned by a new discovery.  We believe that cosmetics are safe based on the best available information, but could new knowledge overthrow this conclusion?   There isn’t much on the horizon that suggests this, but the biggest risk to the consensus is the so called endocrine disruptors.

The idea behind this is that some chemicals have the potential to mimic hormones in the body that control many aspects of how our bodies work.  So if they were to get into the body they might mess up our metabolism in subtle ways.  This might lead to all manner of adverse effects, but cancer and birth defects are the most likely.

Endocrine disruption potential can be measured in laboratories to some extent, though how good the test is for predicting biological activity is a bit questionable.   The effect is basically one that relates to the shape of the molecule fitting into a receptor, so chemists can spot candidates from looking at the structures. For example a paraben with a long side chain looks a lot like something that will fit the bill.  Shorter chain parabens aren’t really the right shape.   When you run the test you get exactly the result you’d expect.  The long chain parabens score highly, while the shorter ones are much less so.  In fact the two shortest chain ones, methylparaben and propylparaben barely register.

But as I say, the correlation between the lab measurement and the effect in real life isn’t all that close, which is why a lot of people found the presence of methylparaben in breast tissues back in 2004 a bit alarming.

Endocrine disruptors can work at very low levels, can take a very long time to have any effect.   If they also slowly build up in the body over time then you can’t rule out the risk of them causing problems.  And it has been observed that fish can have their gender changed in water heavily polluted with the kinds of chemicals that might be expected to disrupt hormones – these weren’t parabens I should say.

To put this in perspective, there has never been any strong evidence to show that any human being anywhere has ever suffered the effects of an endocrine disruption event.    The nearest is that it looks reasonably likely that hormone replacement therapy for the menopause might increase the risk of breast cancer.  This however isn’t hormone mimicking, this is actual hormone.  So even if this link is shown to be real, it isn’t a great proof for the concept of hormone disruption by chemicals.

Anyone who has followed the story will know that it also turned out that the lab work that identified the parabens was a bit questionable in some ways.  It also has yet to be repeated, and one data point is not really enough.  This post isn’t about the paraben story – there is plenty on that elsewhere – and I should point out that I am not a defender of parabens. If there is a case against them I am quite happy to see them banned.  But it is not looking at the moment like they will turn out to be a problem, even if other endocrine disruptors do.

So getting back to endocrine disruptors in general, we are faced with a awkward situation. There is a potential risk posed by some chemicals but where we have almost no way of quantifying it or even of really knowing whether it is a risk or not.   You don’t want to ignore anything related to safety, but how do you handle something so nebulous?

I am sure I wasn’t the only one who was pleased to see that the SCCS, the Scientific Committee on Consumer Safety, has just issued some guidance on the issue.  So what have they said?

In a nutshell, they have just said it is tricky.  They have not concluded that it is a problem, or dismissed it.  They have just listed the reasons it is difficult to come to a decision.  One point they bring up is that is no longer legal to carry out animal tests to evaluate it – though frankly I think it would be almost impossible to infer anything from any animal study that wasn’t very long term and in a very big long lived animal. Screening the thousands of chemicals that might be endocrine disruptors would cost hundreds of millions of pounds and take a generation.

They have taken two pages to be indecisive.  This is laconic in anyone’s book and by the standards of  SCCS reports very much so.

But I wouldn’t say it was a waste of time.  Next time the subject comes up I don’t have to simply shrug my shoulders and say I don’t know.  I can now quote an official text and say that they don’t know either.


I’ve put a post on the same subject on my industry pro blog.



Photo credit: Pam loves pie via photopin cc

4 thoughts on “Endocrine Disruptors”

  1. Great article Colin! I was very interested to read about long- and short-chain parabens and their structural fit with receptors. I shall be having a good read over the SCCS memorandum, so thanks for sharing!

    Have a good weekend,

  2. Hi Colin,

    Thank you for thïs article and your brilliant blog.

    Can you tell me, is there any way that ‘potential’ endocrine disruptors can be identified by the man/woman on the street, to avoid if they wish to?

    Many thanks,

    1. Hello Rachel, there is no way at all I am afraid. I went through a phase in the 90s when I thought I had an idea about what kind of molecule might be suspect, but it turned out that I was wrong when I looked into it a bit deeper. Even the advice that some people give of avoiding cosmetics altogether might not be right. There is just as strong a case for suggesting that parabens are a counter-carcinogen as that they might cause cancer. If you take breast cancer out of the statistics, the rates of cancer in women has been going down for a couple of decades now. It isn’t out of the question that increased exposure to parabens is giving them a slight protective effect. If you could pin breast cancer clearly onto hormone replacement therapy, then the case would be stronger. I am not making this as a serious suggestion, just pointing out that the facts can be made to fit just about any story you choose to if you put your mind to it.

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