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June 2013 Archives

On Tuesday morning I walked on the beach at sunrise, and saw a kingfisher hunting sand hoppers on the tide-line. It seemed somehow fitting for the day when the sun would shine on our old airman's last fiight.

For my father-in-law died on Friday and Tuesday was the day of his funeral: a loving celebration of his life which ended with the RSA's ritual words on the passing of a member of the armed forces, and the playing of the Last Post for one more old WWII veteran (Eric was 21 when he joined the RNZAF and trained in Canada for service in the UK and Europe, and 2 weeks short of his 94th birthday when he died).

We knew him as a lovely, loving, gentle man: a true gentleman who adored his wife, his children, his grandchildren and great-grandchild. Someone who was loyal, generous, with a strong sense of right and wrong, & who gave so much to family, friends, and the various sports and service clubs he belonged to. We knew he'd flown in the war as a wireless operator on Dakotas, but little more than that, for it was something he didn't really care to speak of.

But going through his papers after he died, his children found not only his flight log, but longer, more detailed transcripts of what happened on many of those flights. So now we know (along with much more) that Poppa and his crewmates flew on D-Day, dropping paratroopers over Europe; that the final jumper was a large man & so encumbered by his gear that they couldn't get him out over the drop zone; and that the plane turned and flew 360o through heavy fire - for the enemy were now well aware of their presence - to repeat the drop. And then somehow made it safely home.

So now we know so much more about you, Eric: more memories to treasure.

Rest in peace, you lovely, loving man.

 RIP Eric.jpg


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Reading the comments on a recent Stuff article,I was reminded of the aphorism attributed to Mark Twain: Never let the facts get in the way of a good story.

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At noon today the NZ Herald had an on-line forum around fluoridation. Aside from engendering a bit of frustration (it took ages for comments to get past moderation), following the chat was an interesting experience. It also left me with questions/comments that weren't addressed in the relatively short time available. (The forum included Dr Jonathan Broadbent, who provided the Science Media Centre with expert commentary following Hamilton City Council's decision to stop fluoridation of the municipal water supply, and Mary Byrne, from the Fluoride Action Network.)

One questioner asked if any animals ingest fluoride. Jonathan noted that "the ocean contains 1.3ppm fluoride, and the fish are very happy", and went on to point out that this particular element is pretty much ubiquitous in food and drink. Mary's response was that 

there's very good reasons why sea water is not suitable for human consumption. One of them, being there is too much fluoride.

Actually, the reason we shouldn't drink seawater is that our kidneys can't cope: in attempting to remove the excess salt, they end up producing an excessive amount of urine, so too much seawater will lead to dehydration.

But I wanted to ask: Mary, you've indicated here (& in other comments) that fluoride in any quantity is bad for you. So, would you advocate against eating fish and drinking tea (1-9 mg/L)? After all, both have higher levels of fluoride than our tap water does (or will up until June 21, anyway), we're advised to eat several serves of fish each week, and a lot of Kiwis drink a lot of tea (57-64% were regular drinkers, in a 1999 survey).

There was also the comment that

The evidence that fluoride impacts on other bodily systems is obvious just by using common sense.

The problem here is that common sense is often wrong. That's why decisions like this really should be based on good scientific evidence, and not on common sense. From a piece on Psychology Today

...common sense isn't real sense, if we define sense as being sound judgement, because relying on experience alone doesn't usually offer enough information to draw reliable conclusions... Real sense can rarely be derived from experience alone because most people's experiences are limited.

Maybe that's why (as a species) we're not very good at handling risk assessment - because we place too much emphasis on common sense?

And an aside to our Mayor: if you believe such decisions are best left to central government, then why on earth did you table the motion to change the status quo, and then vote for it? (Not to mention, deciding to overturn the 2006 binding referendum on this very issue?)


This really is one of those issues that won't go away. I wrote about it most recently yesterday, but an earlier piece (back in 2009) garnered some interesting responses.



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I'm currently reading through the background information prepared for Hamilton City councillors ahead of the meeting they had yesterday, at which they decided to end the fluoridation of Hamilton's water supply. Right now I'm beginning to think that those of us who are science educators & communicators have done something very wrong, because in the summary of 'views against' I see things like this (emphasis in the original):

A key sub-theme that emerged within this topic was the view that fluoride is a chemical or poison.

Yes, fluoride is a chemical. So are table salt & dihydrogen monoxide**. So often we see the term 'chemical' used in a pejorative sense, ignoring the fact that everything on the planet, ourselves included, is at some level a concatenation of chemicals. Incidentally, in the right - or should that be wrong? - quantities all are toxic: drinking too much water can be fatal. 

The source of fluoride used in water fluoridation is hydrofluorosilicic acid (HFA).  

Several submitters attached copies of the Material Safety Data Sheets.... which includes various warnings such as "Avoid contact with skin and eyes", "Repeated or prolonged exposure may result in fluorosis" and "Avoid contaminating waterways".

And indeed, there would be major risks in allowing concentrated HFA to come into contact with skin or eyes. But somewhere along the track people seem to have lost track of the fact that people drinking fluoridated water are not exposed to these risks, for the HFA is highly diluted upon being added to the water supply. As above, the dose makes the poison.

One of the papers submitted in support of dropping fluoridation is summarised here (it's sometimes referred to as the 'Harvard study'). The paper itself can be read at this link. It's a meta-analysis of data from China, "where fluoride generally occurs in drinking water as anatural contaminant". Reasonably large areas of China have groundwater with more than 1.5mg/L of naturally-occurring fluoride - above recommended levels. The study found that

children in high-fluoride areas had significantly lower IQ scores than those who lived in low-fluoride areas

and concluded that

[t]he results support the possibility of an adverse effect of high fluoride exposure on children's neurodevelopment.

While I'm sure that this was viewed as significant support for stopping fluoridation, there's something missing:the 'high-exposure' groups were receiving naturally-high levels of fluoride in their water, or were drinking water contaminated by industrial wastes. Levels of fluoride in these groups reached more than 30mg/L. The 'low' groups (also called the 'reference' groups in the study) were getting less than 1mg/L - the same levels found in treated drinking water in New Zealand.

In other words, this study does not demonstrate that the up-till-now-current levels of fluoride in our water represent a danger to children's intellectual development. (Did those citing it in support of removing fluoride from our water, actually read it?)

Science education: we can do better. Much better. 

** You can demonise most things if you try hard enough.

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  • Alison Campbell: Or you could, you know, summarise your own reasons for read more
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  • Alison Campbell: I feel that may have connotations of 'night soil', which read more
  • herr doktor bimler: Would it sound better as "liquid soil"? read more
  • Alison Campbell: The results in the study you linked to look promising read more
  • Alison Campbell: Thanks, Ed. Totally agree - it's just a matter of read more
  • Ed Darrell: Plague? Antibiotics, plus we know the vector and how to read more
  • Matthew: At least you came at this with an open mind. read more
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  • herr doktor bimler: On the other hand, the comments threads certainly provide some read more