An open letter on fluoride, science and kindness

Dear Lorraine,

I noticed that last week you chose to send this message to Green Party MP Julie Anne Genter:


Having read the original message I’ve decided not to identify you other than by your first name (Lorraine), however I do want to say that I was really shocked at the insensitivity of your message – let alone the bad science (I’ll come to that).  I decided to create a flowchart for you to follow for the next time that you decide to interact with another human being, especially when communicating with people that you don’t know.  I’ve called it “Lorraine’s Flow Chart” as it was written with you in mind, but feel free to share it with others.


Lorriane’s Flow Chart For Future Communications With Other Humans

Now, as promised, I would like to clarify some of the science behind your comments.

You wrote:

“People don’t realise how toxic fluoride is, even at low levels”

As you don’t offer any form of reference to your statement, firstly I don’t know who you mean by ‘people’, or what you are classing as a ‘low’ level of fluoride.

Let me offer some scientific evidence:

In a recent paper in the American Journal of Public Health titled “Community Water Fluoridation and Intelligence: Prospective Study in New Zealand” the researchers are very clear in their findings.  They conducted a study on a sample of the general population from people born in Dunedin, New Zealand, between April 1, 1972 and March 30, 1973 and followed them for 38 years.  They found “No clear differences in IQ because of fluoride exposure even after adjusting for potential confounding variables, including sex, socioeconomic status, breastfeeding, and birth weight (as well as educational attainment for adult IQ outcomes).

Their peer reviewed conclusion specifically states that:

These findings do not support the assertion that fluoride in the context of community water fluoridation programs is neurotoxic.

I used this example because it is an amazing, peer reviewed, long-term study of the effects of fluoride in a New Zealand context, which is where you, Julie Anne and I live.

Next point.  In your message you state that “People don’t know how toxic fluoride is”, and you might be right.  So I thought I’d do some calculations, because it is toxic if you consume too much of it.  So of course is vitamin D, calcium and even water…does this mean we need to start warning people about the dangers of drinking water too?

The amount of fluoride in our water supply is adjusted to keep our water supply level to between 0.7 ppm and 1.0 ppm. This is the optimal amount that provides protection against tooth decay, and is monitored to make sure that the levels stay within that range.

So how much fluoridated water would you have to drink before you die from toxicity?

To help out, I decided to make some calculations for you.  I’ve based my calculations Ln taking a look at your LinkedIn profile and estimating that you are an adult female weighing around 68kg. (If I am incorrect on your weight, please feel free to correct me and I will re-calculate for you).

Based on this assumption I made you a personal “Fluoride in New Zealand Tap Water Toxicity” chart:


Table showing that it would take 1220 glasses of fluoridated tap water to possibly be toxic to Lorraine when considering fluoride toxicity risks

So perhaps your next email about the toxicity of fluoride should be more clear and state that “even at levels of fluoride that are in New Zealand tap water, you would need to drink 1220 glasses of water in a day for it to be possibly toxic”.

I think you are missing a very important point.  Perhaps your messages should be less concerned about the levels of fluoride in the water, and more concerned about the dangers of water itself!

I looked up the MSDS (materials safety data sheet) for water which states that:

Toxicity to Animals:LD50: [Rat] – Route: oral; Dose: > 90 ml/kg LC50
MSDS sheets are documents that contain information on the potential hazards of chemical products, and are documents that scientists like myself must use when completing our health and safety programs for any substance that we use.


From this I calculated your personal water toxicity risk:


Table showing that it would take 24 glasses of fluoridated tap water to possibly be toxic to Lorraine when considering hyperhydration

This means that the water itself is far more toxic than the fluoride  in it.  If you want to give medical and scientific advice to people that you don’t know then you should probably focus on the much higher chance that somebody dies from hyperhydration by drinking 24 glasses of water, than the…highly achievable…7000 glasses of water needed for death by fluoride toxicity.

Your next statement says that you think:

“dentists will be extremely embarrassed if it is found that they are wrong”

The thing is, science doesn’t work that way.  We scientists don’t become embarrassed if we are found wrong – we love it.


Let me explain scientific method to you.

Although anybody can do science, professional scientific researchers follow a scientific method which allows them to explain occurrences using a logical, consistent, systematic method of investigation.

This involves collecting large amounts of data from well thought-out experiments and analysing that data to arrive at a well-tested, well documented theory that is supported by the evidence.  The theory is then subjected to critique by other experts in the field and only if approved by them is it allowed to be published in a peer reviewed journal for others to read and learn from.  We can be wrong for sure, but it’s very difficult to publish wrong data without it being picked up.  It’s almost impossible for hundreds of scientists to publish the same wrong data – it’s actually our job as peer reviewers of other people’s science to pick holes in research, trying to prove that it is wrong before allowing it to be published.  So there is no embarrassment in science, just a rigorous method.

You say that:

More and more research is being conducted into fluoride

You are right, and ‘s the great thing about science: we continue to research to find out things that we don’t know.  I spent 7 years of my life researching fluoride, and even back then there had already been a lot of research carried out.  For instance, we knew then what we know now – that the levels of fluoride in the tap water in New Zealand are not toxic, and in fact have been shown to have positive outcomes for our population, including:

  • In children and adolescents, a 40 per cent lower lifetime incidence of dental decay (on average) for those living in areas with water fluoridation.
  • For adults, a 21 per cent reduction in dental decay for those aged 18 to 44 years and a30 per cent reduction for those aged 45+ (as measured by tooth surfaces affected).
  • A 48 per cent reduction in hospital admissions for treatment of tooth decay, for children up the age of four years.

Finally, I took a look at the link that you included, which was notably to a blog site rather than to a peer reviewed scientific article. Carol S. Kopf, the author of the blog,  is also the media director for the Fluoride Action network, an international coalition to end water fluoridation.  As you might expect, her views are heavily biased against fluoride.  

The blog post refers to research from Dr A.K. Susheela of India who states that she talked about the results of her studies on women ingesting fluoride at the 27th Conference of the International Society for Fluoride Research, Beijing, China, Oct. 2007. Her study was called: Fluoride Ingestion and Health Hazards with Focus on Anaemia in Pregnancy and low birth weight babies: Guidelines for rectification: Susheela A.K, Mondal NK, Rashmi G, Ganesh Kamala, Bhasin Shammi, Gupta Gunjan.

So I looked everywhere for a peer reviewed conference paper that Dr Susheela would have written up, which is how science that is presented at conferences is assessed to be accurate with good scientific method.  I couldn’t find any.

I did however manage to find one research paper written by Dr Susheela which seems to be connected to this blog statement in her paper “Effective interventional approach to control anaemia in pregnant women“, published in the journal Current Science, a science journal from India.

Science journals are ranked using an impact factor which is used to compare different journals within a certain field.  For example the highly regarded The New England journal of medicine has an impact factor of 59.558 and the medical journal The Lancet has an impact factor of 44.002. By way of comparison Current Science has an impact factor of 0.83.

The study that the link you provided could be loosely connected to involved only women in India who were already pregnant, medically anemic and showed high levels of fluoride in their blood.

Just to be clear, India is one of several countries known to have dangerously high levels of fluoride in their drinking water, with villages like Sogival having groundwater fluoride levels of 4.84 ppm.  Not only is their water naturally high in fluoride, but the women in this study were also eating black rock salt, a type of salt with high levels (157 ppm) of fluoride commonly found in Indian street food and Indian snacks and spices.


The link that you refer to is not a study that links fluoride to miscarriages and stillbirths as you claim. If you actually read the research you would see that its a study on pregnant women in a “developing country” who are already anaemic, ingesting high levels of fluoride and suffering from other risk factors including dietary deficiencies, parasitic infestations, urinary tract infections and malaria.

The paper itself is clear in it’s conclusion and states:

“The first factor (application of intervention) throws up a bit of a confusing result to which we do not have a concrete answer at the moment”

They find no concrete evidence that the very high levels of fluoride are directly correlated to the low birth weight of some of the babies, but – as you can see when you read the paper – the women in this study are already unwell when judged by western medicine standards.

Back to your original, offensive advice for Julie-Anne. In New Zealand miscarriage affects 1 in every 4 women. Having a miscarriage can be traumatic and many women experience huge grief over their loss.  It is a very sensitive subject and very personal to those involved.  If you haven’t had to experience the grief of a miscarriage or the challenges around infertility then please understand that it can involve pain, a sense of loss, and a daily struggle to try and remain positive while sometimes feeling like a failure.

In closing, I’d like to leave you with a quote that a colleague of mine has on her office wall that I love and hope you might too:

“We’re all smart. Distinguish yourself by being kind

How your daughters future doors may already be closed by the time she is six

Imagine you are reading a story to a child; the story goes something like this:

  “There is one person at work who is really, really smart. They can figure out how to do things quickly, they come up with answers much faster and better than anyone else. 

Now imagine telling this story:

“There is one person at work who is really, really nice. They like to help others with their problems, they are friendly to everyone.”

At the end of the story, you show pictures of adult males and females to the child and ask them which person they think was being described.


What gender do you think they would pick for each story?

This exact experiment was carried out alongside a series of others as part of a recent study published in the journal Science.

The scientists found that a child’s perception of brilliance goes through dramatic changes between ages 5 and 7.

After the story, the five year olds associated brilliance with their own gender at roughly equal levels.

Just one year later, the 6 year old girls were significantly less likely than the boys to associate brilliance with their own gender.

By the age of 7, when given a choice of toys to play with, the majority of the girls chose not to play with games labelled for ‘really, really smart children’.

This is serious! Our girls are making choices by the age of 7 that they are not smart enough, even though at this age they are outperforming the boys academically at school!

What’s sad is that these results agreed with many previous studies that also show the emergence of gender stereotypes starts at the age of 6.


Why don’t our girls believe in themselves?

With children growing up under a myriad of social influences including the stereotyped toys, media and language it’s hard to pinpoint one thing that caused this perception change. Evidence shows that some teachers treat and reward behaviour in their students differently, unintentionally praising the boys more for academic achievement and the girls for being neat and tidy.

Have you ever told a male child that he was really smart and a female child that she was really pretty? Subtle changes in language such as not only encouraging girls to look a certain way, but to act a certain way can help create positive change.

Interestingly, one 2014 study took anonymous, aggregate data from Google searches and found that parents in the US were two and a half times more likely to ask “is my son gifted?” than “is my daughter gifted?”. They also discovered that parents were twice as likely to google “is my daughter overweight?” than “is my son overweight?”. For the record the data shows that boys are 9 percent more likely to be overweight than girls.

Although the exact causes are not clear, a long term lack of belief in their ability to achieve subjects associated with intelligence and brilliance has the potential to steer many young women away from careers requiring these skills.

As an Engineering lecturer at the University of Auckland I can attest to us graduating more students. Data from the Ministry of education shows that out of all of the school leavers who met the university entrance requirement, only 10 percent of females achieved the calculus and physics subject requirements needed to enter the engineering degree compared to 33 percent males. Just like the girls who didn’t play with games labelled for really, really smart children, it seems our female teenagers don’t study the perceived really, really smart subjects.

Diversity is so important; McKinsey research shows that companies in the top quartile for gender diversity are 15 percent more likely to have financial returns above their national industry medians. Having more females in our tech sector is directly tied to the success of our future economy.

Our fight not about academic differences in gender, it’s around the perceived intelligence that our young people have about themselves. 

Next time you tell a story to a five year old, help your future technology economy by making it a stereotype breaking one.


Why Detox Diets Don’t Work – the science behind how your body removes toxins

The health store shelves are filled with optimistic claims of weight loss products. It’s tempting after what may have been weeks of “I’ll start the diet tomorrow” to think about cleansing out your system to kick start your new body.

Quick fix detox teas, juices and supplements are heavily marketed, enticing you to drink a magical natural potion which will rid you of your over-eating and partying sins so you can start afresh.

Combinations of cayenne pepper, lemon juice and honey taste so disgusting, you might be convinced that they must be good for you, but the truth is in the scientific evidence for which there is none.

In fact a 2015 review of clinical evidence about detox diets published in the Journal of Human Nutrition and Dietetics concluded that there is no compelling evidence to support the use of detox diets for weight management or toxin elimination. They found that many clinical studies are hampered by flawed methodologies and small sample sizes and that no randomized controlled trials have been conducted to assess the effectiveness of commercial detox diets in humans.


Detoxing is marketed based on the idea that some combination of alcohol, preservatives and fast food burgers can cause a build-up of toxins in the body. I’m yet to find one detox kit that actually describes and names which toxins that they remove and how they manage to do this.

The reality is that our bodies are constantly being exposed to a huge number of chemicals. Not all chemicals are bad, and the presence of chemicals in the body doesn’t mean that they are doing harm or building up. Some natural chemicals can be much more harmful than some synthetic ones and we have been exposing ourselves to harmful substances since the beginning of man. To survive, our bodies have evolved to defend against and remove unwanted substances. Our skin, lymphatic system, kidneys and liver combine to form an incredible intrinsic detoxification system.

Detox marketing describes how our liver and kidneys act like filters, but need to be cleaned out to remove the toxins that are trapped there, akin to periodically rinsing a dirty sponge. In reality, our liver’s main role is to detox by taking in blood from the digestive system and filtering out toxins like alcohol and medication by-products. It does this by converting the toxins through a series of chemical reactions into substances that can be eliminated in bile.

Our kidneys also detox by excreting waste products into our urine using over two million filtering units called nephrons which remove waste and send useful minerals back to the bloodstream.


The liver is a self-cleansing organ, it doesn’t store toxins unless you have been diagnosed with serious liver disease and no amount of lemon juice concoction can rinse it out in any other way than it is already capable of.

Detox dieters often make claims that they feel better and have more energy on their cleansing diet. The chances are it’s not the juice causing this but the fact that the juice is replacing a diet full of processed fats, sugar, alcohol, soda, and snack foods. By eliminating these, your liver and kidneys are not overburdened with filtering a bad diet and can carry out their normal detoxification duties. What detoxers are likely experiencing is the feeling of a healthy well balanced body functioning normally. The only thing a detox diet is proven to clean out is your wallet, so instead of looking for a quick fix, give your liver a break and consider making evidence based long term healthy lifestyle choices instead.

How Microbeads in your bodywash could be helping chemicals enter the foodchain

In 1976 chemical engineer John Ugelstad invented a technique on earth that other scientists believed could only be carried out in the weightless conditions of space. His discovery enabled the mass production of monodisperse spheres, tiny microscopic spherical plastic beads. The beads were typically 0.5 to 500 micrometres in diameter, about the width of 1 to 5 strands of human hair.

These little beads enabled new advances to be made in cancer treatments and helped create alternative methods for HIV, bacteriology and DNA research. Tiny latex beads still form the basis for some home pregnancy tests today and thanks to Uglestad’s discovery the medical use of microbeads has helped move drug treatments forward.

More recently, microbeads have moved from medical additives to exfoliators found in face washes, toothpaste, body scrubs, and other everyday beauty products. The non-biodegradable solid plastic beads are commonly made from polyethylene, polypropylene, and polyethyleneterephthalate, the same plastics used for single-use shopping bags and plastic bottles.

After washing off your skin, the microbeads go down the plughole and into the waste-water treatment plant where some of them become trapped in the filtering sludge, but due to their small size some microbeads pass through into our waterways and oceans.

Because their size and shape is similar to many plankton species, microbeads are eaten by marine creatures such as shrimp and fish caught for human consumption. Plastic particles from microbeads and other plastic items in the ocean have been found in the stomachs of fish, shellfish, turtles and birds and have caused harm to these creatures.

Plastic microbeads have been found to act like magnets around organic pollutants with reports indicating a single immersed plastic particle can absorb up to 1,000,000 times more of these chemicals than the water around it. The common pollutants including polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), organochlorine pesticides, and perfluorinated surfactants (PFCs) have been found to stick to the beads due to their large surface area and the chemistry of the plastics used.

This absorption transforms the microbeads into chemical carrying dots and new research published in the journal environmental science and technology found that when feeding on similar sized food in the water, fish also ate PBDE exposed microbeads from a commercial facial scrub. After just 21 days, 12.5 per cent of PBDE chemicals were found to have leached from the ingested microbeads into the tissues of the fish causing concern that persistent organic pollutants accumulate in the tissue of fish exposed to microbeads and other plastic debris in their environment. Research is now underway to determine the implications of this chemical exposure pathway for public health by calculating how much pollution could be entering this human food chain.

Although many large cosmetics companies have made voluntary commitments to phase out microbeads by 2020, they are easy to spot as plastic spheres visible in the liquid if consumers wanted to avoid them. Alternatives include sea salt, apricot kernels and ground seeds which can be used as biodegradable skin exfoliates.

Microbeads, are just one source of our oceans plastic pollution problem, and many other plastics grind down over time into small plastic pieces causing similar issues.

This year, Canada became the first country in the world to list microbeads as a toxic substance under the environmental protection act, allowing it to ban them in personal care products. The US has also moved to ban the production of personal care products and cosmetics containing microbeads from July 2017. It’s pleasing to see these other nations leading the way with their legislation, looking at the recent science research let’s hope that New Zealand will follow suit.


This post was originally posted in the New Zealand Herald


The science behind Rio’s green Olympic pool

How an accidental 160 litres of dechlorinating agent enabled green algae to thrive:

The green swimming pool has been one of the big mysteries of this year’s Rio Olympics. Why would one pool turn murky and green when the adjacent pool was still clear and blue?


Olympic pools at Rio this year, with one looking murky and green instead of clear and blue (image source)

The first official line from Olympic officials was that after extensive tests, they had finally pinpointed the reason to be a chemical imbalance caused by too many people using the water.

Mario Andrada, a Rio 2016 spokesman, said last Wednesday morning that “mid-afternoon, there was a sudden decrease in the alkalinity in the diving pool, and that’s the main reason the color changed,”

His interview with the NY Times stated that “He noted that a lot of people had been in the pools in the past week at the Maria Lenk Aquatic Center, and that their presence had touched off changes in the water’s chemical balance.”

The optimum pH for chlorinated pool water is 7.4, since this is the same as the pH in human eyes and mucous membranes and also gives good chlorine disinfection.

So could too many people in a pool make it more acidic?

Well the natural pH of skin is lower than chlorine at around 4.7 so his theory is plausible – too many people in a pool could have made it too acidic.

However, although I’m not a pool owner, I did spend my teens as a competitive swimmer in pools all over the world.  No matter how busy they were, I’ve yet to see one turn green.

Also, you would think that seeing the Olympics is an invite only event, they would have had a heads up around how many people were coming and adjusted for that!

Perhaps it wasn’t just the presence of people in the pool, but what they did in there.

We all know from our childhood paint lessons that blue and yellow = green, so what if all of the Olympic swimmers not only swam but also peed in the pool?


We all know from our childhood paint lessons that blue and yellow = green, so what if all of the Olympic swimmers not only swam but also peed in the pool?

Well, with at least 3.73 million litres of water in the pool,and an average person peeing only 800 to 2,000 millilitres per day you would need at least 1 million people to pee their daily amount in the pool in one day to make any significant impact on the colour  overnight. As there are only 11,000 Olympic athletes in total at the event, I also don’t think pool peeing was cause of the green hue.

Leaking bodily fluids into the pool does cause other issues due to an ammonia derivative called chloramine which forms from the interaction between the urine and chlorine mix. Chloramine however doesn’t usually have a habit of turning the water green, it just irritates the swimmers eyes on contact.

During a press conference today, Rio officials stated that on August 5th, someone accidentally added 160 litres of hydrogen peroxide to the pool.
Accidentally? 160 litres?  How on earth does somebody not notice that?

This is a man standing next to a 200 litre drum.  80 % of liquid from a drum this big seems like quite a lot of liquid to have been poured into the pool without noticing. (Image source)

Hydrogen peroxide is a de-chlorinating agent, with an equation showing that 0.48 mg of hydrogen peroxide removes 1 mg of free chlorine.
Chlorine is added to a pool to kill bacterial and keep it clear.  It breaks down into hypochlorous acid and hypochlorite ions which kill bacteria and microorganisms.  Although the exact mechanism for how chlorine does this is still unclear for some bacteria, it is thought to oxidise them by attacking the lipids in cell walls, destroying enzymes within the cell.
The accidental addition of hydrogen peroxide would have reduced the ability of the chlorine to oxidize matter and kill microorganisms giving them to chance to colonise the pool.
blog-algae-green-pool-algaeAlgae spores and bacteria are constantly entering the pool, being brought in by wind or rain or on the skin or swimsuits of people in the pool.
As living aquatic creatures, algae multiply rapidly and with the addition of sunlight can bloom overnight, thriving in warm water making it look cloudy and green.

So there you go, it looks like the acidic hydrogen peroxide altered the pool water pH while chemically undoing the job of the chlorine by acting as a dechlorinating agent resulting in a pool with perfect conditions for green algae to settle in to.



Nanotechnology helps milk bottles double the shelf life of milk!

New nanosilver containing milk bottles extend the shelf of life of milk up to 15 days (source)

New nanosilver containing milk bottles extend the shelf of life of milk up to 15 days (source)

We have already seen milk bottles get a nanotechnology upgrade with the titanium dioxide filled Lightproof bottles used to extend the life of UV sensitive vitamin B2 in the milk.  Now Brazil is solving the problems of the low shelf life of fresh milk through nanotechnology of a different kind – Nanosilver. Fresh milk has a relatively short shelf life of only a few days which can cause issues in rural areas where the transport times from dairy to customer are long.  For this reason, most of the milk sold in Brazil is UHT milk also known as long life milk which is sterilised using temperatures around 150˚C to kill most of the bacterial spores.  Anyone who has tried UHT milk will know its unique taste and I personally find it quite unpalatable!

Schematic showing how silver nanoparticles could cause cell death (Image source)

Schematic showing how silver nanoparticles could cause cell death (Image source)

A Brazilian company called Nanox has found a solution by combining the antimicrobial and bactericidal properties of nanosilver and mixing them with polyethylene to make antibacterial plastic milk bottles!Although the exact mechanism for how nanosilver kills bacteria is still not fully understood, it is thought that the nanoparticles anchor to the bacterial cell wall causing structural changes to the cell membrane and also that silver ions interact with thiol groups inactivating vital bacteria enzymes.

Schematic of silica core with nanoparticles attached around the surface to prevent them migrating into the milk.

Schematic of silica core with nanoparticles attached around the surface to prevent them migrating into the milk.

To remove the fear of the silver nanoparticles leaving the bottle and entering the milk, core miscospheres of silica ceramic were used as a central material base which are much larger than the nanoparticles and less likely to move out of the plastic. The silver nanoparticles were then attached to the silica to create a larger cluster of nanoparticles with a strong central core, and these were then added to the polyethylene pellets before they were heated up and blow molded into bottle shapes. Nanox have also been able to transfer the technology to flexible milk bags which a packaging type that some dairies use in southern regions of Brazil.  These bags have shown an extended shelf life from four to ten days and now have FDA and EPA approval for overseas use.

Data shows women led companies are better!

How’s that for a conversation starting headline?

Those who know my passion for diversity would expect a headline like that from me, but it actually stems from a report released this week by First round capital, a venture capital firm which provides seed funding to startups.

After analysing 10 years of data covering 300 companies and 600 founders they discovered that startup teams with at least one female founder performed 63% better than all male teams.

Companies with a female founder performed 63% better than investments with all male founding teams (source)

Companies with a female founder performed 63% better than investments with all male founding teams (source)

This comes after a Quantopian study earlier this year shows that 80 women CEO’s in Fortune 1000 companies produced equity returns 226% better than the S&P 500.

Of course I’m excited about this, and the data implies what women have been saying for a while, diversity in senior leadership positions is good for business.  However, it’s not all rosy out there, as globally in 2015 we still only have 18% female founders showing that there is still so much more to be done.

One concern I have is seeing the changing characteristics of our leading females, who say they’ve had to adopt male behaviours (being aggressive, sounding smart, and dictating) to advance their career.

Rock Health 2015 report on state of women in healthcare (source)

Rock Health 2015 report on state of women in healthcare (source)

So where should the world look to for positive female founder stories?  Apparently it’s Wellington, New Zealand  an ecosystem which has been described as light-years ahead in terms of it’s diversity and celebration of its female founders and employees.  What I love about the Wellington trend, is those incredible women named in the article have managed to keep their true to self feminine characteristics throughout their success showing that leadership comes in all shapes and styles.

Let’s hope the trend continues and this time next year we will hear more success stories as women gain both confidence and access to mentors in the startup world.