Celebrity chef Pete Evans has hit the headlines again by jumping on a new study out of Canada that links drinking fluoridated water while pregnant with a drop in babies’ IQs.

“This has been known for ages, and this is just the tip of that iceberg,” Evans told News Corp. “Fluoride is a known neurotoxin and it should not be put in our water supply.”

But there are some big problems with the Canadian study.

Dental public health expert Associate Professor Matt Hopcraft tells Mamamia that while the paper reports a lower IQ score in boys, there’s no difference in girls.

He says the authors also note a number of limitations for their study.

“The paper does not prove a link between water fluoridation during pregnancy and lower IQ in children,” he adds.

Watch: It’s not the first time Pete Evans has made questionable health claims. Post continues after video.

Other scientists have poured cold (fluoridated) water on the study, because it’s a small sample of just 400 women, and involves a lot of estimating of fluoride intake by the women involved.

As Dr Michael Foley from the Australian Dental Association explains, there have already been numerous studies done into whether there’s any link between fluoridation and IQ. One, in Sweden, involved 728,000 people. That study showed no association between fluoride levels in water and child or adult IQ.

But the link between fluoridated water and healthier teeth is pretty clear. Aussie kids living in areas with water fluoridation have 26-44 per cent less tooth decay than kids living in areas without water fluoridation.

So here are five things to say to anyone who questions the benefits of fluoride.

Fluoride is natural.

It occurs naturally in all water, even the sea. The amount of fluoride in a natural water supply, like a lake or river, depends on the kinds of rocks that the water is in contact with. Some towns in Australia, such as Portland and Port Fairy in Victoria, have so much naturally occurring fluoride in their water supply that no more fluoride needs to be added.

People have been adding fluoride to water for a long, long time.

Back in the 1940s, US public health researchers noticed that people living in places where there was a high level of naturally occurring fluoride in the water supply had less tooth decay. They did a trial where they added fluoride to the water supply of Grand Rapids, with the nearby city of Muskegon as a control. After six years, the benefit to the kids of Grand Rapids was so huge that officials in Muskegon started adding fluoride to their water supply too. How big was the benefit? Tooth decay in kids aged 12-14 was lowered by a whopping 50-63 per cent.

We’ve already got proof that adding fluoride to drinking water doesn’t lower people’s IQs.

That proof is right here in Australia.

All Australian capital cities have had fluoride added to their water supplies since the 1960s or the 1970s. All except Brisbane, that is. Brisbane has only had fluoride added to its water supply since 2008. So from the 1970s to 2008, were Queenslanders significantly smarter than the rest of Australia? Of course not.

“NAPLAN results actually suggested the reverse,” points out Dr Foley. And he’s got more.

“Children in Singapore, Hong Kong and South Korea have enjoyed the dental health benefits of fluoridated drinking water for decades, and they also record some of the top academic scores in the world.”

Yes, fluoride is a “known neurotoxin”, but so is caffeine and a whole load of other stuff.

As Dr Foley points out, “Everything is toxic if you have enough of it – water, oxygen, calcium, iron, salt and even caffeine.

“Caffeine is neurotoxic, but only at levels much higher than in a cup of coffee.”

The levels of fluoride in Australian drinking water are kept under 1.1mg/L. That’s something to keep in mind when people refer to studies in China where fluoride levels of more than 10 times that amount have been recorded in drinking water.

Kids from low-income families benefit the most from water fluoridation.

A statement put out by the National Health and Medical Research Council points out that kids from low-income families have higher rates of tooth decay and are less likely to receive dental treatment. That means that fluoridated water is even more important for these kids.

Who wants to condemn more little children to the pain of toothache?