A world-leading team in nanotechnology at Arizona State University tested seven off-the-shelf baby formula products and found two – Nestle's NAN HA 1 Gold and Nature's Way Kids Smart 1 – contained needle-shaped hydroxyapatite nanoparticles.

Regular hydroxyapatite is a naturally occurring, calcium-rich mineral that gives bones and teeth their rigidity, so its presence in formula is understandable. Sometimes it's taken as a dietary supplement.

But it's the needle-shaped, nano-sized version that's alarming some health experts, as its extremely small size may give it unique properties and behaviours, some of which are unknown and could be harmful.

European countries are considering eliminating the particles from oral care products such as toothpaste because of the potential dangers.

Friends of the Earth Australia (FoE), which commissioned the ASU tests, said it was now clear potentially harmful nanoparticles were not only in Australia's food supply, but in baby formula, and the regulator should immediately recall the affected products and conduct further tests.

It referred to a recent study by the European Union's Scientific Committee on Consumer Safety (SCCS) that concluded needle-like nano hydroxyapatite was potentially toxic and shouldn't be used in oral care products such as toothpaste and mouthwash. It also found these nanoparticles were "fully synthetic".

"If it's dangerous in toothpaste, it should certainly not be in infant formula," said FoE's Jeremy Tager.

"Babies are particularly vulnerable to food safety risks since their immune systems are still developing and often infant formula is the only food an infant receives."

Mr Tager said Food Standards Australia and New Zealand (FSANZ) had been failing to give straight answers on whether man-made nanoparticles are being used in food and whether they're safe to consume.

A FSANZ spokesman said the ASU study didn't provide any new information that may suggest the affected formulas posed a public health and safety risk.

It also dismissed the SCCS's conclusion about potential toxicity, saying the study was based on "insufficient" data related to oral cosmetic products and therefore of limited relevance to the "trace amounts" of nano hydroxyapatite in baby formula.

"The presence of a substance in food, regardless of size, that is not in the additive schedule, does not mean there is a safety concern," a spokesman said in a statement.

"Particles, nanoscale or otherwise, could be present in food unintentionally as a result of food processing techniques."

All baby formula sold in Australia must meet the stringent standards of the Food Standards Code and only contain permitted additives and nutritive substances.

In reaction to similar research and findings by a Friends of the Earth US-commissioned study last year, FSANZ published an item on its website that said nanoscale hydroxyapatite, as well as nanoscale titanium dioxide and silicon dioxide, "[were] not permitted additives or permitted forms of the minerals in infant formula in Australia and New Zealand".

Fairfax Media understands that when it became aware of the ASU study on Australian baby formula, it removed the webpage.

FSANZ wouldn't answer questions about why it had pulled down the page or whether the move reflected a change of opinion.

It also did not answer questions on whether its inaction was appropriate considering it must follow the Ministerial Policy Guideline, which says it should conduct a pre-market assessment for any substance proposed to be used in baby formula that doesn't have a history of safe use, or if it does, "has a different form/structure, or is produced using a substantially different technique or technology".

FSANZ did not respond to questions about whether it considered needle-like nano hydroxyapatite as a new, non-traditional or novel food.

Nanotechology is rapidly developing and food companies are increasingly using man-made nanoparticles – engineered on the scale of a billionth of a metre or 1/10,000th the width of a human hair – in food to improve texture, flavour and shelf-life.

The SCCS report said nano hydroxyapatite "in the raw material" was "fully synthetic" and Professor Paul Westerhoff, who led the ASU research team, told Fairfax Media that to the best of his knowledge the needle-shaped type is "man-made".

Mr Tager said this indicated that the nanoparticles were intentionally added to the formulas.

Both Nestle and PharmaCare, which owns Nature's Way, said they did not use nanotechnology or nanoparticles in their infant formula and they stood by the quality of their products and their procedures.

Nestle, among the biggest players in the global infant formula market, said the nanoparticles were most likely generated during the production process.

"The needle-like nano hydroxyapatite particles ... may be either naturally occurring or incidental nanoparticles," a spokeswoman said.

"Engineered nanoparticles, in contrast, are intentionally produced at the nano-scale and designed with very specific properties related to shape, size, or surface properties."

Nestle said the SCCS report was "not considered relevant" and rejected the suggestion that someone may have unknowingly added the nanoparticles during the production process as "there [was] no reason why someone would do this".

It said its NAN HA 1 Gold formula was deleted in early 2016 purely because of a ranging decision.

Australian-owned PharmaCare Laboratories said its Kids Smart formula complied with the Food Standards Code and its suppliers and manufacturers confirmed hydroxyapatite wasn't added.

"The manufacturing procedure is very basic with blending of the three ingredients ... no other materials are added," its domestic manufacturer said.

"In regards to hydroxyapatite, it is plausible that given that most of the added calcium would have originated as calcium carbonate ... it seems conceivable that there could be trace amounts of hydroxyapatite present."

PharmaCare also raised the possibility that the ASU team's testing process, which involves 30 minutes of sonication, broke down ordinary particles into nanoparticles.

Professor Westerhoff quashed this suggestion, saying: "No, this is not possible that we produced, as an artifact, the needle-like shape ... we confirmed it through multiple steps and validation processes."

What's certain is that two of the seven samples were found to contain needle-like nano hydroxyapatite, which the EU's top consumer safety advisory body said is man-made and potentially toxic.

In regards to the other five products, Heinz Nurture Original 1 was found to have rectangular-shaped nano hydroxyapatite, and Aptamil Profutura 1 and Blackmores Newborn Formula were found to contain calcite nanoparticles. There is insufficient data on the safety of these nanoparticles.

Two formulas were free of nanoparticles: Karicare Plus 1 and A2 Platinum 1.

FSANZ said it wasn't concerned by the minuscule size and the needle-shape of the hydroxyapatite detected in the formulas because it would simply "dissolve in the stomach".

It said any safety problems would be related to its components calcium and phosphate, which were "beneficial and required to be added to infant formula".

But many experts believe that safety and risk assessments are necessary for nanoparticles as they may be more chemically reactive and more likely to build up in various organs and even in individual cells.

They say size and shape can turn an innocuous substance into a harmful one.

But Andrew Bartholomaeus, Adjunct Professor of toxicology and pharmacy at the University of Canberra, agreed with FSANZ and said FoE was "scaremongering".

FSANZ's former head of risk assessment said that because the hydroxyapatite crystals would dissolve in the stomach, their size and shape were irrelevant.

"If tiny quantities did get absorbed, they would be processed in the tissues in the same way that naturally occurring hydroxyapatite crystals are processed in our bodies," he said.

Validating the companies' claims, he said while bulk amounts of needle-shaped crystals may have to be artificially made, this didn't mean small quantities couldn't form naturally.

"Just rub two surfaces together and nano particulates are generated," he said. "Human breast milk is a nano food and so is ice cream."

But Professor Thomas Faunce, from the Australian National University's College of Law and College of Medicine, said there was no doubt that the nanoparticles weren't risk free.

"It is true stomach acid may degrade most of it, but the whole issue of buccal (tooth gum) absorption has not been answered," he said.

"Think about the way babies eat, it washes around in their mouth and you've got buccal absorption and that's the same problem the SCCS had with nano hydroxyapatite in toothpaste," he continued.

"It's more problematic in babies because they have developing immune and neurological systems."

Professor Andrew Maynard, director of Risk Innovation Lab at Arizona State University, said ultimately for him there was no compelling evidence that the nanoparticles in infant formula presented a health risk.

"To the contrary, there is some evidence that they will rapidly dissolve in the stomach, thus reducing or eliminating any speculative risks arising from their size and shape," he said.

"That said, it would be prudent for manufacturers and regulators to support further research to establish the safety of the particles if they are to continue to be used in infant formula."

Mr Tager said for FoE it all came down to the precautionary principle.

"We argue that in the absence of evidence of safety, the precautionary principle should be applied to prohibit the use of such materials until safety is assured," he said.

"This doesn't mean an impossible standard of proof, but it does mean undertaking work to determine safety, not simply accepting a lack of evidence of safety as a sufficient standard."

smh.com.au