Concern about the potential damage caused by Friends of the Earth's anti-nanotechnology campaign is so great that public health advocates are abandoning their previous cautions on using sunscreens with nanoparticles.

''In the past I have said that consumers are better to avoid sunscreen with nanoparticles in it,'' said Michael Moore, chief executive of the Public Health Association of Australia. ''But we are rethinking our position as evidence grows of people being reluctant to use sunscreen."

One third of respondents to a federal government survey made public in February said they were aware of possible risks of using sunscreens with nanoparticles. In the group that was aware, 87 per cent said it made them concerned about using sunscreen.

Nanoparticles are so small they are measured in millionths of a millimetre. The concern is that they generate free radicals which could penetrate cells and interact with cell protein or DNA in unknown ways. However, research has yet to establish proof that nanoparticles in sunscreen are harmful to health.

In contrast, it is proved beyond doubt that using sunscreen protects against skin cancer, which causes 200 deaths a year in Australia and for which thousands of Australians are treated every year, said Terry Slevin, chairman of Cancer Council Australia's skin cancer committee. Scaring people based on "extremely unconvincing evidence" of a "theoretical" problem means "public health harm is likely to occur", Mr Slevin said.

"There is more risk from not us using sunscreen and getting burnt than there is from using sunscreen and the potential penetration of nanoparticles,” said Maxine McCall, CSIRO nanosafety research co-ordinator and senior principal research scientist.

Sunscreens with the  “blockers” zinc oxide and titanium oxide scatter or absorb UV radiation across a broader range of the UV spectrum than competing sunscreens relying on chemicals alone.

Sunscreens with metal oxide particles in their traditional or ‘‘bulk’’ form appear milky or white on the skin, such as zinc cream, the ‘‘Aussie war paint’’.  When the metal oxides are in nanoparticle form the lotion is more transparent and so more appealing to many consumers.

Friends of the Earth  wants mandatory safety testing and labelling of sunscreen products using nanoparticles, similar to European regulations to apply from July.

“We sell a product that is safe and it’s nano,” said  Rade Dudurovic, chairman of the listed company Antaria, a Perth manufacturer of zinc-based nanoparticles used in sunscreen.

“Unless [Friends of the Earth] can provide some form of academic, reputable medical evidence to suggest it is unsafe, it’s a spurious debate.”

The Therapeutic Goods Administration said there was “currently no evidence” to suggest a particular safety risk from sunscreens with nanoparticles or to support tougher labelling requirements.  New Zealand will require mandatory labelling from 2015.

Friends of the Earth’s  nanotechnology project co-ordinator Louise Sales said the fault for public concern about sunscreen safety lies not with the campaign group but with the Therapeutic Goods Administration  for failing to act to give consumers  peace of mind.