I have heard rumours some that say helmets have to be aussie approved but I read in this link that they can be british approved. Have also been told that the gold ACU sticker on all british helmets is not in fact an approved sticker for anywhere, it is for racing purposes only in the uk, they used to be perforated into 4 sections where a marshall would tear off 1 section per season raced, at the end of 4 seasons you needed to get a new helmet. This is only what I heard though. Try this link and see what you can find out.
Takes a while to download but this is on page 77:
‘approved’ helmet is a helmet
manufactured, tested and marked
in accordance with the
requirements of the Standards
Association of Australia or the
British Standards Institution, or
manufactured by Arai Hirotake
Limited and marked with the
appropriate model number as
contained in regulation 38 of the
Road Traffic (Miscellaneous)
not sure if this is the latest version but was posted on another site in July this year.
(Edited) Found this newer one http://www.transport.sa.gov.au/pdfs/...dbook_full.pdf
Page 51 says Australian approved only.
Lucky for me my helmet of choice is as cheap as chips in Aus and has a better safety rating than certain other more expensive brands :p