"The chemicals they are using are doing damage to the endocrine and can be hormone-disrupting. The skin is bubbling away under an armour of sunscreen."
He said places in the world with the highest skin cancer rates also had the highest prevalence of sunscreen.
"If they were that brilliant, it wouldn't be that way."
He suggested zinc or coconut oil as an alternative.
But a cosmetic specialist at Auckland Dermatology, Susan Devonshire, said people looking for an organic sunscreen would be disappointed.
"There are chemicals in sunscreen. Whether it's organic or not is a moot point."
She said she often talked to people who were worried that sunscreen's ingredients could give them cancer. "There's no conclusive evidence that sunscreen causes cancer, but sun damage definitely does."
Paraben-free products and those that did not contain talc or silicones were becoming popular, especially with people who had sensitive skin.
"But the number one rule is if people don't want to go through the palaver of locating one, they still have to wear sunscreen. Anything is better than nothing by miles."
Dermatologist Louise Reiche said most people who had a reaction to sunscreen were allergic to the fragrances in the creams.
Unless skin was broken, sunscreens were "negligibly absorbed".
University of Auckland associate professor of pharmacology Malcolm Tingle said "natural" sunscreens were almost certainly not an improvement on traditional varieties.
If parabens or standard preservatives were removed from a product, they were usually replaced by something else - and that product was often not as extensively safety tested.
"Weighed against this hocus-pocus are two important considerations. What would be the consequences of not using sunscreen?
" I don't think too many rational people question the association between UV irradiation and skin cancer. Do you know the safety of the alternatives? I would far rather go with what I know than what I don't."
Reiche said Rands' suggestion to avoid sunscreens that contained retinyl palmitate made sense, as it could increase sensitivity to the sun.
Consumers should realise products labelled as a moisturiser-containing sunscreen, rather than purely sunscreen, did not have to meet the same regulatory standards.
"They don't have to specify how much is in there."