Slapping on the sunscreen is not necessarily as effective as one may hope, a new survey shows (File photo).

Almost half our sunscreens are failing their most-basic test - protecting us from the sun as much as they say they do.

The results, which also slam some makers of "natural" sunscreens, now removed from shelves, some from a Consumer NZ survey leading to calls for mandatory standards for sunscreen in New Zealand, which on Friday entered its first day of summer.

The consumer watchdog tested 17 sunscreens and found that only nine met the promises made on the label about sun protection factors (SPF). A further six of the 17 failed the same test, though these companies were able to provide laboratory tests showing they did.

123RF The sun hat may be a good sun protection. The sunblock may not be (File photo).

The survey results were sent to companies and led to two producers of "natural" suns screens pulling products from shelves.

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Those sunscreens were Pure Blend Sunscreen SPF15++ and Pure South 100% Natural Sunscreen - which had actual SPFs of four and five respectively. Though Pure South made no direct SPF claim, it did say one if its ingredients - raspberry oil - had a factor of 28 to 50.

The manufacturers of Pure Blend in response told Consumer NZ its sunscreen had not been tested on people and it couldn't back-up its claim.

Pure South did marginally better - its human test was on a single person.

"Companies don't have to regularly test their products to ensure they still meet SPF claims, even if an ingredient supply changes, and some companies may go for years without re-testing. Our testing has also highlighted the lack of consistency between labs even when products are tested the same way," Consumer NZ chief executive Sue Chetwin said.

MEETS CLAIMS FOR SPF PROTECTION AND BROAD SPECTRUM:

Cetaphil Suntivity Oily Skin Ultra-light Lotion SPF50+

Daylong Suntivity Liposomal Sunscreen Lotion SPF50+

Smart365 Sun Sunscreen Lotion SPF50+

Invisible Zinc Face + Body Sunscreen SPF50

Neutrogena Beach Defense Sunscreen SPF50

Surf Life Saving Sunscreen Lotion SPF50

Le Tan Coconut Oil Sunscreen SPF30+

Soleo Organics All Natural Sunscreen SPF30+

Skinnies Sungel SPF30

DOES NOT MEET ALL CLAIMS FOR SPF PROTECTION AS WELL AS BROAD SPECTRUM (LISTED FROM BEST TO WORST):

Nivea Sun Protect & Moisture Moisturising Sunscreen Lotion SPF50+

Sungard Moisturising Sunscreen SPF50+

Banana Boat EveryDay SPF50+

Cancer Society Everyday SPF50+

Natural Instinct Invisible Natural Sunscreen SPF30

Snowberry Family+ Sunscreen SPF30

Badger Active Unscented Broad Spectrum Zinc Oxide Sunscreen Cream SPF30

Pure South 100% Natural Sunscreen

Pure Blend Sunscreen SPF15++

* Correction: Oasis Sun Sensitive Skin Family Sunscreen SPF30 met its SPF claim, but failed Consumer NZ's broad spectrum test.