A new study by British media group Which? has found a leading brand’s SPF factor fell by 59% after its user spent 40 minutes in salt water and moving water.
Manufacturers allow a product to claim it’s water-resistant if its SPF drops by less than 50%.
Another favourite own-brand cream fell by 34% in both salt water and chlorine water.
Furthermore, the magazine added that protection from the sun is likely to fall much further when factoring in reflection from the water, heat, light, sweat, towelling and rubbing.
Which? Director Nikki Stopford said: “With 15,400 new cases of melanoma in the UK alone each year, manufacturers should be required to robustly test their products and make only claims that can be relied on.”