Bundchen is quoted as saying, "I cannot put this poison on my skin. I do not use anything synthetic."
Instead, the 30 year old avoids serious damage to her body by only exposing her skin to sunlight before 8am.
But Bundchen's attitude to the use of sunscreen has infuriated medics, who have blasted the model for stirring "confusion" among the public.
Dolival Loao, head of dermatology at Brazil's National Cancer Institute, tells DailyMail.co.uk, "Sunscreen prevents damage to the skin and is of fundamental importance for the prevention of cancer. This is not any poison.
"When a public person makes a statement like this, it creates confusion."
The runway star is no stranger to courting controversy - new mum Bundchen previously found herself under attack by insisting breastfeeding newborns should be a "worldwide law".
She told Harper's Bazaar magazine, "Some people here (in the U.S.) think they don't have to breastfeed, and I think, 'Are you going to give chemical food to your child when they are so little?' I think there should be a worldwide law, in my opinion, that mothers should breastfeed their babies for six months."