Because the extent and frequency of use of sunscreen are unknown, the significance of the role that sunscreen may play in reducing vitamin D synthesis is unclear [1]. (ods.od.nih.gov)
Reducing the body's vitamin D levels through the constant use of sunscreen, especially in young children, can cause a serious deficiency and open the door to disease. (mommyish.com)
We passed the «Dick Parade» where 150 men bicycled through camp, bottomless, while gentle hecklers (a thing) encouraged the liberal use of sunscreen. (developmentalscience.com)