On 2015 Nov 25, David Keller commented:

There is no safe way to expose the skin to solar radiation. Obtain vitamin D from food or pills, not sunbathing

This paper concludes: "The best way to obtain a given dose of vitamin D with minimal carcinogenic risk is through a non-burning exposure in the middle of the day, rather than in the afternoon or morning." This message is misleading, and potentially very dangerous from a public health point of view. Dermatologists and other physicians are trying to convince patients that there is no safe time of day to sunbathe, and no safe amount of solar radiation to the skin. To send patients out to obtain "non-burning exposure in the middle of the day" is courting disaster. They should be informed that the only recommended way to meet their vitamin D requirement is through diet or supplementation [1]. This paper could pose a setback to anti-sunbathing efforts and thereby contribute to the rising death rate from melanoma [2].

References:

1: "American Academy of Dermatology recommends that an adequate amount of vitamin D should be obtained from a healthy diet that includes foods naturally rich in vitamin D, foods/beverages fortified with vitamin D, and/or vitamin D supplements; it should not be obtained from unprotected exposure to ultraviolet (UV) radiation. Unprotected UV exposure to the sun or indoor tanning devices is a known risk factor for cancer."

2: National Cancer Institute website, SEER (Surveillance, Epidemiology, and End Results Program. accessed on 1/7/2016. http://seer.cancer.gov/statfacts/html/melan.html

On 2015 Nov 25, David Keller commented:

There is no safe way to expose the skin to solar radiation. Obtain vitamin D from food or pills, not sunbathing

This paper concludes: "The best way to obtain a given dose of vitamin D with minimal carcinogenic risk is through a non-burning exposure in the middle of the day, rather than in the afternoon or morning." This message is misleading, and potentially very dangerous from a public health point of view. Dermatologists and other physicians are trying to convince patients that there is no safe time of day to sunbathe, and no safe amount of solar radiation to the skin. To send patients out to obtain "non-burning exposure in the middle of the day" is courting disaster. They should be informed that the only recommended way to meet their vitamin D requirement is through diet or supplementation [1]. This paper could pose a setback to anti-sunbathing efforts and thereby contribute to the rising death rate from melanoma [2].

References:

1: "American Academy of Dermatology recommends that an adequate amount of vitamin D should be obtained from a healthy diet that includes foods naturally rich in vitamin D, foods/beverages fortified with vitamin D, and/or vitamin D supplements; it should not be obtained from unprotected exposure to ultraviolet (UV) radiation. Unprotected UV exposure to the sun or indoor tanning devices is a known risk factor for cancer."

2: National Cancer Institute website, SEER (Surveillance, Epidemiology, and End Results Program. accessed on 1/7/2016. http://seer.cancer.gov/statfacts/html/melan.html