[A-AS11] Atmospheric Chemistry

[AAS11-11] A study on elucidating the appropriate solar UV exposure time based on the relationship between UV-B exposure and serum 25(OH)D amount in mother’s body

*Hideaki Nakajima^1,2, Toru Sasaki¹, Yuko Sakamoto³, Yuka Honda⁴ (1.National Institute for Environmental Studies, 2.Graduate School of Environmental Studies, Tohoku University, 3.Nerima Hospital, Jyuntendo University, 4.SFC Laboratory, Keio University)

Keywords:Vitamin D, Solar UV, UV-B, 25(OH)D, Ozone hole, BDHQ

Vitamin D (VD) deficiency has been recognized as a major cause of rickets and severe hypocalcemia in infants after birth. Maternal VD status during pregnancy is considered to affect the baby’s VD status. Recently, Japanese pregnant women are reported to be highly VD deficient compared with other countries. In this study, we tried to elucidate the factors which affect the VD status of Japanese pregnant women who visited a hospital’s obsterics and gynecology department in Kanto area, by taking blood sample and asking to fill out questionnaire about their dietary history and habitual outgoing lifestyle until 3 days ago prior to their blood take. The purpose of this study is to investigate the key parameters, especially dietary VD intake and UV-B exposure, which affect the VD status in pregnant women, to improve the VD status of mothers and children. We have already developed a procedure to estimate the VD synthesis in human’s body from the actual UV-B measurement and outgoing history of the subject1). We investigated 309 28-weeks of pregnant women who were examined at the hospital between August 2018 and October 2019. From their blood, serum 25-hydroxyvitamin D (25(OH)D) levels were measured as a proxy of VD status.

Figure 1(a) shows the correlation between VD intake estimated by BDHQ and serum 25(OH)D level for weak UV-B period. Significant positive correlation (R=0.30) was found. Figure 1(b) shows the correlation between VD synthesis in human body estimated from 14-day averaged UV-B exposure prior to blood take and 25(OH)D level for strong UV-B period. Significant high positive correlation (R=0.51) was found. It was found that human acquire VD from different sources depending on the UV-B levels in the season.