Scientific Explanation
Radium's alpha radiation accumulates in bones, causing necrosis and osteosarcoma. The horrific health damage to "Radium Girls" who licked brushes while painting radium dials was the decisive blow.

The dangerous beauty advisor who believed in radioactive miracles
A 20-something beauty advisor. Glows pale blue in the dark, innocently distributing "the miracle cure of unknown power (radiation)." Promoted radium water, radium toothpaste, and radium cosmetics until horrific radiation injuries erupted, teaching humanity the terror of blindly trusting new powers.
Right after the discovery of radioactivity, its unknown power was marketed as a cure-all. Dangers became clear through the Radium Girls case and others.
Radium's alpha radiation accumulates in bones, causing necrosis and osteosarcoma. The horrific health damage to "Radium Girls" who licked brushes while painting radium dials was the decisive blow.
"New" does not equal "good." The danger of applying unknown forces before understanding them. Real harm from lack of scientific literacy.
Catchphrase“With the power of radium, you too can glow!”
Lead is a radiation shield. The natural enemy that blocks Radiumia's "blessings."
“ラジウムの輝きは美の源! お肌にも、お水にも、歯磨き粉にも!”
“見て、私の肌、光ってるでしょ?これが健康の証!…なぜか顎が痛いけど”
“ラジウム・ガールズの話は…聞きたくない”
“新しい発見は、すべて善だと信じていた。それが…最大の間違いだった”
“エバース氏の顎が溶けたとき…やっと気づいた”
(Faintly glowing in the dark) ...Look! This glow! The blessing of radium! Want to try?
...Huh? Dangerous? What are you saying! New energy is humanity's hope!
Radiumia: "Lead! Want to glow too? I'll apply some radium cream!"
Lead: "...I'm a radiation shield. I'm the one who stops your radiation."
Radiumia: "Why block it? This glow is a miracle cure!"
Lead: "Do you know how many people lost their jaws and lives to this 'miracle cure'?"
Radiumia: "...I know. I know, and that's why... I must keep telling this story."
I blindly trusted "new." I reread "unknown" as "wonderful." Those who paid the price weren't me—they were the people who believed.
The reason to study science is to avoid repeating such mistakes. "I don't understand but it seems amazing" is the most dangerous thinking.