Recently, Reddit user u/pinkyfirefly asked, "What is something that used to be considered safe/okay but now we know is harmful?"
Here are some of the super disturbing responses:
1. "Arsenic. It's wild to us now, but in the 1800s, someone figured out how to make a green dye out of arsenic."

2. "My mother talks about how when she was in high school in the 1970s, they would roll mercury around in their hands during science class with no gloves on."

3. "Heroin. It was originally sold as a cough medicine by Bayer."

4. "All of the snow in The Wizard of Oz was asbestos. They used to sell it for your own Christmas tree at home, too; you'd just spray it out of a can."

5. "Smoking. My grandmother's doctor prescribed smoking cigarettes. She was experiencing anxiety while she was pregnant with my mother (1951)."

6. "Radiation makeup."
7. "There used to be [radiation] devices to measure children's feet. Basically, the children would put their shoes on, stick their feet into this machine, and it would blast their feet with radiation so that nervous parents could see the children's feet inside the shoes to be sure they fit. Congrats, the shoes fit, but now your child has a ton of other health concerns!"

8. "Cocaine. I've heard it used to be used in place of caffeine and in certain medicines."

9. "Playing with mercury from broken thermometers."

10. "Lysol as a douche. Look it up."

11. "Lobotomies."

12. "Keeping/adding lead to gasoline. It was literally getting in the air causing people to behave more violently."

13. "DDT. My mom said that the American military used to spray all the students (in post-war Japan) to get rid of lice."

14. "Radium paint [was] used for glow in the dark clock hands. Women were hired to paint the clock hands, but were never told it was hazardous. Many suffered radiation poisoning."

15. "Teflon. Or the chemicals used in its production: C8. It’s present in every American’s blood."

16. "Benzene ... [was] used to make deacaffeinated coffee."

17. "Letting little kids sit in the front seat of the car. I remember being early elementary age and having fights with my younger sisters on who got to sit in the front seat."

18. "Solid metal dashboards in vehicles without seatbelts. A friend of mine in the Army had a vintage car from the 1950s before seat belts were mandatory equipment. He was a reckless driver who liked to speed and weave in and out of traffic on the interstate. I only rode with him once."

19. "Mercurochrome used to be a common disinfectant all the way until the late '90s. It was banned in the US and several other countries due to its high mercury content. Skinned knee? Slather on some bright red Mercury liquid, heal you right up!"

20. "Lead paint."

21. And finally..."Meth. In WWII Germany it was widely used among the general population and in the military."

Submissions have been edited for length/clarity.