[greygoo222]

Titanium dioxide is naturally occurring.

[Retric]

The poster was using the phrase natural dye.

It’s a naturally occurring non organic molecule, but it’s not naturally a white pigment. It takes a lot of processing to get that brilliant white powder and as such it’s not something our ancestors dealt with.

[hollerith]

It is not naturally occurring in the human diet.

[halJordan]

This is the same argument people use against bread, and against meat.

[hollerith]

Huh? Our ancestors have been eating meat for 2 million years. We know because bones do not biodegrade so we've found many prehistoric bones with tool marks left when prehistoric people cut the meat off the bone.

[Incipient]

So is arsenic.

[dlivingston]

Totally off-topic, but your comment reminded me of some lyrics to a song by one of my favorite folk singers [0]:

  [Weed is] jus' a plant
  Like poppies and sugar cane
  Coca and some science make some good cocaine

[0]: https://youtu.be/ixE73z_a37U