We use Swheat Scoop.

Cats will not get silicosis from it. Clay litter might cause silicosis.
Cats can ingest and it will pass through their system safely.
It can go down the drain and will eventually decay and not clog the pipe (in reasonable quantity) Clay litter will eventually clog the pipe.
It weighs a lot less than clay

Pine pellets are similar but instead of clumping in Swheat Scoop, Pine pellets will turn into powder.

I guess Shweat Scoop is eco-friendly. We really haven't noticed the dust problem. They do offer regular and multi-cat formula. They are slightly different.

We recommend using Swheat Scoop to the adoptive family of a very young kittens.