Contains sugar and vanillin. But what is vanillin exactly? According to Wikipedia: 4 -hydroxy-3-methoxybenzaldehyde, so C8H8O3. It also notes that vanillin is R22, S24/25. That means:
R22: Harmful if swallowed.
S24: Avoid contact with skin.
S25: Avoid contact with eyes.
This is why traditional vanilla sugar contains only 2% vanillin and 98% sugar. Avoid the use of this compound.

This is deceptive, too. You can buy so-called Bourbon Vanilla Sugar in Hungary produced by one of the popular companies. This is better than the traditional vanilla sugar, because, though only in 3%, it contains real vanilla powder - the slightly grey colour of the sugar can be easily observed. Besides vanilla it contains sugar and natural vanilla extract. I’d rather recommend this one than the traditional vanilla sugar.

This is what I use. The spice (Vanillae Fructus) is a 10-20 cm (4 in -8 in) long and 3-10 mm (0,12 in -0,4 in) thick pod. It has a shiny, slightly wrinkled surface where sometimes white vanillin crystals can be seen. The aroma, colour and flexibility characterises the quality of the vanilla pod. The green vanilla is rich in moisture. It becomes fragile -and less valuable- only when dried. Vanilla contains aroma, vanillin acid, fat and resin. Thus I campaign for real vanilla pod because it is natural and has an intensive favour.