What is the composition of writing brush? Will it volatilize toxins?

Eraser pen contains formaldehyde, which is a carcinogenic chemical? It is recommended that children use it less. There are basically two kinds of "inks" for pens, one is water-based and the other is oily (such as oily markers and ballpoint pens). Generally speaking, the ink we use at present is mainly oily. Oily inks all contain volatile organic compounds, which are slightly toxic. The water used to erase such characters is also organic volatile and slightly toxic. If used in pure water-based (such as pen ink) wiping water, it is basically non-toxic.