No, the fake snow on Christmas trees is not toxic. It is usually made from a non-toxic material such as polyester or acrylic fibers. While it may not be as environmentally friendly as natural snow, it is safe for use in Christmas decorations. It is important to note that some artificial snow products may contain irritants or other chemicals that could be harmful if ingested, so it is always best to check the label before use. Additionally, it is important to keep in mind that artificial snow may not have the same look or feel as natural snow, so it may not be as realistic or appealing for some people.