ok... let's clear this up.
The original question asked was what chemicals are found in styrene. The question was answered by referring to the wikipedia article.
But as Christian pointed out, the plastic that most model kits are made of is polystyrene, which is a compound in which styrene is one of the components. Styrene on its own is carcinogenic, polystyrene has been accepted worldwide as being "safe"... after all, it's what many plastic food containers, and plastic knives, forks and spoons are made of!