I avoid them, because they are carriers of certain plant viruses. That probably isn't an issue for you. What type of chameleon do you have?
As long as the chameleon isn't eating large amounts of them, the plant itself should cause no harm, BUT they may have been treated with systemic pesticides that could take up to 4 months to dissipate. Systemic pesticides are inside the plant tissues and can't be washed away. The most commonly used systemic is safe enough to be used in dog and cat flea collars, but I wouldn't want my chameleon eating large amounts of it.