Glow sticks contain dibutyl phthalate, which has a low toxicity to humans, according to Carolinas Poison Center. The Pet Poison Helpline, however, states that this substance has a mild to moderate toxicity to cats.
To humans, dibutyl phthalate, also known as DBP, is an irratant to skin, eyes and mucous membranes. If ingested, the individual should drink water to clear it from the mouth. If DBP gets in a person's eyes, he should perform water irrigation for at least 10 minutes and contact local poison control if irritation persists. Pet owners should call a veterinarian for advice on the best course of treatment.