Is it safe to do intense workout dvds while breastfeeding or does it release harmful toxins?

Do it: Ignore whoever told you that it might "release harmful toxins." that's crazy talk. I'm very pleased -- that you're a new mother, that you're breast-feeding, that you want to exercise, and that you want the best for baby. Best wishes.

Maybe: I would probably take the baby off the breast while you worked out as it might affect the latch... Lol. Kidding aside it should be fine. You just want to make sure you are getting enough calories because you are eating for two. All "toxins" should be cleared by your liver and kidneys.