PVC in itself is not toxic. However to make PVC more stable or more flexible, lead or phthalates are often added to its composition. Lead is a potent neurotoxin that can easily migrate out of the plastic. Phthalates are hazardous chemicals classified as endocrine disruptors and have been linked to a range of health problems. Therefore, it's important to take precautions such as choosing PVC pipes made from safe, food-grade materials and approved by the FDA. If you must use PVC products, look for those that are labeled as "phthalate-free" or "lead-free" and avoid heating or burning PVC products.