Left alone PVC is pretty much the safest stuff on the planet.
Burning it without scrubbing the fumes is seriously unhealthy as it releases chlorine compounds into the atmosphere. Some studies have linked PVC incineration with elevated levels of dioxins in nearby soil - although the evidence is less clear-cut than some environmentalists make out.
Vinyl chloride monomer is known to cause liver and bone damage as well as an almost unrivalled range of cancers. Fortunately modern PVC plants have tightened up their emissions and rates of liver cancer in particular amongst workers and those living nearby are almost indistinguishable from the population as a whole.
PVC can be nasty when it is softened using phthalate plasticisers. This used to be very common in products like children's toys, and baby's bottles. The phthalates can leach into the body either directly or when picked up by fatty substances (such as milk). Phthalates are known gender benders and cause infertility in even limited amounts. Some of them are also known carcinogens.
Most Western manufacturers have banned certain phthalates - especially diethylhexyl phthalate - from toys, although they are used in other PVC products where ingestion is unlikely - but they will most likely still eventually enter the environment as the products are disposed of.