The basics: What are PVC, BPA, phthalates, and dioxins?

We keep reading about how bad the stuff in our house is, but I'm still confused about what it all is and why I should be worried about it. So here is the Cliff's Notes version:
  • Bisphenol-A (BPA) is a component in plastics (mainly polycarbonate [recycling #7], which is clear and shatter-resistant) and the epoxy linings of food cans. There are two camps on the safety of BPA. The American Plastics Council maintains that the potential human exposure to BPA is extremely low and poses no known risk to human health. On the other side are groups maintaining that the APC is basing their recommendation on outdated research and that over 100 newer studies are showing adverse effects of BPA exposure in animal models, suggesting that it does have a biological effect. Structurally BPA is very similar to naturally occurring estrogen and there is evidence that it disrupts endocrine function in the body and it has been linked to low sperm count, hyperactivity, early puberty, obesity, small testes size, and enlarged prostates.
  • Polyvinyl Chloride (PVC; recycling #3) is used in a great many products. From construction materials such as sprinkler pipe and vinyl siding to credit cards and music records nearly all of us come into contact with it on a daily basis. It can be made softer with the addition of phthalates, making it useful in the manufacture of clothing, vinyl toys, and flexible hoses such as those used in medical applications.
  • Phthalates are used as plastic softeners, oily substances in perfumes, additives to hairsprays, lubricants, cosmetics, and wood finishers. One of these, DEHP (diethylhexyl phthalate), has been banned in the European Union out of concern for children's safety. Health concerns surrounding PVC are related to both contact exposure (e.g. children mouthing toys) and offgassing (e.g. compounds released into the air--see 'new car smell'). High doses are known to be toxic, but the current research is focused on the effect of chronic, low-dose exposure, and exposure to children and fetuses during critical periods of development (e.g. DEHP was found to produce dramatic changes in male sexual development with low-dose exposure in utero). Additionally, it has been related to exacerbating allergic reactions to an allergen. (Here is a fairly non-neutral source of additional information including a list of products to avoid if you're trying to stay away from phthalates.)
  • Parabens widely used as preservatives in the cosmetic and pharmaceutical industries, as well as in food products (here is a not-too-biased source of information about these products). Long-term studies have generally found parabens to be safe. However, other studies have found the presence of parabens in cancerous breast tumors, leading to concern that parabens in underarm deodorants may be related to the development of cancers. Further, parabens have been found to have weak estrogenic activity in the body. This category seems to still have a big question mark.
  • Dioxins are produced as a biproduct of PVC manufacture, and are also found in a variety of household goods such as most brands of baby diapers. They are considered to be a global health threat because they persist in the environment for an extended period and appear to be very toxic. At even very low levels, near those to which the general population is exposed, dioxins have been linked to immune system suppression, reproductive disorders, a variety of cancers, and endometriosis.
I hope you found this as helpful as I did. My head was really starting to spin trying to figure out which was which, and how bad any of this really is.
The basics: What are PVC, BPA, phthalates, and dioxins? SocialTwist Tell-a-Friend