I find it interesting that David Wallinga believes that there are cost-effective alternatives coming from benign chemical processes for the majority of PVC products being produced today (“Reader says there's no safe level of PVC,” Aug. 14, Page 6). If this is the case, why aren't they being used? Do they cost and perform satisfactorily or are they just near or under development? I also find it irritating that he can state without qualifications that throughout its entire life cycle, PVC releases toxic substances on the worker and the community.
Chemically, vinyl chloride monomer is a gas, and PVC is a solid plastic made from that gas, primarily in a chemical process called emulsion polymerization, a controlled reaction in an aqueous solution. The technology of even a decade ago is not the same as today. The chemical industries have learned better reaction and handling techniques and have implemented them. A starting raw material, VCM, may have nothing in common with the chemical properties of its polymer, PVC. Breathing VCM is not good for you, but neither is breathing gas fumes, ethylene, smoke, flour dust or steam. Why are vinyl chloride and PVC being talked about as if they were the same? In addition, most “PVC” products are actually formulated products containing many other materials.
Not to get too carried away, but another example where the starting material and the final polymer have nothing in common as far as hazards are concerned are urethanes. Phosgene, a gas, has little to do with the final properties and health effects of poly¼urethane, a polymer made from a raw material starting with phosgene. Most people know of phosgene, if for no other reason than it was a gas tried in World War I as a weapon of destruction. Urethanes are ubiquitous in today's world and are not considered to be a major hazard.
Not wanting to get into a diatribe, I would like to offer that Dr. Wallinga should at minimum cite the “studies” he refers to in his letter. Are the sources reputable and cited publications, or are they political sources with an objective behind them? Have the sources been accurately cited or just parts chosen for discussion? One cites a study so others can read it and judge for themselves. In addition, he appears to use the same scare tactic being used by most anti-PVC groups by paraphrasing some uncited study, scaring the hell out of everyone who reads the letter — some of whom may have a limited scientific background — and then stating that PVC was not directly implicated but could have been the cause, or that the hazards were just like those of PVC or vinyl chloride monomer exposure, i.e., “... even if vinyl chloride exposure per se could not be implicated.”
It is true that corn- and potato- based polymers are having more developmental success all the time and it is also true that they have very limited real-world use to date. I am a strong proponent of American ingenuity and the use of biomaterials, but things under development are just that — under development. They need a lot of ingenuity before they can serve a useful function. The Institute for Agriculture and Trade Policy is a farm advocacy group, so I cannot fault Dr. Wallinga's desire to promote corn and potato products. I also would in his position. I can only guess what his motives are for getting involved with the PVC issue and then talking about possible vinyl chloride monomer studies, but chemical ignorance is not acceptable when discussing chemicals.
I do know that the hemicelluloses derived from corn are not the most benign materials, but can be converted into a very fine beverage which, when imbibed in excess, has documented deleterious effects on mankind. Similarly the starches in potatoes. Should we ban corn and potatoes based on these facts? Again, although I work for a great company which extrudes rigid PVC, the above are my personal opinions and may or may not be those of my employer.
Director of Research and Development