Positive Responses to Negative Statements About PVC: Part 4

Statement: “Phthalate plasticizers used to keep PVC membranes flexible are dangerous to human health.”

The facts: The Duro-Last membrane uses a plasticizer that has been determined to be non-toxic to humans with no negative environmental impacts. There is no reliable evidence that any phthalate has ever caused harm to anyone. In over 40 years of study and use, phthalate plasticizers have never been shown to cause harm to humans from their normal use. The Consumer Product Safety Commission has studied the use of plasticizers in vinyl toys and found no demonstrated health risk.

In the 1980s, some phthalates were shown to cause liver cancer in rodents when administered at high doses over long periods of time. Follow-up research showed that the cancer was caused by a biological process in rodents that does not occur in humans.

A study of questionable reliability claims a statistical relationship exists between phthalates and asthma, rhinitis and eczema. The study was found to be of poor quality and the conclusions to be based on assumptions unsupported by the evidence. The conclusions disagree with recent experimental evidence showing no immune system response of the kind associated with asthma. Many risk factors associated with asthma such as dust, molds, mildew, and dander were not controlled for and so could not be ruled out.

A study by Shanna Swan claimed that prenatal exposure to phthalates affected the reproductive development of infant boys. However, a review of the study by a leading scientific research firm found that the study researchers used the wrong statistical model to obtain results and the relationship claimed is not biologically plausible. When an explanation of the study methods and a set of the data were requested from Swan, the request was refused. The failure of a scientific study’s author to disclose data for peer review leads to suspicion about its reliability because scrutiny is part of any valid scientific process.

Junk science is often used to create an emotional connection with perceived facts. One way to fight junk science and maintain credibility is to require public disclosure of data.

In our next installment, we’ll look at this statement: “PVC building products create poisonous gasses when they burn.”