NRDC Senior Scientist Jennifer Sass Talks About: Vinyl Chloride: A Case Study of Data Suppression and Misrepresentation

Bill Walsh | May 04, 2005 | Policies

Jennifer Sass

[1] Jennifer Sass[2] is a senior scientist with NRDC's public health group, where her work includes oversight of toxic chemical regulations and investigations of corporate influences in government policy decisions. In May, 2005 she and two co-authors published a peer reviewed analysis in the influential journal Environmental Health Perspectives[3] (advance version available online March 2005) documenting sometimes successful attempts by the chemical industry to weaken evaluations posted on the US Environmental Protection Agency's influential IRIS[4] health impacts database.

HBN: Why is this study important to the green building community?

JS: This study is important to anybody who relies upon governmental chemical exposure standards or risk assessment because we found that the EPA employed discredited scientific practices at the behest of the chemical industry in order to lower estimates of vinyl chloride's cancer potency by tenfold. That means if a green building group relies upon the IRIS assessment in its evaluation of vinyl chloride, for example, it will likely plug in a number that allows people to be exposed to 10 times as much vinyl chloride as was previously advised. That increase was not justified by the data.

The EPA IRIS assessment estimates that a lifetime of breathing an average of 1 microgram per cubic meter of vinyl chloride would result in 9 excess cancer cases per 1 million people exposed. Less than ten years before, and with the same available data, EPA had calculated that this same exposure would result in 85 excess cancer cases.

HBN: What prompted you to do this case study?

JS: Two things. This case involves a US EPA database known as IRIS that is probably the most influential database in the world when it comes to setting standards for human exposure to chemicals. IRIS is highly valued by scientists and regulators because it considers all toxicological effects, not just cancer impacts, and assigns a numerical risk value to chemical exposures. It is not itself an enforceable standard, but because it supposedly represents EPA's scientific consensus, IRIS is the basis for many state, federal and even world wide chemical standards that are written into environmental laws. This is a database that gets half a million visits per month.

HBN: According to your article in Environmental Health Perspectives, there were problems both with the scientific analysis and the review process itself. What evidence justifies your charge of discredited scientific practices?

JS: First, according to the Agency's own guidelines, it must consider all cancers when evaluating a chemical's cancer potency. After all, by developing liver cancer, one is not then protected from developing cancer in other body organs. With its vinyl chloride assessment, the EPA agreed to the chemical industry request to use a mathematical model that could only accommodate liver cancer, thereby ignoring reports of other cancer types in the published literature, including industry-sponsored studies. Risk of cancer to the brain, lung, and blood systems, in particular, has been documented in occupational studies and scientific reviews. Vinyl chloride-related brain cancer has been the subject of litigation by former vinyl chloride workers.

Stretching over years, with the most recent published in 2000, chemical industry studies consistently document excessive brain cancers in occupationally-exposed workers. These risks are not calculated into the vinyl chloride assessment now on IRIS.

Second, following a request by the vinyl chloride industry, the EPA removed a sentence from its draft assessment that stated there was, "suggestive epidemiological evidence" that vinyl chloride exposure was associated with cancers of the brain, lung, and blood system. Such a phrase would have warned the public that EPA acknowledged such risks, though they were not calculated into the assessment. At the same time, EPA removed a three-fold protective factor that it had proposed in its draft assessment to adjust for these cancer risks. By removing this warning statement, the EPA negotiated away the science. By removing the protective factor, it negotiated away health protective policy.

There is a well-documented history of the vinyl industry suppressing data, pressuring their own experts to contradict themselves, and offering up unproven hypotheses to undermine the actual data in their own studies. This has been documented many times by respected scientists and journalists, including an extensive expose by the Houston Chronicle in 1998,[5] and more recently in the 2003 book "Deceit and Denial: The Deadly Politics of Industrial Pollution," by historians Gerald Markowitz and David Rosner.[6]

HBN: Many will find it hard to believe that the scientific process could be so manipulated. So often these disputes sound like reasonable, if passionately held, disagreements among experts who are talking well above the heads of the rest of us.

JS: It is not too hard to understand the problem when one considers that of the 19 external peer reviewers on the vinyl chloride assessment, at least seven were chemical industry employees or consultants, four were from government, and not one was from a labor union, occupational health group or a public interest group. Also, this case stands out in that so much of the scientific information is quite accessible. We are convinced that the vinyl chloride case is evidence of a much bigger problem.

We need a much greater investment to protect the public brain trust in government, with greater support of independent academics to provide scientific oversight to ensure that EPA is carrying out its objective to protect public and environmental health. After all, its name is the "Environmental Protection Agency." Have the "E" and "P" gone silent?



Since its triumphant debut at the 2002 Sundance Film Festival and its broadcast on HBO in 2003, BLUE VINYL has been part of a revolution to reduce our country's dependence on polyvinyl chloride (PVC), the most ubiquitous plastic in our consumer society and one of the most toxic known to science.

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Ecologist and author Sandra Steingraber's article about PVC entitled "The Pirates of Illiopolis: Why Your Kitchen Floor May Pose a Threat to National Security" is the cover story of the May/June 2005 edition of Orion Magazine, winner of the 2004 Independent Press Award for General Excellence. Steingraber, who wrote an essay for Healthy Building News about the PVC plant explosion in Illiopolis, Illinois last spring, explores the intersection of public health and national security issues with PVC. To read the article, go to


[1] Jennifer Beth Sass, Barry Castleman and David Wallinga. "Vinyl Chloride: A Case Study of Data Suppression and Misrepresentation," Environmental Health Perspectives, published online 24 March 2005, doi:10.1289/ehp.7716

[2] Dr. Sass received her undergraduate and graduate degrees in anatomy and cell biology at the University of Saskatchewan and her postdoctorate in neurotoxicology at the University of Maryland. Sass is currently a Senior Scientist with the Natural Resources Defense Council

[3] Environmental Health Perspectives (EHP) is a monthly journal of peer-reviewed research and news on the impact of the environment on human health. EHP content is free online and available in print issues through paid subscription.

[4] Integrated Risk Information System.

[5] "In Strictest Confidence: The Chemical Industry's Secret," Jim Morris, The Houston Chronicle 1998.

[6] Gerald Markowitz is Professor of History at John Jay College and the Graduate Center of the City University of New York. David Rosner is Professor of History and Public Health at Columbia University and Director of the Center for the History and Ethics of Public Health at Columbia's Mailman School of Public Health.