Sunday, May 08, 2005

Benzene: doubtful uncertainty

A classic way to describe the difficulty of managing risks in public health is to say it a problem of making decisions under uncertainty. Indeed there are many things we would like to know more about and often important pieces of information that are missing. But not all "uncertainties" are the same.

For example, while there is the uncertainty that comes from truly not knowing the answer to an important question, there is also the uncertainty that comes from systematically not asking the question. Then there is the uncertainty that comes because you asked the question in the wrong way and thus don't get the answer you need. Or the uncertainty that comes because you didn't even know there was a question to ask (because, say, the existence of the question and the answer was concealed, as with undisclosed studies or results about a chemical).

And then there is the uncertainty that isn't really uncertain at all -- in David Ozonoff's double entendre, "manufactured uncertainty." In a similar vein, historian of science Rob Proctor's book Cancer Wars has a chapter about chemical industry trade associations entitled "Doubt is our product." Manufacturing uncertainty is a tactic we have seen frequently: in global climate change, endocrine disruptors, evolution and even well recognized chemical poisons. There is a recent example for the known human leukemogen, benzene.

It has been known for almost a half century the aromatic hydrocarbon benzene can cause cancer in humans, primarily cancers of the blood forming organs (the acute and chronic lymphocytic and non-lymphocytic leukemias; multiple myeloma; lymphomas; myelodysplastic disease; and aplastic anemia [a preleukemic condition often fatal on its own]). Because benzene is encountered so frequently (it is added as an anti-knock agent to gasoline, for example), the levels at which benzene causes cancer is a matter of importance both to workers and the general public. Several years ago the US National Cancer Institute (NCI) published a paper showing workers in Shanghai exposed at what were considered acceptable levels had a four-fold increased risk for non-Hodgkin's lymphoma, one of the cancers of the blood system (immune cells). This contradicted industry's position that benzene only causes one kind of blood cancer (acute non-lymphocytic leukemia) and that current standards were "safe." It was time to cast doubt on the results.

The Houston Chronicle is now reporting (Dina Capiello, by-line; no link), using information revealed in legal depositions, that shortly after the NCI paper appeared, five major companies (BP, ChevronTexaco, ConocoPhillips, Exxon Mobil and Shell Chemical) decided to fund a "follow-up" study in China and allocated $27 million to the effort. It began in 2001 and is expected to be completed in 2007. But perhaps we already know the results. Court documents also reveal that the outcome is already envisioned:
But in depositions, proposals to oil companies and other documents collected by a Houston law firm in unrelated lawsuits and provided to the Chronicle, the results of the study already have been predicted.

And while the actual data may be years away, the conclusions are expected to contradict earlier research linking low- and mid-levels of benzene to cancers and other blood diseases - findings that could spawn tighter regulations.

"The proposed research is an investigation ... to respond to allegations from a nationwide study of benzene exposed workers," read a proposal sent to Craig Parker, manager of toxicology and product safety for Marathon Oil Corp.


Soon after, industry experts started visiting China to map out a follow-up study.

Financial consequences Oil companies have a vested interest in such results because of the financial consequences. If lower levels of benzene are shown to cause disease, the concentration allowed in the workplace, in gasoline, or in communities could be lowered.

Among the concerns identified in the consortium's pitch for funding in the late 1990s were increased litigation, more stringent cleanup standards and the reformulation of gasoline. Benzene is a natural component of gasoline.

"Every time somebody regulates benzene, it has an impact on gasoline production," said Gerhard Raabe, a toxicologist who, as an employee of Mobil Oil and chair of a petroleum institute committee, visited various companies seeking funding in the late 1990s. His comments were part of a deposition taken by attorney Lance Lubel in 2004.

"There is a whole bunch of business reasons (for) getting a good scientific answer as to what ... are the risks," he said.

The proposal received by Marathon Oil stated that the benzene research was expected to provide scientific support for the lack of a leukemia risk to the general population, evidence that current occupational exposure limits do not create a significant risk to workers and proof that non-Hodgkin's lymphoma could not be caused by benzene exposure.

Otto Wong, one of the investigators in the industry-funded Shanghai study, said he had no preconceived ideas of the study's results. "That's not my wording," said Wong, who works for Applied Health Sciences, Inc., in San Mateo, Calif. His firm, along with Fudan University in Shanghai and the University of Colorado Health Sciences Center, is in charge of the research.

"The obvious reason (we are doing the study) is to learn more about benzene and other chemicals in the development of leukemia and other diseases," he said.

However, Wong said he had opinions about what he might find based on previous research.

"I do know benzene and non-Hodgkin's lymphoma quite well, and there is one study that says there is an association, and all other studies say no," Wong said. "Based on what we do know, we do have some opinion, we have some idea of what the situation will be, but no one can predict how a particular study will turn out." [Houston Chronicle]
Yeah, right. Unfortunately for the oil companies while all this was going on, so were other studies. Last year a paper in Science (3 December 2004; 306: 1774-1776) showed significant damage to cellular genetic machinery of blood cells in workers exposed to benzene at just 1 part per million, the current occupational standard. So Dr. Wong, an industry-fed consultant who had traveled to Taiwan in the late nineties to exonerate a particularly egregious groundwater pollution problem outside an RCA plant, will have to work just that much harder to cast even more doubt.

But I guess that's what he gets paid the Big Bucks for.