Experts question CDC’s downplaying of benzene in childhood leukemia

Epidemiologist Peter Infante, who originally identified occupational benzene exposure as a leukemia risk in the 1970s, Thursday questioned a decision by the Centers for Disease Control (CDC) and editors to remove mention of benzene exposure as a childhood leukemia risk factor from a 2007 CDC review published in the U.S. government’s flagship public health journal, Environmental Health Perspectives.

The review originally listed both benzene and ionizing radiation as significant risk factors for childhood leukemia in its summary, a section of the paper entitled “risk factors,” and the conclusion section. But the authors of the review asked editors to remove benzene within two to three months of the paper’s publication in 2007, spokeswoman Christine Bruske Flowers told epiNewswire Thursday.

Flowers works for National Institute of Environmental Health Sciences (NIEHS), which publishes the journal.

“At the time, the data didn’t indicate benzene was a risk factor for childhood leukemia specifically,” Flowers said. “I think there’s a distinction to be made between saying benzene’s a human carcinogen and saying benzene’s linked to childhood leukemia.”

Strangely, while the summary and “risk factors” section no longer list benzene as a childhood leukemia risk, the paper’s conclusion section continues to do so:

In general, benzene and ionizing radiation are two environmental exposures strongly associated with the development of childhood AML or ALL.

The correction and removal of benzene from the review’s summary came as a surprise to NIEHS’s top leukemia researcher, James Huff.

“I do not know what this means,” Huff said. “Of course benzene in our experiments and now others does cause leukemia (and) lymphoma in mice, correspondent with humans.”

Infante also questioned the decision to remove benzene from the review of childhood leukemia risk factors. He was quick to say the CDC authors were free to change their opinion and ask for their paper to be changed.

But the rationale offered by Flowers — that there is or was insufficient evidence tying benzene to childhood leukemia — “doesn’t make sense scientifically,” Infante told epiNewswire.

There are large studies tying fetal and childhood exposure to benzene to childhood leukemia risk, he said. In-utero exposures to paint, which contains benzene, is a risk factor for childhood leukemia, Infante added.

Moreover, Infante questioned the scientific basis for assuming children are not susceptible to benzene’s carcinogenicity.

Benzene is best established as a risk factor for Acute Myeloid Leukemia (AML), Infante said.

“Why would children be any different than adults,” he asked. “Children aren’t a different species. So you have to demonstrate benzene causes AML in children? There are hardly any studies of leukemia in people over 75. Do you have to have evidence it (benzene) specifically causes leukemia in patients in that age group, too?”

Removing mention of benzene from the list of significant risk factors in the EHP review was not a trivial move, Infante said.

“It’s unfortunate in terms of public health that they would not include benzene,” Infante said. “It’s not informing people about the hazards their children may be having.”

Children’s exposures to benzene are frequently preventable, Infante said — if parents know about the risks.

The assumption that benzene is not carcinogenic in children is “lacking in mental rigor,” Infante said.

The EHP correction notification describing the removal of benzene was noticed by Terry Nordbrock, executive director of the National Disease Clusters Alliance (NDCA), who brought it to the attention of epiNewswire’s Bryant Furlow.