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Environmental Factor, May 2012

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Birnbaum discusses 12th ROC at congressional joint hearing

By Ian Thomas

NIEHS/NTP Director Linda Birnbaum, Ph.D.

Birnbaum was accompanied to the hearing by members of the NIEHS staff located in Bethesda, Md. (Photo courtesy of Steve McCaw)

NIEHS/NTP Director Linda Birnbaum, Ph.D., addressed questions regarding NTP’s 12th Report on Carcinogens (RoC) April 24 during a U.S. House of Representatives joint subcommittee hearing. Testifying in front of the Committee on Science, Space, and Technology, Subcommittee on Investigations and Oversight, as well as the Committee on Small Business, Subcommittee on Healthcare and Technology, Birnbaum addressed a wide range of questions regarding the RoC’s contents, and the rigorous peer review process by which scientific research and public feedback are used during its compilation.

“The RoC is a science-based, public health document that provides information about the relationship between the environment and cancer,” explained Birnbaum. “The Report lists a wide range of substances, including metals, pesticides, drugs, natural and synthetic chemicals, and biological agents that are considered cancer hazards for people in the U.S.”

Launched in 1978 as part of the Public Health Services Act, the RoC takes into account a number of different factors when determining a substance’s potential hazard for cancer. These include such things as the amount and duration of exposure, as well as an individual’s susceptibility to a substance. Still, Birnbaum was quick to point out that the RoC is not a tool for risk assessment.

“This is not a regulatory document,” she noted. “However, the RoC does provide decision makers and the public with information they can use to make decisions about exposures to cancer-causing substances.”

A pair of categories

The RoC lists substances in one of two categories, “known to be carcinogens” and “reasonably anticipated to be carcinogens.”

For a substance to be listed in the known category, there must be sufficient evidence from human studies that indicates a causal relationship between exposure to the substance and human cancer. For a substance to be classified in the reasonably anticipated category, it must fit one of three scenarios: limited evidence it causes cancer from studies in humans; sufficient evidence it causes cancer from studies in animals; or evidence that the substance is a member of a class of substances already listed in the Report or that it causes biological effects known to lead to the development of cancer in humans. “The decision to list a substance in the RoC is based on scientific judgment, with consideration of all relevant research data and input from both advisory groups and the public,” said Birnbaum.

Involving the public

While the preparation of each edition of the RoC involves a multi-step process, including expert advisory reviews, independent external peer reviews, and outside input from agencies, such as the U.S. Food and Drug Administration, U.S. Environmental Protection Agency, and Consumer Product Safety Commission, among others, Birnbaum added that anyone can nominate a substance for listing or removal from the Report, be it a field-leading scientist or a private citizen.

“In the case of the 12th RoC, we actually increased the number of opportunities for public review and input,” said Birnbaum, adding that public comments were solicited on six different occasions.

Looking ahead

As NTP moves forward on the 13th RoC, Birnbaum and her staff have revised the process for preparation of the report with regard to the transparency and efficiency, while continuing to maintain the rigorous investigative standards for which the document has long been known.

“We believe the RoC is, and will remain, an important public health document, because it empowers the public and decision makers with the information they need to make informed choices about potentially cancer-causing substances and hazards,” said Birnbaum. “However, a process like this can never be too thorough, which is why it’s vital for us, as researchers, to always be mindful of new ways to improve it.”

(Ian Thomas is a public affairs specialist for the NIEHS Office of Communications and Public Liaison and a regular contributor to the Environmental Factor.)

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