This article originally appeared in Economics21 on September 17, 2018 and was written by Ross Marchand, Director of Policy for Taxpayers Protection Alliance.

For businesses that market their goods across the country, California is a tough sell. That’s because it’s hard for these firms to advertise their products to California consumers without incurring the wrath of state regulators. A regulation known as Proposition 65, originally passed in 1986 and compounded by new rules that went into effect in August, require warning labels on products containing substances “known to the State of California” to cause cancer, birth defects, or reproductive harm. These sorts of precautions could be useful, if the substances in question were in fact dangerous.

But unbeknownst to the millions of consumers who have to pay higher prices because of these draconian rules, the danger designation comes in part from the EPA—and in part from an international organization called the International Agency for Research on Cancer (IARC) pushing flawed science. A sub-agency and scientific body of the World Health Organization (WHO), IARC relies on false-positives and scientists with vested interests to classify substances as dangerous to human health.

IARC relies on false-positives and scientists with vested interests to classify substances as dangerous to human health.

For decades, IARC has pushed for dubious designations of hundreds of substances as carcinogenic or possibly carcinogenic to humans. On the surface, the organization appears to have rigorous evaluation standards. In its Preamble, for instance, IARC states that Working Group members must make clear “the strength of the evidence for each group of studies, citations to indicate which studies were pivotal to these conclusions, and an explanation of the reasoning…in weighing data and making evaluations.”

For decades, IARC has pushed for dubious designations of hundreds of substances as carcinogenic or possibly carcinogenic to humans.

But on closer inspection, the process for determining what substances are carcinogenic is quite sloppy. Here’s how it works: IARC can select a substance for review based on a “suspicion of carcinogenicity.” There’s formally a nomination process for “candidate agents,” but anyone, including private citizens, can nominate whatever substance they find threatening. IARC then convenes scientists to prioritize nominated substances for evaluation; the highest priorities get sent to Working Groups for study, which is where the trouble begins. Typically, Working Group members are scientists who have produced studies on the substances under consideration, and IARC finds these experts via searches of the scholarly literature.

This process is problematic, since scientists are biased toward their own published findings. Take, for instance, IARC’s evaluation of azo dyes, found in jeans, silk products, and various textiles. When the agency evaluated the dyes’ carcinogenicity in 2008, it enlisted the help of scientists such as King-Thom Chung of the University of Memphis and Harold S Freeman of North Carolina State University, who have published articles for decades on links between azo dyes and different types of cancer. While their work has done much to advance our understanding of the subject area, they’re naturally unlikely to raise methodological concerns with their work or works they cite in their papers. Despite biases, IARC stacks the deck against including cancer experts outside of the immediate subject matter who nonetheless can lend a fresh pair of eyes to the debate. University of New South Wales ProfessorBernard W Stewart is one such expert. He holds critical views of the link between azo dyes and cancer. Yet he wasn’t included in the monograph process, despite being cited in the report about other matters.

IARC also keeps industry voices out of the process, further ensuring that critical feedback is sidelined. Excluding the perspective of businesses close to the action makes little sense, considering that everyone (including scientists) have a vested interest in the result. Regulatory authorities such as the EPA have long recognized that scientific peer review benefits from industry participation. The EPA’s own chemical advisory committee has business and trade group representation, comparing their own data to that of scientists and officials at the agency.

IARC also keeps industry voices out of the process, further ensuring that critical feedback is sidelined.

IARC’s one-sided process ensures that all sorts of safe substances get labeled as dangerous. Substances such as aloe vera, d-limonene (found in citrus), and aniline (found in carrots) are all considered at least “possibly carcinogenic” by the organization. IARC also considered coffee possibly carcinogenic for 25 years, despite ample evidence of its protective effectsagainst various varieties of cancer. Even after retracting the “possible carcinogen” status of coffee, IARC refused to reclassify it to the category of “unlikely to cause cancer in humans.” This is unsurprising, since fewer than 1 percent of the more than 1,000 substances evaluated by the organization are deemed unlikely to cause cancer.

Fortunately, IARC is finally considering changes to its Preamble in order to make for a more rigorous process. IGO Watch, a project of the Taxpayers Protection Alliance dedicated to holding global bureaucracies accountable, submitted comments to IARC on the Preamble change, calling for more inclusive Working Groups and better statistical evaluation of studies.

IARC has the chance to adopt a more thorough, transparent method of review that safeguards everyone involved.

And, with the naming of Karolinska Institutet and Arctic University of Norway epidemiologist Elisabete Weiderpass as new IARC director in 2019, IARC has the chance to adopt a more thorough, transparent method of review that safeguards everyone involved. Weiderpass, who will have a five-year term, brings significant expertise in the field of cancer epidemiology. But until the IARC process of review becomes more rigorous, it’s unreasonable to hold businesses hostage to its findings.