California's java joke is a wakeup call on cancer warnings

International Agency for Research on Cancer is known to cherry-pick data to reach politically motivated findings

by Dr. Henry I. Miller and Jeff Stier @ The Mercury News June 8, 2018

It's often said that California is a bellwether, a place where nationwide trends begin. For the sake of farmers, particularly those in poor countries where coffee is an economically important crop, let's hope not.

Last month a California judge ruled that because of the state's decades-old notorious Proposition 65, which has given rise to warnings about non-dangerous chemicals everywhere from supermarkets to libraries, coffee sellers must now post warnings about the possible cancer risk posed by a compound in coffee.

The Council for Education and Research on Toxics brought the lawsuit against Starbucks and 46 others coffee retailers, claiming the presence of high levels of acrylamide, a chemical created when coffee beans are roasted, is carcinogenic and requires a "clear and reasonable" warning. (Acrylamide is converted in the body to a compound called glycidamide, which damages DNA.)

But acrylamide is also commonly found in other foods, such as French fries, bread, and olives. Its presence in fries previously resulted in litigation from the same activists.

How could warnings of hidden "carcinogens" be without merit? Well, many compounds, both natural and synthetic, in food test positive for carcinogenicity. UC Berkeley biochemist Bruce Ames and his colleagues observed that the cooking of food is a major dietary source of potential rodent carcinogens: "Cooking produces about 2 g (per person per day) of mostly untested burnt material that contains many rodent carcinogens." Should there be a Prop 65 warning in every kitchen in California?

Coffee will join more than 800 chemicals on California's Proposition 65 list, which is intended to alert the public about "substances identified as human or animal carcinogens by the International Agency for Research on Cancer" (IARC). But therein lies another problem: That agency, which is part of the World Health Organization, has long been criticized for using a flawed approach - basing its decisions on hazard (the possibility of harm at any dose) instead of risk (the probability of harm, taking exposure into consideration).

IARC is known to cherry-pick data to reach politically motivated findings. The agency has reviewed nearly 1,000 substances and activities, and only one has been deemed non-carcinogenic. IARC looks for any shred of evidence to prove that something might cause cancer, even under extreme circumstances. It is confirmation bias at its worst: Reach a conclusion first, find the evidence later.

Moreover, inexplicably, IARC itself issued a press release on June 15, 2016, about the lack of evidence of carcinogenicity of coffee:

After thoroughly reviewing more than 1000 studies in humans and animals, the Working Group found that there was inadequate evidence for the carcinogenicity of coffee drinking overall. Many epidemiological studies showed that coffee drinking had no carcinogenic effects for cancers of the pancreas, female breast, and prostate, and reduced risks were seen for cancers of the liver and uterine endometrium. For more than 20 other cancers, the evidence was inconclusive.

This is the folly at the heart of proposition 65: If there's a scientifically insignificant amount of a chemical that causes cancer in high-dose animal experiments, a warning is required, even if consumption of the product doesn't actually cause cancer. Indeed, in the case of coffee, where evidence suggests a protective effect against certain cancers, a warning is necessary nonetheless. How can that be? In the California court's contorted opinion, "Defendants failed to satisfy their burden of proving by a preponderance of evidence that consumption of coffee confers a benefit to human health."

If California is truly a bellwether, be forewarned: Common sense and justice are under attack.

Dr. Henry I. Miller, a physician and molecular biologist, is the Robert Wesson Fellow in Scientific Philosophy and Public Policy at Stanford University's Hoover Institution. Jeff Stier is a senior fellow at the Consumer Choice Center.