[Cass R. Sunstein] Bad nudge from California

Should coffee come with a cancer warning?

As a matter of policy, the answer seems obvious: Of course not. As a matter of law, it’s much more complicated, at least in California. A tentative judicial ruling in Los Angeles County last week suggests that when people go to the local coffee place, their morning ritual is going to be accompanied by a jolt of fear.

It could potentially turn into a fiasco, I think, and it tells us something important about how well-intentioned laws can go badly wrong.

The background comes from California’s Proposition 65, a state ballot referendum designed to reduce health risks associated with certain chemicals. Its key provision states, “No person in the course of doing business shall knowingly and intentionally expose any individual to a chemical known to the state to cause cancer or reproductive toxicity without first giving clear and reasonable warning to such individual.”

For carcinogens, here is some acceptable wording: “WARNING: THIS PRODUCT CONTAINS CHEMICALS KNOWN TO THE STATE OF CALIFORNIA TO CAUSE CANCER.”

That’s pretty scary. It also raises an immediate question: What does it mean to “cause cancer”? Under the law, which was adopted in 1986, a chemical can be exempted if it poses “no significant risk.”

A risk is not significant if it results in one or fewer excess cancer cases in an exposed population of 100,000, “assuming lifetime exposure at the level in question, except where sound considerations of public health support an alternative level.” To claim the benefit of the exemption, those who seek an exemption have to offer a “quantitative risk assessment,” or so the law seems to say.

That brings us to the neighborhood coffee shop.

When coffee beans are roasted, a chemical reaction occurs, producing a chemical, called acrylamide, which California has long listed as causing cancer. Acrylamide dissolves in water, which means that it can be found in brewed coffee.

With these simple facts in mind, the Council for Education and Research on Toxics brought suit against a large number of companies, including Starbucks, arguing that they were obliged to give the appropriate warning to their customers.

The central question in the case was whether the companies could claim an exemption. Among other things, they argued that for coffee, “sound considerations of public health support an alternative level.” They contended that the risks associated with acrylamide were low -- and that current levels of acrylamide in coffee cannot be reduced without adversely affecting safety and taste.

In a “proposed statement of decision,” the judge found these arguments unpersuasive. In particular, he objected that the companies had not provided a quantitative risk assessment, specifying the risk of acrylamide in coffee.

Given Proposition 65 and the evidence provided at trial, the judge’s conclusions were not unreasonable. The defendants have a few weeks to respond. Perhaps they will prevail.

But let’s step back a bit. There are good reasons to object to cancer warnings for coffee.

For one thing, such warnings would mislead and frighten a lot of people. When we see a cancer warning, many of us greatly exaggerate the size of the risk. It’s not in the public interest to produce unjustified fear.

True, some people will ignore the warning.

But a lifetime risk in the vicinity of 1 in 100,000 is very low. According to some recent estimates, a mortality risk of that magnitude is about the same as that of being killed by a dog; 17 times lower than the risk of drowning in a swimming pool; 60 times lower than the risk of being killed from a fall on stairs or steps; and 90 times lower than the risk of being killed in a motor vehicle accident.

The cancer risk of smoking is over 10,000 times higher. And because people inevitably face a wide range of risks, the idea of a 1 in 100,000 mortality risk is deceptive: In all likelihood, you’ll end up dying from something else.

Another consideration is that with respect to acrylamide, we probably shouldn’t worry a whole lot. The American Cancer Society notes that when rats and mice are given very high amounts -- 1,000 to 10,000 higher than the levels to which human beings might be exposed in foods -- the incidence of cancer does increase.

But with respect to human beings, the evidence is mixed. Indeed, “there are currently no cancer types for which there is clearly an increased risk related to acrylamide intake,” which means that the evidence from human studies is “somewhat reassuring.”

Proposition 65 does have laudable goals. Across a population of tens of millions, a risk of 1 in 100,000 is not exactly trivial. One of the law’s evident aims is to change corporate behavior: Because companies will lose business if they inform customers that their products contain carcinogens, they will have an incentive to adopt safer substitutes.

Fair enough. But cancer warnings on coffee? That’s silly.


Cass R. Sunstein
Cass R. Sunstein is a Bloomberg View columnist. -- Ed.

(Bloomberg)