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"By denying scientific principles, one may maintain any paradox." – Galileo Galilei

Prop 65: How IARC’s Flawed Science Has Negative Policy Implications for Americans

It has been well established that the International Agency for Research on Cancer’s (IARC) research procedures need a major overhaul, but little is known about the negative policy implications that the small, France-based research outfit has on nearly 40 million Americans living half a world away. Examination into California’s Proposition 65 explains how IARC’s determinations are imported into the United States.


About Prop 65  

The state of California enacted the Safe Drinking Water and Toxic Enforcement Act of 1986, better known as Prop 65, after the ballot initiative passed in November 1986. The proposition was intended by its authors to protect Californians and the state’s drinking water sources from chemicals known to cause cancer, birth defects or other reproductive harm, and to inform citizens about exposures to such chemicals.

While a laudable goal, the scientific approach behind Prop 65 is fundamentally flawed for several reasons, one of which is its reliance on  IARC research. According to California’s Office of Environmental Health Hazard Assessment (OEHHA), the state government agency that implements  Prop 65, anything IARC classifies as “possibly carcinogenic,” “probably carcinogenic,” or “carcinogenic” is fair game for listing on Prop 65.


Flawed Scientific Approach: Risks vs. Hazards and Why it Matters in Prop 65

There is a wide gulf between the evaluation of risk, and the identification of a hazard. A hazard is anything that has the potential to cause harm, whereas a risk is the likelihood that the hazard will cause harm under certain conditions. When scientists and policymakers substitute one for the other, public confusion gets compounded. As Reuters has pointed out:


“The public sometimes misunderstands what IARC means by its classifications. The agency says it assesses ‘hazard’ – the strength of evidence about whether a substance or activity can cause cancer in any way. It takes no account of typical levels of human exposure or consumption. So it is not measuring ‘risk’ or the likelihood of a person getting cancer from something.”



The Campaign for Accuracy in Public Health Research (CAPHR) has also documented the important differences between risks and hazards, noting that a risk assessment takes a known hazard and evaluates its impact in real-world applications. Risk assessments also take into account the following factors to determine the likelihood that any given hazard will actually pose a risk of harm.

Scientific Risk Assessments: Evaluation Criteria

  • Dose/concentration
  • Exposure pathways, and the
  • Probability of exposure

Hazard assessments serve a scientific purpose as a screening tool for future risk assessments; however, conflating the two approaches under Prop 65 results in misclassifications and overregulation. As a result, nearly 80 substances are listed on Prop 65’s list because research by IARC has evaluated the potential of their harm, rather than the risk.


Unnecessary Alarm and Conflicting Guidance

Prop 65 and its IARC-backed listings negatively impact Californians. Due to its hazard-based listing criteria, the Prop 65 list includes nearly 1,000 agents, many of which are included in everyday products.

For example, acrylamide is an example of a chemical that has been deemed carcinogenic by IARC and is also listed on Prop 65’s list. Acrylamide is a chemical that naturally occurs in roasted coffee beans, potato chips, cooked vegetables and baked goods.

The basis for the chemical’s listing on Prop 65 originated in IARC’s 1994 declaration that acrylamide was “probably carcinogenic” despite “inadequate” evidence in humans. To this day, there still is no scientific proof linking acrylamide to cancer in people. Meanwhile, federal regulatory agencies say acrylamide is not harmful in the small doses typically found in table food. According to the U.S. Food and Drug Association (FDA), Americans should not stop eating foods that are fried, roasted or baked because of their acrylamide levels. Additionally, a regulatory report coauthored by FDA scientist Lauren Posnick Robin, SC.D., states that acrylamide is “unlikely to have neurological, reproductive or developmental effects” in human foods.”

However, per the state regulation, all acrylamide products –like all Prop 65 substances– must contain a carcinogenic warning label to inform Californian consumers and discourage use discourage use. [1]

The warning label does not only affect and influence the behaviors of Californians; many other Americans are indirectly impacted by Prop 65. Given the difficulty in ensuring unlabeled products with Prop 65-listed ingredients do not end up on store shelves in California, many companies stamp the CA-required warning label on products destined for other states that do not have this requirement. This label causes unnecessary alarm and confusion for many other Americans, thus widening the reach of IARC’s bad science across our country.

Lisa Halko, a Sacramento lawyer, expands upon Prop 65’s false-alarm warning labels versus the FDA’s approach:


“There are better ways to get that information to people than putting a warning on just one theoretical risk. The U.S. Food and Drug Administration has more complete, better targeted information on possible risks.”


Halko raises an interesting point.  Why should Californians be subjected to Prop 65’s alarmist notices, when federal regulatory organizations like the FDA have more complete information and appropriately communicated warnings about the risks in food?  Acrylamide is just one example of how IARC’s carcinogen classifications conflate risks with hazards and negatively impact Californians.


Prop 65’s Money Trail

Prop 65 has also been a big moneymaker for powerful trial lawyers, due to the “citizen suit” provision. This provision allows opportunistic lawyers to file lawsuits against any company in the country that sells products in the state containing listed substances that do not have a warning label. According to California Citizens Against Lawsuit Abuse, over 20,000 lawsuits have resulted in settlement payments totaling $500 million since 1986.

Additionally, between 2000 and 2010, businesses paid $142 million in Prop 65 settlements, including $89 million in attorney fees. These settlements tend to discriminate against small businesses that do not have the financial ability to defend lawsuits like larger corporations. As Art Torres, one of the authors of Prop 65 has admitted:


“Some of these small businesses have had to declare bankruptcy because of the lawsuits that were filed against them. Rather than having ‘gotcha’ lawsuits, we have to have a more reasonable approach for dealing with the issue.”


Among other things, Prop 65 was intended to protect Californians from exposure to cancer-causing chemicals and products. Instead, it has turned into a cash cow for trial lawyers who have used Prop 65 listings and IARC’s hazard assessments as reason to collect damages from businesses across the state.

IARC’s influence on Prop 65 carcinogen lists creates unnecessary alarm for California consumers, and in some cases, contradicts federal regulatory guidance. Furthermore, Prop 65 Program has led trial lawyers and activists alike to seek financial gains at the cost of businesses small and large.  In a world full of dangerous and potentially harmful substances, Prop 65 is blissfully ignorant to its own stated purpose of informing Californians about exposure to known carcinogens. Prop 65 should focus on scientific consensus, rather than science for alarmism and profit.


[1] If exposure to the product is deemed above the safe harbor level