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The words “hazard” and “risk” are often used interchangeably or confused with each other, but understanding the differences between the terms is important for scientists, policymakers, and the public. According to a paper by the Campaign for Accuracy in Public Health Research (CAPHR):

  • A hazard is anything with the potential to cause harm. It is the first step in a series of several steps needed to assess the danger that an ingredient or activity might pose under a particular circumstance.
  • A risk is the likelihood that a hazard will cause harm. Determining the level of risk requires assessment of whether, how, and how much a person is exposed to a hazardous substance or activity.

One analogy that CAPHR cites involves bodies of water. Any body of water (whether a puddle, bathtub, river, or ocean) poses a hazard because someone could slip, fall, or drown in the water. But the risk changes if a person is able to step over or easily walk through a small puddle (small risk) compared to diving into an ocean without being able to swim (significant risk).

Another example involves sunlight. Sunlight can be a hazard in that it can cause sunburn, skin damage, and skin cancers. But the level of risk the sunshine represents depends on the amount of exposure, including factors such as time spent in the sun, whether protective clothing or sunscreen is worn, and differences among people’s sensitivity to sunlight.

So, the fact that something can cause harm doesn’t automatically mean that it will cause harm.

ASSESSING LIKELIHOOD. A risk assessment is needed to determine the real impact of a hazard. It involves reviewing factors such as doses received, time of exposure, and probability of exposure. Assessing these various factors can help determine the likelihood that a hazard poses a risk of causing harm.

For example, the risk of sunburn or other skin damage is higher if a fair-skinned person spends several hours on the beach during the middle of a sunny day; but it is reduced for a person who wears sunscreen, a hat, or other sun-blocking clothing and goes to the beach earlier or later in the day when the light intensity is not as great.

Another everyday example cited by CAPHR is that of driving a car. This can be a hazard because it has a potential to cause harm. But we know the risk of having an accident is quite low if the driver follows safe-driving practices. Risk assessments also show that the risk of harm associated with driving a car increases if a person is texting while driving.

The confusion over the meaning of the terms hazard and risk come into the public view periodically, such as when the International Agency for Research on Cancer (IARC), an independent agency affiliated with the World Health Organization, issues a cancer classification on an ingredient or food. In recent years, IARC has issued findings on cancer hazards associated with coffee, tea, bacon, and other processed meats, and with glyphosate, an ingredient found in a commonly used weed killer. In 1991, IARC classified coffee as “possibly carcinogenic.”

In the 25 years since IARC’s initial classification of coffee as a possible carcinogen, numerous studies conducted by multiple agencies and research labs testing the claim failed to show any conclusive link between coffee and cancer. In fact, multiple studies showed that coffee consumption is linked to several health benefits. Finally, in June 2016, IARC downgraded its initial classification of coffee to “unclassifiable as to carcinogenicity to humans.”

But even that change raised questions as to why IARC did not classify coffee as probably not carcinogenic in light of the evidence showing the significant health benefits of its consumption, such as protection against Parkinson’s disease (The Journal of the American Medical Association, 2000), type 2 diabetes (American Diabetes Association, 2006), and liver disease (U.S. National Library of Medicine, National Institutes of Health, 2014). IARC officials were quoted as saying they could not say coffee was completely safe because of the difficulty in proving a negative.

Since 1971, IARC monographs have assessed about 1,000 substances. Nearly 50% of the time, the assessments have found the substance or activity to be a possible, probable, or certain carcinogen. Only one has been found to be probably not carcinogenic: Caprolactam, a chemical in nylon, according to a compilation by CAPHR. The rest state that the evidence is not sufficient to make a classification as a carcinogen.

That CAPHR compilation found the following breakdown of IARC’s classifications:

  • Group 1, carcinogenic to humans: 120 substances or activities.
  • Group 2a, probably carcinogenic to humans: 81.
  • Group 2b, possibly carcinogenic to humans: 294.
  • Group 3, carcinogenicity not classifiable: 505.
  • Group 4, probably not carcinogenic: 1.

As noted previously, IARC monographs do not determine cancer risk (i.e., the likelihood that its identified hazard will cause harm), but this fact has often been overlooked or mischaracterized, leading to public confusion on what steps to take following an IARC determination. For example, in a quote cited by CAPHR, an expert estimates that, in terms of IARC’s classification of coffee, it would take nearly 100 cups per day to reach a dangerous dose. When consumers understand the risk vs. the hazard, they realize that, because they are not consuming 100 cups of coffee per day, the risk of drinking coffee is non-existent.

In October 2015, IARC ranked processed meats, such as bacon, in its top category of known carcinogens, the same category it has for plutonium, tobacco, sun, and welding fumes. It also classified red meat as being in Group 2a, probably carcinogenic.

In April 2016, a Reuters investigative report of IARC’s methods and determinations, headlined “Who Says Bacon is Bad?”, cited the public consternation and confusion from the meat determinations: “The risks of public misapprehension were evident in some of the media reaction to IARC’s announcement on red and processed meats. The Huffington Post said: “Meat is the new tobacco”; Britain’s Daily Mail stated that “health chiefs” had “put processed meat on same level as cigarettes.”

Additional IARC monographs and determinations on other substances and activities are expected, ensuring that the debate and discussion will continue. The Grocery Manufacturers Association has urged that IARC adopt a risk-based approach when making its assessments so that policy makers and consumers receive information that is not confusing and is useful for making healthy choices.

The author is GMA Analyst, Ingredient Safety.