Comparing the risk of dying in a terrorist attack to a common household accident like slipping in the bathtub is inappropriate. After all, inanimate objects like bathtubs do not intend to kill, so people rightly distinguish them from murderers and terrorists. My research on the hazard posed by foreign-born terrorists on U.S. soil focuses on comparing that threat to homicide, since both are intentional actions meant to kill or otherwise harm people. Homicide is common in the United States, so it is not necessarily the best comparison to deaths in infrequent terror attacks. Yesterday, economist Tyler Cowen wrote about another comparable hazard that people are aware of, that is infrequent, where there is a debatable element of intentionality, but that does not elicit nearly the same degree of fear: deadly animal attacks.



Cowen’s blog post linked to an academic paper by medical doctors Jared A. Forrester, Thomas G. Weiser, and Joseph H. Forrester who parsed Centers for Disease Control and Prevention (CDC) mortality data to identify those whose deaths were caused by animals in the United States. According to their paper, animals killed 1,610 people in the United States from 2008 through 2015. Hornets, wasps, and bees were the deadliest and were responsible for 29.7 percent of all deaths, while dogs were the second deadliest and responsible for 16.9 percent of all deaths.



The annual chance of being killed by an animal was 1 in 1.6 million per year from 2008 through 2015. The chance of being murdered in a terrorist attack on U.S. soil was 1 in 30.1 million per year during that time. The chance of being murdered by a native-born terrorist was 1 in 43.8 million per year, more than twice as deadly as foreign-born terrorists at 1 in 104.2 million per year. The small chance of being murdered in an attack committed by foreign-born terrorists has prompted expensive overreactions that do more harm than good, such as the so-called Trump travel ban, but address smaller risks than those posed by animals.

In addition to the data analyzed in the Forrester et al. paper, the CDC has mortality data for animals back to 1968. This period includes the 9/11 attacks, the deadliest terrorist attacks in world history, which helps to take account of the fat-tailed distribution of actual terrorist attacks. From 1975 through the end of 2016, 7,548 people have been killed by animals while 3,438 have been killed by all terrorists. Even during this time, the annual chance of being killed by an animal is far higher than being killed in a terrorist attack (Table 1).



Table 1



Annual Chance of Being Killed by Different Means, 1975-2016



Means of Death

Annual Chance of Dying Homicide

1 in 14,296 Animal Attack

1 in 1,489,177 All Terrorists

1 in 3,269,432 Native-born Terrorists

1 in 27,482,415 Foreign-born Terrorists

1 in 3,710,897

Sources: John Mueller, ed., Terrorism Since 9/11: The American Cases; RAND Database of Worldwide Terrorism Incidents; National Consortium for the Study of Terrorism and Responses to Terrorism Global Terrorism Database; U.S. Census Bureau, “American Community Survey”; Disaster Center, “United States Crime Rates 1960-2014”; Centers for Disease Control and Prevention (CDC); and author’s calculations.



One reason people fear terrorism so much is that it appears random and there is little one can do to avoid it. While terrorism certainly appears random, not living in New York City or Washington, DC would have substantially reduced one’s chance of dying in a terrorist attack since 1975. But just because terrorist attacks strike randomly and infrequently does not mean that the fear that those attacks create needs to be addressed through new public policies that spend trillions of dollars and kill many people in addition to making daily life just a little more inconvenient for little to no benefit.



As far as I can tell, nobody suggests banning bees, dogs, or other animals just because they have killed 7,548 people since 1975. But it is common for people to argue for banning immigrants due to the manageable hazard posed by infrequent terrorist attacks by foreign-born individuals. Animals can be scary and they are infinitely more in control of their actions than inanimate objects like bathtubs, although probably not as much in control of themselves as human beings. Adjusting for an American’s number and frequency of contacts with animals relative to people is essential to understanding the relative risks of dying from animals or other people. Many of us have zero daily interaction with animals but talk to many different people.



The chance of dying in any of these types of incidents, whether terrorism or homicide or animal attack, is small and manageable. Certain precautions do make sense but only if they pass a cost-benefit test that counter-terrorism spending is guaranteed to fail. Evaluating small and manageable threats such as that from terrorism relative to other small and manageable threats from homicide or animal attacks is a useful way to understand the world and where we should focus our energies and worries.