A Natural Experiment Demonstrating Alcohol's Downsides

Prohibition didn't work. But its proponents weren't crazy. 

The societal downsides of widespread alcohol consumption are real, especially in the case of heavy drinkers, as a recent "natural experiment" in South Africa when liquor stores were shut down due to COVID demonstrated:

This paper evaluates the impact of a sudden and unexpected nation-wide alcohol sales ban in South Africa. We find that this policy causally reduced injury-induced mortality in the country by at least 14% during the five weeks of the ban. We argue that this estimate constitutes a lower bound on the true impact of alcohol on injury-induced mortality. We also document a sharp drop in violent crimes, indicating a tight link between alcohol and aggressive behavior in society. Our results underscore the severe harm that alcohol can cause and point towards a role for policy measures that target the heaviest drinkers in society.

From here.

The body text provides background:

The sudden and unexpected ban on the sale of alcohol in South Africa on July 13, 2020 provides a rare opportunity to understand how alcohol consumption influences behavior and outcomes at a societal level.3 Research by health scientists has identified alcohol consumption as a major risk factor for injury-related deaths globally.4 This suggests that reducing alcohol consumption in an entire country could lead to a large reduction in injury-related mortality. It is therefore of key importance to test these predictions by assessing how mortality is actually affected when a policy that drastically reduces alcohol consumption is introduced. 

This paper uses the exogenous variation provided by a natural experiment in the form of a sudden alcohol sales ban to study the causal impact of alcohol on mortality due to unnatural causes at a societal level.5

We also present evidence on one key potential mechanism behind this relationship by evaluating the impact that the ban had on aggressive behavior in society (e.g., homicides, assaults, reported rape cases). This is valuable as it provides policy-makers with robust evidence about the harm that alcohol consumption generates in society and informs our understanding of whether reducing alcohol consumption is an effective way to save lives and alleviate interpersonal violence. It therefore contributes evidence towards the larger discussion regarding the aggregate costs and benefits of alcohol consumption for society. . . . 

Our main result is that the alcohol ban reduced the number of people dying from unnatural causes in South Africa by at least 120 per week. This reflects the lowest estimate of the effect size that we obtain across a range of different empirical specifications. It represents a substantial reduction in mortality due to unnatural causes, since it implies a 14% reduction in all unnatural deaths in the country when compared to the average level during the five weeks immediately preceding the July Alcohol Ban. In the analysis below, we show that this reduction in mortality is almost entirely confined to men. This is not entirely surprising since, in South Africa, men are far more likely to die of unnatural causes than women (approximately 78% of the over 150 000 deaths from unnatural causes recorded in our dataset between 2017 and 2019 were males).7

This pattern is not unique to South Africa. For example, Gawryszewski and Rodrigues (2006) describe the gender distribution of injury-related mortality in Brazil in 2003 and show that 84.3% of the people that died from injury-related causes (e.g., homicides, suicides, transport-related deaths) were men. Furthermore, as in many countries around the world (e.g., Brazil, Russia), in South Africa men are far more likely than women to engage in heavy drinking.

We find that the ban on alcohol reduced the number of men dying due to unnatural causes by at least 120 per week, but find no evidence that it had a statistically significant effect on the mortality of women in the population as a whole. (Importantly, this does not imply that the absence of alcohol had no impact on other outcomes for women, such as gender-based violence, which often does not result in death.) 

Further, we provide evidence that approximately half of the observed reduction in mortality is found amongst young men aged 15-34. To provide support for the validity of these main results, we conduct several robustness exercises. These include running placebo regressions, varying the window size around the policy change used for our analysis, and relaxing the assumptions made on the error structure. We also address two key concerns regarding the quality of the natural experiment and the assumptions underlying our ability to use it to identify the impact of alcohol on mortality.8 . . . 

We document evidence suggesting that the alcohol ban resulted in a sharp drop in all of these outcomes, with at least 77 fewer homicides, 790 fewer assaults and 105 fewer rape cases reported per week during the alcohol ban period in comparison to the preceding five weeks. These constitute a drop in each outcome of 21%, 33% and 19% respectively.

To illustrate the dynamic effects of the alcohol ban over time, we also report the results from event study analyses considering the evolution in unnatural mortality and also the three violent crime outcomes.The general pattern that emerges is that the effect of the ban appears to have been strongest in the first few weeks. A speculative possible reason for this is that black market trade and production started to reduce the effectiveness of the ban. Overall, the results provide compelling evidence that alcohol is causally responsible for inducing aggressive behavior in society at a significant scale, resulting in substantial harm.

What lessons can be drawn from these results?

First, these findings are highly informative for policy discussions within South Africa as they provide clear causal evidence of a strong relationship between alcohol consumption and both interpersonal violence and unnatural mortality. This evidence therefore helps to support the conclusions drawn from comparative risk assessment (CRA) analyses by health scientists.

Second, this paper provides a valuable contribution to the collective global effort to better understand the relationship between alcohol, violence and injury-related outcomes more generally. This is an extremely important endeavour, since alcohol is estimated to have been responsible for 5.3% of all deaths worldwide in 2016 (3 million), with 0.9 million of those being injury-related deaths. In addition, alcohol is implicated in many more incidents of violence and non-lethal injuries and was the leading risk factor for premature death in individuals 15-49 years old worldwide in 2016. 

While it is essential to acknowledge that any evidence collected within a single country relates to behavior that occurs within a particular societal context, collecting rigorous evidence across a range of contexts makes it possible to aggregate the evidence and identify which alcohol-driven relationships occur systematically across contexts, and which are context-specific (i.e., mediated by an interaction between alcohol consumption and other societal factors). The evidence presented here is particularly useful for this exercise since South Africa is part of a class of countries: (i) for which alcohol is estimated to be responsible for a large number of injury-related deaths, and (ii) that make up a large part of the world’s population, but tend to be underrepresented as the focus of academic research relative to more developed nations due partially to constraints on the availability of highly detailed data. 

In South Africa a minority of individuals drink (31% of individuals aged 15 years and older, 43.2% of men and 19.4% of women). However, those who do drink, tend to drink heavily: six out of every ten drinkers (59%) engage in heavy episodic drinking (HED), which corresponds to 18.3% of the population over 15 years of age, or 30.6% of men and 6.5% of women.9 South Africa is also a country that suffers from a relatively high rate of mortality due to unnatural causes (e.g., interpersonal violence, road traffic collisions, and suicide), with approximately 50.000 injury-rated deaths recorded per year between 1997 and 2012, and also between 2015 and 2019 (own calculations).10

Therefore, this evidence on the impact of alcohol from South Africa provides an informative benchmark for countries characterised by high levels of injury-related deaths, a sizable fraction of the population that drinks excessively, a strong asymmetry in drinking patterns between men and women, and high levels of poverty and inequality. This set of characteristics is reflective of several countries in Eastern Europe and South America, such as Brazil (where 32.6% of men and 6.9% of women were HEDs in 2016, which is nearly identical to the pattern in South Africa) and Russia (where 48.4% of men and 24.2% of women were HEDs in 2016). Both countries also share many other structural similarities with South Africa that could interact with alcohol consumption in influencing behavior, such as suffering from social issues including poverty, inequality and high levels of violence. Both countries are also characterized by a strong gender asymmetry in unnatural deaths, like South Africa.

Third, our results provide a society-level demonstration of the way in which alcohol can act as a catalyst in inducing violence. While contextual factors in different countries may shape the way in which excessive alcohol consumption manifests in behavior, the growing body of evidence of a deep link between excessive alcohol consumption and aggressive behavior is important for all countries. The evidence discussed in this paper complements a large body of existing work showing that there is a strong association between alcohol consumption and aggressive behavior across a range of domains. More specifically, our causal evidence contributes to the existing literature that documents a strong association between homicides and alcohol, finding that a high fraction of homicide offenders (and victims) were under the influence of alcohol at the time of the offence.

For example, Kuhns et al. (2011) reports that from over 70,000 toxicology test results from 13 countries (predominantly from the United States), 48% of homicide victims tested positive for alcohol, while Kuhns et al. (2014) reports that from almost 30 000 homicide offenders across 9 countries (mostly Australia, the United States and Europe), 48% were reported to be under the influence of alcohol.12 

The presence of a link between alcohol and aggression has also been demonstrated in the laboratory by experimentally varying the alcohol present in an individuals’ system as they complete a task that involves administering electric shocks to a fictitious opponent. The authors found a strong link between the dosage of alcohol in an individual’s system and the aggression they showed in administering the electric shocks.

Taken together, this body of work on the underlying psychological mechanism relating alcohol to aggression indicates that it is also important for countries that differ substantially from South Africa, such as high-income countries, to pay attention to the evidence in this paper showing how large an impact alcohol can have on behavior at a societal level, since: (i) heavy episodic drinking is substantially more prevalent in many higher income countries, such as the USA, UK, Germany and France, than it is in South Africa, (ii) in these countries, the aggression triggered by excessive alcohol consumption may manifest in harmful behaviors that result in harder-to-detect outcomes, such as sexual and gender-based violence, child abuse and emotional abuse, and (iii) it is not common to observe a societal level source of exogenous variation in alcohol consumption, which makes it challenging to evaluate the effect of alcohol in society even when the data on the relevant outcomes is available.13 . . . 

This paper contributes to several strands of the literature. It relates most closely to the body of work that studies the short-run relationship between alcohol and harmful behavior, such as violence, suicide and crime, risky sexual behavior, and outcomes such as mortality and morbidity. There are two main empirical approaches that have been employed in this literature to provide this type of causal evidence: (i) using changes in underage drunk driving laws or minimum drinking age laws, or (ii) using changes in the alcohol trading hour regulations.14

Each of these approaches generates valuable insights regarding the influence of an important alcohol control policy margin (i.e., restrictions on young adults on the verge of legal adulthood, or restrictions on late-night on-premise drinking or late-night purchases). 

Collectively, this evidence points towards alcohol control policies being effective in reducing short-run social harms on these margins. 

To the best of our knowledge, we are the first to document causal evidence of the short-run impact that alcohol consumption has at a societal level in contemporary times. In this, our paper joins a long history of research trying to understand the relationship between alcohol and mortality and morbidity more broadly. This work emanates from the contentious social debates of the late nineteenth and early twentieth century in many Western societies, including the United States, about whether allowing alcohol consumption is good for society. A set of more recent studies have tried to estimate the effect that state and federal prohibition statutes enacted in the United States during the early decades of the twentieth century had on mortality and morbidity. 

This literature portrays a highly ambiguous picture regarding the health and safety impacts of alcohol prohibition. However, in a recent contribution, Law and Marks (2020) argue that they overcome several empirical challenges faced by the prior work and conclude that early prohibition laws enacted between 1900 and 1920 significantly reduced mortality rates in the United States.15

Our results are in line with the conclusions of Law and Marks (2020). However, our study differs from the research examining the United States Prohibition era in several important ways. The Prohibition research typically considers a substantially longer time horizon, often using yearly data. This implies that it is evaluating the composite effect of prohibition laws, along with all the social changes that occur as society shifts to a new equilibrium. 

Additionally, the following considerations suggest that these evaluations are likely to be measuring the influence of alcohol together with other social changes: (i) endogenous community characteristics influenced where dry laws were passed prior to 1920, and the degree to which they were enforced after National Prohibition came into force in 1920, (ii) the first decades of the twentieth century constituted a period of substantial turbulence in the prevailing social norms regarding alcohol, and (iii) the gap between prohibition laws being enacted and becoming effective was up to two years.

In contrast, we use daily mortality data to study the impact of an immediate and unanticipated five-week drop in alcohol consumption. Therefore, the interpretation of our results is complementary but different: our results examine the short-run influence of alcohol on mortality in society as it currently is, rather than the influence of alcohol prohibition policies on medium and long-run mortality after adjusting to the new equilibrium. In addition, society has changed in the last hundred years, which makes it useful to document modern evidence.

Footnotes

1 Alcohol consumption may also lead individuals to harm themselves—intoxication can reduce self-control, inducing myopic behavior that the individual would avoid if sober.

2 The causal evidence that does exist typically focuses on specific segments of society, with evaluations of the impact of changes to the minimum legal drinking age providing the main example of this.

3 This five-week long ban was the second ban on alcohol sales implemented by the South African government in 2020, but unlike the earlier ban it did not occur amid the initial upheaval caused by COVID-19 in which many new regulations were introduced and individuals were rapidly changing their everyday behavior.

4 For example, the WHO (2019) estimates that alcohol was responsible for 0.9 million of the 5.9 million global injury-related deaths in 2016, while Probst et al. (2018) use a comparative risk assessment approach to estimate that over 12 000 of the approximately 50 000 injury-related deaths in South Africa in 2015 were attributable to alcohol consumption.

5 In the paper we use the terms “injury-induced mortality” and “unnatural mortality” interchangeably. We do this because we find the former to provide a more natural terminology, and is therefore more suitable for an interdisciplinary readership, but the latter corresponds to the designation of these deaths in the National Population Register dataset and on abbreviated death certificates in South Africa. Deaths due to unnatural causes include deaths with an external cause, such as homicide, traffic injuries and suicide, while natural deaths pertain to conditions resulting from aging and illness.

6 The July Alcohol Ban was in force between July 13, 2020 and August 17, 2020. It therefore divides the Level 3 period, which spanned June 1, 2020 to August 17, 2020, neatly in half. It is worth noting that there were 5 Levels of policy response, such that Level 3 involved intermediate restrictions that were far lighter than the Level 5 restrictions.

7While detailed cause-of-death data is not yet available in South Africa for 2020, Matzopoulos et al. (2015) report that for 2009, the three leading causes of unnatural mortality in South Africa were homicides, road-traffic injuries and suicide. Homicides constituted 36% of unnatural deaths, with 86% of these being male deaths. Road-traffic injuries resulted in 33% of unnatural deaths, with 76% of these being male deaths. Suicides made up 12.3% of unnatural deaths, with 82% of these being male deaths.

8 In addition, using data from previous years (i.e. excluding 2020) we document systematic regularities in the pattern of unnatural deaths observed: (i) a weekly pattern: mortality due to unnatural causes follows a highly predictable weekly pattern, with an increase of over 50% in daily unnatural deaths on Saturdays and Sundays relative to weekdays, (ii) a monthly pattern: unnatural mortality is highest during the last and first few days of the month (over 30% higher), suggesting that this monthly pattern may be related to wage payment schedules. Our data allow us to control for these systematic mortality patterns in our analysis.

9 The average absolute amount of alcohol consumed per day by those who drink is 64.6 g or 5.4 standard drinks in South Africa. However, it is important to exercise caution in interpreting these consumption amounts that condition on being a drinker, especially in cross-country comparisons, since there is substantial heterogeneity across countries in the fraction of the population that drinks. Therefore, a country with a larger fraction of social drinkers will tend to have a lower conditional consumption amount, even if heavy drinking is present in society. For example, in Germany and France, the average daily consumption of alcohol conditional on drinking is 36.5 g and 36.1 g respectively. However, in these two countries, 79.4% and 73.3% of the population are classified as drinkers. This means that the individuals in the right-tail of the alcohol consumption distribution in these two countries are likely to drink substantially more than than 36.5 g or 36.1 g per day. In Germany, 34.2% of the population over 15 years of age are classified as heavy episodic drinkers (HEDs), while in France, this percentage is 31.2%, implying both countries have substantially more HEDs than the 18.3% in South Africa. 

10 The population of South Africa has grown from 43 million in 1997 to almost 58 million in 2018, implying a gradual reduction in the per capita rate.

11 In line with this, the WHO (2019) provides estimates for the age-standardized alcohol-attributable injury death rate in countries around the world. These estimates are high for the majority of countries in Sub-Saharan Africa, South America, and Eastern Europe (typically above 10.8 per 100 000 people), with South Africa in the interior of the range of estimates. Similarly, the prevalence of heavy episodic drinking amongst current drinkers is high in the same regions (Sub-Saharan Africa, South America, and Eastern Europe), with South Africa fairly typical in this.

12 In recent work that explores the causal role of alcohol in victimization more broadly, Bindler et al. (2021) show that obtaining increased access to alcohol at ages 16 and 18 in the Netherlands results in sharp discontinuous increases in the risk of being a crime victim.

13 One example of a recent paper that does manage to find an interesting source of exogenous variation is the work by Ivandic et al. (2021) that exploits the timing of football games to examine the effect of alcohol consumption on domestic abuse in the Greater Manchester area in the United Kingdom, finding that alcohol consumption results in an aggregate increase in domestic abuse.

14 An exception to this is Nakaguma and Restrepo (2018), who study the impact of a single-day alcohol sales ban during the 2012 municipal elections in Brazil and find that motor vehicle collisions and traffic-related hospitalizations were reduced by 19% and 17% respectively.

15 Bhattacharya et al. (2013) reach a similar conclusion in their insightful analysis of the 1985-1988 Gorbachev Anti-Alcohol campaign, showing that the campaign was associated with a marked reduction in mortality during the late 1980s, while the demise of the campaign saw increased mortality in the early 1990s. Interestingly, much of this effect was lagged due to the delayed effect of alcoholism on several health outcomes leading to mortality, e.g. liver cirrhosis and heart disease. Our paper complements their work by providing an analysis of the short-term behavioral impact.

The authors estimate that the alcohol ban caused a significant decline in homicides, assaults, reported rapes, and "unnatural mortality", defined so that it "includes deaths precipitated by road traffic injuries, interpersonal violence, and suicide, but excludes all deaths due to natural causes, such as illness (e.g., COVID-19)."

Note that the Y-axis does not have a zero baseline and thus visually exaggerates the effect observed somewhat.

The authors consider this a "lower bound" of an effect, but the allocation of the risk between staying at home more due to a lockdown and not consuming alcohol is a tricky one. They estimate the alcohol specific source by comparing results after the alcohol ban that was put in place ended but the curfew remained in place, to the time period when both were in place. In this regard, the paper states that:

(i) for individuals aged 14 or younger, we find no effect of the alcohol ban on mortality, (ii) for individuals between 35 and 54 years, we estimate that the alcohol ban resulted in 6.7 fewer male deaths per day, with a possible smaller reduction in the mortality of women by 1.3 deaths per day, (iii) for individuals over 55 years, we estimate that there were 2.5 fewer male deaths per day, and 1.6 additional female deaths per day during the alcohol ban period. 

Overall, the results indicate that most of the effect of the alcohol ban on unnatural mortality was concentrated amongst younger male adults, with a smaller, but still sizable, impact also observed amongst middle aged men. . . .

we note that when the July Alcohol Ban ended, the curfew remained in place and . . . that unnatural mortality increased sharply at this point in time and remained at pre-2020 levels despite the ongoing curfew. Second, we estimate the impact of a one hour reduction in the curfew length which occurred in the middle of the July Alcohol Ban period. We show that it did not have a statistically significant impact on unnatural mortality.