V. Time-Precedence and the Dawn to Dusk of Delinquency
The time-precedence indicator of causation requires, at a minimum, that the suspected cause precede the effect. The statistical best-fit time lags relating trends in lead exposure with crime and unwed pregnancy trends present an especially compelling case of time precedence because they are all consistent with neurobehavioral damage in the first years of life. The surge in youth crime over the 1960s and plummeting youth arrest rates since the early-1990s present more time-precedence evidence, because younger age groups would be the first to show the neurobehavioral effects of both rising and falling trends in preschool lead exposure.
In response to reader questions about the October 2015 Coates article, The Atlantic published a follow up on whether lead poisoning contributed to mass incarceration, citing my research and a 2002 Cook and Laub study that questioned my 2000 study findings. Cook and Laub focused on black male homicide victimization rates to show that violence fell across several age groups over the 1990s, but lead exposure trends are expected to affect offending by age, not victimization by age. There has been a historical correlation between offending and victimization by age, but the fall in lead exposure has weakened that correlation: From 1993-2013 there was a 73% decline in juvenile homicide offenders, but only a 57% decline in juvenile victims, as the percent of juvenile victims killed by an adult increased from 51% in the early-1990s to 66% in 2010-2013. Cook and Laub also made the following important statement about how further research could help to answer their questions:
“Given the volatility in the rates of juvenile violence, forecasting rates is a risky business indeed. Effectively narrowing the range of plausible explanations for the recent ups and downs may require a long time horizon, consideration of a broader array of problem behaviors, and comparisons with trends in other countries.” (Cook/Laub, 2002)
That was a perfectly reasonable statement about plausible explanations for USA juvenile crime trends in 2002, but research since 2002 has addressed the additional perspectives suggested, and the evidence all points to lead exposure as the key determinant of crime trends. My 2007 study provided “comparisons with trends in other countries” and found that lead exposure trends explained violent and property crime trends around the world. With respect to “consideration of a broader array of problem behaviors” the relationship between lead exposure and unwed youth pregnancy rates has now demonstrated remarkable ongoing strength and predictive power.
My 2007 study also provided the following “long time horizon” perspective on property crime arrest rates by age: “The overall USA property crime rate was about the same in 1970 and 2003, but the property crime arrest rate for youths under age 15 fell 45% from 1970–2003 … and the arrest rate for adults over 24 rose 58%.”
The 1970-2003 drop in the under-15 property crime arrest rate compares young juveniles in 1970, born during the mid-1950s surge in gasoline lead emissions, versus their counterparts in 2003, born after the 1980s phase out of leaded gasoline. The 1970-2003 increase in the over-24 arrest rate compares adults in 1970, born before the post-WWII rise in gas lead, versus their 2003 counterparts born before the 1980s fall in lead emissions.
In 2014, the under-15 property crime arrest rate was down 80% compared to 1970, and down 69% compared to 1960. The under-15 property crime arrest rate fell to a new record low every year from 2000 through 2014. Forecasting the juvenile crime rate has become much less risky over recent years – it just goes down.
Now, let’s consider an even longer time horizon.
The “Dutch process”, producing white lead in large batches, began to spread across Europe in the 1700s, and the use of white lead in paint surged in the early-1800s with the dawn of the industrial revolution. Pulsifer observed that white lead manufacture in the late-1700s “must have assumed considerable importance in Great Britain, as several patents were granted for improvements in the old process and for its manufacture by new methods.” In 1810, Britain produced 12,500 tons of lead - more than the rest of Europe combined. British output then surged to 46,000 tons in 1845 and peaked at 73,000 in 1856, before falling to 54,000 in 1873.
In 1816, following the late-1700s flurry of white lead patents, the English language recorded its first known use of the term “juvenile delinquency”. King explains that juvenile crime was not thought to be a “particularly threatening problem” in the 1700s, but had become a “major focus of anxiety” in England by the mid-1800s. Magarey called this the “invention of juvenile delinquency”, but King found that this perspective was based on national data from the 1830s and 1840s, and earlier local records show that the juvenile crime surge was quite real. That crime wave began in large cities in the 1810s and 1820s, creating a large 1820s urban-rural difference in juvenile crime, but then rural juvenile crime rates surged after 1825 and had largely caught up with city juvenile crime rates in the 1840s.
In London, the percentage of property crime offenders who were juveniles nearly doubled from the 1790s to the early-1820s. Total nationwide arrests also tripled from 1805 to the early-1820s, driven by the juvenile crime surge in cities. In the 1820s, juveniles accounted for 22% to 34% of property crime arrests in large cities but only 4% to 8% of property crime arrests in rural areas. By the mid-1840s, the percent of property crimes committed by juveniles was roughly the same in cities (30%) and rural areas (28%).
The early-1800s juvenile crime surge in Britain, like the early-1900s USA homicide surge, was presaged by a surge in white lead output. The early-1800s juvenile crime surge in Britain was concentrated in cities where white lead was widely available after 1800. The 1840s convergence of urban and rural juvenile arrest rates in Britain, like the USA 1901-1911 convergence of urban and rural murder rates, was presaged by a transportation revolution that made white lead available in rural areas. Bogart and Majewski show that Britain enacted many improvements to roadways and canals from 1800-1830, enabling freight transport to rural areas.
The amount of lead used in European paint declined over the second half of the 1800s as zinc pigments became available amid increasing concern over occupational lead poisoning risks. Orfila became a leading figure in the Paris medical community in the 1830s after publishing a book on toxicology in 1818 that included warnings about the causes of lead poisoning, a.k.a. “painter’s colic”. In 1839, Tanquerel des Planches published a study of 1,207 persons with lead colic in France, showing two-thirds were painters or lead pigment manufacturing workers. Osmond states that French concern about white lead health risks and French efforts to produce safer zinc pigments date from 1780, and “production in the 1840s then facilitated a rapid and wider adoption of zinc oxide to protect the health of French pigment manufacturers and painters”.
That early concern about white lead presaged a large crime decline in France over the 1800s: “Violent crimes declined from 6 per 100,000 inhabitants in 1826 to 4.3 in 1913, while property crimes precipitated from about 15.9 to 3.4 per 100,000 over the same period”. The property crime rate decline was especially steep from the mid-1850s through the 1860s (from about 15 to 6 per 100,000), after zinc pigment output surged in the 1840s.
In Britain, an 1825 painter's manual described symptoms of severe lead poisoning, “known in some parts of England by the name of the painter's colic”. In 1831, Thackrah published his influential work on the effects of “Arts, Trades and Professions . . . on Health and Longevity", noting his wish to “diminish the ill health of plumbers, painters … [and] the far greater misery and mortality of the manufactures in which white lead is prepared”. Charles Dickens, better known for his writing in Oliver Twist about delinquents in 1830s London, also described the suffering of workers in London’s white lead mills in 1868: "Sure 'tis the lead-mills … and 'tis lead-pisoned she is, sur … and her brain is coming out at her ear, and it hurts her dreadful”. In 1897, an Illustrated London News advertisement for “Aspinall’s Enamel” emphasized that this product was “NOT MADE WITH LEAD” and was “NON POISONOUS”, showing broad awareness of lead paint poisoning risks in late-1800s Britain.
Himmelfarb states that births to unmarried women in Britain fell from 7% of all births in 1845 to less than 4% by 1900, and the indictable offense rate fell by almost 50% from 1857 to 1901, which she attributes to “Victorian virtues”. Vickers and Ziebarth recently discovered another piece of that late-1800s crime decline puzzle: “The fraction of offenders over 40 among male offenders convicted of economic crimes increases from 18.9% in the 1860s to 35.4% in the 1890s”, and the average age of men accused of simple larceny increased by seven years. In other words, the steep decline in late-1800s offending in Britain was associated with even steeper declines in juvenile and young adult offending.
Himmelfarb notes that Britain maintained a low crime rate through the early-1950s, but crime began a “dramatic rise” starting in the mid-1950s. My 2007 study highlighted 1958-1997 shifts in British caution and conviction (arrest) rates by age for indictable offenses, showing that the latest crime wave in Britain began with a new generation of Oliver Twist delinquents:
“Age-14 British males had the highest caution and conviction rate for indictable offenses in 1958, but peak offending shifted to age 18 by 1997. The age-10 offense rate fell 70% from 1958–1997, as age 18–29 offending rates increased three to five-fold. Males ages 12–14 in 1958, born as gas lead exposure rose after World War II, had higher offending rates than older teens born before that rise in lead exposure. By 1997, offending declined relative to 1958 only for males under 14, born after the mid-1980s fall in British gas lead use, while offending rates rose for older teens and adults born over years of rising gasoline lead use.” (Nevin, 2007)
In 1986, Britain lowered the maximum lead content of gasoline from 0.4 to 0.15 grams per liter and began the sale of unleaded gasoline. Unleaded gas grew to 19% of total gasoline sales in Britain by 1989. In 2016, Britain’s Ministry of Justice reported that juvenile arrests fell 73% from 2006/2007 through 2014/2015.
In Canada, the overall index crime rate fell by 18% from 1998-2008. Over those same years, the juvenile index crime arrest rate fell by 36% as the adult arrest rate fell by just 6%. In the past decade, Canada introduced their “crime severity index” that takes into account both the change in the volume of crime and the relative seriousness of crimes committed. From 2007 to 2014, the Canada youth crime severity index fell by 41%.
From 2008/09 to 2014/15, Australia burglary arrest rates fell 46% for ages 10-19 and 33% for ages 20-29, and robbery arrest rates fell 35% for ages 10-19 and 25% for ages 20-29.  Over those same years, Australia burglary arrest rates increased 26% for ages 45-49 and 37% for ages 50-59, and robbery arrest rates increased 18% for ages 45-49 and 27% for ages 50-59.
From 1994 to 2014, New Zealand index crime arrests fell 42% for ages 14-16, 38% for ages 17-20, and 18% for ages 21-30. Over those same years, New Zealand index crime arrests increased by 28% for ages 31-50 and 96% for those over age 50.
All over the world, the sun is setting on the era of juvenile delinquency. Remember what this era was like, because your grandchildren are going to love to hear you tell the story about how teenagers were dangerous in the olden days.
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