Review of Unleaded: How Changing Our Gasoline Changed Everything By Carrie Nielsen, New Brunswick: Rutgers University Press. 2022. 163 pp.

Daniel Renfrew

West Virginia University

For over 5000 years, humans have been using lead in innovative ways, from transporting water to sweetening food and producing written language. For just as long, humans have been poisoning themselves and others with this “mischievous” (as Benjamin Franklin put it) metal. Most people growing up in 20th century United States are likely aware of the health hazards of lead in paints, gasoline, industrial smelters, or water pipes, and recurrent public scandals like the recent Flint, Michigan lead water crisis serve as reminders of lead’s latent and continuing menace. Biologist and environmental scientist Carrie Nielsen, author of Unleaded: How Changing Our Gasoline Changed Everything, displays an admirable knack for clearly identifying the deeper stakes of the country’s lead exposure experience: “…back in the 1960’s and 1970’s, all of Flint’s children had elevated levels of lead in their blood. In fact, nearly all preschool-age children in the entire United States had elevated blood lead levels” (x). The root cause of this nearly universal exposure, and the subsequent dramatic decline in population blood lead levels, or as Nielsen simply puts it, how the “rise and fall of leaded gasoline has affected every generation of Americans alive today” (1), is the central focus of this book.

The story Nielsen tells will be familiar to lead researchers and historians of public and environmental health. In the 1920s, Charles Kettering of GM assigned Thomas Midgley to figure out a way to reduce engine knock and increase octane levels in the increasing and ever-faster automotive fleet. Midgley, through the newly formed Ethyl Corporation, patented the use of tetraethyl lead (TEL) as a gasoline additive, which was then mass produced by DuPont. From the beginning, pioneering labor and occupational health advocates like Dr Alice Hamilton sounded the warning of the deadly hazards of this “looney gas” (20) for workers producing TEL, and for the public at large. The lead industries promoted their own in-house science, led by Robert Kehoe, to “demonstrate” the safety of TEL, society’s “Gift of God” (20), and discredit critics as unhinged, unethical, and ideologically motivated. They hired PR firms to bolster their image and mobilize scare tactics against critics. Governments at the state and federal levels opted for a laissez faire approach that favored industry, downplayed lead exposure risks, and shifted the burden of proof of TEL’s harms to the public. The result, as Nielsen highlights in her book, was 5 decades of children growing up in a “lead-saturated environment” (6) that indelibly marked the fate of entire generations. Lead poisoning was devastating for individuals, particularly children, but its effects were also expressed collectively, through increased spending on special education, social services, and health care. Lead poisoned children grew up more predisposed to learning, behavioral, and health problems, and even to violence, contributing, as young adults, to the violent crime wave at the end of the 20th century. Lead exposure was also and continues to be uneven, inflected by the structural disadvantages of housing discrimination and environmental racism, with Black children burdened with up to 40% more lead than their White counterparts (7).

Unleaded, however, highlights not just the rise but the fall of leaded gasoline. The book recounts the important and inspirational story of maverick independent scientists like Clair Patterson, Herbert Needleman, Philip Landrigan, Howard Mielke, Rick Nevin and so many others, who refuted lead’s “natural” presence in bodies and the environment, while demonstrating lead’s impacts on IQ, the links between lead and delinquent behavior and violence, and ultimately that there is “no safe level” (83) of lead exposure. Nielsen’s book not only recounts the rise and fall of leaded gasoline. It serves as both a cautionary and inspirational tale, respectively, of industrial malfeasance and scientific advocacy, with extraordinary real-world consequences. Average population blood lead levels (BLLs) fell dramatically as TEL was phased out in the 1970’s and 1980’s, with average BLLs dropping from an estimated 20 μg/dL in the late 1960’s and early 1970s, to less than 2 μg/dL today, although significant spatial and racial disparities persist (44–45). Lead represents, despite its devastating impacts, a “story of amazing progress” (108) as one of the 20th century’s most remarkable public health successes.

The book follows a clear structure. The early chapters take the reader from the Flint water crisis to a broad overview of lead in 20th-century United States, and the specific origins and history of TEL, alongside other industrial and consumer uses of lead. The middle sections of the book focus on the scientific battles over lead’s impacts on health, the contested and evolving role of regulatory institutions and laws, and the developing mass of epidemiological and toxicological studies of pediatric lead poisoning, including the links between lead exposure and violent crime. The final chapters of the book examine the persistent legacies of lead in dust and soil, recent litigation against lead industries, and cost-benefit calculations of lead abatement. Nielsen draws upon the lessons of the history of leaded gasoline in the United States to inform other environmental debates, in this case climate change.

Much of this story, though always valuable to recount, is not particularly original for those well versed with the history of lead. What I found most valuable and intriguing, is the focus in chapters 5 and 6 on lead’s physiological impacts on the brain, coupled with the foregrounding of research on the links between lead exposure and violent conduct and crime. Although also well known, the links between lead poisoning and violence often get corollary treatment in other social scientific and historical accounts of lead. In Unleaded, Nielsen meticulously details the statistical evidence pointing to a strong causal (if not exhaustive) relationship between lead exposure and crime, while engaging with important criminological theories and caveats of the “sordid history [of] biological explanations of criminality” (78). Her discussion of lead’s impacts on brain function is among the clearest I have read. She brilliantly sums up the double violence of lead, and TEL in particular: “Arguably, leaded gasoline was not just a cause of violence; it was itself a form of systemic violence done to America’s children” (115). While individuals should be held accountable for crime, Nielsen concludes, so too should the corporations that manufactured a product that for half a century significantly contributed to spikes in violent crime. Eliminating TEL from gasoline highlights the urgency of eliminating lead from other ongoing and legacy sources. Nielsen summarizes the positive impacts of “un-leading” the nation: “…we got the lead out of our gasoline, and more than 90 percent of the lead out of our preschool children. Today’s children and young adults are healthier, smarter, and less violent than they would have been if not for that extraordinary effort” (108).

Unleaded is a short book with concise arguments and eminently readable prose. Particularly impressive is the way Nielsen explains and distills complex biological and engineering processes, from lead uptake in the brain to the mechanics of octane in engine performance. The book would be of particular interest to undergraduate courses covering critical health studies, environmental studies, or science and technology studies. Its focus on violence could make it suitable for sociology or criminology courses as well. For anthropology or history, the book would pair nicely with more detailed ethnographic or historical case studies of lead poisoning in the United States or around the world.