June 2025

In her new book Murderland: Crime and Bloodlust in the Time of Serial Killers, the Pulitzer Prize-winning author Caroline Fraser maps the rise of serial killers in the Pacific Northwest to the proliferation of pollution. In this case, the lead- and arsenic-poisoned plume that flowed from Asarco’s metal smelter northwest of Tacoma, which operated for almost a century and polluted more than 1,000 square miles of the Puget Sound area, the source of the famous “aroma of Tacoma.”

Fraser grew up in the 1970s on Mercer Island, connected to Seattle by a floating bridge with a deadly design, not far from a terrifying lineup of serial killers. George Waterfield Russell Jr., who went on to murder three women, lived just down the street, a few years ahead of Fraser at Mercer Island High School. (No surprise, his family once lived in Tacoma.) She had always thought the idea that the Pacific Northwest was a breeding ground for serial killers was “some kind of urban legend,” she told Grist.

But after much time spent staring at pollution maps, and looking up the former addresses of serial killers, she came up with an irresistible hypothesis: What if lead exposure was warping the minds of the country’s most harrowing murderers? In Murderland, Fraser makes a convincing case that these killers were exposed to heavy metal pollution in their youth, often from nearby smelters and the leaded gasoline that was once burned on every road in the country.

Studies have shown that childhood lead exposure is connected to rising crime rates, aggression, and psychopathy. In children, it can lead to behavior that’s been described as cruel, impulsive, and “crazy-like”; by adulthood, it’s been linked to a loss of brain volume, particularly for men. Fraser doesn’t pin sociopathy solely on exposure to lead, though she suggests that it’s a key ingredient.

Two thousand years ago, even the Romans noticed health problems among those who worked with lead: they became pale and sickly, and too much exposure could even lead to paralysis and delirium. But lead was useful and Roman medicine hardly an exact science; some illness might simply be the price society paid for such a versatile mineral.

With two thousand years more of medical knowledge, we can be more precise about lead’s impact on the body. If you ingest lead, it is absorbed through the gut; if you inhale it, it enters through the lungs. From there, it passes into the bloodstream, where it is deposited into the bones and organ tissues.

If it stayed there, perhaps lead exposure could be ignored. But, like all body systems, the bones are not static. Lead re-enters blood in the churn and change of resorption, the nonstop process that dissolves the bones’ contents into the bloodstream as part of the metabolic replacement of old bone tissue with new.

Once released into the bloodstream lead harms the endothelial cells that line the inner walls of blood vessels, while causing a different type of cell – known as vascular smooth muscle cells – to proliferate, simultaneously stiffening and clogging the arteries. At the same time lead damages the kidneys by both hardening the organs’ blood vessels and poisoning the tubes responsible for filtering blood.

These processes, in combination, substantially raise the risk of conditions like high blood pressure, heart disease, stroke, and kidney disease. A national observational study showed that, after adjustment for various other risk factors, American adults with higher levels of blood lead had a 37 percent higher overall mortality risk, 70 percent higher cardiovascular disease mortality risk, and 108 percent higher coronary heart disease mortality risk.

From the blood, lead also slips into the brain. The blood-brain barrier, which protects the neural tissue from most toxins, lets lead through principally because lead ions chemically resemble calcium ions, vital to the proper functioning of brain cells. Once in the brain, lead degrades cell membranes, blunts neurotransmission, and deregulates intracellular signaling pathways that depend on calcium ions. It even directly kills off brain cells.

This can cause a laundry list of neurological and mental disorders: cognitive impairment, nerve damage, hearing loss, dementia, schizophrenia, and behavioral and attention problems. Many studies have found that lead exposure increases violent crime.

While both adults and children can suffer severe consequences from lead exposure, it is generally young children who receive the most exposure and who suffer the gravest consequences.2

To begin with, normal play and hand-to-mouth behavior make young children much more likely than other groups to ingest lead from sources like dust and soil, which can contain lead from paint chips, mining activity, and legacy contamination from gasoline. As they grow and develop, they absorb four to five times as much lead per unit of exposure as adults do, in part because of how lead imitates the chemistry of calcium. Children use much more calcium than adults because they are still growing new bones; replacing their calcium ions with lead is therefore particularly dangerous.

Most things that sicken children leave evidence for parents and doctors. But children exposed to lead don’t have a giveaway fever, or rash, or cough. There is no way for parents to tell that their children have been exposed, only the silent accumulation of cellular damage that, down the line, can cause long-term disease and impaired brain functioning.

Perhaps unsurprisingly, as human lead use ramped up, so too did human exposure to lead. By the 1980s, people were exposed to 1,000 to 10,000 times as much lead as ancient humans.