The story of American scientist Thomas Midgley Jr. is among the most controversial in 20th-century science. His discoveries advanced industry and technology, yet they also caused decades-long human and environmental disasters.
Midgley, a mechanical and chemical engineer who worked at General Motors in the 1920s, invented tetraethyl lead as an additive for gasoline to prevent engine knocking and improve performance. Despite the scientific community’s awareness of lead’s neurotoxic effects, the product was widely marketed under the trade name “Ethyl” without disclosing its poisonous nature, according to leravi.org.
In 1924, a tragic accident at a New Jersey plant killed five workers and poisoned dozens more, yet manufacturers continued to promote the substance globally.
Decades later, geochemist Clair Patterson revealed the scale of the catastrophe while researching at the California Institute of Technology. He discovered widespread lead contamination in soil and the atmosphere, prompting him to develop the modern “clean room” to prevent contamination in scientific experiments.
Patterson’s subsequent studies showed that environmental lead levels had skyrocketed since the introduction of leaded gasoline, leaving modern humans with lead concentrations in their bones far higher than those of previous generations. These findings ultimately led to stricter environmental regulations in the United States and worldwide, culminating in the Clean Air Act, which gradually phased out leaded gasoline in the 1970s.
Modern research estimates that more than half of all Americans were exposed to elevated lead levels during childhood, resulting in a collective loss of over 800 million IQ points, in addition to chronic exposure being linked to higher rates of heart disease and premature death.
