In 1925, General Motors found that they needed to improve their engine performance as a way to compete with Ford’s new and more powerful Cadillac. The octane boosting properties of Tetraethyl Lead (known as TEL) had been discovered in 1921 by General Motors’ chief chemist Thomas Midgley, who suggested adding it to petrol as an anti-knocking agent. This decision would have deadly long-term repercussions, with millions of people still suffering the effects of lead poisoning to this day.
A Well-Known Peril
Lead came into widespread use during the Roman era as a by-product of silver mining. Due to its abundance and low melting point, lead was found to be ideal for producing many common household items, including pots, wine urns, plates, and water pipes. However, as early as the first century AD, the toxic properties of lead were well-known; early symptoms of lead poisoning that various Roman sources describe included weakness, fatigue, nausea, and abdominal pain.
Throughout the centuries, the ill-effects of lead continued to be documented. In 1696, the Count of Wurttemberg banned the addition of lead to wine after an outbreak of lead poisoning, and in 1892 the first accounts of children dying from ingesting lead paint began to emerge.
Even a mere decade before the introduction of lead to petrol, physicians were still documenting the poisonous effects of lead. In 1914, conclusive proof had been found that numerous childhood deaths had been caused by lead poisoning. Many people were therefore rightly worried that adding lead to petrol would cause lead oxide to be released into the air in huge quantities.
‘No Evidence of Harm’
In response to these concerns, the Ethyl Corporation, which was owned by General Motors, funded a number of studies to try and convince the public that TEL in petrol was perfectly safe. One such study, conducted by the Bureau of Mines, reported that ‘animal studies indicated no risks to the public’. However, the report was widely criticised by a number of respected scientists.They argued that the number of animals used was too small, and the duration of exposure was too short to draw any reliable conclusions about TEL’s safety.
The Ethyl Corporation also had the support of some health officials. Dr Emery Hayhurst of the Ohio Department of Health stated that from ‘observational evidence’ he could conclude that TEL was completely safe. However, few people at the time knew that Dr Hayhurst was also a paid consultant to the Ethyl Corporation, and an advisor to the Bureau of Mines.
Many reputable scientists, including Alice Hamliton, the US’s foremost expert on lead, argued that the risk to public health was perfectly clear. Not only that, but there were also several safer alternatives to lead. Ethanol had been demonstrated to be just as efficient as in experiments conducted by the US Navy in 1908. However, the Ethyl Corporation denied that alcohol was an alternative to TEL, and did everything they could to bury the evidence. Indeed, until 1965, all studies on TEL were funded by the Ethyl Corporation and General Motors.
In the end, the short term economic benefits of leaded petrol were prioritised over the risks of long term health problems, and leaded petrol became a mainstream commercial industry.
Why is Lead so Dangerous?
While lead is dangerous to both adults and children alike, children are more severely affected by lead poisoning. It has been shown to cause a huge number of developmental problems and cognitive disorders, and there is now no known safe threshold for exposure. For example, in his 1979 study, Needleman showed that the higher the lead content in children’s blood, the greater the negative impact on IQ. Later studies found that an estimated gain of around 5 points in IQ score was associated with the decline in average blood lead concentrations as leaded petrol was phased out.
Even at lower levels of exposure that were touted by petrol companies as safe, lead is known to cause numerous long term health problems. As well as diminished cognitive ability, lead exposure has also been linked to shortened attention span, dyslexia, attention deficit disorder, hypertension, kidney damage, and reproductive problems. Numerous studies conducted between 1943 and 1996 have confirmed the link between lead exposure and anti-social behaviour. More recent studies have suggested that the rate of degenerative brain diseases such as alziemers has also been increasing at a rate consistent with the number of adults who were exposed to lead as children.
The Truth Starts to Come Out
Though scientists had lost the initial battle against leaded petrol in 1926, many continued to doubt the claims that lead exposure was ‘normal and safe’ as the Ethyl Corporation claimed. In 1965 geochemist Clair Patterson published a paper showing that alongside the severe illness that was seen with exposure to lead, there were also a number of negative effects caused by constant low level poisoning. Once again, the Ethyl Corporation attempted to bury the evidence by attempting to bribe Patterson. When he refused, they ensured he was removed from professional boards, and he lost his contract with the Public Health Service.
Following Pattersons revelations, the government began to express more concern about the impact of lead exposure. In 1966, Patterson and a number of other scientists once again testified the dangers, and criticised the Public Health Service for relying on data provided by the Ethyl Corporation, which was undoubtedly biased. As a result, in 1970 Federal funds were allocated for the first time to study the impact of lead exposure in children, ending the monopoly on scientific data that the Ethyl Corporation had held since 1925. Herb Needleman conducted a groundbreaking study where he analysed the milk teeth of more than two thousand children and correlated their lead content with the childrens’ later cognitive development. His findings influenced the EPA’S clean air criteria in 1977, which recognised the extreme risk of brain damage occurring in individuals who showed no other symptoms of lead poisoning. His and many other studies proved beyond a doubt what scientists had been saying for decades; lead was demonstrably and devastatingly poisoning children.
Phasing Out
An inquiry led by Senator John Muskie ended the government’s complacency towards lead pollution, and steps began to be taken to actively try and reduce the concentration of lead in the air. With the introduction of the Clean Air Act in 1970, General Motors announced that they would be phasing out leaded petrol because it damaged the platinum needed in new catalytic converters. However, leaded petrol was not completely phased out in the US until 1995.
In the UK, the government was slow to force industries to withdraw leaded petrol from use, as the production and export of TEL was a major economic contributor. Finally bowing to public and scientific pressure, the UK began to phase out leaded petrol from 1987, when the government introduced a preferential tax rate on unleaded fuel. Leaded fuel was completely banned by the EU in 2000, a full seventy-five years after its introduction.
Sources and Further Reading
https://penelope.uchicago.edu/~grout/encyclopaedia_romana/wine/leadpoisoning.html
https://en.wikipedia.org/wiki/Lead_poisoning
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6454899/