Sometimes an event occurs that marks a turning point in someone’s life. For Dr Herbert Needleman it took place when a little girl, very ill with acute lead toxicity, arrived in the Infant Ward of the Philadelphia Children Hospital where he was working.

Dr Needleman treated the child and she recovered, but he warned her mother that this would count for nothing if they didn’t move house. “If she eats more paint, she’ll be brain-damaged”, he said, referring to the lead in substandard paint and buildings.

But he realised “the issue was not just making diagnoses and treating them. It was in the life story of people.”

For Dr Needleman, who has died aged 89, this was — as he would recall years later — “a very powerful learning experience” that would take him on a crusade to discover whether, as he suspected, even minute amounts of lead could harm children’s development.

To prove it, he developed his own, highly original, research methods. Aware that only bone samples would provide evidence of lead build-up in the body, he came up with the idea of analysing the only bones that are discarded painlessly by young children: their milk teeth. In what became known as the ‘Tooth Fairy’ approach, Dr Needleman paid kids for their discarded baby teeth, and tested them for traces of lead.

The results, published in a 1972 paper revealed that the lead levels of inner city children were five times higher than suburban kids. An even more revolutionary 1979 paper in The New England Journal of Medicine, concluded there was a connection between exposure to lead and lower IQ. Working with teachers, Dr Needleman established that children with high lead levels tended to be hyperactive, and performed worse at school.

Herbert Leroy Needleman was the son of Jewish immigrants: Joseph, a furniture salesman, and Sonia Shupak whose family pickle-making business started as a pushcart operation and grew into the Shupak Pickle Factory.

The first in the family to go to college, he went to the University of Pennsylvania medical school. While a student, Dr Needleman had spent a summer working in a plant that used lead and he never forgot how ill he felt during that time.

His subsequent experiences as a paediatrician and child psychologist had alerted him to the dangers of even minimal lead exposure, but his commitment to social justice made him pursue the subject with dogged determination.

As a result of his findings, by the mid-1980s lead started being phased out from petrol and lead pipes were banned. But Dr Needleman’s success conflicted with the powerful lead industry which tried to destroy his reputation by accusing him of scientific misconduct. In the early 1990s the federal Office of Research Integrity investigated his research methods, concluding that some math errors, which Dr Needleman himself acknowledged, were too minor to affect the results.

The ethics panel of the University of Pittsburg, where he was working at the time, reached the same conclusion. However, this was a difficult time for Dr Needleman who felt abandoned by the institution, and denied access to his own files. Finally vindicated and hailed as “a hero” by many, Dr Needleman received a number of honours, among them the $250,000 Heinz Award.

But awards had never been his main drive. Throughout his life Dr Needleman had been motivated by a combination of scientific curiosity and a desire for social justice. An opponent of the Vietnam War from the beginning, once he ended up in jail with another anti-war protester, a certain Dr Benjamin Spock.

In 1966 he helped found the Committee of Responsibility (COR) to Save War-Burned and War-Injured Vietnamese children which brought wounded children to the US for medical care. Dr Needleman’s first marriage to Shirley Weinsten ended in divorce. He is survived by his second wife of 54 years, Roberta Pizor, a son from his first marriage, Samuel, and two children from his second: Joshua and Sara, as well as seven grandchildren and three great-grandchildren.

Herbert Leroy Needleman, born December 13, 1927. Died July 18, 2017