There is a scene in James Redford’s new film, Resilience, in which a paediatrician cites a parental misdeed so outmoded as to seem bizarre. “Parents used to smoke in the car with kids in the back and the windows rolled up,” she says, incredulous. How long ago those days now seem; how wise today’s parents are to the dangers of those toxins. Yet every week in her clinic in the Bayview-Hunters Point area of San Francisco, children present with symptoms of a new pollutant – one that is just as damaging. But unlike the smoke-filled car, this new pollutant is invisible, curling undetected around children’s lives and causing lasting damage to their lungs, their hearts, their immune systems.

“Stress,” Redford says. “It is a neurotoxin like lead or mercury poisoning.” He mentions the city of Flint in Michigan, where residents were exposed to lead in drinking water. “And that’s literally what’s going on” with children who are “coming from really stressful environments. We know what environmental toxins are. Well, this is an environmental toxin.” The proliferation of so-called “toxic stress” among children, Redford says, “is a public health crisis”.

He had just finished working on a film about dyslexia when he and his film partner, Karen Pritzker, were casting around for their next story. Pritzker came upon the 1998 research by Vincent Felitti and Robert Anda into adverse childhood experiences (ACEs). “She said, ‘Read this.’”

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