The fire in Notre-Dame in April destroyed the cathedral's roof and tower, covered with 460 tons of lead tiles. Tiny particles of some lead mingled with the cloud of smoke that hung over Paris.
So this lead-bound dust settled on buildings, squares, parks, and squares, the tests indicate. It is also likely to have passed through open windows, air conditioning ducts and other building ventilation systems.
Here's what we found out about the potential risks, how the French authorities dealt with them, and what you need to know if you've visited Paris since the fire or are planning on going.
The authorities were slow to respond
Early indications that lead contamination was a problem were discovered two days after the fire, in a daycare center at the police headquarters across the street from the cathedral.
However, the response was interrupted:
Authorities have closed two day care centers for police officer's children, allowing other children of the general public to play for weeks or months in school yards and day care centers and to sit in classrooms with contaminated surfaces.
Authorities waited a month before conducting the first lead tests at nearby public schools, leaving children – who are most at risk – exposed to high levels of lead.
City and health officials could not get a complete picture of the schools that could have been contaminated, carrying out tests by the end of July, more than four months after the fire.
Authorities were unable to clear the surroundings of the cathedral shortly after the fire, waiting more than four months to complete a full decontamination of the neighborhood.
For more than three months, the Ministry of Culture, responsible for the Notre-Dame construction site, failed to pay attention to labor inspectors that safety measures were not being followed by workers exposed to alarming levels of lead.
Authorities downplayed health risks
Even as the problem became clearer, the French authorities delayed exposing its scope to avoid alarming the public and instead issued reassuring statements that minimized the risks.
According to one participant, Ministry of Culture officials downplayed the risks at meetings until May with city, labor and law enforcement officials. The ministry denies this.
Health officials declined to share the results of blood lead testing of workers operating in a heavily contaminated area, citing the confidentiality of medical records.
Authorities have ruled against mandatory blood tests for thousands of children living in the area or attending nearby schools.
With the exception of residents of Île de la Cité, where Notre-Dame is located, parents who wanted their children tested – or their schools – faced delays and obstacles.
Of the approximately 400 children who were tested, 8.5% had levels at or above the risk thresholds, according to the Regional Health Agency.
Is it still safe to visit Paris?
All the experts consulted by The Times said yes, although they differed in the level of precautions that should be taken.
Experts in France said the risks of lead were low and advised against "paranoia".
Business in the cathedral area was clean. Eating a croque-monsieur at a restaurant on Île de la Cité, where Notre-Dame is, or having a glass of rosé on a restaurant's terrace is unlikely to result in lead contamination, French experts said.
However, while no one suggested canceling a trip to Paris or, for residents leaving the city, all health experts consulted by The Times suggested a series of measures, out of prudence.
What precautions should I take?
Some experts recommend staying away from the immediate vicinity of Notre-Dame, especially if you have children under 6.
"I said to parents, 'Don't panic, these are the three or four things you should do,'" said Sean Palfrey, professor of pediatrics and public health at Boston University and director of Lead Poison Prevention. from Boston. Program, a state public health service.
Palfrey said residents should take care to wash their babies' hands so that they do not pick up dust and put it in their mouths.
He also asked parents to make sure that their children have a diet with a good nutritional dose of iron and calcium that can displace lead in the body and make the body less likely to absorb it.
Residents should clean their apartments with wet mops or cloths, not brooms, which may simply raise dust. Vacuum cleaners with special filters, called Hepa filters, can also be used, experts said.
"If I can tell parents one thing, they should leave their shoes on the door, keep the house really clean of dust and make sure everyone does the dishes before eating," said Jessica Wolpaw Reyes, professor of economics at Amherst, in Massachusetts, which has done extensive studies on lead.
And everyone said the government needed to clean the city and its schools as soon as possible.
What if I have visited Paris since the fire?
Given the fragmentary information that has been made available, health experts vary from how dangerous they believe exposure to lead dust was.
"We need to put things in perspective: lead is a problem in France, as elsewhere, and we must deal with contamination," said Philippe Glorennec, professor of health risk assessment at the École des Hautes Études school in Paris.
"We should pay attention to the situation in Notre-Dame," he said. Be ‘But be alarmed? Not."
Local authorities in Paris say they have encouraged parents of children who may have been affected to test their children's blood lead levels, but have refused to make such tests mandatory.
French experts and regional health officials who asked for moderation said they believed the children who were the most exposed were tested and that for others the exposure to lead dust presented minor risks.
"A high level of lead on the surface does not mean that the child will be automatically contaminated," said Fabien Squinazi, a Parisian physician and lead expert who advised authorities against widespread and mandatory testing.
These statements were reviewed by other employees.
In a telephone interview, Paris Deputy Mayor Anne Souyris said she was in favor of mandatory testing, but health officials decided otherwise.
Dr. Palfrey also said that France has an obligation to track as many children as possible.
Others also encouraged the practice of caution.
The best way for people to know about your exposure is to get tested, said Dr. Morri Markowitz, director of the lead treatment and poisoning prevention program at Montefiore Children's Hospital in New York.
"While transient tourists probably haven't accumulated much lead, the same may not be true for those who live and work nearby," said Markowitz.
Who is most at risk?
Among the most at-risk groups are children who still put their hands on the floor, toys and other surfaces – which may be contaminated – and then put their hands in their mouths.
If pregnant or nursing mothers have been exposed to lead, their children may also be at risk, Dr. Markowitz said.
Lead passes through the placenta, so lead levels in the mother's and fetus's blood tend to correlate, he said. And during breastfeeding, if a mother has high levels of lead in her blood, some of that lead can be passed to the baby in milk.
Professor Reyes said no level of lead was safe for a child.
Their studies have shown that a level of 5 micrograms per deciliter can lead to a significant increase in behavioral problems, youth violence and at-risk adolescent behavior.
"Lead is very toxic and very harmful to people," Reyes said. “There are well-established effects on IQ. and behavior. "