Lead dust emitted into the atmosphere, as during the Notre-Dame fire, is a potential source of contamination, especially for children, although it is difficult to quantify this exposure, according to a report by the ANSES health agency published on Friday.
Waste incineration, coal combustion, metallurgy ... A certain number of industrial activities release this toxic heavy metal into the air, contaminating particles which are then deposited on sidewalks, roads or in schoolyards. A similar phenomenon occurred on April 15, 2019, when the fire that ravaged Notre-Dame de Paris melted 300 tonnes of lead contained in the boom frame and the roof.
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Today, the main known sources of lead exposure are water, food, or lead paint in old buildings. "When the lead concentration in the water exceeds a certain value, you must change the pipes," recalls Guillaume Boulanger, from ANSES. Rules also exist for polluted soil, or food, but "not for this dust" which is deposited on roads or playgrounds, he explains.
After the concerns caused by the measurements carried out around Notre-Dame after the disaster, the authorities therefore asked ANSES two questions: are these dusts a source of exposure to lead for the population? And if so, to what degree compared to already known sources?
There are very few studies, in France or elsewhere, but the available data show that "it is relevant to consider the dust deposited on the surfaces of outdoor public spaces as a source of exposure" , replies the Agency, which judges that contamination of these surfaces can have an impact on the level of lead in the blood (blood lead level). But "it is difficult to quantify this exposure, to say if it is more or less important than the other sources of exposure" , adds Guillaume Boulanger.
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Despite the lack of data, the report identifies populations at risk, primarily young children. Their metabolism more easily absorbs this product which, in them, can be toxic even at low doses. The fact that they put their hands, toys and other objects lying around on the floor by mouth is also in question, contamination seems to be mainly by ingestion of lead dust. So when a risky situation is identified, it is necessary to put in place “preventive actions” , such as washing your hands often or taking off your shoes before going home.
In addition, the child's blood lead level "must be measured" , recommends ANSES. This has been done on more than 1,000 children after the Notre-Dame fire. According to the Ile-de-France Regional Health Agency (ARS), 13 cases have exceeded the threshold for mandatory lead poisoning (50 micrograms per liter of blood). And for the majority of them, the source of contamination was found at home.
ANSES also insists on the need to protect workers exposed to contaminated outdoor dust by measuring their blood lead level. She recommends for them the establishment of "reinforced medical monitoring" if the biological reference values for adults are exceeded, values which should moreover be greatly lowered, she believes.
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In the long term, the Agency especially calls for carrying out new targeted environmental measures in places frequented by children, to estimate the exposure of the population to these dusts. "When we have these data, we can use them to establish a threshold and say, for example, we must clean up this playing area , " comments Guillaume Boulanger, who notes that obtaining a national map could take years.
In Paris, on the other hand, the ARS has already started the process after the cathedral fire and hopes to have by the end of 2020 elements to draw up a state of the “background noise” of lead in Paris, that is ie the independent pollution of Notre-Dame. "The sources of lead are very numerous in Paris" , notes its director Aurélien Rousseau, noting that the fire put the subject "at the top of the pile" . After the 2019 ` ` crisis ' ', "we are still on active watch on this subject" , he assures, stressing that the ANSES recommendations corresponded to the measures taken after the Notre-Dame fire.
