Asbestos can cause multiple cancers when it is breathed in, but does it also pose a risk when it is swallowed, especially in tap water?
Impossible to say in the current state of knowledge, explained Wednesday, November 10 the French health authorities.
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"
The data published to date do not make it possible to comment on the possibility or absence of an association between asbestos ingestion and digestive cancers
", explains the National Health Security Agency (ANSES) in a press release.
Asbestos, a fiber used for several decades during the 20th century in the construction of buildings, is now banned in many countries such as France, due to its dangerous effects on health.
4% asbestos in tap water
When inhaled, it promotes the appearance of several types of deadly cancers, both respiratory and digestive tract.
But it is not known if there is an equivalent danger when asbestos is swallowed.
However, this substance can be found in France in tap water, since part of the pipes - 4% according to ANSES - contains it.
To draw conclusions, the agency's experts examined some 80 studies on the subject.
Some assess the effects of inhaling asbestos in humans, others in animals.
Finally, a third category looks at the health consequences of exposure to asbestos among workers, primarily in construction, but without distinguishing between inhalation and ingestion.
In the end, it is not possible to conclude to a link between the appearance of cancer and the fact of having swallowed asbestos.
ANSES is particularly critical of two studies, published in the 2010s by the same Italian research team, which considered that the risks of ingesting asbestos were underestimated.
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These studies themselves, compiled by compiling other works, suffer from significant methodological biases and imprecision in the choice of data collected, according to ANSES, which qualifies them as “
alarmist
”.
However, the agency admits the existence of "
signals
" that prevent a link between the ingestion of asbestos and certain digestive cancers to be excluded.
Indeed, a review of studies carried out on workers exposed to asbestos confirms the higher risk of digestive cancers, potentially because they have ingested it.
But it is not possible to determine, from these studies, what proportion of cancers is linked to ingestion of asbestos and not to inhalation.