Work is starting throughout rural France to replace plastic water mains which release a poisonous gas into the water – after strict limits were imposed by the European Union back in 1998.
Called vinyl chloride monomer (VCM), the gas causes two types of liver cancer.
It is released when chlorinated drinking water passes through PVC pipes made between 1960 and 1980.
“It is scandalous that it has taken so long for action to be taken,” said Gaspard Lemaire, from research unit Earth, attached to the Centre Jean Bodin at the University of Angers.
“We knew VCMs caused cancer in 1980 when the process of making pipes containing them was banned, but it took until 1998 for the EU to fix a limit for water supplies.
"It then took until 2002 before France made the limits law and until 2019 before water was systematically analysed to find out just how much VCM it contained.
“Comparisons to the asbestos scandal, where France was also slow to react, are obvious.”
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VCM linked to two liver cancers
VCM has been classed as carcinogenic since 1987, and is mainly linked to two sorts of liver cancer, carcinome hépatocarcinome and angiosarcome hépatique
.
Of these, the first is a “common” type of liver cancer with other contributing factors including drinking too much, smoking and eating fatty food.
The other type, angiosarcome hépatique, is rarer and linked specifically to VCM exposure or exposure to radioactive materials.
“There are around 20 of these angiosarcome hépatique cases across France each year, and originally they were all from people working in the plastics industry,” said Mr Lemaire.
“But now there are cases in which people have no link with the industry.”
Little research has been done into the effects of VCM exposure on humans since its link to cancer was made in the United States in the 1980s.
Research is complicated by the fact that the cancers can kill people very quickly – sometimes within two weeks of a diagnosis. However, studies on laboratory mammals have shown a definite link between VCM and cancers.
The EU limit is 0.5 microgrammes of VCM per litre of water.
Among the highest levels recorded in drinking water in France was one of 738 microgrammes per litre of water in the commune of Val de Louyre et Caudeau between Périgueux and Bergerac (Dordogne), taken in July 2022.
The mayor said the local water company only told him of the problem two years later when it carried out priority work to replace the old plastic pipes with new ones which do not release VCM.
Cheap PVC piping
Dordogne is thought to be the department in France where the most people are exposed to VCM.
Official estimates put the number of people exposed to VCMs through the water supply in France at 600,000, with most in the west of the country where mains water only arrived in many rural communes in the 1970s.
However, Mr Lemaire said that he and other researchers believe the methods of counting are wrong, and that the number could be higher.
Parts of the south of France, where there was a move to bring piped water to villages and farms at around the same time, also see high VCM numbers.
Cheap PVC piping was seen as a boon, replacing the need for steel pipes, which were heavier, more expensive and which needed more qualified staff to install.
“Also, at that time many water systems were designed so that a branch of the network ended at a house, usually on a hill, without the pipes being joined to form a ring,” said Mr Lemaire.
“In general, the measurements have shown that isolated houses at the end of a water main, on a hill, are likely to have higher VCM measurements because the water does not move as much as in the centre of a town.”
VCM levels are also higher in hot temperatures because heat increases the leaching of toxic substances from the plastic into the water.
“We know, too, that VCM measurements vary tremendously – one house can have very high levels while a neighbour is very low,” said Mr Lemaire.
“Most scientists think that the substance dilutes all through the network, so if you have high levels at the test point at the top of a hill, you are likely to have significant VCMs in water throughout the village.”
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VCM measurements
The government and water companies have used the differences between houses to avoid giving general warnings about water to whole communes.
You can ask for the VCM measurements of your commune directly from your water company, details of which can be found at the mairie.
Water companies often install purges at the highest point of pipes to reduce VCM levels, but they have limited effectiveness.
At this reporter’s home in south Charente, levels of 4 microgrammes per litre were recorded by the regional health authority in 2019, which dropped to around 1.5 microgrammes per litre when an automatic purge, which released water for three hours a night, was installed.
Work to replace the old pipes started in June.
The cost is usually around €100,000 per km of pipe, but can vary according to the number and complexity of connections and the type of earth.
A trench of at least 1.5m deep is dug, a sand bed put in, then the pipes laid. More sand is added before the trench is backfilled.
The cost of replacing the pipes is mainly borne by the water companies, which are funded by part of the taxe foncière.
Water suppliers such as SAUR also make a contribution through a special fund added to water bills, and the government has made limited grants available.
