Is it safe to drink tap water? There is a health risk, but it’s small. Is it still safe to drink tap water? Philippe Hartemann, Professor of Health Safety and the Environment at the University of Lorraine, France, is a specialist in water and a member of a Ministry of Health working group on eternal pollutants. He is one of Europe’s leading water specialists and is involved in a wide range of research on water quality, pollution and its impact on health.
The subject of tap water quality is a highly inflammatory one, and Philippe Hartemann is not an easy man to interview. Water, an essential element of life that should flow freely and reliably, has become a public health issue and even a source of conflict in our modern societies. “We shouldn’t be afraid, but we should be cautious in our thinking, because life expectancy has been rising steadily for the last thirty years,” he begins.
Can we drink tap water today without worrying too much about our health?
Water is the most closely monitored foodstuff, with Maximum Allowable Concentrations (MACs) set for each substance according to its toxicity – if the MAC is exceeded, the water is declared undrinkable. There is a health risk associated with tap water, but it is small. Nowadays, tap water is not the riskiest source of water; it is very carefully monitored using increasingly sophisticated techniques. We’re looking for more and more things, so we end up finding more, sometimes too much! And the quality of the water is not the same in the east, in New Aquitaine like you, a very agricultural region, or in Nice – it comes straight from the Alps. So there is a degree of inequality, but the standards of drinking water are the same everywhere.
“Epidemiological studies are very sensitive and it is very likely that few people are affected by MVC.”
In the Dordogne, “worrying” levels of vinyl chloride monomer (VCM) have been found, exceeding European approvals. What are the risks?
PVC pipes were used in the 1950s and 1960s, probably the cheapest, but they deteriorate over time and need to be replaced urgently in certain sectors. High levels of MVC increase the risk of liver cancer associated with its absorption, but this cancer may also be linked to other uses. At present, despite the epidemiological studies that have been carried out, there is no evidence of an excess risk to health in these communities. At this stage, it is very likely that only a few people will be affected by MVC.
How are the levels of potential toxicity set?
Based on a fundamental principle: no more than one case of induced pathology (e.g. cancer) per million consumers over a seventy-year lifetime. This is calculated on the basis of toxicological data evaluated in animals and adapted to humans. Let’s go back to the risk of drinking water with too high a level of MVC, and suppose that one person in a million develops liver cancer: will this be linked to MVC, to a specific pesticide, or will it have another origin, such as alcohol?
In some parts of France, there are groups of children with the same cancer in the same area. Could water be the cause?
Yes, and clusters of children with similar cancers are the subject of extensive epidemiological studies. But so far there is no conclusive evidence that water pollution is to blame. There are many other sources of pollution, including pesticides in the air – the causes of these cancers are multifactorial.
If water analysis methods have developed, we now have more accurate information…
It’s true that methods have evolved incredibly and we now find elements in water that we didn’t know were there before. For example, we know that water drunk decades ago contained toxic molecules linked to pollution. As far as pesticides are concerned, the situation is delicate because of the standards applied. France has stuck to the rule of 0.1 micrograms per litre (µg/L), the analytical reference limit set by the European Commission in the 1970s and never re-evaluated. Pesticides were not supposed to be found, but they are.
Today, our latest analytical methods offer an infinitesimally low detection threshold, down to 1 nanogram per litre, or 100 times lower than 0.1 µg/L. For certain toxic pesticides, we have been able to lower the MAC below 0.1 µg, but it is not possible to raise it for other substances that are not very toxic.
What kind of ‘toxic’ pesticides are we looking for? And what about drug residues?
We are currently looking for between 200 and 300 molecules, and we have revised certain thresholds imposed by Europe because pesticides that are supposed to disappear after decades are still present in the form of residues. If we add up these residues, we exceed the thresholds. How can we classify them? Some no longer have a pesticidal effect, others are still toxic and in some areas the water no longer meets drinking water standards.
The controversy surrounding pharmaceutical residues is exaggerated because the levels are low: when found in treated water, they are up to a million times lower than the doses used for therapeutic purposes. On the other hand, the cocktail effect of these residues is worrying and is currently being studied in animal species.
What do we know today about the presence of endocrine disrupters and PFAS (per- and polyfluoroalkylates) in the water we drink?
Every new product on the market goes through a series of tests. At the moment I’m looking at insecticides and disinfectants. There have been tests for endocrine disrupters, but so far there have been no conclusive results for humans. As for PFAS, they are everywhere, even in Antarctica. They never degrade and there are many of them. As of 2023, the European Union will impose a new MAC… Yes, if you change the filter regularly, otherwise the carbon will release the molecules… In France, 10% of the 20,000 or so distribution units do not comply with the standards. Treatment is expensive and affects the price of water.
