According to a new study | Perfluorides are also harmful to the liver

Chemicals that linger in the environment for a very long time are causing serious liver problems, according to a new California study released this week. Perfluorids may be responsible for a recent increase in one type of hepatitis.

Mathieu Perreault
The Press

Too much fat in the liver

After cancer and immune disorders, hepatitis. Several animal and human studies in recent years have seemed to indicate that perfluorides are associated with a harmful increase in the amount of fat and inflammation in the liver. But was it a coincidence? By cross-checking all these studies, researchers at the University of Southern California have demonstrated a causal link between perfluorinated drugs and non-alcoholic fatty liver disease (NAFLD, according to the English acronym). “Human studies were limited because it’s too invasive to do liver biopsies,” says one of the study’s authors.Environmental Health Perspectives, Liz Costello. We use liver enzymes and other biomarkers associated with the amount of lipids in the liver, but it’s not perfect. There are attempts to use magnetic resonance or ultrasound imaging, but this remains to be improved. In addition, these liver biomarkers in animals and humans are quite different. So we had to combine all these studies to establish a causal link. »

sugar too

Another clue militates in favor of the role of perfluorides in NAFLD: obesity, also associated with this hepatitis, does not explain all of the increase in its prevalence. “Therefore, chemicals are thought to influence liver metabolism and lead to NAFLD,” says Sarah Rock, another co-author. It was therefore plausible that perfluorides were involved. The figures on the prevalence of NAFLD are very varied, precisely because of the difficulty of screening. The California study gives 25% for the United States, based on a projection that the prevalence of NAFLD will increase from 25% to 30% by 2030, published in 2018 in the journal Hepatology. The authors provided The Press another study, published in 2020 in the journal BMJ Open, which reports a 7% to 10% increase in the prevalence of NAFLD in the United States between 1990 and 2017. One of the experts on the link between obesity and NAFLD, Robert Lustig, of the University of California at San Francisco, rather estimates its prevalence at 45%. The D^r Lustig, who has distinguished himself for ten years by his fight against sugar (he had even called for a minimum age as for alcohol), however, believes that perfluorinated drugs cannot cause NAFLD. “Western diets cause NAFLD, but perfluorids hasten the transition from NAFLD to a more severe form of liver disease,” says Dr.^r Lustig. Jennifer Schlezinger, who developed transgenic mice with more human-like livers at Boston University, disagrees with Dr.^r Lustig. “Perfluorides change the management of lipids by liver cells,” says the biologist from Boston.

What is the danger?

The strongest evidence of the harmful effect of perfluorines relates to a perfluorine factory in West Virginia whose massive spills inspired the film. Dark Waters (2019). The neighbors of the factory, who had a blood concentration of perfluorines 10,000 times higher than the average, had a risk of cancer up to 2.8 times higher than normal, a similar increase to the risk of certain cancers conferred by obesity. By way of comparison, the sites considered to be the most at risk for exposure to perfluorides, near airports and military bases, generate concentrations 10 times greater than the average. More recently, studies on children from the Faroe Islands have shown that perfluorides reduce the effectiveness of vaccines. Which effect is more concerning, cancer, NAFLD or immune disorders? “I would worry more about immune disorders”, answers the D^D Schlezinger. Marc-André Verner, toxicologist at the University of Montreal who published a study in February showing that the concentration of perfluorides in breast milk can be high, notes for his part that the regulatory agencies seem to base their recommendations concerning perfluorines on their immune effects, which appear at lower doses.

The a bc of perfluorinated

Perfluorides are molecules discovered by chemists in the 1940s and 1950s, notably by the 3M company. The best known have led to Scotchgard stain-resistant and Teflon non-stick compounds, and others resist grease, water, heat, making them very attractive to manufacturers of carpets and furniture, fire-fighting foams , clothing and food packaging, among others. Three perfluorines are banned by the Stockholm Convention on Persistent Organic Pollutants. This is an international agreement covering 30 substances that persist for a long time in the environment and the human body. The first 12 substances banned by the Convention included the pesticide DDT. They were called “the dirty 12”, a phrase taken from a 1960s American war film.