French health authorities have announceda permanent ban on a widely used pesticide, after alarms were raised when several dozen people fell ill in western France recently.

The ANSES health security agency said on Monday the decision to outlaw all products containing metam sodium came after a new safety review launched earlier in 2018, before at least three outbreaks of illness were reported in the Maine-et-Loire region beginning in September.

The outbreaks had already prompted the government to suspend the use of metam sodium, a ground disinfectant that is not supposed to come in contact with plants or farm workers.

The product must be used in high doses to be effective, and about 700 tons are used annually in France.

At least 70 people, many of them farm workers, complained of burning eyes and throats and respiratory difficulties near Angers, a farming basin that specialises in lamb’s lettuce, also known as corn salad.

“These episodes confirm the soundness of our decision, but they did not precipitate it,” Francoise Weber, deputy director at ANSES, told the Ouest France newspaper on Monday.

One of the most widely used pesticides in the US and Europe, metam sodium is considered a “probable human carcinogen” by the US Environmental Protection Agency.

The compound, sold under brand names including Vapam and Sectagon, has been authorised in Europe until 2022, when a new safety review is scheduled.

“There was no other choice but to remove it from the market, whether or not alternatives exist,” Weber told the paper. “We’re aware of the difficulties this will present to lamb’s lettuce growers, to farmers in general, but public health comes first,” she said.

Farmers had already fumed against the government’s suspension in October in an area whose economy relies heavily on intensive agriculture. The region near Nantes produces more than half the 35,000 tons of lamb’s lettuce, a popular salad green, consumed each year in Europe.

“There will be much less lamb’s lettuce, radishes and leeks” available next season, Philippe Retiere, head of the Nantes growers’ federation, saidafter the suspension was announced in October.