This is an Unearthed and Public Eye investigation

The news that the first tanker of clean water was on its way to Cipreses was proof to residents who had raised the alarm about pesticide contamination that the government was finally taking them seriously. The authorities decided to start delivering water to the small Costa Rican mountain town by truck after lab tests of local water sources found residues of the fungicide chlorothalonil, at levels up to 200 times greater than the legal limit. The substance is widely used on Costa Rica’s farms, but is banned in Europe after it was found to be a groundwater contaminant and “presumed human carcinogen”.

It was Saturday, 22 October 2022, two days after Costa Rica’s health ministry had issued an order that the more than 5,000 people who relied on the Cipreses water system should stop drinking the water or using it to prepare food. The tanker arrived at the entrance to the town at 08:50 am. The small activist group EcoCipreses was pleased to finally see some progress – eight years after a resident first raised concerns – but were also very aware that the problem was unlikely to be confined to their town.

Those fears were confirmed less than two weeks later. The authorities had been looking into the possibility of hooking Cipreses up to the water sources used by its neighbouring town of Santa Rosa, but lab tests found that most of these springs too were contaminated with breakdown products of chlorothalonil. On 4 November, the ministry of health issued another order, closing five of Santa Rosa’s springs. A later round of testing found the contamination present in another of Santa Rosa’s springs, and in March this year that too was closed for human consumption.

Residents of Cipreses fill containers from the back of the truck, which delivers clean water to the town. Photo: José Diaz

According to José Sánchez, president of the local authority responsible for administering Santa Rosa’s water system (known as an ASADA from its initials in Spanish), their problem is likely to be the tip of the iceberg. Cipreses and Santa Rosa both sit in an agricultural region in the north of Cartago province, close to the capital of San José, where farmers have been spraying huge amounts of chlorothalonil for decades. This area, on the fertile slopes of the Irazú volcano in Costa Rica’s central mountain range, produces 80% of the country’s vegetables and is home to tens of thousands of people. Sanchez believes the contamination is likely to be widespread throughout the region.

‘A regional emergency’

“Logic dictates that as more lab tests are done, we will continue to find that springs in this entire area are contaminated, because the type of agriculture and the type of soil are the same,” he told Unearthed and Public Eye in March, days after receiving the news that would mean another of his town’s water sources having to close. “This is no longer one town’s local problem, but a regional emergency.”

No one knows how many people in Costa Rica have been exposed to these contaminants, or for how long. The Costa Rican authorities have never systematically tested drinking water for the presence of one of the country’s most widely used pesticides. Nor do the national authorities even have the capability to test for metabolites of chlorothalonil. These are substances created when the pesticide starts to break down in the environment, which can also pose risks to health. 

It was metabolites of chlorothalonil that were found to have polluted the drinking water of Cipreses and Santa Rosa. But they may never have been discovered had it not been for the suspicions of a group of residents who organised themselves to call for the water to be tested, or for the work of specialists at the National University of Costa Rica’s Regional Institute for Studies on Toxic Substances (IRET, from its initials in Spanish), who agreed to do tests on the water free of charge. 

“We just trusted that the government was testing the water twice a year, and we never imagined this was happening,” says Sánchez. 

Sánchez is not the only one who fears that the contamination may be much more widespread than so far detected. In April, the Costa Rican health and environment ministries issued a joint report in response to the situation in Cipreses and Santa Rosa. The report noted that in the agricultural region immediately surrounding these communities, there were around 65,000 people who relied on similar water supplies. Many of these supplies, it added, were under “the same conditions”, with farming so close to water sources that it was “affecting the water quality of these sources” and leading to “a very high probability of pollution due to the use of chemical products”. The report concluded by recommending a national ban on the use of chlorothalonil.

But for now, farmers in this region – where nearly everyone’s livelihood depends on the production of potatoes, carrots, onions or cabbages – continue to spray chlorothalonil on their crops. And despite this pesticide now being banned across the European Union, Switzerland and the UK because of the dangers it poses to water sources and human health, European companies continue to sell it in large quantities in countries like Costa Rica.

Farmers harvest cabbages (above), and apply pesticides to their fields using backpack sprayers (below). Photos: José Diaz

According to official Costa Rican customs data analysed by Unearthed and Public Eye, the Swiss-headquartered pesticides giant Syngenta accounted for more than a quarter (26%) of all the chlorothalonil products imported into Costa Rica between 2020 and 2022. This represented a larger share of the market than that of any other manufacturer. Other European agrochemical companies, including Germany’s BASF, are also marketing chlorothalonil in Costa Rica. Some chlorothalonil products have even been sent to the country directly from Europe. Italy, Belgium, Denmark and the UK have all exported chlorothalonil to Costa Rica since passing domestic bans on the substance in 2019, customs data shows.

Syngenta declined to comment for this story. 

A spokesperson for BASF told Unearthed and Public Eye: “BASF is informed that traces of chlorothalonil metabolites have been observed in water systems in Cipreses, Costa Rica. Such reports are of great concern to us.”

The company is convinced that its products are safe “when they are used correctly following the label instructions and stewardship guidelines”, he added. “As an additional safety layer, we voluntarily assess all uses of products having potential health risks and only support them when the assessments confirm farmer safety under conditions of local use. Our employees live and work in the countries where we sell our products, and they are out in the fields with the local farmers.”

A clean water delivery is handed to a woman in Cipreses. The town has now been receiving water by truck for over eight months. Photo: José Diaz

It is now more than eight months since the tanker trucks began bringing water to Cipreses, and there is still no solution in sight. New building construction is currently prohibited in the town because of the lack of water pipe permits.  By mid-June, Costa Rica’s Water and Sanitation Institute, the central government body responsible for overseeing water supply services, had already paid out $200,000 for the truck deliveries.  

Nor is any quick or simple solution likely to be found. The evidence from studies in European countries where the chemical is already banned is that chlorothalonil metabolites are highly persistent in the environment, and are likely to “significantly impair groundwater for many years”. The technologies available for removing these contaminants from drinking water are prohibitively expensive and energy-intensive.

“We need to do more testing in the area, but we need resources and we need to know how to move forward with this problem. It’s not sustainable to keep taking water to the population by truck every day, nor is it an option to let people keep taking their chances with the tap water. We need to think about how to recover the springs, but it is not easy to solve, which is very sad,” says Clemens Ruepert, the IRET chemicals inspector whose tests proved the contamination in Cipreses and triggered  intervention by the national authorities. “The people are drinking water that undoubtedly contains breakdown products of certain pesticides which are widely used in the area,” he adds. “We have no doubt.”