Across the former Soviet Union harmful agricultural chemicals were either buried or improperly stored. Now the process of clean-up has begun

At Tegul'det (population 3,000), a village in the south-east corner of Tomsk oblast, it takes a lot to upset the residents, busy hunting, fishing and preening their vegetable patches, except during the six long winter months, when their only distraction is cutting holes in the ice on the river and fishing.

Nothing really bothers Alexei, a retired FSB (former KGB secret police) major. Not even the mound of earth that looms just next to his home. Yet 20 tonnes of DDT are buried there, between the settlement and the river Chulym.

In the 1970s, when no one lived here, the local authorities thought that Tegul'det was an ideal spot to bury unwanted pesticide. DDT was produced in large quantities in the 1950s and 60s, until growing awareness of the hazards led to a ban on further use.

This left the question of what was to be done with the huge stockpile that had accumulated. Burying the stuff was cheap and easy. Furthermore Siberia was big. Tomsk oblast alone (316,000 sq km) is almost as large as the whole of Germany. The woodland, with its peat bogs and oil reserves, was sparsely populated.

Time passed and several families settled near the Tegul'det mound. It was an attractive spot, close to the river and not far from the main village. The newcomers built little wooden houses with corrugated iron roofs, each with an adjoining plot of land for growing potatoes and cabbages.

That was when the trouble started. "People started complaining of headaches and sickness. Something had to be done. So the local authorities shipped in sand to make a thicker layer over the buried pesticides. The vegetable gardens were moved a bit further away. The residents stopped complaining but we have to admit that the land and river are contaminated," says Piotr Chernogrivov, head of the Green party in Tomsk oblast.

Still, "the villagers are in good health", contends Gennady Zavilevich, an official with the Emergency Control Ministry. A pollution and radiation specialist, he is also a keen naturalist, and is determined to "leave clean land" to his descendants, as he explains when he proposes a toast at a social gathering in the bear-hunt cabin near the village.

Tegul'det is far from being an isolated case. All over the former Soviet Union, nearly 250,000 tonnes of pesticides and farm chemicals have been stored in ramshackle warehouses, land-filled or dumped. After the USSR splintered the authorities lost the thread, so no one knows exactly where this toxic waste is.

Chernogrivov fears such dumps may be a bigger hazard than even nuclear waste because of the confusion surrounding them. France dispatches regular consignments of depleted uranium for processing at Severesk (formerly Tomsk-7), a closed military complex near Tomsk, but this circuit is under control. The same is not true of pesticides.

Chernogrivov advocates collecting toxic agricultural substances at the "pilot polygon", of which he is the deputy head. It occupies 38 hectares of land near Tomsk. Two-thirds of the land is owned by the Russian state, which provides funding. Since 1992, waste has been stored here in secure buildings, monitored by Chernogrivov. The centre also accepts waste from surrounding oblasts: Kemerovo, Omsk and Tyva.

"Many people criticise the polygon for this reason. They don't understand why Tomsk should collect other people's waste," says Pavel Gagarin, an expert at the regional farm supervision department. "People round here won't believe something is dangerous unless it affects them straight away. So, for instance, a local farm engineer painted his house with Granozan [ethylmercuric chloride] because it produced a nice blue colour."

The oblast authorities have recently woken up to the gravity of the situation. Teams have been trained, under Chernogrivov's supervision, to track down pesticide depots, secure them and find the owners.

In August 2011 Russia ratified the Stockholm Convention, which bans the most hazardous chemicals. The Green Cross, an environmental NGO set up by former Soviet president Mikhail Gorbachev and based in Geneva, promptly entered the fray, offering the benefit of its know-how and services.

"Storing waste securely is a good idea, but the packaging has to be changed every year. It costs too much to export the waste. The ideal solution would be to destroy it all, but you need an incinerator. In short, it's all very expensive," says Dr Stephan Robinson, a Green Cross expert versed in post-Soviet environmental issues. "The top priority is to make a list of sites," he explains.

Environmental activists and Green Cross representatives visited a former collective farm near Pervomayskaya, about 100km from Tomsk. The journey along the narrow, pot-holed roads was long and tiresome. On arrival the team put on white protective suits, boots, masks and goggles, then set to work.

A Granozan dump represents a hazard for miles around. The actual chemicals were removed a year ago, but the building is still a major source of pollution. Samples were taken. The structure will probably have to be dismantled and transported to the polygon.

At the site a man walks past, leading a cow to the stable. He takes absolutely no interest in the white-suited team. But another man, his coat wide open despite the bitter Siberian breeze, seems delighted. "Goodness me! The village hasn't seen anything like this for centuries. And everyone dressed in white! So smart. But who are you? Riot police, I suppose ..."

Environmental activists want to clean up their homeland. They dream of the day when Tomsk will attract foreign investors and tourists, perhaps even bear hunters.

At the hunting lodge, the remains of large bears decorate the walls. "Don't worry," says Chernogrivov, "there are plenty left."

• This article appeared in Guardian Weekly, which incorporates material from Le Monde.