Parts of this text were published on Atlatszo.hu .
In October 2010, a toxic spill from a red sludge reservoir in Kolontár  caused the greatest environmental disaster in Hungary's recent history. Toxic water and mud flowed through the nearby villages, killing ten and injuring many inhabitants who had not been informed about the danger of getting close to the deluge.
Since the production of alumina stopped, some alumina production waste sludge reservoirs in Hungary – similar to those that caused the October 2010 catastrophe – were or are being used for dumping other types of hazardous materials. Hungarian aluminium factories were privatized after 1990 at conveniently low prices. In exchange, the buyers had to take over the reduction of the previous environmental damages.
One of these factories – in Almásfüzitő, a town by the Danube River in north-western Hungary – has long stopped producing alumina. Its waste sludge reservoirs, however, are being used for hazardous waste produced elsewhere.
According to a document published by Atlatszo.hu  [.pdf, hu], a staff member of Tatai Környezetvédelmi Zrt. (Tata Environmental Protection cPlc., also known as TKV Zrt.) claimed this 15 years ago, in a university lecture about a technology used in “fixing” one of Hungary’s alumina production waste sludge reservoirs (at Almásfüzitő): “We are replacing an existing risk with another one.”
The lecturer added at the time: “The only way to sort out this area would be to remove the whole lot of 11,000 tons of waste from here.”
The document, which is a transcript of the lecture, proves that with the excuse of “reducing the damages,” these containers get infected with hazardous waste and even heavy metals that are dumped there by specialist companies. The consequences of this are unpredictable, but profits can be huge.
Olajos, a Hungarian blogger, wrote in a 2010 post  [hu] that, according to documentation on hazardous waste, even in 2000 alumina production generated 14.45 percent of the industrial dioxin  and furan :
[…] What is dioxin? Those who've been following the Ukrainian politics in the past few years have heard of it, since [Victor Yushchenko , one of the presidential candidates in the 2004 election ] was poisoned with dioxin at the time.
The full name of dioxin is Tetrachlorodibenzo-p-dioxin (TCDD). This compound doesn't exist in nature, it is a by-product of human, industrial activity, it disrupts the immune system and causes cancer, and has a DNA-damaging potential. The long and short of it: this is an insidious poison and it can't deplete from the body. Factories release into the environment by-products containing dioxin. In Hungary, dioxin got out from a waste reservoir in Garé, a place which also turned into a symbol of environmental damage.
Less has been heard about furan, this compound didn't get as famous as its companion, but the environment can be polluted with this by-product as well, deriving from the alumina production. […]
By the end of 2011, Greenpeace started a campaign in Hungary drawing attention to the reservoir in Almásfüzítő. Pacsker of Greenr blog shared a Greenpeace video titled “A Street of Cancer Patients in Almásfüzítő ” [hu] and commented on it  [hu]:
There must be a very serious case for ELTE University's Cooperative Research Center for Environmental Sciences (CRCES) to be talking in a Greenpeace video. The case of Almásfüzítő is like that.
Judit Molnár [the young woman talking in the video] is 24 years old and she has gone through two neoplasia diseases, her sister has 19 malignant lumps in her body.
1.5 meter deep it's already oil that is flowing in the soil.
Red sludge is bagatelle compared to other materials poured into the reservoir.
The frogs are red [because of the liquid leaking from the reservoir].
The reservoir leaks in many places. The low tide [of the Danube right next to the reservoir] has proved this perfectly. The whole Budapest is drinking these industrial poisons and carcinogenic by-products!
And, in addition to this, the Tata Environmental Protection (SIC!) cPlc. is able to call this simply “composting”… Man, how can you compost inorganic waste?!
This is pouring hazardous waste into a reservoir leaking like a sponge. In Germany and Austria it is forbidden to mix different types of hazardous waste and to deposit them together. [Meanwhile] we are intentionally creating an environmental powder keg…
Since the publication of the transcript of the 1996 lecture, TKV Zrt. has contacted atlatszo.hu to claim – among other things – that the documents mentioned above had been manipulated and that the red sludge reservoirs at Almásfüzitő are not at all dangerous to the environment. Yet, a study  [hu, with a summary in English] published in 2004 by the Geographical Institute of the Hungarian Academy of Sciences supports the facts stated in the document published by Atlatszo.hu.