[9] The red mud involved in the accident is a waste product of the Bayer process, which refines bauxite into a form of aluminium oxide called alumina.

The mud primarily contains non-aluminium compounds present in the bauxite ore and left as residues after its refining along with sodium hydroxide used to dissolve aluminium oxide.

"[14] The main damage caused by the accident first arose from the high pH of the mud, which was responsible for both severe chemical burns to humans and animals and killing specimens in the rivers and in the contaminated soils.

However, after dissipation of acute effects by dilution and progressive carbonation of the sodium hydroxide by CO2 from the air, the chronic toxicity of heavy metal traces is expected to be limited by their low solubility and high sorption under slightly alkaline conditions.

[6][7] The cause of death of the Kolontár victims has not been formally confirmed;[needs update] a spokesman for the National Directorate General for Disaster Management (NDGDM, Országos Katasztrófavédelmi Főigazgatóság) said that they had probably drowned.

The spill reached the Danube on 7 October, prompting countries located further down the river (Croatia, Serbia, Romania, Bulgaria) to develop emergency plans in response.

The Torna (Hungarian pronunciation: [ˈtornɒ]) river runs through the affected area, and emergency workers were pouring tonnes of plaster into the waterway to try to bind the sludge and prevent it from continuing downstream.

[23] The European Union Monitoring and Information Centre (MIC) communicated the request for expert assistance to the 30 participating countries (27 EU member states, Iceland, Liechtenstein, Norway).

[26] In 2019, a criminal negligence case closed with the conviction of 10 people - managerial staff and employees - who were found guilty for security protocol infractions relating to waste storage and processing.