In Bhopal no-one uses the term "accident" to describe the calamity that took place here in the early hours of 3 December 1984.
For "accident" implies blamelessness. And in Bhopal the hunger for justice among those who suffered seems undiminished.
Those who survived remember the terrible randomness of it.
Eyewitnesses saw a dense cloud of poisonous gas settle on the slum areas that crowded the Union Carbide pesticide plant.
As it passed through the dimly lit streets, the direction of the wind determined who lived and who died.
Within three days, 8,000 were dead. Thousands more died in the months afterwards. And 500,000 people were exposed to the gas. Many still suffer life-long chronic illnesses.
The Chingari Rehabilitation Centre is a small charitable organisation - a drop-in day centre for children born with severe disabilities, whose parents were exposed to the gas.
"These are the second generation affected," says Tarun Thomas, who runs Chingari.
"These children are like this because of the gas, or because their parents drank contaminated water afterwards. We are determined to collect the statistical data that will prove it."
The neighbourhood of PJ Nagar was one of the worst affected areas.
Leela Bai's son, Jagdeesh, is usually taken for a 10-year-old boy. But he is one of many children born after 1984 whose growth and development have been severely impaired.
In fact, Jagdeesh is 22. But he has never developed into adulthood.
"The gas ruined his life," says his mother. "Sometimes I wish God had never given Jagdeesh to us. It would have been better if he had never been born."
There is some evidence that inhalation of the gas can impede the production of testosterone in boys whose parents have been exposed to it.
Campaigners say the statistical evidence is all around. But proving the direct causal link is hard.
Campaigner Satinath Sarangi says he has ample evidence that the Union Carbide plant is still, after all these years, leaking toxins into the ground water supply on which many people still depend.
"We are talking about thousands of tons of waste that was dumped here and covered over. It has never been cleaned up," he says.
"Every time it rains it washes toxins into the ground water. We have ample evidence going back many years."
Chief Minister of Madhya Pradesh Shivraj Chouhan dismisses the claims.
In an interview with the BBC to mark the 25th anniversary of the disaster, he told me that the communities around the plant had been supplied with clean drinking water.
"It took some time," he said. "But... we can say that we are providing 100% clean water."
The Union Carbide plant had also been made safe, he said.
Campaigners angrily dismissed his claims.
"Even with people who settled here long after the gas," says Satinath Sarangi, "what we find is a very high incidence of diseases: damage to the kidneys, the liver, the brain, the skin. The incidence of birth defects in these areas is at least 10 times what you would find in similar socio-economic populations."
In a neighbourhood just north of the Union Carbide plant, we found people drawing groundwater from a pump. We took a sample and had it tested at a laboratory in the United Kingdom.
The test found that it contained nearly 4,000 micrograms per litre of carbon tetrachloride - nearly 1,000 times the World Health Organisation's safe limit. "Carbon tet", as it is known, is a highly toxic pollutant which is known to cause cancer and liver damage.
In 1989, Union Carbide reached an out-of-court settlement with the government of India.
The company agreed to pay $470 million. The Indian government had initially demanded nearly 10 times that.
The money built a hospital for those who continued to suffer ill-health. The survivors of the gas got about $1,000 each in compensation.
The agreement represented a full and final settlement of Union Carbide's civil and criminal liabilities.
'Night of the gas'
"The environmental damage caused by the toxic contamination was never part of that settlement," says Mr Sarangi.
"Very little was known about the toxic contamination at the time. Data started coming out in 1990 and 1991 about the high levels of organochlorines, talids, polynuclear aromatic hydrocarbons and heavy metals."
Sambhavna, the charity Mr Sarangi runs, wants Dow Chemical, the US company that bought Union Carbide, to pay to clean up the ground.
In a statement the company said: "The groundwater issue at the Bhopal site is best addressed by the state government of Madhya Pradesh, which owns the site and is responsible for clean-up activities.
"Our understanding is that the central and state governments have plans for the site clean-up and we're hopeful they will follow through with their remediation plans, including addressing concerns about groundwater."
For Union Carbide the matter is, in a legal sense, closed.
For the people of the affected areas, it is far from closed.
In 25 years, no-one has been successfully prosecuted, either for the original leak, or for the continuing alleged groundwater contamination.
And the shadow of what happened on that toxic night reaches down through the decades, and into the lives of generations who were not even born on what everyone in Bhopal refers to as "the night of the gas".