Major Environmental Disasters: Bhopal, Chernobyl and Minamata

The correct answer is A, methyl isocyanate. Methyl isocyanate, or MIC, was stored at the Union Carbide India Limited plant in Bhopal as an intermediate for making the pesticide carbaryl. Water entering a storage tank set off a runaway reaction, and the gas escaped over the surrounding settlements on the night of 2-3 December 1984. Option B is wrong because carbon monoxide is the product of incomplete combustion and was not the agent here, though candidates confuse the two as colourless poisons. Option C is wrong because chlorine, though a notorious industrial gas, was not involved at Bhopal; it is remembered instead from the First World War and from water treatment accidents. Option D is wrong because phosgene, although it is used in making isocyanates and is sometimes listed among the minor constituents, is not the gas named in the tragedy. Examiners test the single name MIC.

The correct answer is A, 2-3 December 1984. The leak at the Union Carbide India Limited plant in Bhopal began late on 2 December 1984 and the gas spread through the early hours of 3 December, which is why India observes 2 December as National Pollution Control Day. Option B is wrong because 26 April 1986 is the date of the Chernobyl reactor explosion in the Ukrainian SSR, now marked by the United Nations as International Chernobyl Disaster Remembrance Day. Option C is wrong because 11 March 2011 is the date of the Tohoku earthquake and tsunami that flooded the Fukushima Daiichi nuclear plant in Japan. Option D is wrong because 10 July 1976 is the date of the dioxin release at Seveso in Italy, the accident behind the European Seveso Directive. Keeping these four dates apart is the whole exercise in this question.

The correct answer is C, Ukraine. Reactor Number 4 of the Chernobyl Nuclear Power Plant, near the town of Pripyat, exploded on 26 April 1986. The site then lay in the Ukrainian Soviet Socialist Republic of the USSR and lies in independent Ukraine today, which is why the question is usually framed as present-day country. Option B is wrong, although it is the most tempting distractor: Belarus lay downwind and received a large share of the radioactive fallout, but the plant itself was not on Belarusian soil. Option A is wrong because Russia, though the successor state of the Soviet Union, did not contain Chernobyl; the Soviet-era Kyshtym accident of 1957 at the Mayak plant is the Russian one. Option D is wrong because Kazakhstan is associated with the Semipalatinsk nuclear test site, not with Chernobyl.

The correct answer is B, mercury. The Chisso Corporation discharged methylmercury compounds into Minamata Bay in Kumamoto Prefecture; the mercury accumulated through fish and shellfish into the people who ate them and attacked the central nervous system, producing numbness, loss of coordination, blindness and congenital deformity. The disease gave its name to the Minamata Convention on Mercury, adopted at Kumamoto in 2013. Option A is wrong because cadmium causes Itai-itai disease in the Jinzu river basin of Toyama Prefecture, the standard partner question to this one. Option C is wrong because lead poisoning is called plumbism or saturnism and is linked with paints, pipes and battery work, not with Minamata. Option D is wrong because chronic arsenic poisoning from groundwater is a problem of West Bengal and Bangladesh, where it causes arsenicosis and black-foot disease.

The correct answer is A, cadmium. Mining waste carrying cadmium entered the Jinzu river in Toyama Prefecture and reached people through irrigated rice and drinking water. Cadmium damages the kidneys and softens bone, so that bones fractured under ordinary use; the Japanese name itai-itai is the cry of pain the sufferers made, and the condition is also described as osteomalacia with osteoporosis. Option B is wrong because excess fluoride causes fluorosis, with mottled teeth and bent limbs, a problem of parts of Rajasthan, Andhra Pradesh and Telangana in India. Option C is wrong because mercury is the agent of Minamata disease, the other Japanese pollution disease and the commonest confusion in this pair. Option D is wrong because nickel is associated with contact dermatitis and lung effects in refinery work, not with itai-itai. Remember the pair: mercury to Minamata, cadmium to itai-itai.

The correct answer is B, mercury. The Minamata Convention on Mercury was adopted at Kumamoto, Japan, in 2013 and entered into force in 2017. It is named after the Japanese town whose people were poisoned by industrial methylmercury, and it controls the supply, trade, use and emission of mercury, phasing out mercury mining and many mercury-added products. Option A is wrong because persistent organic pollutants are the subject of the Stockholm Convention of 2001, which covers the so-called dirty dozen chemicals. Option C is wrong because ozone-depleting substances fall under the Vienna Convention of 1985 and the Montreal Protocol of 1987. Option D is wrong because the transboundary movement of hazardous wastes is governed by the Basel Convention of 1989, adopted after rich countries were found dumping waste in poorer ones. Examiners regularly place these four treaties in one matching question.

The correct answer is B, the United Kingdom. From 5 to 9 December 1952 an anticyclone settled over London, a temperature inversion trapped the smoke and sulphur dioxide of domestic coal fires, and the resulting smog killed thousands. Public outrage produced the British Clean Air Act of 1956, which created smokeless zones and moved households away from raw coal. Option A is wrong because the United States passed its own Clean Air Act in 1963, strengthened in 1970, after episodes such as the Donora smog of 1948 in Pennsylvania and the photochemical smog of Los Angeles. Option C is wrong because Belgium is remembered for the Meuse Valley fog of 1930, an earlier inversion disaster, but not for this law. Option D is wrong because Japan is associated with Yokkaichi asthma and its own Basic Law for Environmental Pollution Control of 1967.

The correct answer is B, an earthquake and the tsunami that followed. The Tohoku earthquake of 11 March 2011 shut the reactors down as designed, but the tsunami that arrived minutes later flooded the emergency diesel generators at the Fukushima Daiichi plant on Japan's Pacific coast. Without power the cooling systems failed, three reactor cores melted and hydrogen explosions wrecked the buildings. Option A is wrong because a failed safety test caused Chernobyl in 1986, not Fukushima, and this is the commonest mix-up between the two Level 7 accidents. Option C is wrong because no sabotage was involved; the accident is classed as a natural hazard striking an inadequately protected site. Option D is wrong because a turbine hall fire is not the recorded cause here, although fires did follow the explosions. Remember the chain: earthquake, tsunami, loss of power, loss of cooling, meltdown.

The correct answer is C, the Environment (Protection) Act, 1986. Parliament passed it under Article 253, to give effect to the Stockholm Conference decisions, and in the direct shadow of the Bhopal leak of December 1984. It is called an umbrella law because it empowers the Central Government to set standards, restrict industries and issue rules for almost every medium, and most later rules on hazardous waste, noise, plastic and e-waste are framed under it. Option A is wrong because the Water Act of 1974 precedes Bhopal by a decade and created the pollution control boards. Option B is wrong because the Air Act of 1981 also precedes the tragedy, though it was passed after Stockholm. Option D is wrong because the Wild Life (Protection) Act of 1972 concerns species, protected areas and hunting, and has nothing to do with industrial accidents.

The correct answer is B, 2 December. India keeps 2 December as National Pollution Control Day because the leak of methyl isocyanate at Bhopal began on the night of 2 December 1984; the day is used to review pollution control laws and to remember those killed. Option A is wrong because 5 June is World Environment Day, marking the opening of the United Nations Conference on the Human Environment at Stockholm in 1972. Option C is wrong because 26 April is International Chernobyl Disaster Remembrance Day, declared by the United Nations General Assembly for the 1986 reactor accident. Option D is wrong because 16 September is World Ozone Day, which marks the signing of the Montreal Protocol in 1987. All four dates belong to the same chapter, so a paper setter can build a matching question from them alone.