Bhopal, India, methyl isocyanate pollution

The other source of water pollution is toxic chemicals, of which the chemical and petroleum industries are a major source. The oil spiU from the Exxon Valdez in Alaska and the methyl isocyanate release from Bhopal, India, are the most widely known examples. Here the overall problem is that chemicals are released that are not normally found in nature, and consequently plants and animals have no defenses against them. 

In 1982, the European Union s Council Directive 82/501/EEC on the major-accident hazards of certain industrial activities, also known as the Seveso Directive, was adopted. The Directive was mostly designed to promote information flow and created the requirement that each Member State (i.e., each country belonging to the European Union) appoint a Competent Authority to oversee safety issues. The Seveso Directive was amended twice, following major accidents at the Union Carbide chemical factory in Bhopal, India in 1984 (a leak of methyl isocyanate caused thousands of deaths), and at the Sandoz chemical warehouse in Basel, Switzerland in 1986 (fire-fighting water contaminated with mercury, organophosphate pesticides and other chemicals caused massive pollution of the Rhine River and the death of hundreds of thousands of fish). Both amendments, broadened the scope of the Directive, in particular to include the storage of dangerous substances. 

The chemicals listed in Tables 7.1 and 7.2 contain numerous hydro-philes and lipophiles. The number of mixtures possible is impossible to calculate. When people are stricken following exposure to polluted air, health effects are often attributed to an inordinately high concentration of a particular toxicant. An example of such a situation is what occurred in Bhopal, India, in 1984 when a huge quantity of methyl isocyanate was released from a chemical plant. Such single chemical effects, however, are the exception, rather than the rule. Most polluted air contains complex mixtures of chemicals that often produce effects that cannot be attributed to the known toxicology of the individual species. 

India currently has a better record of environmental compliance, although one need only look at the covers of back issues of Chemical Engineering News to find pictures of polluted effluent from Indian manufacturers. The industrial accident followed by the airborne dispersal of methyl isocyanate at Bhopal was not so long ago and was perhaps the event that triggered the Indian industry to better manage its processes and effluent. 

Other disasters at chemical plants followed in 1976 at Seveso (Italy) there was a dioxin escape which polluted over 4000 acres of farmland, killed 100 000 grazing animals and led to the evacuation of 1000 people. Later (1984) in India a release of 40 tonnes of methyl isocyanate from a batch operation at Bhopal resulted in 40 000 deaths and 100 000 injuries. Incidents such as these would have either been avoided or extensively mitigated had the processes been intensified. In the Flixborough case, a very much smaller vapour cloud would probably have been incapable of developing the shock wave which proved to be so damaging. A continuous intensified version of the Bhopal reactor may still have caused fatalities, had the contents been released, but there would have been very many less than actually CKCurred. 

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