Examples of Pollution Incidents

To put this incident into perspective, consider that, in the United States over the seven-year period that encompassed 1984 (1981-1987), only 309 deaths were reported nationwide associated with chemiccd releases into all media combined. The Bhopal incident was unique both in the severity and the large number of people effected over a single release at one time. The Bhopal incident had a regulatory impact worldwide. In the United States, for example, it helped build support for a more stringent amendment to the Clean Air Act, first signed in 1970, that finally went into effect in 1990. This amendment listed 189 chemicals for which special standards and risk assessments were required by the end of that decade. These chemicals were selected by the U.S. EPA based on their relative toxicity and the volume of release. Methyl isocyanate was on that list. 

More typically, chemical releases have an impact over a long period of time. An example is the release of dioxins into the air and soil at Seveso, Italy, in July 1976. The release was related to the production of trichlorophenol at a plant about twenty miles north of Milan. No explosion occurred. Instead, the release occurred more than six hours after a chemical reaction within a chemical reactor at the plant had been completed. The chemical reaction produced heat, which raised the temperature of the contents of the reactor. This rise in temperature led to additional, spontaneous chemical reactions that increased pressure within the reactor. The increased pressure ruptured a seal, which led to release of the reactor contents into the atmosphere. The resulting toxic cloud of vapors released from the plant contaminated several thousemd acres of a densely populated cu ea of Seveso. Vegetation, birds, and animals near the plant were affected within days of the release. Many herbivorous animals (e.g., rabbits, sheep) died from eating contaminated plants. Nine days cifter the release, dioxins were found to be present in the plants, cmimals, and soils of the ctfea. Skin lesions were reported by residents, especially in children who had more direct contact with the contaminated soils than adults. Two 

Overall, the accident was considered directly responsible for the deaths of about 3,300 small animals, and about a dozen domestic animals. Over the next two years, cleanup activities were conducted. Soil was excavated and removed from the contaminated zones, and some homes were destroyed due to contamination. Based on uptake of dioxin from soil and food, an additional 77,000 small animals and domestic cmimcds were killed over this time period to prevent them from spreading contamination to predators eating the small animals and humans eating the domestic animals. 

After this two-year period, the majority of evacuated residents were allowed back into their homes. Based on medical records, no human deaths were attributed to the release. However, 15 people had some scarring from severe skin lesions due to contact with the dioxin. An additioncd 183 people fully recovered from skin lesions. The skin lesions caused by dioxin cu e known as chloracne. 

This incident, and follow-up research on toxicity over time resulting from the release, led to the tremendous precautions taken related to the Times Beach, Missouri, and Love Canal, New York, removal efforts of dioxin found in soil. You may remember the pictures of people walking around in moon suits excavating soil from these areas. More recently, after the U.S. EPA more fully evaluated dioxin toxicology in humans, they admitted that they took extreme measures that were likely not necessary to deal with these situations. 

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