SEVESO, THE DIOXIN DISASTER

AKSHIT ARORA(201)

YASH BHAYANI(202)

Introduction

It was 10th July 1976. The ICMESA plant (Industrie Chimiche

Meda Società Azionaria) A plant that manufactures intermediate

chemicals for Herbicides, Cosmetics & Pharmaceutical industry

The Seveso disaster was so named because Seveso was the community most affected. Seveso is a small town with a population of 17,000 in 1976.

What Happened

1. On 10th July 1976 12:37 PM a bursting disc on a chemical reactor ruptured

2. Maintenance staff heard a whistling sound and a cloud of vapor was seen to issue from a vent on the roof. A dense white cloud, of considerable altitude drifted offsite. 

3. Duration of hazardous discharge: 20 minutes.

4. A complex mixture of chemicals weighing 3 tonnes were discharged into the air.

5. This had terrible effects, AFFECTING EVEN UNCONCEIVED HUMAN BABIES.

What were the chemicals Released into the Air??

Hydrogen was the propellant that quickly helped the chemicals spread out into the air.

Highly toxic 2,3,7,4 tetrachlorodibenzo - p - dioxin which is known by the trivial name of ‘dioxin’ and as TCDD

sodium salt of trichlorophenol. sodium glyoxides. Sodium oxalate

THE REACTIONS INSIDE THE REACTOR ON A NORMAL DAY

What went Wrong on the Judgment Day of Seveso??

1. Seveso Plant used the heat from the steam turbine to help in providing the activation energy for the above reaction.

2. BUT A REGULATION IN ITALY REQUIRED THAT PLANTS HAD TO COMPLETELY SHUT DOWN FOR WEEKENDS, THIS WAS THE ROOTCAUSE THAT HAD LED TO THE ERROR.

3. This led to a shutting down of parts and processes without shutting down the steam turbine(steam turbine is also being used for electricity generation)

4. The reaction turns exothermic after breaching 230 deg C.

5. Many other batch processes were shutdown in a similar fashion. This led to overheating.

6. Reaction became exothermic

At controlled temperatures dioxin produced is normally seen only in trace amounts of less than 1 ppm

 In the higher-temperature conditions, TCDD production apparently reached 100 ppm or more.

The production cycle was interrupted, without any agitation or cooling, allowing a prolonged holding of the reaction mass.

There was no device to collect or destroy the toxic materials as they vented. The manufacturer of the bursting disc recommended the use of a second receiver to recover toxic materials. No such vessel was fitted.

Reactor diagram

Bad Effects of Dioxin

FIRST 7 years: Changed Sex Ratio from 62% for girl babies and 38% for baby boys.

Direct or Indirect Exposure from 1976-1991:36589 people exposed to disaster:

- 5.7 % of Exposed got cancer.- Breast Cancer- Lymphatic and hematopoietic risk.

- Extreme Chloracne( Facial acne from Chlorine)

4% of local farm Animals DEAD!!

AFTERMATH EFFECTS

Reactive Measures by Italy After Disaster

80000 Animals killed to avoid the spread of dioxin & further mutations in genes.

Within 3 Wks: 736 people living in vicinity of plant evacuated.

Law was bent to allow abortions, there were mass abortions by pregnant women to avoid malformed children.

Eating local agricultural produce was banned.

15 children were quickly hospitalized with skin inflammation.

447 were found to suffer from skin lesions or chloracne

Consequences

Herwig von Zwehl (Technical Director of ICMESA) and Paolo Paoletti (director of production at ICMESA) were arrested.

Two government commissions were established to develop a plan for quarantining and decontaminating the area, for which the Italian government allotted 40 billion lire.

Background

Only in 1972, ICMESA tried to use the incinerator for burning phenol and establishing a water treatment plant.

Would never tell regulators, what chemicals were being manufactured. If Regulators persisted with questions, ICMESA used connections in bureaucracy to undercut the regulatory bodies.

TCP(Tri chloro phenol) which caused the accident wasn’t even known in the records of the government until the disaster happened. ICMESA had kept TCP a secret operation.

Reasons

According to law, ICMESA needed to have its plant far away from human civilization.

Regulators were required to be informed if TCP, Phenol etc. were produced. But ICMESA didn’t do so.

Employees were not educated about the risks of the chemicals they were handling.

No employee safety training nor booklets issued. Lack of proper safety training by managers which

led to inefficiency by the employee. ICMESA was totally a careless organization with

regards to safety.

Chloracne

Withered Leaves

Disaster Map