1. Bharti Singhla 2011CH10151
Archana Kumari 2009CH70125
Criti Mahajan 2009CH70134
Paridhi Khandelwal 2009CH70150
Sweekriti Dhanpuri 2010CH10

2. • Background
1. Background of Union Carbide
2. Chemical reaction in the plant
3. Bhopal Plant Layout
4. Methyl isocyanate: physical and chemical properties
5. Safety systems installed in case of MIC leak
6. Events prior to the tragedy
7. Chronology of events on 2nd Dec, 1984
8. Theories for the cause of event
9. After effects of the disaster
10.Treating the waste
11.Changes in the policies introduced
12.Fate of the company
13.Lessons from Bhopal gas tragedy
14.Suggested checklists to monitor small and large chemical disasters

3. • Union Carbide India Ltd. (UCIL) – Indian subsidiary of Union Carbide
Corporation (UCC), American firm
• 1969 – UCIL plant in Bhopal begins operating , formulation of
carbamate pesticides from chemicals imported from US
• 1975 – License issued to manufacture carbaryl pesticide (Sevin)
• 1979 – Production started, capacity of the plant – 5250 tons/year
• Demand decreasing every year and so the production also decreasing 1981 – 2704 tons/year, 1983 - 1657 tons/year

4. • Manufactured by the reaction of monomethlyamine and phosgene.
1. Monomethyl amine 2. Phosgene 3. Methyl Isocyanate (MIC)
4. Alpha – Naphthol
5. Sevin

5. Phosgene
Stripper
Tail Gas
Pyrolysis
COCl2
MMA
Reactor
Chilling Unit
HCl
MIC
MIC storage

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Volatile, liquid, colourless gas with strong and sharp odour
Flash Point – -18oC
Molecular weight: 57.051 g/mol
Low solubility in water
Flammability: Highly flammable
Flammable Range: 5.3% to 26% (concentration in air)
Highly volatile
Reacts readily with many substances that contain N-H or O-H groups.
With water, it forms 1,3-dimethylurea and CO2 with the evolution
of heat (325 calories per gram of MIC)
• If the heat is not efficiently removed from the mixture, the rate of
the reaction will increase and rapidly cause the MIC to boil
• Easily polymerizes (exothermic process)

7. Hazard Rating
Flammability
Reactivity
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NFPA
3
2
Flammable and Reactive
Poison Inhalation Hazard
Poisonous Gases are produced in fire
In UC, it was called Liquid Dynamite
Exposure symptoms includes coughing, chest pain, dyspnea, asthma,
irritation of the eyes, nose and throat, as well as skin damage. Higher levels
of exposure, over 21 ppm, can result in pulmonary or
lung edema, emphysema and hemorrhages, bronchial pneumonia and death.
Hazard Rating Key: 0-minimal, 1-slight, 2-moderate, 3-serious, 4-severe

8. 1. Vent Gas Scrubber - used caustic soda to neutralize toxic gas exhaust
from MIC plant and storage tanks before release through vent stack or
flare
2. Flare - burnt toxic gasses to neutralize them
3. Refrigeration System – Refrigeration unit with capacity of 30 ton was
installed to keep MIC at temperatures of 0-5 degrees C
4. Firewater Spray Pipes - to control escaping gases and cool over-heated
equipments
5. Safety valve - this valve was placed between MIC storage tanks and
MIC holding tank in SEVIN production area
6. Extra tank – Tank E610 and E611 were for normal use , and E619 for
emergency

9. Dec
1981
Plant
operator
killed by
Phosgene
Gas Leak
• Medical Officer brought
into notice the hazard
posed by the factory
•Jan 1982- 24 persons
affected by phosgene
•Feb 1982 – 18 persons
affected by MIC leak
May
1982
Report by
Americans
on UCC
plant
1983
onwards
All energy
concentrat
ed on cost
cutting
• 200 skilled workers asked to
• Reported leaks of phosgene,
resign
MIC and chloroform
• Only 1 person in control
• Ruptures in pipework and
room
sealed joints
• June 1984 - 30 ton
•Poor adjustment of certain
refrigeration unit cooling the
devices where excessive
MIC system was shutdown
pressure could lead to water
• Oct 1984 - Vent Gas
entering the circuits
Scrubber was turned off,
Flare was extinguished

10. 8-9pm
Around
9:30 pm
By
10:30pm
• MIC unit workers to flush several pipes running from the
phosgene system to the scrubber via the MIC storage tanks
• Maintenance Dept not asked to install the slip bind
• Temp. of MIC tank between 15 & 20 deg C.
• One Bleeder valve blocked, water accumulated in the pipes
• Plant supervisor still ordered to continue washing
• Water entered the relief valve pipe
• Water flows from the relief valve pipe into the process pipe
and then flows into the tank E610
• Change of Shift, Water Washing still continues

11. 11 pm to
12 am
12:30 am
• Pressure rise in tank E610 from 2psi to 10 psi
• MIC leak near the scrubber
• Set-up water spray to neutralize leaking MIC
• Pressure indicator of Tank E610 pointing to the maximum reading
of 55psi
• Hears safety valve pop, rumbling sound from the tank , and heat
from the tank
• Tries to engage gas vent scrubber but caustic soda doesn’t flow
• Cloud of gas escapes from the scrubber stack
• Operators turn on the fire water sprayers but water cannot reach
the gas cloud
From 12 :40
• Try to cool Tank E610 with the refrigeration system but the Freon
onwards
had been drained. Gas escapes for about 2 hours.

12. The disaster happened as a result of exothermic
reaction between water and MIC which led to the
rupture of safety valve of the MIC storage tank.
There are two theories explaining how water
entered the tank:
1. Water Washing Theory (theory taken by Indian government)
2. Sabotage Theory (theory taken by Union Carbide Corporation)

13. Water Flushing Theory:
• The media played a significant role in establishing the WATER
WASHING THEORY as a plausible explanation.
• At the time, workers were cleaning out a clogged pipe as a
part of routine maintenance.
• They did not go through the plant standard operating
procedures and hence they failed to insert the slip-blind plate
used to prevent water from going inside the tank.
• The water was supposed to be drained through drainage
nozzles. Due to the existence of large quantities of rust in the
pipe, these nozzles were plugged with dirt.
• Water supposedly backed up into the pipelines and eventually
found its way into the tank because the slip blind plate wasn’t
in its place.

14. Sabotage Theory:
• The investigation was done by the engineering consulting firm
“Arthur D. Little”.
• It was concluded that an angry employee secretly introduced
a large amount of water into the MIC tank by removing a
mete and connecting a water hose directly to the tank
through the metering port.
• Carbide claimed that such a large quanitity of water could not
enter the tank by accident, available safety systems couldn’t
deal with intentional sabotage.
• UCC found three main weak points in the water flushing
theory.
Water head was not enough to push such a large quantity (2000 lbs) of water
to the MIC tank
An intermediate valve found closed after the accident.
The intermediate line found dry.

15. Weather Conditions:
• The high moisture content in the discharge when evaporating,
gave rise to a heavy gas which rapidly sank to the ground.
• A weak wind which frequently changed direction, which in
turn helped the gas to cover more area in a shorter period of
time (about one hour).
• The weak wind and the weak vertical turbulence caused a
slow dilution of gas and thus allowed the poisonous gas to
spread over considerable distances.

16. Supporting events:
• Not following safety regulations as that followed by
UCC plants in USA. For eg. to reduce energy costs,
the refrigeration system was idle. The MIC was kept
at 20 degrees Celsius, not the 4.5 degrees advised by
the manual.
• The flare tower and the vent gas scrubber had been
out of service for five months before the disaster.
• The MIC tank alarms had not worked for four years.
• The steam boiler, intended to clean the pipes, was
out of action for unknown reasons.

17. Contd…
• Use of a more dangerous pesticide manufacturing method for
decreasing generation cost.
• The gas leaked from a 30 m high chimney and this height was
not enough to reduce the effects of the discharge.
• Insufficient maintenance and inadequate emergency action
plans.
• Lack of awareness of the potential impact of MIC on the
community by the people operating the plant.
• Lack of skilled operators.
• Inadequate community planning, allowing a large population
to live near a hazardous manufacturing plant.

20. •A house to house symptom survey conducted in 1993:
Respiratory diseases
65.7%
Neurological
68.4%
Ophthalmic
49%
Reproductive
43.2% (of people in reproductive age)
• 1990 : Bhopal Group for Information and Action (BGIA)
― Testing by Citizens Environmental Laboratory, Boston
― Presence of at least seven toxic chemicals
• Lead and mercury found in breast milk samples: Greenpeace

21. •Poorly understood, 120000 chronic
survivors
•Respiratory: Persistent fibrosis, Chronic
Bronchitis, TB
•Ocular: Chronic conjunctivitis, Corneal
opacity
•Reproductive: Pregnancy loss, Higher
infant mortality
•Gastro-intestinal: Hyperacidity, Chronic
gastritis
•Neurological: Impaired memory and motor
skills
•Genetic damage to plants
•Rivers and lakes polluted by chemicals:
destroying aquatic and animals thriving on
the sources
Children born with genetic defects
Polluted water sources
Raina V. , Survivors of the Bhopal Gas Disaster, Twenty five years after

22. •350 metric tonnes of toxic waste
•Global toxic hot-spot : Greenpeace
•Groundwater and soil contaminated with
heavy metals and carcinogenic chemicals
•Dicholorbenzene,
Hexachlorobutadiene,
Tricholoroethane
•Mercury, lead, cadmium
•Poisoning drinking water sources in 16
communities: effecting 25,000 people
•Hexachlorobutadiene : potent
kidney toxin , a possible human
carcinogen.
•Trichloroethene: impairs foetal
development
The solar evaporation pond
Factory’s chemical waste
Broughton E. , The Bhopal disaster and its aftermath: a review, Environmental Health: A Global Access Science Source 2005, 4:6

23. •Pyrolisis by plasma torches: Dissociate the organic molecules
•Stoichiometric amount of oxygen: Reforms the dissociated
elements of the waste into Syngas
•Syngas can then be used as a fuel
•Metals can be recovered by HCl or Na2S

24. •Environment Protection Act (1986):
•Stronger inspections standards and control over hazardous
substances
•Personal responsibility from corporations
• Ministry of Environment and Forests (MoEF)
•Factories (Amendment) Act (1987):
•Safeguards in use and storage of hazardous substances
•Mandatory worker safety training
•Air (Amendment) Act (1987):
•Governmental consent to release pollutants
•Hazardous Waste Rules (1989):
•Government “authorize” companies as to what they can
pollute with
•Public Liability Insurance Act (1991):
•Insurance to cover death, injury, or damage resulting from a
disaster

25. •Emergency Planning and Community Right to Know Act-1986,
U.S.
•An annual report on all toxic, hazardous chemicals released
•List of chemicals to fire department, emergency responders
and local government
•Emergency response plans to handle accidental emission:
local agencies
•Accident to be reported immediately
•Responsible Care Program-1985, Canada
•Performance measurement and reporting
•Implementation of a security code
•Management system to achieve and verify results
•Independent certification of standards
Sheehan H. E.(2011), The Bhopal gas disaster: focus on community health and environmental Effects, Indian Journal of Medical Ethics, VIII- 2

26. •1989: All settled for a mere 450 million USD
•Amounted to Rs. 10,000 per victim
•Charges against Warren Anderson
•1999: Dow chemicals purchased UCIL for 3.9 billion USD
•Dow chemicals refuses to take responsibility for the toxic waste
•Nature of the chemical industry
•Re-think the necessity to produce potentially harmful products in
the first place
•Despite greater government commitment to protect public health,
forests, and wildlife, policies geared to developing the country's
economy have taken precedence

27. 1. Management of major hazard installations: competent management, should be
familiar with exigencies of major hazard operation
2. Hazard from highly toxic substances has been insufficiently appreciated.
3. Runaway reaction in storage.
4. Hazard of an exothermic reaction between a frozen fluid and water (corrosion,
blockage or freezing)
5. Relative hazard of materials in process and in storage
6. Relative priority of safety and production
7. Limitations of inventory in the plant
8. Set pressure of relief devices.
9. Disabling of protective systems
10. Maintenance of plant equipment and instrumentation
11. Isolation procedures for maintenance
12. Control of plant and process modification
13. Information for authorities and public
14. Planning for emergencies
The lessons of Bhopal [toxic] MIC gas disaster; Scope for expanding global biomonitoring and environmental specimen
banking Elsevier, Amsterdam (1997) (pp. 2237–2250) (Sriramachari, 1997)

28. •
Recommendations for prevention:
– 1st layer: Immediate technical recommendations
– 2nd layer: Recommendations to avoid the hazards
– 3rd layer: Recommendations to improve management systems.
Event
Recommendations for prevention
Public concern compelled other
companies to improve standards
Provide information sheet will help public
keep risks in perspective
Emergency not handled well
Provide and practice emergency plans
About 2000 people killed
Control building factories near major
hazards
The lessons of Bhopal [toxic] MIC gas disaster; Scope for expanding global biomonitoring and environmental specimen banking

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Multiple aims of patient care, detoxification and medico-legal issues
The importance of clinical pathology and toxicology
The need for cumulative study and analyses of each and all ‘on-site accidents’
Studies and collection of data and samples from sporadic severely and moderately
ill patients and controls
Detailed information of associated chemicals, record of chemical-induced deaths
and sickness on site
Clinical toxicology of patients exposed to chemicals
Clinicopathological guidelines
Clinical illustrations and x-rays
Continuing studies of individuals at risk
Long-term follow-up studies
Clinical biochemistry
Post-mortem or autopsy studies
Background paper on Pathology—Collection, Processing and Storage of Pathological Material for Immediate Analysis and
Later Study of Toxicological Effects and their long-term Implication (Sriramachari, 1989)

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Photographs for identification of victims
Forensic examination of the body
X-ray records
Detailed autopsies of victims
Late autopsies amongst exposees
Histopathology
Light and electron microscopy
Routine and special staining procedures
Immuno-histochemistry and immunological studies
Biochemical analysis of biological fluids and tissue samples
Teratogenic and mutagenic studies
Experimental studies and animal tissues
Detoxification measures
Establishing the ‘biochemical lesion’
Background paper on Pathology—Collection, Processing and Storage of Pathological Material for Immediate Analysis and
Later Study of Toxicological Effects and their long-term Implication (Sriramachari, 1989)