1. Chemical Hazards
BOHS Series

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December 3rd 1984

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Bhopal Gas Disaster
 The Union Carbide Pesticide Plant in Bhopal, released 40 tons of Methyl
Isocyanate (MIC) gas, killing between 2,500 to 5,000 people in the early hours
of the morning.
 The World’s worst Industrial Disaster

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 The gas being heavier than air, started entering into the homes of the unwary
population. Many who panicked and ran out also got crushed in stampedes.
 Around 500,000 were estimated to be exposed to the gas & around 20,000
have died as a result. Over 120,000 continue to suffer from the from the effects
of the disaster.

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 Doctors and Hospitals were unaware of the nature of the Gas, nor were
they informed of the proper treatment of the inhalation of MIC gas,
being merely asked to give cough medicine & eye drops.
 If they were informed about the same, proper treatment could have
been instituted & a lot of lives could have been saved.
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Red Page in Annals of Occupational Health
 The Bhopal disaster brought into sharp focus the unprecedented
potential of hazardous chemical release in terms of loss of life, health,
injury and evacuation.
 It created a compelling evidence to approach disaster management
and chemical safety holistically.
 The disaster brought in its wake, an era of restructuring and inducting
new hazardous chemical control systems and procedures all over the
world
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 There have been many more such incidents of a relatively minor
nature. One such was a Petroleum tanker accident on the highway near
Mumbai. Spillage of the chemical on to the road came to the attention
of the local impoverished tribal population, which started collecting the
liquid, presuming it to be cooking fuel. A spark led to a conflagration
consuming the lives of innocents.
 Such incidents brought into focus the vulnerability and the need for Risk
assessment of transportation of Hazardous chemicals.
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 Another frequent accident occurs when workers descend into empty
confined spaces such as disused Wells, Food silos, Sewage channels
etc, due to presence of noxious gases such as H2S & CO.
 Many a lives have been lost and even those who tried to save the
victims, due to lack of knowledge, have fallen prey to the same gas
exposure.
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Post Bhopal Gas Disaster
 Factories Act was amended to assign responsibility for workplace safety to
the Occupier.
 Environment Protection Act was introduced in 1986.
 The Manufacture, Storage & Import of Hazardous Chemicals Rules,1989.
 The Chemical Accidents, Emergency Planning, Preparedness and
Response,1996 introduced.
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 India at present is achieving new milestones, major economic
breakthroughs and moving ahead towards the vision of a developed
nation. A sustained industrial growth including progress of the chemical
sector is crucial to attaining this goal.
 The growth of the chemical sector has led to increase in the
manufacture, storage and use of Hazardous chemicals (Hazchem)
resulting in enhanced threats of accidents. Occurrence of accidents
remains a cause of concern.
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The Indian Chemical Industry contributes to 6.7% of the GDP.
Indian Fertilizer Industry is the fourth largest in the world.
Largest manufacturer of Pesticides in Asia second only to Japan.
Indian Pharmaceutical industry is the largest in the developing world

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 There are around 1790 Major Accident Hazard units in the country,
handling large number of chemicals as raw materials, in processes,
products and wastes with flammable, explosive, corrosive, toxic and
noxious properties.
 Handling of large quantities of hazardous chemicals in installations,
isolated storages and during transportation, poses grave risk of sudden
release of copious quantities of toxicants. This may adversely impact
both the communities in and around the area and the environment.
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Impact of a chemical Disaster
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 A chemical substance is a material with a definite chemical composition.
 New chemicals are being discovered daily & at last count there are about 30
million chemical compounds
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Toxicology
 Toxicology is the science concerned with poisons and how they affect the
body.
 The main factors which determine the Toxicity of a substance are
 Chemical Composition- Some more poisonous than others
 Physical State-More toxic in soluble form than gas
 Amount
 Concentration
 Particle Size -especially when inhaled
 Routes of Absorption- Inhaled, Skin Contact or Ingestion.
 Presence of other poisons -Additive effects
 Duration of Exposure
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Duration of Exposure to Chemicals
 Acute - Short Mins to Hrs
 Sub acute - Longer up to 90 days
 Chronic - Prolonged /Repeated over days, months & years.
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Measurement of Toxic Substances
 Threshold Limit value (TLV): Time weighted (average)
concentration of an airborne substance to which workers could be
safely exposed over an Eight hour working day throughout a life time.
 Maximum Allowable Concentration (MAC) Peak or
Maximum conc. of an airborne substance to which workers could be
safely exposed.
 Biological Limit values (BLV) : Concentration of the substance
in body fluids such as blood & urine below which no toxic effects should
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Susceptibility to Toxic Chemicals
Genetic factors
State of Health
Hypersensitivity or Allergy
Personal Hygiene & other personal habits such
as Smoking etc.
 Pregnancy & lactation.
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Effects, Metabolism & Excretion of Poisons
 Local- contact site such as Skin, URT
 Systemic Organs other than portal of entry
 In general, effects are on the metabolic processes of the body, especially
enzymes. Others combine with substances essential for metabolism eg-CO
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 Poisons are detoxified in different organs
notably the Liver.
 Excretion takes place thro gut, urinary tract,
skin or lungs. May also pass thro placenta &
milk.
 Dose -Effect & Dose response demonstrate the
response between the dose and the magnitude
of effect.
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Hazards
 Skin Irritation
 Eye Irritation
 Inhalation Effects
 Ingestion Effects
 Carcinogenicity
 Mutagenecity
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Nature of Chemicals
 Inorganic and organometallic Substances- Antimony, Arsenic, Barium,
Beryllium, Cadmium & Chromium compounds, Fluoride, Lead, Manganese,
Mercury, Nickel etc.
 Organic Chemicals - Aliphatic Hydrocarbons such as Cyclohexane, n-Hexane,
Methyl pentane
 Aromatic Hydrocarbons such as Benzene, Styrene, Toluene & Xylene.
 Halogenated Hydrocarbons - Halothane, Trichloroethylene & Vinyl Chloride.
 Amino & Nitro derivatives - Aniline, Nitroglycerine, Trinitrotoluene

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 Alcohols, Glycols & derivatives- Ehtylene glycol, Methanol
 Cetones- Acetone
 Aldehydes-Formaldehyde
 Amides & Phenols
 Asphyxiants such as Acrylonitrile, Carbon Monoxide,Cyanide &
Aliphatic Nitriles.
 Pesticides such as Baygon, Carbaryl, Chlorphenoxyacetic acid
derivatives
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 DDT, Dieldrin, Endrin, Hexachlorbenzene
 Carbamate Insecticides
 Lindane
 Organophosphorus esters
 Parathion
 Mutagenic and carcinogenic Substances
 Others such as Carbon Disulfide, Diethylstilboesterol & Ethylene Oxide
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Lead
Inorganic & Organic
Inorganic Lead  Mining & Smelting
 Lead Paint
 Lead Storage Batteries
 Pottery enamelling & glazing
 Polyvinyl Plastics-Lead stabilisers
 Glass manufacture
 Fire arms
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Effects of Lead Exposure
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Peripheral Neuropathy
Anaemia
Nephrotoxicity
GI Spasm
Treated with Chelating agents such as BAL, EDTA& Penicillamine.
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Mercury
Inorganic & Organic
 In Scientific Measuring Instruments-Thermometers,
barometers,Transformers, Rectifiers
 Mercury Vapour Lamps & Storage batteries
 Amalgams for Dental use & Jewellery
 Seed Dressings & as Pesticides
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Effects of Mercury Exposure
 Miamata Bay,Japan- (Untreated Inorganic Mercury released into sea
waters-contaminated Fish.)
 Stomatitis, Gingivitis
 CNS Dysfunction
 Erethism
 Tremors
 Chronic Nephritis
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Other Metals
 Phosphorus - Phossy Jaw (matches)
 Arsenic - Smelting, Pesticides, Weed Killer, Metal
smelting, refining, in manuftrng of chemicals &
electronic equipment- Irritant, Peripheral Neuropathy
Haemolytic.
 Manganese - Dry Electric batteries- Parkinsons
Syndrome, Psychosis, Pneumonitis
 Cadmium - Used as alloy in Welding, batteries,
Dentistry, pigments,paints,pesticides- Nephrotoxic,
Emphysema.
 Nickel- Dermatitis
 Chromium- Chrome Ulcers, Necrosis of Nasal Septum
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Carbon Compounds
Aliphatic & aromatic
 Aliphatic -Methyl Alcohol, Tetrachlorethane, Carbon tetrachloride,
Trichlorethylene & Glycols
 Aromatic - Benzene, Toluene, Xylene etc.
Exposure- Degreasing, Metal Machining, painting, Welding, Wood working &
Printing.
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Health Effects
 Occupational Dermatitis
 CNS depressants
 CVS disturbances esp CS2
 Nephro toxic
 Bone Marrow Depression & Leukemia
 Carcinogenesis
 Chromosomal aberrations
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Pesticides
Poisoning through skin absorption & GI tract.
 Insecticides & Fungicides - - Pyrethrum & Pyrethrins (Mosquito Coils),
Organochlorine Compounds such as DDT, Lindane, Dieldrin & Aldrin,
Organophosphate compounds such as Parathion, Dichlovos,
Carbamates & Organic Mercurials.
 Herbicides - Arsenicals, Dinitrophenol,Di nitro Ortho cresol,Phenol
herbicides, Paraquat, Diquat, Phenoxy herbicides.
 Rodenticides & Fumigants -Calcium Cyanide, Methyl bromide,
Phosphine, Anticoagulants.
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Gases
Inert, Irritant & gases with Systemic Effects
 Inert gases - Act by displacing O2 -Anoxic Anoxia, eg: Methane
 Irritant Gases - Flourine & its compounds, Ammonia, Sulphur Dioxide,
Ozone, Phosgene.
 Gases with Systemic effects- Carbon Monoxide (Toxic Anoxia),Carbon
Disulfide (Chemical Anoxia), Hydrogen Cyanide & Cyanide Salts, Acetylene
(Cyanide has a Bitter almonds smell whilst Benzaldehyde has a sweet almonds smell)
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 Halogen Gases like Cl2,Br,Flourine,Iodine have an Irritant effect on URT.
 Flourine could cause Flourosis, Fits & Coma.
 Ammonia- Irritant, Brochospasm, Pulmonary Oedema & Respiratory Arrest
 Sulfur Dioxide So2 - Lassitude, Chronic Bronchitis, Loss of Smell.
 Ozone-Irritant, emphysema, Pulmonary Fibrosis.
 Phosgene-Pulmonary Oedema, Fibrosis & Emphysema
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 Carbon Monoxide - Anoxia, Headache, Cough, Paralysis, Sensory Loss,
Parkinsonism, Death.
 Hydrogen Sulphide - Irritant, Loss of Smell, Giddiness, Unconsciousness,
Death.
 Hydrogen Cyanide - Extremely Poisonous. Bitter Almond Smell, Dermatitis,
Headache & Motor Weakness at low conc. Breathlessness & Coma..
 Acetylene - Fume Fever
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General Principles for Prevention & Control of
Exposure at Worksite
 Substitution
 Segregation
 Enclosure
 Ventilation
 Wet Methods
 Personal Protective Devices
 Monitoring of Work Environment
 Monitoring of Exposed Workers
 Education & Supervision
 Enforcement
 Emergency Measures
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Management of Poisoning Cases
Basic Principles
 Removal from further Exposure / Evacuation
 Detoxification eg Chelating agents
 Supportive Therapy - Oxygen & IV Fluids.
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Conclusion
Need to increase Awareness
 About the Industries in your area
 About the nature of Chemicals being used, stored and
transported
 About their hazards and treatment procedures in the event of
exposure.

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Thank you
Acknowledgements: Dr Chaitanya S Gulvady
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