Chemical HazardsBOHS 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 occur.

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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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LeadInorganic & 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 Peripheral Neuropathy Anaemia Nephrotoxicity GI Spasm Treated with Chelating agents such as BAL, EDTA& Penicillamine.

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MercuryInorganic & 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 CompoundsAliphatic & 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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PesticidesPoisoning 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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GasesInert, 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