Occupational Chemical Hazards Dr Faris Al Lami MB,ChB MSc PhD FFPH

Objectives Identify the main chemicals imposing occupational hazards, and routes of exposure Describe occupational dermatitis Describe main types of occupational cancers Define methods of prevention and control of chemical hazards in occupational setting

Chemicals There are 5-7 million chemicals known in the world. At least 400 million tonnes of chemicals are produced worldwide each year (including agricultural chemicals, food additives, fuels for power production, chemical consumer products, etc.) For the majority of chemicals used in the workplace, little or nothing is known about their possible immediate or long-term health effects.

OCCUPATIONAL DISEASES Chemical Agents causing Occupational Diseases Gases - * Simple asphyxiants : N2, CH4, CO2 * Chemical asphyxiants : CO, H2S, HCN * Irritant gases : Ammonia, SO2, Cl2, * Systemic poison : CS2

Dusts (Pneumoconiosis) Inorganic dusts: Coal dust - Anthracosis Silica - Silicosis Asbestos - Asbestosis. Iron - Siderosis Organic dusts : Cane fiber - Bagassosis Cotton dust – Byssinosis. Hay or grain dust – Farmer’s lung

Metals - Lead, Mercury, Chromium, Manganese arsenic, cadmium, zinc, beryllium, tin, silver, etc) Chemicals - Acids, Alkalies Solvents - Benzene, Trichloroethylene, Toluene, Zylene, Phenol, Nitrate, Napthalene, Isocyanates, Carbon tetrachloride, Carbon disulphide, Vinyl chloride monomer, etc

Routes of Exposure Inhalation Absorption Ingestion Injection airborne contaminants Absorption through the skin or eyes Ingestion eating drinking Injection high-pressure sprays into skin or eyes

Gases Sulphur oxides, Nitrogen oxides, Chlorine, Ammonia Some toxic gases are corrosive and irritating to the respiratory system. Some gases can pass through the skin Hydrogen cyanide Some gases may enter the blood circulation. Carbon monoxide

Carbon-Dioxide • Has no odor • Heavier than air • TLV exposure limit is 5,000 ppm • Can cause death by asphyxiation

Ammonia • Odor detection limit 1-5 ppm • Irritating 50 ppm (eyes), 100 ppm (respiratory tract) TLV 25 ppm Lethal 10,000 ppm Irritant in nature

Hydrogen Sulfide (H2S) Flammable, colorless gas that is toxic at extremely low concentrations Other names include sour gas, stink damp Smells like rotten eggs even at low concentrations Causes a worker to quickly loose the sense of smell Heavier than air and can accumulate in low-lying areas In exposure of >500 ppm can lead to unconsciousness, dizziness, death

Solvents Most industrial solvents are liquid organic chemicals Many of them evaporate rapidly at ambient temperatures They are often flammable and may ignite by heat from smoking, welding or static electricity. Example of very dangerous solvents:Benzene, carbon tetrachloride, carbon disulphide.

Metals Metals can enter the body in the form of dust and fumes (in grinding or welding) or even through the skin. Lead is used in various industries: battery, glass and mining industries, cable manufacturing, foundries and in printing works. It can cause serious damage to the nervous system, kidneys, a rise in blood pressure. Mercury is present in many pesticides. Mercury vapours are inhaled, as this liquid metal evaporates readily at room temperatures. Mercury poisoning has serious effects on the nervous system.

Nickel is present with other metals in various alloys Nickel is present with other metals in various alloys. Nickel and its compounds are known to be sensitizers. Some compounds of nickel can cause cancer. Chromium compounds, are widely used in industry. Some compounds can cause allergy and even lung cancer. Chromium compounds may cause birth defects. Arsenic compounds are used in pesticides, insecticides and in some colouring materials. Arsenic and its compounds can cause cancer.

Pesticides Pesticides are used in industry, for example, to impregnate wood, and in agriculture to control insects, weed, fungi, and rats. The most commonly reported effects is Dermatitis Some individuals tend to cough,wheeze, or sneeze In advanced poisoning cases, the individual may experience changes in heart rate, difficulty breathing, convulsions, and coma, which could lead to death. Inorganic mercury compounds, camphechlor, chlordane, dieldrin, DDT, HCH (lindane), heptachlor, hexachlorobenzene, and nitrofen were banned in some countrie

Occupational Dermatitis Endogenous (constitutional) Exogenous (contact) Irritant (acute/chronic) Allergic (immediate/delayed)

Occupational Dermatitis Allergic Latency Lag period Eyelid swelling Papules and vesicles Exposure to a known sensitizer Irritant usually involves the hands Scaling and redness Papules and vesicles are unusual Exposure to a known irritant

Some of the chemicals that cause contact dermatitis are: Formaldehyde Nickel compounds Epoxy resins and catalysts used in the plastics industry Germicidal agents used in soap and other cleaners Chromates

History Duration Site Work history Exposure to known allergens/irritants Improvement away from work

Management Avoid exposure Allergen/irritant replacement Skin protection Change job Drug treatment

Occupational Cancer Target Organ Lung Nasal sinuses Urothelial tract Liver (angiosarcoma) Carcinogen Asbestos, As, Be, Cd, Cr, Ni, Fe Ni Rubber, Dyes, Al, Tar Vinyl Chlorides

Steps to Protect Workers Anticipate potential hazards Recognize potential hazards Evaluate exposure and risk Control exposure and risk Eliminate Substitute Enclose/separate PPE/vaccinate

Controls Engineering controls (remove hazard) process change, chemical substitution ventilation, shielding, guarding requires little or no worker action Examples: Self-capping syringe needles, Ventilation systems such as a fume hood Sound-dampening materials to reduce noise levels Safety interlocks Radiation shielding

Controls Administrative (or work practice) controls (manage exposure) Changes in work procedures such as: written safety policies, rules, supervision, schedules, training worker, rotation controlled access areas requires worker action The goal is reducing the duration, frequency, and severity of exposure to hazardous chemicals

Controls Personal protective equipment (PPE) respirators, gloves, clothing requires individual worker action last line of defense

MEDICAL MEASURES Pre-employment medical check up Periodic medical examination Health promotion Health education Specific protection Assessment of risk by supervision of working environment

Pre-employment Medical Examination To determine the physical and emotional capacity of the individual to perform the job. To provide baseline health data for epidemiological and legal purposes. To counsel the person for correction of diseases / habits which may harm later. Assessment of pre-existing toxicity / impairment due to past exposure, if any.

Pre-placement Medical Examination

Periodic Medical Examination Evaluation of general health status. Earliest detection and prevention of work related disorders. Early detection, control and prevention of any health disorder which may affect the ability to perform the job. To detect deviation in health status from baseline data. Detection of infectious / communicable diseases which may affect others.

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