Occupational poisoning deals with the chemicals found in the place of work. Persons working in various industries may be exposed to various agents during the synthesis, manufacture or packaging of these substances or through their use during the occupation. Under the Workmen's Compensation Act, 1923, if workman contracts any disease specified therein as an occupational disease peculiar to that employment, such as anthrax, primary cancer of the skin, pathological manifestations due to X-rays, radium, etc., poisoning by lead, arsenic, mercury, phosphorus, etc., it is deemed to be an injury by accident for purpose of compensation.

Hazardous materials are substances that can potentially cause adverse health effects in individuals through contact with skin or mucous membrane or absorption through skin, respiratory, or gastrointestinal absorption. They include chemicals, biological agents and radioactive substances, which may be in the solid, liquid or gaseous state.

Potential poison or toxic exposures on the farm include a wide assortment of pesticides, noxious fumes, solvents, corrosive agents, fertilizers, envenomations (bites by snakes, scorpions, bees and wasps, centipedes, spiders, ticks, marine animals, caterpillars, etc.), and natural poison aerosols.

Anthracosis, asbestosis (audits complications, such as pulmonary adenocarcinoma and mesothelioma), silicosis, brucellosis occur due to occupational exposure. Gas and wood stoves, chemically treated furniture and fabrics and domestic pest control are some of the examples of non-occupational exposures.

Environmental poisoning:

It deals with potentially harmful impact of chemicals present as pollutants of the environment, to living organisms. Environment includes all the surroundings of living organisms, especially the air, soil and water. A pollutant is a substance present in the environment due to human activity, and which has a harmful effect on living organisms. More than 60,000 chemicals are said to be in common use. With advances in technology, pollution is increasing. The main causes of pollution are the production and use of industrial chemicals, increased use of insecticides, etc., in agriculture and production and use of energy. Threshold limit values (TLV) for about 600 chemicals commonly used have been prepared in USA.

Ecotoxicology:

It is concerned with the poisonous effects of chemical and physical agents on living organisms, especially in populations and communities within defined ecosystems. It includes the transfer pathways of those agents and their interactions with the environment.

All substances causing methaemoglobinaemia, and smoke inhalation can cause upper airway obstruction, lower airway obstruction, bronchospasm, pulmonary edema, and tissue hypoxia. Smoke may contain acrolein (aldehyde), ammonia, CO, cyanide, oxides of nitrogen, hydrogen sulphide, sulfur dioxide, hydrogen chloride, chlorine, phosgene, isocyanates, etc., depending on the material burnt. Acute respiratory failure may occur due to atelectasis, airway obstruction, or pulmonary edema. Poison-induced effects may contribute to adult respiratory distress syndrome (ARDS), sepsis, pneumonia, leading to prolonged illness or delayed death. Poison combustion products depress CNS by acting as anesthetic agents.

The following poisonous inhalants, with principal source of exposure (as given in brackets) cause acute respiratory disease:

• Acrolein: For plastic, rubber, textile, resin making.
• Acrylonitrite: For synthetic fiber, acrylic resin, rubber making, fire fighting.
• Ammonia: For fertilizer, refrigeration, explosive production, household cleaning.
• Arsine: For smelting, refining.
• Cadmium: For Ore smelting, alloying, and welding.
• Carbon dioxide: Foundry work, mining.
• Carbon disulfide: Degreasing, electroplating, sulfur processing.
• Carbon monoxide: Foundry work, petroleum refining, mining.
• Chlorine: Bleaching, disinfectant, plastic making, household cleaning.
• Chromic acid and chromates: for electroplating.
• Copper fumes: for welding.
• Cyanide: for gold extraction, chemical laboratories, electroplating.
• Formaldehyde: as disinfectant, embalming fluid, paper and photography industry, pathology departments.
• Hydrogen chloride: for refining, dye making, organic chemical synthesis.
• Hydrogen cyanide: for electroplating, fumigant work, steel industry.
• Hydrogen fluoride: for etching, petroleum industry, silk working.
• Hydrogen sulfide: for natural gas making, paper pulp, sewage treatment, tannery work, oil prospecting.
• Magnesium oxide fumes: for welding, alloy, flare, and filament making.
• Manganese fumes: for foundry work, battery making, and permanganate manufacture.
• Mercury vapor: for electrolysis.
• Methane: for mining.
• Methyl bromide: for fumigating dye and refrigerant making.
• Natural gas: for mining, petroleum refining, power plant work.
• Nitrogen: for underwater work, mining.
• Nitrogen dioxide: for welding, dye and fertilizer making, farming.
• Osmium tetroxide fumes: as alloy making, platinum hardening.
• Ozone: for arc welding, air, sewage and water treatment, photocopiers, laser printers.
• Phosgene: for chemical industry, dye and insecticide making.
• Platinum, soluble salts (mist): for alloy, mirror making, electro-plating, catalyst, ceramic work.
• Propane: for cooking, heating.
• Sulfur dioxide: as bleaching, smelting, paper manufacture, refrigeration industry.
• Vanadium pentoxide fumes: as glass, ceramic, alloy making, chemical industry (catalysis).
• Zinc chloride fumes: for dry cell making, soldering, textile finishing.
• Zinc oxide fumes: are used for welding.

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