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Safety in a Chemical UNIT 5 SAFETY IN A CHEMICAL Laboratory LABORATORY Structure 5.1 Introduction Objectives 5.2...

Safety in a Chemical UNIT 5 SAFETY IN A CHEMICAL Laboratory LABORATORY Structure 5.1 Introduction Objectives 5.2 Maintenance of Safety in a Chemical Laboratory Safety Aspects in the Design of a Chemical Laboratory Safety Aspects of a Functional Chemical laboratory Code of Practice in a Laboratory Personal Protective Devices 5.3 Chemical Hazards in the Laboratory Modes of Exposure to Chemicals Effect of Chemicals on Body Acute and Chronic Effects The Fume Cupboard 5.4 Classification of Hazardous Materials Carcinogens 5.5 Storage and Handling of Chemicals Incompatibility of Chemicals Handling of Chemicals 5.6 Safe Handling of Glassware 5.7 Equipment and Electrical Safety 5.8 Emergency Procedures 5.9 Summary 5.10 Terminal Questions 5.11 Answers 5.1 INTRODUCTION A laboratory is an integral component of any scientific pursuit. It can be a place of discovery and learning. However, by the very nature of laboratory work, it can be a place of danger if proper common sense precautions are not observed. A Chemistry laboratory is full of potential hazards; sometimes even life threatening. It is, therefore, desirable that we follow good laboratory practices and work towards the safety of ourselves as well as that of the fellow workers. As trained analytical chemists you would be working extensively in the laboratory or you may have to manage a laboratory. This unit aims at apprising you of the potential hazards in the chemistry laboratory and empowering you with the essential information and knowledge that can make you a safe and informed worker in the laboratory. This unit begins with the safety aspects to be considered in the design and development of the laboratory. This would make one understand the laboratory better. This would be followed by the potential chemical hazards in the laboratory and the ways and means of their safe handling. The discussion on the potential hazards in handling glassware and ways of minimising them is dealt with thereafter. The accidents may and do happen, even in the most well organised laboratories. Therefore, the unit also covers the first aid procedures to be followed in the event of an accident. Objectives After studying this unit, you should be able to: list the potential hazards in a chemical laboratory, 37 Initiation into state the need for wearing the appropriate protective clothing in a laboratory, Analytical Laboratory recognise the necessity for personal code of behaviour in a laboratory, state do’s and don’ts in a chemical laboratory, explain the possible means of chemical exposure to the human body, state possible hazards from commonly used chemicals, identify the nature of chemical and the required handling precautions from its level, explain the importance of compatibility of chemicals while storing them in the laboratory, follow appropriate safety precautions while dealing with chemicals, glassware, apparatus and electrical equipments, and take steps to provide help to yourself and the fellow workers in the event of an accident. 5.2 MAINTENANCE OF SAFETY IN A CHEMICAL LABORATORY The chemistry laboratory is quite exciting and engaging but we should not forget that it is full of hazards and risks too. Would you agree? There are many potential hazards in the chemistry laboratory. The hazards arise due to the use of unavoidable hazard associated with the use of a variety of chemicals and glassware. The chemicals could be explosive, highly toxic, and carcinogenic substances for some of the experiments performed. Some of them can cause quite a serious accident. However, many such accidents in the laboratory can be prevented if adequate precautions are observed while working there. This calls for following proper experimental techniques and procedures while performing the experiments in the laboratory. In addition, the very design of the laboratory also contributes towards minimising the accidents. Let us learn about the safety aspect of the design of the laboratory. 5.2.1 Safety Aspects in the Design of a Chemical Laboratory You may be aware that before the construction of any building, the building plan has to be approved by the local bodies like Municipalities, Corporations, etc. the same is true of building a laboratory. The design of the laboratory buildings should be made in accordance with safety norms; there are specific guidelines to this effect. The Bureau of Indian Standards (BIS) has prepared the Code of Safety in chemical laboratories where a specific attention is given to a laboratory design. The essential features of laboratory rooms, fire safety equipments, fume cupboards, gas and water lines, sinks and drains, laboratory furniture, stores, first aid kit, etc. are available in detail in the BIS publication on chemical laboratories. The following are some of the general requirements that are required as per the norms in a chemical laboratory. There should be adequate provision for lighting and ventilation and, reasonable temperature. The chemical laboratory should be comfortable place for work. There should be effective measures to prevent the inhalation of fumes that are likely to arise during work. The dangerous part of machinery like a vacuum pump must be properly fenced so as to avoid mishaps. 38  The laboratory must have first-aid boxes with the essential constituents. Safety in a Chemical Laboratory Adequate fire prevention measures must be undertaken. There should be safe means of escape for all persons in the event of a fire. The necessary equipment and facilities for extinguishing fire should be available and handy. The photograph of a modern chemical/chemistry laboratory is given in Fig. 5.1. Fig. 5.1: A modern Chemical/Chemistry laboratory 5.2.2 Safety Aspects of a Functional Chemical Laboratory Once the laboratory becomes functional it needs to be suitably maintained in safe working conditions. The following measures are essential for the effective running of the chemical laboratory. i) The condition of the building, furniture, fire safety units, electrical connections and appliances, water pipes etc. may be checked at least once a year. Any repairs required must be attended to. ii) At the time of purchase of gas cylinders (chlorine gas, oxygen gas) etc., the safety instruction sheets must be obtained from the dealer and preserved for use. iii) The lab staff should be provided with protective clothing and must be immunised against tetanus. In addition, the laboratory staff must have appropriate training in the following aspects. Handling equipment and chemicals, etc. Using gas cylinders and fire fighting equipment Storage of chemicals Moving load Waste disposal Administering first aid Accidents do not happen iv) The lab must have a list of important phone numbers and addresses for use on their own. Accidents during emergency. The said list should be prominently exhibited in the occur due to negligence at laboratory and should include the contacts of the following. some level. Nearby doctors, hospitals and ambulance services 39 Initiation into Police Analytical Laboratory Fire service authority (fire service may also offer help for rescue operations during building collapse, explosion, drowning, gas leakage etc.) Electricity supply agency Gas and Water supply agencies and Fire fighting equipment dealers This list should be prominently exhibited in the laboratory. Having learnt about the safety requirements in the design of the laboratory and the basic safety needs of a chemical laboratory to be functional, let us learn about the code of practice that must be followed by all the users of the laboratory to make it a safe place. 5.2.3 Code of Practice in a Laboratory A Chemical laboratory can be safe only when each and every individual using the laboratory is cautious of basic facts and rules regarding safety. These rules should not only be known but also be followed genuinely if we want to avoid mishaps. The do’s and don’ts regarding the code of conduct are stated below Do’s 1. Always wear the required protective clothing like laboratory coat, goggles, gloves, etc. 2. Wear shoes that adequately cover the whole foot; low-heeled shoes with non- slip soles are preferable. Do not wear sandals, open-toed shoes, open-backed shoes, or high-heel shoes in the laboratory. 3. Tie long hair and secure loose clothing especially the loose long sleeves, neck ties, or scarves, etc. 4. Keep the hands away from the face, eyes, mouth, and body while using chemicals. 5. Find out the positions of the main valves or switches for controlling supplies of water, gas and electricity to the laboratory. 6. Familiarise yourself with the locations of telephones, fire alarms, first-aid kit, fire extinguishers, and other safety equipment and that you know how to use them. 7. Inspect all equipment for damage (cracks, defects, etc.) prior to use; do not use damaged equipment. 8. Inform other lab staff and teachers regarding any breakage, faulty equipment and any other defects immediately. 9. Wipe off any spilled chemicals immediately, especially corrosive acid or alkali and mercury. 10. Keep the apparatus which is no longer required in the cupboards. 11. Use a fume cupboard for transferring highly toxic substances or for carrying out experiments which may produce harmful gases. 12. Operations considered hazardous should be carried out only in the place designated for the purpose and ensure that you can get assistance, if required. 40 13. Always label containers correctly with the full name and concentration of the Safety in a Chemical contents. Laboratory 14. Use a hot water bath to heat flammable liquids. Never heat directly with a flame. 15. Weigh out or remove only the amount of chemical required for the experiment. Do not return the excess to its original container, but properly dispose of it in the appropriate waste container. 16. Always use safety bulbs when pipetting. 17. Always use a spatula to remove a solid reagent from a container. Never use a metal spatula when working with peroxides. Metals will decompose explosively with peroxides. 18. When transporting chemicals (especially 250 cm3 or more), place the container in a secondary container or bucket (rubber, metal or plastic) for carrying it. The secondary container should be large enough to hold the entire contents of the chemical. 19. Always wash your hands before leaving the laboratory. 20. Clean your laboratory work space at the end of the laboratory session. 21. Make sure you know the emergency procedures and emergency exit routes of your laboratory. 22. Ensure that the doorways and emergency exits are not obstructed with trolleys, furniture, etc. 23. In case of an emergency or accident, follow the established emergency plan as explained by the teacher and evacuate the building via the nearest exit. Don’ts 1. Never eat, drink or smoke in a laboratory. Also don’t store food drinks in a laboratory. Eating, drinking or storing food in a laboratory may result in contamination by chemicals or bacteria. 2. Do not sniff materials which may be toxic and never taste chemicals. 3. Smell the contents of a test tube or other container should be smelt by waving some of the escaping vapors toward you; the container should never be brought close to the nose. 4. Never work alone in the laboratory. 5. Never perform any unauthorised experiment or leave any experiment unattended. A person looking into the test tube which spurts-a 6. Do not leave lit Bunsen burners unattended. simple and sure way to invite danger for the face! 7. Do not remove any equipment or chemicals from the laboratory. 8. Do not allow organic solvents to accumulate in the laboratory. It may cause a fire accident, especially while flammable solvents are stored. 9. Minute particles in smoke may interfere with or spoil purification, chemical processes and electronic parts. 10. Hot zone of a lighted cigarette may help in the formation of poisonous substances in presence of some chemicals. 41 Initiation into 11. Don’t look into the mouth of a test tube or flask while you are heating it or Analytical Laboratory adding reagents. Never point test tubes at other people. 12. Before using flammable solvents, check that all Bunsen burners are put out and that there are no naked flames. Remember to warn everyone near the fire risk area. 13. Do not engage in practical jokes or boisterous conduct in the laboratory. 14. Avoid touching hot objects. Remember, hot glassware looks just like cold glassware. 15. Do not run or play about in laboratories. 16. Make sure you know the nature of the substances you handle. Do not handle materials or operate apparatus that you do not fully understand. 17. Never try to stop or slow down a centrifuge with your hands. The speed at the outer edge may be greater than 150 kilometer per hour (or 90 kilometer per hour at least). 18. While diluting strong acids, add the acid in small amounts at a time with stirring to water. Do not add water to acid. 19. Passage between benches must be kept clear to permit evacuation during emergency. The exits and the access to switches must be kept clear. Storage of In research laboratory, materials behind and above benches must be avoided. there may be need for protecting the face during 20. Always exercise care when opening and closing doors of the laboratory. certain operations. You may know that a mask is 21. Ensure that your footwear is adequate for the lab work. Open toed shoes or a protective covering for sandals offer no protection against injury. the face or head. While working with hazardous 22. Long hair, ties and loose jewellery could be a problem during laboratory work materials, dust masks and due to possibilities of entanglement in a moving mechanical equipment or respirators may also be trailing over contaminated surface on the work bench. Try to avoid this. used. A dust mask may be used when transferring large quantities of 5.2.4 Personal Protective Devices powders or grinding In the do’s and don’ts given above, we have mentioned about using personal chemicals by hand. A protective devices. The aim of protective devices is to minimise the risk of personal respirator is an apparatus injury and damage through contact with hazardous substances. Let us learn about for giving artificial breathing; it may be used some of the personal protective devices to be used in the laboratory. when working with highly toxic materials. Lab coats It is mandatory to use lab coat while working in the laboratory. These should cover the knees and have full length sleeves. The purpose of the lab coat is to cover your regular clothes to minimise nonobvious contamination, splash hazards and check the saturation of regular clothes or skin from exposures to harmful substances. In addition, these also provide some temporary protection against fire. The material of the lab coats is not impermeable to hazardous substances or flameproof, however, as these can be quickly removed, they provide additional safety from harmful exposures or flames. The lab coat should fit well and should be buttoned up correctly at all times. It is strongly recommended that you use a cotton lab coat as these are more suitable than those made from nylon as the former could absorb more liquid and offer more protection against spilled chemicals. An added advantage is that the cotton coats do not generate sparks by static electricity which might ignite highly flammable organic 42 solvents. Nylon melts when heated and can stick to the flesh. It also dissolves in Safety in a Chemical some organic solvents. Laboratory Sometimes an additional protection, such as a rubber apron is recommended. These should be used while working with large amounts of chromic acid, hydrofluoric acid and other highly corrosive liquids. Safety goggles You would agree that eyes are precious and we should be utmost careful so as to avoid any injury to them. It is therefore advisable that safety goggles should be used where there is the slightest risk of splashes of chemicals or fragments of dust, glass, etc. getting into the eyes. Goggles are available to be worn over prescription glasses. It is not advisable to use contact lenses in the laboratory. If one does use then in such a case it necessary to use protective goggles while working in the laboratory. Gloves Gloves are recommended to be used while transferring toxic, radioactive and carcinogenic compounds, irritants and corrosive liquids. The practice of wearing rubber gloves continuously for laboratory work is not recommended as the hands become very moist and sweaty. These may also lead to skin infection. Rubber gloves also make it difficult to hold wet glass and may cause serious accidents due to dropped bottles or glassware. SAQ 1 Enlist three requirements that must be met while designing a chemistry laboratory. …………………………………………………………………………………………... …………………………………………………………………………………………... …………………………………………………………………………………………... SAQ 2 What kind of training is required for a personnel working in a Chemistry laboratory? …………………………………………………………………………………………... …………………………………………………………………………………………... …………………………………………………………………………………………... 5.3 CHEMICAL HAZARDS IN THE LABORATORY Chemicals are present in all laboratories. It is prudent to consider that all chemicals are toxic and flammable unless one has definite information regarding its nature. Ideally speaking no chemical can be considered totally safe or hazard free. The nature and extent of hazard varies and more so the long time effects of many chemicals are not known as yet. One is therefore advised to exercise caution in handling all chemicals and minimise exposure to them. Let us learn about possible ways in which the chemical exposure can occur. 5.3.1 Modes of Exposure to Chemicals In a laboratory, the chemicals can cause harm in a number of ways. These are: Dermal exposure; direct contact from spills or by improper handling 43 Initiation into Inhalation; of the vapours, fumes or dust Analytical Laboratory Ingestion; i.e. the oral route Fire; caused by flammable liquids Explosion; caused due to improper handling of chemicals Let us learn about these in detail and the precautionary measures required to avoid these. Dermal Exposure Our skin is an effective barrier for many chemicals however; it is a common route of chemical exposure. Dermal exposure to different chemicals can cause irritation and damage to the skin and/or eyes. The effects of dermal exposures can range from mild temporary discomfort to permanent damage depending on the chemical involved and the length of exposure. The toxicity of the chemical depends on the extent of its absorption by penetration through the skin. The absorbed chemical enters the blood stream and is carried to all parts of the body. The absorption of chemicals is much more if the skin is injured, chapped, or cracked. Organic chemicals generally are more likely to penetrate the skin than inorganic chemicals. Inhalation Inhalation is the most dangerous route of chemical exposure into the body. This is so because unlike the skin, lung tissue does not have a protective barrier against the ac- cess of chemicals into the body. It therefore requires the most immediate response. Chemicals in the form of gases, vapours, mists, fumes, and dusts entering through the nose or mouth can be absorbed through the mucous membranes of the nose, trachea, bronchi, and lungs and can damage the lung surface. Most poisonous gases, such as chlorine, hydrogen sulphide, ammonia and hydrogen cyanide, are detectable by their odour or by their irritating effect on the nose, throat, etc. One should not ignore these initial warning signs as the nose quickly becomes insensitive to smell. For example, hydrogen sulphide is almost as toxic as hydrogen cyanide, but because of the paralysing effect of the gas, it seems to be odourless when highly concentrated. As inhalation of gases can be disastrous, all possible situations that may allow it to happen should be avoided. You would recall that in the don’ts given in Sec. 5.2 it was stated that direct smelling of the chemicals should be avoided. In addition, the reactions involving generation of poisonous gases should be conducted in fume cupboard. Ingestion Ingestion refers to the chemicals entering the body through the mouth i.e., the oral route. Chemical dusts, particles and mists may be inhaled through the mouth and swallowed. They may also enter through contaminated objects, such as hands or food that come in contact with the mouth. Absorption of the chemicals into the bloodstream can occur anywhere along the length of the gastrointestinal (GI) tract. Safe laboratory practices like, never pipetting by mouth, never eating in the lab, washing hands after working with chemicals, etc. as discussed earlier minimise ingestion accidents. 5.3.2 Effect of Chemicals on Body No one can disagree with the saying, “Prevention is better than cure”. It therefore becomes important to know about the chemicals we generally handle in the lab and their effects on the body. Some of the classes of chemicals and their effects on the body are as follows. 44  Safety in a Chemical Acids: These cause severe burns and tissue damage. Some of the commonly used Laboratory acids are acetic, chromic, hydrochloric, nitric, sulfuric, and carbolic (phenolic) acids. Alcohols: These irritate mucous membranes. Methanol can cause blindness on ingestion or on prolonged inhalation. Aldehydes and Ketones: These cause: irritation of the tissues and produce narcotic effects on inhalation, absorption or ingestion. Alkalies: Sodium, potassium and ammonium hydroxides cause severe tissue burns and bronchial spasms. Carbon monoxide: Prolonged exposure to carbon monoxide is toxic and may prove to be deadly. It makes the haemoglobin of red blood cells ineffective for the transport of oxygen. Compounds of Sulfur, Phosphorus, Nitrogen: These substances corrode the skin and destroy respiratory tissues. Cyanides: These are highly toxic if absorbed, inhaled or ingested. Esters: Exposure to esters causes tissue poisoning and irritation. Ethers: These produce a powerful narcotic effect on inhalation. Halogens: These are corrosive and highly irritating to tissues. Hydrocarbons: Inhalation of hydrocarbons causes irritation and tissue destruction. Prolonged exposure can be very dangerous; some hydrocarbons are carcinogenic in nature. The chlorinated hydrocarbons like chloroform can form highly toxic phosgene gas. Mercury: Mercury is quite toxic in nature. Extensive handling of mercury or inhalation of its vapours may cause tissue poisoning. The toxic effects of exposure to mercury are compounded with prolonged exposure. 5.3.3 Acute and Chronic Effects The effects of accidents due to chemicals are severe and immediate on the human body. These effects are called acute effects and can be traced without difficulty. Frequently, poor lab practice or an unsafe system of work will lead to gradual poisoning. At first, effects may go unnoticed; or the effects may be attributed to the wrong cause. It may be hard to trace the real cause of these chronic or long term effects. In some cases, final results could be much worse than the immediate results. For instance, consider the effects of ingested alcohol given below. Acute effect – drunkenness and vomiting Chronic effect – addiction, liver damage, etc. Safe lab practice will also minimise chronic effects. An example of good practice is ventilating the lab in the morning; this will minimise immediate poisoning or asphyxia (acute effect) and longer term poisoning (chronic effect) due to inhalation hazards. 5.3.4 The Fume Cupboard If a reaction uses or produces harmful gases, dusts or vapours, it poses a risk of inhalation. As mentioned above, such reactions should not be carried out at open bench but in a fume cupboard. A fume cupboard contains the normal laboratory 45 Initiation into services like, gas, water and electricity to be utilised. In addition an air extraction Analytical Laboratory system i.e. an exhaust fan, with a minimum statutory air flow, ensures that dangerous vapours are vented to the atmosphere. A typical laboratory fume cupboard is shown in Fig.5.2. Fig. 5.2: A fume cupboard. Note the provision for gas, water and electrical supply Access to the fume cupboard is via sliding panels of safety glass. It is important to note the maximum height to which these panels can be safely raised before the air flow into the fume cupboard drops below the required rate. SAQ 3 What are different modes of direct human exposure to the chemicals? …………………………………………………………………………………………... …………………………………………………………………………………………... …………………………………………………………………………………………... 5.4 CLASSIFICATION OF HAZARDOUS MATERIALS A hazardous substance is the one which has the potential to cause harm to human beings, other living creatures, plants, microorganisms, property or environment. It therefore becomes important to stress that adequate care should be exercised in handling the hazardous materials. This becomes all the more important because any lapse in their handling may cause harm even to those who are away from the location where the hazardous material are handled. The classification of chemical hazards as recommended by the UN Committee of Experts on the Transport of Dangerous Goods has been widely accepted. According to this classification, the hazardous chemicals are segregated into nine basic classes represented numerically from 1 to 9. Many of these classes are further separated into divisions and subdivisions. A brief description of the classes is as follows: Class-1 Explosives The explosives are defined as the chemical substances and preparations which may explode under the effect of flame or which are more sensitive to shocks or friction than dinitrobenzene. These include the commercial explosives, preparations and substances used as blasting agents, ammunition, fireworks, etc. Some examples are, gun powder, chlorate mixtures, nitrate mixtures, nitro compounds, fulminates, ammunitions, fire works, detonators, gels, etc. This class has been further divided into 46 six divisions; in addition, this class has 13 compatibility groups that identify the kind Safety in a Chemical of explosive articles and substances deemed to be compatible. Laboratory Class-2 Gases A substance which has a critical temperature below 50°C, has a vapour pressure of more than 3 bars absolute is classified as a gas. Gases which are compressed, liquefied or dissolved under pressure or refrigerated come under the category of hazardous gases. These are further divided into 3 subclasses on the basis of their hazardous nature, these are detailed below. In addition, some gases have subsidiary risk classes; poisonous or corrosive. Flammable Gases: Gases which ignite on contact with an ignition source, such as acetylene and hydrogen. Flammable substances are Nonflammable Gases: Gases which are neither flammable nor poisonous. Include the substances which cryogenic gases/liquids (temperatures of below -100°C) used for cryo-preservation catch fire on exposure and rocket fuels, such as nitrogen and neon. to air without application of energy, Poisonous Gases: Gases liable to cause death or serious injury to human health if or inhaled; examples are fluorine, chlorine, and hydrogen cyanide. readily catch fire after brief contact with a Class-3 Flammable Liquids source of ignition, or You must remember that the word flammable has the same meaning as inflammable. The liquids or mixtures of liquids or liquids containing solids in suspensions or evolve highly solutions which give off flammable vapour at temperature of not more than 60.5°C are flammable gases in called flammable liquids. Examples of flammable liquids are petrol, alcohol, contact with water or petroleum, naphtha, hexane, benzene, toluene etc. The liquids are flammable to damp air. different degrees, accordingly there are three categories. Liquid chemicals and preparations having flash point and a boiling point lower than or equal to 35 degree Celsius are called extremely flammable liquids. The examples are diethyl ether and carbon disulfide, etc. Further, the liquid substances and preparations with boiling points greater than 35o C and having a flash point below 23o C but which are not extremely flammable are called highly flammable liquids. Gasoline (petrol) and acetone are some of the examples. The third category includes the flammable liquids that do not belong to the above two categories. Examples are: kerosene and diesel. Class-4 Flammable Solids Solid substances and preparations which may readily catch fire after brief contact with a source of ignition and which continue to burn or be consumed after removal of the source of ignition are put in the class of flammable solids. In addition, some solids are flammable or liable to spontaneous combustion or emit flammable gases on contact with water. Examples are: camphor, cinema films, hay and straw phosphorus, triethylaluminium, sodium sulphide, alkali metals, alkali amalgams, uncoated aluminium powder, etc. Like flammable liquids the flammable solids are also further subdivided. These sub classes are given below. Flammable Solids: These include solid substances that are easily ignited and readily combustible, for example, nitrocellulose, magnesium, safety or strike-anywhere matches. 47 Initiation into Spontaneously combustible solids: These are the solid substances that ignite Analytical Laboratory spontaneously; for example, alkyl aluminiums, white phosphorus. Class-5 Oxidising Substances Chemicals and preparations which give rise to highly exothermic reaction when in contact with other chemicals, particularly flammable chemicals belong to this category. Oxidising substances are by themselves not combustible but by feeding oxygen to other substances cause or contribute to their combustion. Organic peroxides (having O-O-bond) undergo thermal decomposition leading to explosion and/or rapid burning. Oxidising substances include chemicals like, nitrates, nitrites, permanganates, chromates, dichromates, chlorates, perchlorates, and peroxides. Oxidising agents have been further subdivided into following three classes. Oxidizing agents other than organic peroxides: Common examples of this subclass are calcium hypochlorite, ammonium nitrate, hydrogen peroxide and potassium permanganate. Organic peroxides: These may be either in liquid or solid form, for example, benzoyl peroxides, cumene hydroperoxide. Dangerous when wet: Solid substances that emit a flammable gas when wet or react violently with water are grouped in this class, for example, sodium, calcium, potassium, calcium carbide. Class-6 Poisonous and Infectious Substances Poisonous substances are the substances that are liable to cause death or serious injuries to health, if swallowed or inhaled or allowed to come in contact with skin. The infectious substances on the other hand are those which are contaminated with disease inducing microorganisms. This class has two subclasses as follows. Toxic substances: these are the substances which are liable to cause death or serious injury to human health if inhaled, swallowed or by skin absorption the examples are potassium cyanide, mercuric chloride, etc. Biohazardous substances: as the name suggests these are the substances of biological origin. These are further subdivided as follows: Infectious substances affecting humans and animals: An infectious substance in a form capable of causing permanent disability or life-threatening or fatal disease in otherwise healthy humans or animals when exposure to it occurs. Bio-hazard Waste or reusable material: These are derived from medical treatment of an animal or human, or from biomedical research, which includes the production and testing of biological products. Class-7 Radioactive Substances Radioactive materials are articles or substances, which spontaneously and continuously emit certain types of radiation that can be harmful to health but which cannot be detected by any of the human senses. As you know, the radioactive emission is classified into three major types – alpha (α ), beta (β ) and gamma (γ). The International Ionising Radiation symbol is used to indicate the presence of intermittent or continuous ionising radiation. The symbol for a radioactive substance is usually black, on a yellow background. Radium, uranium, thorium, etc. are few of the examples. 48 Class-8 Corrosive Substances Safety in a Chemical Laboratory These substances cause severe damage by chemical action when in contact with living tissue. These may destroy/damage other materials which come in their contact. In other words, these are the substances that in the event of leakage can cause severe damage by chemical action when in contact with living tissue or that can materially damage other freight or the means of transport. The mineral acids like hydrochloric acid and sulphuric acid and alkalis like sodium hydroxide belong to this class. Class-9 Miscellaneous Dangerous Substances This class includes other hazardous substances not covered in the above classes. Hazard Identification Each United Nations hazard class (with the exception of class 9) has a distinctive diamond shaped label bearing a pictogram for quick hazard recognition. Each label has a characteristic background colour. These colours convey the nature of different chemical substances as given below. The typical labels have been shown along with different classes above. Colour Nature Explosive Orange Flammable Red Water reactive Blue Oxidiser Yellow Toxic or Infectious White Radioactive White or Yellow and White Corrosive Black and White 5.4.1 Carcinogens In addition to the above recognised classes for hazardous chemicals, there is another very important class of compounds which you should be aware of. These are called carcinogens. These are the substances which cause cancer. There are a number of substances which are known to induce cancer many months or years after the initial exposure. Some substances which are known or suspected carcinogens are aniline, chloroform, benzyl chloride, chromates of lead and zinc, hydrazine, etc. In addition, ninhydrin – the reagent used in biological and biochemical tests for the presence of amino acids and proteins, is also thought to be a possible carcinogen, but this has yet to be confirmed. Similarly some stains like fuschin used in biology lab also belong to this category and extreme care should be exercised in their use. The examples given here are very few, however more and more substances are being shown to be carcinogenic and the fact that even quite common substances may have some carcinogenic activity emphasizes the necessity of consulting reference literature before starting work with materials when you are ignorant of their potential hazards. SAQ 4 What is the difference between poisonous and infectious substances? …………………………………………………………………………………………... …………………………………………………………………………………………... …………………………………………………………………………………………... …………………………………………………………………………………………... 49 Initiation into Analytical Laboratory 5.5 STORAGE AND HANDLING OF CHEMICALS As you are aware, the apparatus and chemicals are stored in areas dedicated for them. The chemicals are to be stored only in approved, locked cabinets within the store rooms. The rooms storing the chemicals must be well ventilated and dry and must have adequate protection from direct sunlight. In addition, the lighting should be adequate. The hazardous nature of the chemicals demands that they are stored and handled carefully. Storage of chemicals whether in small amount or in bulk is an important aspect of laboratory safety. Have you ever wondered, what are the considerations that are kept in mind while storing the chemicals? Or what kinds of precautions must be followed while handling the chemicals? Let us learn about the storage and handling of chemicals for a safe laboratory experience. 5.5.1 Incompatibility of Chemicals Compatibility of chemicals is the prime concern during the storage of chemicals; two different chemicals should be stored at the same place only when these will not react with each other in a harmful manner i.e. are compatible in nature. As the fuel must be separated from ignition sources so as to prevent a possible fire the incompatible chemicals should also be separated. Before learning about incompatible chemicals let us first analyse the benefits and drawbacks of the possible ways by which storage of chemicals may be attempted by user of the laboratory. These are given below. Random storage: As the name suggests in this system, there are no restrictions to where chemicals are stored. You may find acids next to bases, oxidisers next to flammables, water reactive chemicals next to the sink and severe poisons next to the writing desk. In such a situation innumerous potentially hazardous reactions may occur due to incompatible contacts. As this is the sure way of causing an accident in the laboratory we must NOT ever follow this method of storage. Alphabetical storage: This is probably the most commonly used method for chemical storage in the chemistry laboratories. Though it is convenient for locating and placing the chemicals it does not take care of the storage of the incompatible chemicals and may lead to undesirable consequences. Categorical Storage: As the name suggests categorical storage schemes involve storage on the basis of the different categories of chemicals. Some of the common categories are flammable chemicals, oxidants, concentrated acids, bases, water reactive chemicals, toxic compounds, gases, etc. This approach is also useful but a little inconvenient to use. Thus, the recommendations for the safe storage of chemicals can be summarised as follows: 1. All chemicals must be properly labeled and be stored in an orderly manner keeping in mind their compatibility. There should be an efficient retrieval system to locate the chemicals. Alphabetical order can be used within a compatible group of chemicals. 2. Properly labeled safety containers must be used to store liquids that are highly volatile, potentially explosive, or flammable. Table 5.1 gives a list of some common chemicals used in the laboratory and the corresponding incompatible chemicals. It is not a complete list; however, it can be used as a guide for proper storage and use in the laboratory. It is advised that the risk associated with incompatible chemicals coming into contact must be avoided wherever chemicals are handled or stored. 50  Table 5.1: List of some common chemicals showing the corresponding Safety in a Chemical incompatible chemicals Laboratory Chemical Incompatible with Acetic acid chromic acid, nitric acid, hydroxyl compounds, ethylene glycol, perchloric acid, peroxides, permanganates Acetylene chlorine, bromine, copper, fluorine, silver, mercury Acetone concentrated nitric acid and sulphuric acid mixtures Ammonia (anhydrous) mercury(e.g., in manometers), chlorine, calcium hypochlorite, iodine, bromine, hydrofluoric acid (anhydrous) Ammonium nitrate acids, powered metals, flammable liquids, chlorates, nitrites, sulphur, finely divided organic combustible materials Aniline nitric acid, hydrogen peroxide Bromine see chlorine Calcium oxide water Carbon (activated) calcium hypochlorite, all oxidising agents Chlorates ammonium salts, acids, powered metals, sulphur, finely divided organic or combustible materials Chromic acid and acetic acid, naphthalene, camphor, glycerol, alcohol, chromium trioxide flammable liquids in general Chlorine ammonia, acetylene, butadiene, butane, methane, propane (or other petroleum gases), hydrogen, sodium carbide, benzene, finely divided metals, turpentine Cyanides acids Flammable liquids ammonium nitrate, chromic acid, hydrogen peroxide, nitric acid, sodium peroxide, halogens Fluorine all other chemicals Hydrocarbons (such as fluorine, chlorine, bromine, chromic acid, sodium peroxide butane, propane, benzene) Hydrogen sulphide fuming nitric acid, oxidising gases Hypochlorites acids, activated carbon Iodine acetylene, ammonia (aqueous or anhydrous), hydrogen Mercury acetylene, fulminic acid, ammonia Nitrates acids Nitric acid acetic acid, aniline, chromic acid, hydrocyanic acid, (concentrated) hydrogen sulphide, flammable liquids and gases, copper, brass, any heavy metals Potassium glycerol, ethylene glycol, benzaldehyde, sulphuric acid permanganate Sulphuric acid potassium chlorate, potassium perchlorate, potassium permanganate (similar compounds of light metal, such as sodium, lithium) 51 Initiation into 5.5.2 Handling of Chemicals Analytical Laboratory Everybody working in the laboratory need to be aware of the potential danger of the substances to be handled by them and must follow the requisite precautions while handling them. The label on the chemical bottle provides an initial guide to the nature of the chemical and the associated risks. Let us learn about the information on the label. Label As mentioned above, in order to minimise the hazards associated with using a particular substance it is necessary to know what the precise dangers are. The label on the container has the following information that provides a general guide on handling of the chemical. the name of the substance (IUPAC name as well as their trivial name, if available). an indication of the general nature of the risk accompanied by the corresponding warning symbol if the substance is explosive, oxidising, flammable, toxic, harmful, corrosive or irritant. a risk phrase which underlines and explains the general nature of the risk, and a safety phrase which gives advice about precautions to be taken. the name and address of the manufacturer. The information on the label may be sufficient if only small amounts of the material are being used occasionally. However, before carrying out extensive work or purifying a chemical, one must refer the published sources to obtain full details of the substance’s physical and chemical properties, of its particular hazards, and of the disposal procedure or first aid treatment to adopt in the event of spillage or an accident. Having become aware of the potential hazards of a given chemical, the required handling procedure and the precautions to be followed would depend on the activity involved. The common handling of chemicals involves the following activities. Decanting dangerous liquids Transport of bulk chemicals Let us learn about the safety precautions to be followed during these activities. Decanting Dangerous Liquids As with all dangerous operations, it will pay you to think what the worst possible accident may be that could result from your actions and what would you do in this event. Thus, in the event of decanting dangerous liquids from a large container you can expect the following. a) Drips and spillage: In such a situation some of the obvious questions that must be addressed to before taking up the activity are as follows. Is there a fire hazard? If so, what extinguishers are available? Is there a risk of corrosion? Is the platform on which the respectable standing on stable? Are the neutralising agents available? Do we have mopping up facilities? Is there a sand bucket? etc. 52 b) Splashes and fumes: In addition to the questions raised in case of drips and Safety in a Chemical spillages we need to address the following questions Laboratory Should this operation be conducted in a ventilated area? Do I need protective clothing? Is there someone nearby to give first-aid if there is a bad accident? etc. If a nonconducting fluid is being decanted from a glass or plastic container, consideration must be given to earthing containers and funnels. Sufficient static electricity could be built up to spark off a fire or explosion. Transport of Bulk Chemicals In an ideal situation, only requisite amounts of concentrated acids, flammable solvents and other hazardous chemicals are kept in the laboratory for immediate requirements. The larger amounts, e.g. 500 cm3, 1 litre and 2 litre (Winchester) bottles, carboys and metal drums, are always stored separately. The storage of concentrated sulphuric, nitric and other acids should be done in acid resistant trays or troughs. While transporting larger amounts of hazardous chemicals, the following precautions must be observed Never carry the bottle by the neck as it can easily slip out of your hand and smash on the floor. Also, do not carry these bottles in the arms or in the hands. A proper carrier must always be used for transporting them from the store or from one lab to another. Carboys of concentrated acids and other liquids should be vented otherwise, the increase in pressure as the contents heat up on being brought from a cold store into a warm room is sufficient to burst the carboy. Whenever possible, carboys should be left in the bulk store and liquids dispensed as required using a siphon. SAQ 5 Why is it important to know about the compatibility of chemicals while storing them in a laboratory? …………………………………………………………………………………………... …………………………………………………………………………………………... …………………………………………………………………………………………... …………………………………………………………………………………………... 5.6 SAFE HANDLING OF GLASSWARE Glass apparatus is an integral part of a chemistry laboratory. Different glassware is made for a specific purpose and it is expected to be used only for that purpose. If not used and handled in proper manner the glassware may lead to accidents. In fact, one of Broken glassware causes the main hazards of working in a laboratory comes from handling glassware. How do more laboratory accidents we protect ourselves from glassware accidents? The potential injuries can be avoided than any other hazard. if people are given appropriate training on correct procedures and handling techniques. Following are some precautions which could be important in reducing the risks involved. These may appear to be simple common sense. 53 Initiation into Keep glassware away from the edge of the bench top. Analytical Laboratory Always clamp your reaction flask and the suction flask securely to a ring stand to prevent them from falling over. Check each piece of glassware for hairline or star cracks before using it. In case there are any cracks the apparatus should be discarded or sent for the repair. Be aware of the compatibility of glassware with the chemicals being used. Although glass is one material that is highly unreactive to most of the chemicals yet there could be some chemicals which might react with the glass. In such cases one should not store or carry out the reaction using glassware. Strong acids and alkalies need special attention here. When performing a distillation, clamp each piece of glassware securely. If you do break a piece of glassware, do not leave it in the sink or on the bench top because someone may inadvertently get hurt. In case you are using a heating mantle or steam bath, the glassware or the clamps used to hold glassware can become hot enough to cause a thermal burn on your skin. Use heavy gloves in such a situation. Not all types of glass apparatus can sustain high temperature and pressure. If excess heat or pressure is given, the glass is likely to break and hurt the worker. You may use thick gloves while washing glassware so as to prevent cuts in case the glassware breaks. Avoid routine cleaning with aqua regia, chromic acids or other caustics. Simple detergent powders or liquids are generally sufficient. Never use worn out cleaning brushes as these can cause scratches. Always wear closed-toed shoes. These provide protection to the feet not only from the dropped glassware, but also from broken pieces of glass which may be on the floor from a previous lab section. Always wear your goggles to protect your eyes from flying broken glassware. Use thick gloves, brush and dustpan to sweep up the broken glass. Alternatively, you may use pieces of cardboard, heavy paper, or dustpan and brush; never with bare hands. The collected broken glass is disposed off in the container earmarked for the same. Smaller particles should be picked up with several thicknesses of wet paper towels then discarded. Cloth napkins, cloth towels, sponges or ordinary mops should not be used for clean up because they can harbor tiny glass particles. For broken glass containers with liquids, an ordinary long range rubber squeegee or broom used with a dustpan provides the safest removal. Until the glass breakage can be cleaned up, a warning sign should be posted in the area to alert others of the danger. Always use two hands to hold any glassware and position one hand under the glass for support. Approved gloves and eye protection should be worn in environments where glass is handled frequently and where there is the possibility of exposure to disease, toxics or harmful irritants. Safety glasses should be required in the vicinity of machinery, conveyors, shipping operations and other locations where glass may be broken or where there is any possible hazard of flying glass fragments. 54  Safety in a Chemical 5.7 EQUIPMENT AND ELECTRICAL SAFETY Laboratory In a laboratory a number of instruments and specialised equipments and computers are used. As these operate on electricity which presents a number of hazards, one has to be aware of potential hazards and the precautions to be used while handling them. Most electrical accidents are caused by worn out equipment or improper use both of which are avoidable. You’ve probably read about, or heard of, people falling onto high voltage rails or cables and surviving thousands of volts. As a contrast, you might have also had a small electric shock from the mains yourself. It does not mean that it is safe because it only needs a few milliamperes across the heart to stop it. There are serious physiological consequences of passing an electric current through the body. Many a times the reason behind the electrical mishap is due to negligence of the very fundamentals of electricity. Some of the possible causes that may lead to a shock or cause an electrical mishap are as follows. Improper wire / wiring Improper choice of fuse Deterioration in the insulation system Accidental touches Break in earthing system Improper operation/use of unconventional tools Some simple precautions that must be followed so as to avoid mishap from electrical appliances are as follows: Use electrical equipments like, heating mantles, motors, hot plates etc. properly to prevent electrical shock. Check the cord or plug to make sure that it is not damaged; replace if damaged. Always disconnect the plug from the socket by pulling firmly on the plug, do not pull it out by the cord! Keep water away from all electrical equipment. Dangling electrical wires running across the floor are a trip hazard. This assumes greater significance in a chemistry lab as one may be carrying a corrosive or flammable chemical. CAUTION: Never touch a person suffering from electric However, despite all precautions if someone gets electrocuted, you must not touch shock until you are that person. The first objective should be to isolate the victim from the electric certain that the current power source. For this, switch off the power either at the nearest appropriate mains has been turned off. socket or at the nearest cut-out or main switch. SAQ 6 What are the possible reasons for electrical mishaps in a chemistry laboratory? …………………………………………………………………………………………... …………………………………………………………………………………………... …………………………………………………………………………………………... …………………………………………………………………………………………... …………………………………………………………………………………………... …………………………………………………………………………………………... 55 Initiation into Analytical Laboratory 5.8 EMERGENCY PROCEDURES As mentioned earlier, we can minimise the accidents by following the precautions but we can’t eliminate them. There is always a probability of accidents to occur. It is imperative, therefore, that necessary preparations should be there to cope up any eventuality. The relevant first aid procedures for the common accidents likely to occur in a chemistry laboratory are given below. These are not the treatments for the accidents but are mere procedures that would minimize the possible damage from accident. A timely first aid can, at times, provide more relief than a delayed medical aid. Let us learn about different possible accidents and the suggested first aid. Chemical Burns These are caused by accidental exposure to acids, bases and other corrosive chemicals. The long-term effect of these burns is scarring and, depending on the site of the burn, can be quite disastrous. Phenols are exceptionally dangerous. These are highly caustic and are very rapidly absorbed through the skin. First aid The first step in such a situation is to remove the offending agent at the earliest. Remove contaminated clothes, longer they stay, greater the damage. Remove rings, watches and other ornaments in the affected area as these may trap the contaminants. Wash the affected portion under running water for about 10 - 15 minutes to limit the tissue destruction. Take care that the washings do not go onto the unaffected portion of the skin. Save yourself also. Avoid using neutralising solutions. These generate heat, which increases damage. In case the corrosive chemical falls in the eye i.e. it is a case of an ocular burn Remove the contact lens, if it is there, as the chemical can get in between the lens and cornea and cause damage. Do not let the patient rub his /her eyes. Wash the eye with gently running water from the tap, an eyewash bottle or eye wash station for10 to 15 minutes. Open the eyelids and ensure that water drenches the eyeball. All eye injuries must be seen by a doctor preferably within an hour. Eye wash station Thermal Burns These can be contact burns caused by direct contact with open flame or contact with a hot object like a hot flask, the injury being confined to the point of contact or scalds which result from contact with hot liquids. First aid Remove the victim from the source of the burn. Cool the burn using large amounts of cool water. Do not use ice except in small superficial burns. It may cause body heat loss. 56  Once the burn has been cooled, cover the burn using dry, sterile dressing or the Safety in a Chemical cleanest cloth available. Laboratory Refer patients with critical burns to a regional burn center for further management. Cuts and Wounds Cuts and wounds from broken glass are probably the most likely accidents in a laboratory. The injury may vary from a minor cut to a profusely bleeding wound. First aid In case of a minor cut or abrasion, clean the wound and surrounding skin with soap and water. To avoid contamination, wash away from the wound and not towards it. Pat the wound dry, with a sterile pad or the cleanest cloth available and, apply a suitable bandage as required. For a major wound involving profuse bleeding, apply firm pressure over and around the wound with a sterile pad or the cleanest cloth available, to reduce bleeding as much as possible. Make the victim lie down with bleeding part raised higher than rest of his / her body. Apply a tight bandage and call for the physician, if not done so far. Meanwhile keep the victim warm and give him (if he is conscious) a lot of nonalcoholic liquid to drink. Ingestion of Chemicals Incidents of ingestion of chemicals are far less common than the ones involving other routes of exposure. However, significant quantities of toxic chemicals can be ingested e.g. in a mouth-pipetting experiment. First aid If the corrosive material is confined to mouth only then repeated mouthwash is probably the best bet. 3 However, if the chemical has been ingested give about 250 cm of water to dilute the contents. Do not try to neutralise the chemical as the heat generated may cause additional injury. Do not try to induce vomiting. This may cause injury to the delicate tissues of the esophagus. Arrange for the medical help, better transfer to the hospital. Inhalation of Gases and Vapours Inhalation of toxic gases and obnoxious vapours of certain volatile liquids is another common situation in a laboratory that demands prompt first aid. Inhalation of gases and vapours can cause varied effects ranging from irritation of eyes and mucous membrane to drowsiness to unconsciousness. First aid Move the victim immediately to fresh air. 57 Initiation into If the victim is unconscious , place in a face down position and check for the Analytical Laboratory breathing. On the first sight of difficulty in breathing or stopped breathing apply artificial respiration immediately ( mouth to mouth method). Keep the patient warm and as quite as possible till the help arrives. Call for the medical help. If needed transfer the victim to the hospital. Splashing of Chemicals on the Skin and in the Eye Splashing of chemicals on the skin and in the eye is a common occurrence in a chemistry laboratory. No chemical can be considered totally hazard free, though some are relatively safer. It is good, therefore, to regard all chemicals as hazardous and proceed for the first aid. First aid Wash the affected portion immediately under running water for about 10 -15 minutes. Take care that the washings do not go onto the unaffected skin. Remove contaminated clothes, rings, watches and other ornaments in the affected area. In such cases the quickness with which the splashed chemical is removed really matters. However, do not get affected in the process. If situation so warrants a medical advice should be sought. For the splashing of the chemical into the eye, proceed as instructed under chemical burns. Fractures It is not our intention to introduce you to many types of fracture that can occur or all the ways a first aider might deal with them. The essential thing is that you know that complications can arise from moving a casualty with a fracture without first taking steps to immobilize the fractured limb. Any broken or cracked bone is referred to as a fracture. The general symptoms of a fracture are as follows. Tenderness when gentle pressure is applied to the affected area and localized pain which increases if the injured part is moved. Some fractures such as those of the wrist of fingers produce little pain and the casualty may feel that he/she Bruise: Bleeding beneath the has only bruised or strained the affected area. surface of the unbroken skin. Swelling occurs as a result of blood loss into the surrounding tissues and may mask other symptoms. Deformity or unnatural movement; wherever possible the injured and uninjured limbs should be compared. Splint: A thin, rigid strip of wood, metal etc. used to Shock. keep a broken bone in place. It can be improvised by flat The recommended action in any accident in which a fracture is suspected is to keep wood or newspapers. the casualty still and not to move him/her unless it is necessary to separate him/her from some other hazard which could endanger his/her life. Remember that any movement can cause further injury and the part should be immobilized by means of a body bandage or by the use of splint and bandages. The best general treatment is to given below. 1. Cover the casualty with a blanket. 58 2. Keep the casualty warm. Safety in a Chemical Laboratory 3. Send for an ambulance. 4. Treat for shock and do not give any drinks. Fires The following steps should be followed in case of a fire. If your clothing catches fire, immediately drop to the floor and roll to smother the flames and call for help. If a compound or solvent catches on fire, if you can, quickly cover the flames with a piece of glassware. If it is feasible, use a fire extinguisher to put the fire out. Do not put water on an organic chemical fire because it will only spread the fire. If the fire is large, do not take chances: evacuate the lab and the building immediately and tell your TA or the Coordinator what has happened. If no one in authority is available, pull the fire alarm in the hallway. If the fire alarm sounds for any reason, leave the room immediately and exit the building. 5.9 SUMMARY A laboratory is an integral component of any scientific study and can be a place of danger if proper certain precautions aren't taken. It is all the more significant in the case of Chemistry. The chemistry laboratory is full of potential hazards; sometimes even life threatening. The hazards arise due to the unavoidable hazard associated with the use of a variety of chemicals, glassware and equipments. The risk from such hazards in the laboratory can be prevented if adequate precautions are observed while working there. It is therefore desirable that we follow good laboratory practices and work towards the safety of ourselves as well as that of the fellow workers. The safety aspect of a laboratory comes into play right at the stage of the construction of the lab. For this, the design of the laboratory buildings should be made in accordance with safety norms formulated by the Bureau of Indian Standards (BIS). The essential features of the laboratory that need attention are the lab rooms, gas and water lines, sinks and drains, laboratory furniture, stores, first aid kit etc. in addition, adequate provision for lighting, ventilation, fume cupboards, fencing of the dangerous parts of the machinery like vacuum pumps, fire prevention measures, escape routes, fire extinguishers, first-aid boxes etc., are some of the essential requirements for a safe lab. The safety of a function laboratory requires that the laboratory staff must have appropriate training in handling equipment and chemicals, using gas cylinders and fire fighting equipment, moving load, waste disposal, and in administering first aid. In addition it is essential that there is a regular monitoring of the condition of the building, water and gas lines, fire safety equipments, first aid kits etc. A Chemistry laboratory can be safe only when each and every individual using the laboratory is cautious of basic facts and rules regarding safety. The do’s and don’ts in a chemistry laboratory should not only be known but also be followed genuinely if we want to avoid mishaps. Further, the use of personal protective devices like, lab coats, safety goggles, gloves etc. help in minimising the risk of personal injury and damage through contact with hazardous substances. 59 Initiation into It is prudent to consider that all chemicals are toxic and flammable unless one has Analytical Laboratory definite information regarding its nature. In a laboratory, the chemicals can cause harm in a number of ways like, direct contact from spills or by improper handling, inhalation of the vapours, fumes or dust, ingestion, fire from flammable liquids and explosion due to improper handling of chemicals. It is therefore important to know about the possible hazards of a chemical and take adequate precautions while handling them. The hazardous substances are classified into nine categories by the UN Committee of Experts on the Transport of Dangerous goods. These are represented numerically from 1 to 9. Many of these classes are further separated into divisions and subdivisions. Knowledge about the nature of the chemicals is also useful while storing and handling them. It is highly desirable that the compatibility of the chemicals is kept in mind while storing them so as to avoid any untoward accident. Further, while handling the chemicals one must study the label on the bottle of the chemical as it contains the requisite information about the nature and handling precautions about the chemical. It has been observed that the broken glassware causes more laboratory accidents than any other hazard. Therefore, one should be careful while handling the glassware. Similarly, one must be cautious of the potential hazards from the electrical equipments and take adequate preventive steps while handling them. 5.10 TERMINAL QUESTIONS 1. What is the difference between acute and chronic effect of a chemical? Explain with the help of an example. 2. Define the following terms. a) Hazardous chemical b) Fume cupboard c) Flammable liquid 3. What is the importance of personal protective devices? 4. What are the drawbacks of random storage of chemicals? 5. What is the importance of a label on the chemical bottle? 6. What is meant by a bulk chemical in the context of a chemistry laboratory? What precautions should be observed while transporting bulk chemicals in the lab? 7. Why is it important for a person working in a chemistry laboratory to know about the first aid procedures? 5.11 ANSWERS Self Assessment Questions 1. Some of the essential requirements that must be met as per the norms in a chemistry laboratory are: adequate provision for lighting and ventilation, effective measures to prevent the inhalation of fumes that is the provision of fume cupboards, fencing of the dangerous part of machinery like a vacuum pump 60  adequate fire prevention measures including safe means of escape Safety in a Chemical Laboratory first-aid boxes with the essential constituents 2. The personnel working in the chemistry laboratory should have training in the following handling equipment and chemicals etc., using gas cylinders and fire fighting equipment, moving load, waste disposal, and in administering first aid 3. The different modes of direct human exposure to the chemicals are : Dermal exposure: direct contact from spills or by improper handling: Inhalation: of the vapours, fumes or dust Ingestion: i.e. the oral route 4. Poisonous substances are the substances that are liable to cause death or serious injuries to health, if swallowed or inhaled or allowed to come in contact with skin. The infectious substances on the other hand are those which are contaminated with disease inducing micro-organisms. 5. It is important to know about the compatibility of chemicals while storing them in a laboratory because storing incompatible chemicals together can lead to undesirable reactions with dangerous consequences. As the fuel must be separated from ignition sources so as to prevent a possible fire the incompatible chemicals should also be separated so as to prevent undesirable reactions. 6. The possible reasons for electrical mishaps in a chemistry laboratory are as follows: Improper wire / wiring improper choice of fuse deterioration in the insulation system accidental touches break in earthing system improper operation/use of unconventional tools Terminal Questions 1. The severe and immediate effects of the chemicals on the human body are called acute effects and can be traced without difficulty. On the other hand the effects that arise due to gradual and prolonged exposure to the chemical are called chronic or long term effects. In some cases, the chronic effect could be much worse than the acute effect. For instance, the ingestion of alcohol may cause acute effects like drunkenness and vomiting whereas prolonged usage of alcohol may lead to chronic effect like, addiction, liver damage, etc. 2. a) A hazardous chemical is the one which has the potential to cause harm to human beings, other living creatures, plants, microorganisms, property or environment. 61 Initiation into b) A fume cupboard is a portion of the laboratory dedicated for carrying out Analytical Laboratory the reactions that uses or produces harmful gases, dusts or vapours which pose a risk of inhalation. A fume cupboard contains an air extraction system i.e. an exhaust fan to ensure that dangerous vapours are vented to the atmosphere. In addition, it has the normal laboratory services like, gas, water and electricity to be utilised. c) The liquids or mixtures of liquids or liquids containing solids in suspensions or solutions which give off flammable vapour at temperature of not more than 60.5°C are called flammable liquids. 3. The use of personal protective devices like, lab coats, safety goggles, gloves etc. help in minimising the risk of personal injury and damage through contact with hazardous substances. 4. The random storage of chemicals in the laboratory may cause potentially hazardous reactions due to incompatible contacts. These may lead to accidents in the laboratory and should be avoided. 5. The label on the chemical bottle provides an initial guide to the nature of the chemical and the associated risks. 6. In the context of a Chemistry laboratory the chemicals in containers of more than 500 cm3 capacity may be termed as bulk chemicals. The following precautions must be observed while transporting such amounts of hazardous chemicals Never carry the bottle by the neck it can easily slip out of your hand and smash on the floor Also, do not carry these bottles in the arms or in the hands. A proper carrier must always be used for transporting them from the store or from one lab to another. Carboys of concentrated acids and other liquids should be vented otherwise, the increase in pressure as the contents heat up on being brought from a cold store into a warm room is sufficient to burst the carboy. Whenever possible, carboys should be left in the bulk store and liquids dispensed as required using a siphon. 7. There is always a probability of accidents to occur in a chemistry laboratory. It is imperative, therefore, that necessary preparations should be there to cope up any eventuality. It is important for a person working in a chemistry laboratory to know about the first aid procedures for the common accidents likely to occur in the laboratory because a timely first aid can, at times, provide more relief than a delayed medical aid. 62  Safety in a Chemical SOME USEFUL BOOKS AND WEBSITES Laboratory 1. S.M. Khopkar. Basic concept in analytical chemistry, 3rd edition, New Age International publishers (2008). 2. Gary D. Christian. Analytical Chemistry, 5th edition. John Wiley and Sons, Inc. (2001). 3. Bretheric, I., Handbook of Reactive Chemical Hazards, 4th ed., CRC Press (1990). 4. Furr, A. Keith, Handbook of Laboratory Safety, 5th Ed., The Chemical Rubber Company (2000). 5. Patnaik, Pradyot, Comprehensive Guide to Hazardous Properties of Chemical Substances, Wiley and Sons, NY (1999). http://the-nec.com/hazchem/ http://www1.cbsju.edu/chemistry/curriculum/chem/chapter3.htm 63 Initiation into Analytical Laboratory INDEX Absorber characterisation 26 Container Washing and Preparation 14 Absorption in Liquids 25 Copper 15 Acidity 14 Critical temperature 45 Acute and chronic effects 43 Cyanide 15 Adsorption on Solids 27 Dechlorination of Samples 18 Air Sampling 19 Dussart Sampler 11 Alkalinity 14 Effect of chemicals on body 42 Ammonia-Nitrogen 16 Emergency procedures 54 Ball-valve type sampler 11 Chemical burns 54 BOD 13 Cuts and wounds 55 Carcinogens 47 Fractures 56 Characteristics of Adsorbents 27 Ingestion of chemicals 55 Inhalation of gases and vapours 55 Characteristics of Adsorbents 27 Splashing of chemicals on the skin Chemical Absorption 25 and in the eye 56 Chemical Adsorption 27 Thermal burns 54 Chemical Characteristics 26 Fires 57 Chemical hazards in the laboratory 41 Equipment and electrical safety 53 Acute and chronic effects 43 Factors Influencing Adsorption 27 Effect of chemicals on body42 Acids 42 Freedinger Sampler 11 Alcohols 42 Gaseous Pollutants 24 Aldehydes and ketones 42 General Procedure for Sampling 12 Alkalies 42 Grab or Catch Samples 9 Carbon monoxide 43 Compounds of sulfur, Handling of chemicals 50 phosphorus, nitrogen 43 Hardness 15 Cyanides 43 Hazard identification 47 Esters 43 Incompatibility of chemicals 48 Ethers 43 Integrated samples 10 Halogens 43 Hydrocarbons 43 Kemmere and Ruttner type Sampler 11 Mercury 43 Maintenance of safety in a laboratory 36 Classification of hazardous materials 44 Code of practice in a laboratory 38 Explosives 44 Do’s 38 Flammable gases 45 Don’ts 39 Nonflammable gases 45 Personal protective devices 40 Poisonous gases4 5 Lab coats 40 Flammable liquids 45 Safety goggles 40 Extremely flammable liquids 45 Metals Groups 14 Highly flammable liquids 45 Miscellaneous Techniques 28 Flammable solids 45 Modes of exposure to chemicals 41 Spontaneously combustible Dermal exposure 41 solids 45 Inhalation 42 Oxidising substances 46 Ingestion 42 Organic peroxides 46 The fume cupboard 43 Oxidizing agents other than Modes of exposure to chemicals 41 organic peroxides 46 Poisonous and infectious substances 46 Personal protective devices 40 Biohazardous substances 46 Physical Adsorption 27 Infectious substances affecting Physical and Mineral Group 14 humans and animals 46 Physical Characteristics 26 Toxic substances 46 Physical or Dissolution Absorption 25 Waste or reusable material 46 Radioactive substances 46 Preservation and Storage 19 Corrosive substances 46 Preservation of Samples of Organic Miscellaneous dangerous substances 47 Groups 14 Code of practice in a laboratory 38 Preservation of Samples 13 Collection Efficiency 25 Procedure for Operating Suspended Composite samples 10 Particulate Sampler 21 Condensation or `Freeze out' of the Filter preparation 21 Sa