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Laboratory Safety Principles

The most important rule is that everyone involved in laboratory operations from the highest administrative level to the individual workers must be safety minded. Safety awareness can become part of everyone's habits only if the safety is discussed repeatedly and only if senior and responsible staff demonstrate a sincere and continuing interest in safety. Over familiarity with a particular laboratory operation may result in overlooking or underrating its hazards. This attitude can lead to a false sense of security, which frequently results in accidents. Be alert to unsafe conditions and call attention to them so that corrections can be made as soon as possible. Every laboratory worker has a basic responsibility to himself/herself and colleagues to plan and execute laboratory operations in a safe manner.

Unattended Operations

Frequently, laboratory operations are carried out continuously or overnight. It is essential to plan for interruptions in utility services such as electricity, water, and inert gas. Operations should be designed to be safe, and plans should be made to avoid hazards in case of failure. Wherever possible, arrangements for routine inspection of the operations should be made and, in all cases, the laboratory lights should be left on and an appropriate sign should be placed on the door.

Working Alone

Generally, it is prudent to avoid working in a laboratory alone. Under normal working conditions arrangements should be made between individuals working in separate laboratories outside of working hours to crosscheck periodically. Alternatively, security guards may be asked to check on the laboratory worker. Experiments known to be hazardous should not be undertaken by a worker who is alone in a laboratory.

Under unusual conditions special rules may be necessary. The supervisor of the laboratory has the responsibility for determining whether the work requires special safety precautions, such as having two people in the same room during a particular operation.

Eating, Drinking and Smoking

Contamination of food, drink, smoking materials, and cosmetics is a potential route of exposure to toxic substances. Food should be stored, handled, and consumed outside the laboratory in an area free of hazardous substances. Non laboratory areas, such as nearby break rooms, lounges, or conference rooms should be designated for storage and consumption of food and beverage for laboratory personnel. Coffee, soft drinks, snacks, and lunches are not to be brought into laboratory areas. Areas where food is permitted should be prominently marked and a warning sign posted (e.g., EATING AREA - CHEMICALS NOT PERMITTED). Glassware or utensils that have been used for laboratory operation are not to be used for food or beverages. Laboratory refrigerators, ice chests, cold rooms and such are not to be used for food storage. Separate equipment should be dedicated to that use and prominently labeled.


There is a definite relationship between safety performance and orderliness in the laboratory. When housekeeping standards fall, safety performance inevitably deteriorates. Work areas are to be kept clean, and chemicals and equipment must be properly labeled and stored. Cleanup should follow the completion of any operation or at the end of each day. Wastes are to be deposited in appropriately labeled receptacles. Temporary holding containers must be clearly marked. Chemicals that are no longer needed should not be permitted to accumulate in the laboratory. Stairways and hallways should not be used as storage areas. Access to exits, emergency equipment, and controls, must be maintained free from obstruction.

Warning Signs and Labels

Laboratory areas that have special or unusual hazards must be posted with warning signs. Standard signs and symbols have been established for a number of special situations, such as radioactive materials, radiation hazards, biological hazards, fire hazards, and laser operations. Other signs should be posted to show the locations of safety showers, eyewash stations, exits, and fire extinguishers. Waste containers must be labeled with the type of waste for which they are intended. The safety and hazard sign systems in the laboratory should enable a person unfamiliar with the usual routine of the laboratory to escape in an emergency (or help combat it if appropriate).

Maintenance Personnel

Facilities management, housekeeping, and other support personnel may also be exposed to potential physical and chemical hazards in connection with work going on in the laboratory. They must be informed about the risks involved and educated about how to avoid potential hazards.

Guarding for Safety

All mechanical equipment is to be equipped with guards that prevent access to electrical connections or moving parts (such as the belts and pulleys of a vacuum pump). Each laboratory worker should inspect the equipment before using it to ensure that the guards are in place and functioning.

Careful design of guards is vital. An ineffective guard can be worse than none at all, because it may give a false sense of security. Emergency shutoff devices may be needed in addition to electrical and mechanical guarding.

Shielding for Safety

Safety shielding is to be used for any operation having the potential for explosion such as (a) whenever a reaction is attempted for the first time (small quantities of reactants should be used to minimize hazards) (b) whenever a familiar reaction is carried out on a larger than usual scale and (c) whenever operations are carried out under non-ambient conditions. Shields are to be placed so that all personnel in the area are protected from the hazard.

System Under Pressure

Reactions should never be carried out in, nor heat applied to, an apparatus that is a closed system unless it is designed and tested to withstand pressure. Pressurized apparatus should have an appropriate relief device. If the reaction cannot be opened directly to the air, an inert gas purge and bubbler system should be used to avoid pressure buildup.

Cold Traps and Cryogenic Hazards

The primary hazard of cryogenic materials is their extreme coldness. The surfaces they cool can cause severe burns if allowed to contact the skin. Gloves and a face shield may be needed when preparing or using some cold baths. Neither liquid nitrogen nor liquid air should be used to cool a flammable mixture in the presence of air because oxygen can condense from the air leading to an explosion hazard. Appropriate insulated gloves should be used when handling dry ice. Dry ice should be added slowly to the liquid portion of the cooling bath to avoid foaming over. Workers should avoid lowering their head into a dry ice chest: Carbon dioxide is heavier than air, and suffocation can result.


Accidents involving glassware are a leading cause of laboratory injuries. Careful handling and storage procedures should be used to avoid breaking glassware. Adequate hand protection should be used when inserting glass tubing into rubber stoppers or corks or when placing rubber tubing on glass hose connections. Tubing should be fire polished or rounded and lubricated and hands should be held close together to limit movement if glass should fracture occur. The use of plastic or metal connectors should be considered. Glass blowing operations should not be attempted unless proper annealing facilities are available. Vacuum jacketed glass apparatus should be handled with extreme care to prevent implosions. Equipment such as Dewar flasks should be taped or shielded. Only glassware designed for vacuum work should be used for that purpose. Proper instruction should be provided in the use of glass equipment designed for specialized tasks, which can represent unusual risks for the first time user (for example, separator funnels containing volatile solvents can develop considerable pressure during use). Glassware, which is to be heated, should be Pyrex or a similar heat treated type. Hand protection should be used when picking up broken glass. Small pieces should be swept up with a brush into a dustpan. Broken glassware should be disposed of in a special container marked "BROKEN GLASS".

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