Common types of accidents in laboratories and prevention methods

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When conducting chemical experiments, safety is of utmost importance to us. This article outlines common experimental accidents that occur in laboratories, as well as the emergency procedures to follow when such accidents happen. Laboratory safety concerns all of us; prevention is key. Types of common laboratory accidents: 1. Fire-related accidents. Fire-related accidents are quite common; they can occur in almost any laboratory. The direct causes of such accidents are: ① Forgetting to turn off the power, which results in the equipment or electrical appliances remaining powered on for too long, leading to excessive heat and subsequent fires ； (August 8, 2005: A fire broke out in a laboratory at Capital Normal University. Cause of the fire: Wei, a master’s degree candidate at the university, was conducting experiments in the lab in the morning. At noon, he went out for lunch without turning off the power; the “rotor” of the experimental equipment continued to operate. A short circuit in the electrical wiring led to the fire.) ② Aging and overloaded power lines can cause them to heat up, resulting in fires ； ③ Careless handling or improper storage of flammable and explosive materials can allow a source of ignition to come into contact with combustible substances, resulting in a fire ； ④ Throwing cigarette butts around and coming into contact with flammable materials can cause fires. 2. Explosive accidents
Explosive accidents often occur in laboratories where flammable, explosive materials and pressure vessels are present. The direct causes of such accidents are: ① Using equipment or pressure vessels (such as high-pressure gas cylinders) in violation of operating procedures, leading to explosions ； ② The equipment is aging, and it has faults or defects that cause the leakage of flammable and explosive substances, which can lead to an explosion when exposed to sparks. ③ Improper handling of flammable and explosive materials led to combustion and explosion ； Such items (such as trinitrotoluene, picric acid, ammonium nitrate, azides, etc.) can undergo violent chemical reactions when exposed to external factors such as high heat, friction, impact, or vibration, or when in contact with substances that are incompatible with their properties; this leads to the generation of large amounts of gas and intense heat, thereby causing an explosion. ④ When strong oxidizers are stored together with substances whose properties are incompatible, decomposition may occur, leading to combustion and explosion. ⑤ Explosions of instruments, equipment, medicines, etc., caused by fire incidents. 3. Toxicity-related accidents: Toxicity-related accidents often occur in laboratories that handle chemical substances and highly toxic materials, as well as in laboratories where toxic gases are emitted. The direct causes of such accidents are: ① Bringing food into a laboratory containing toxic substances, leading to accidental ingestion and poisoning. (For example: In summer, a staff member at a university in Nanjing mistakenly drank an intermediate product containing aniline from the refrigerator, thinking it was plum juice. This resulted in poisoning; the reason being that plum juice intended for staff consumption had previously been stored in that same refrigerator.) ； ②Aging equipment and facilities with malfunctions or defects can lead to leaks of toxic substances or the inability to discharge toxic gases, resulting in poisoning ； ③Poor management, careless handling or improper operations, as well as inadequate disposal of toxic substances after experiments, can lead to the leakage and dispersion of such substances, causing poisoning of people and environmental pollution ； ④Blockages or improper rerouting of wastewater discharge pipelines result in untreated toxic wastewater flowing out, causing environmental pollution. 4. Mechanical and electrical injury accidents
Mechanical and electrical injury accidents often occur in laboratories where there is high-speed rotation or impact motion, in laboratories where live electrical work is performed, and in some laboratories where high temperatures are generated. The accident manifestations and direct causes were: ① Improper operation or lack of protection, resulting in crushing, dislodging, and collision injuries ； ②Violations of operating procedures, or faults and defects resulting from the aging of equipment and facilities, can lead to electric leakage, electric shock, and injuries caused by arc sparks ； ③Improper use can cause harm to people from high-temperature gases and liquids. 5. Equipment damage accidents: Equipment damage accidents often occur in laboratories where electric heating is used. The symptoms and direct cause of the accident are: a sudden power outage caused by a line fault or lightning strike, which prevented the heated medium from returning to its original state as required, resulting in equipment damage. For example, the two incidents that occurred not long ago at a university in Hunan, in which around 20 mercury tubes were rendered unusable (resulting in losses of about 15,000), were caused by sudden power outages. Methods for dealing with common laboratory accidents 1. Prevention and handling of fire accidents: When using volatile and flammable organic solvents such as benzene, ethanol, ether, and propane, carelessness in handling can easily lead to fire accidents. To prevent accidents, it is necessary to always pay attention to the following points: (1) When handling flammable and explosive solvents, keep away from sources of fire ； The residues of explosive solids must be destroyed carefully (for example, by decomposing metal acetylide with hydrochloric acid or nitric acid) ； Don’t litter unextinguished matchsticks around ； Substances prone to spontaneous combustion (such as Raney nickel, a catalyst used in hydrogenation reactions), as well as filter paper contaminated with them, must not be discarded carelessly to avoid creating new sources of fire that could lead to explosions. (2) Before the experiment, carefully check whether the instruments and equipment are correct, secure, and airtight ； Proper and strict operational requirements are necessary ； When operating at atmospheric pressure, never seal the system, as this could lead to an explosion ； For liquids with a boiling point below 80°C, a water bath should generally be used for heating during distillation; direct heating with fire is not allowed ； During experimental operations, it is necessary to prevent organic vapor leaks, and heating with open-ended devices must be avoided. If solvent removal is to be performed, it must be done in a fume hood. (3) A large amount of flammable materials are not allowed to be stored in the laboratory. In the event of a fire during the experiment, it is crucial not to panic; one must remain calm. First, immediately cut off all sources of fire and power inside the room. Then, carry out rescue and fire extinguishing actions appropriately based on the specific circumstances. Common methods include: 1. When a flammable liquid is on fire, immediately remove all flammable materials from the area where the fire is occurring and turn off the ventilation systems to prevent the fire from spreading. 2. When alcohol and other water-soluble liquids catch fire, water can be used to extinguish them. 3. When organic solvents such as gasoline, ether, and toluene catch fire, they should be extinguished using asbestos cloth or dry sand. Water must never be used, as it will only expand the area of the fire. 4. When metal potassium, sodium, or lithium catches fire, it is absolutely forbidden to use water, foam extinguishers, carbon dioxide, carbon tetrachloride, etc. to put out the fire; instead, dry sand or graphite powder can be used to extinguish it. 5. When electrical equipment wires are on fire, do not use water or carbon dioxide extinguishers (foam extinguishers) to avoid electric shock. The power supply should be turned off first, followed by using a carbon dioxide or carbon tetrachloride fire extinguisher to put out the fire. 6. If clothing catches fire, never run; instead, immediately cover it with asbestos cloth or a thick coat to extinguish the fire, or quickly take off the clothing. If the fire is large, roll on the ground to put out the flames. 7. If an unusual odor or smoke is detected in the oven, the power supply should be turned off immediately to allow it to cool down slowly, and a fire extinguisher should be kept on hand. Never rush to open the oven door, as sudden intake of air can fuel the fire (cause an explosion) and lead to a fire. 8. When a fire breaks out, care should be taken to preserve the scene. In the event of a large fire, the police should be called immediately. Those with more severe injuries should be taken to the hospital immediately. 9. Be familiar with the locations of fire-fighting equipment in the laboratory and how to use fire extinguishers. In case of a fire, one must know three things: ① How to report a fire ； ②Fire-fighting equipment will be used to extinguish incipient fires ； ③Be able to save oneself and escape. Usage of a portable dry powder fire extinguisher: ① First, tear off the small lead weight and pull out the safety pin ； ②Use one hand to press down on the handle and then lift the fire extinguisher ； ③Hold the nozzle in the other hand and direct the dry powder jet at the base of the flame in the combustion area. 2. Prevention and handling of explosion accidents (1) Some compounds are prone to explosion. For example, peroxides in organic compounds, aromatic polynitrocompounds and nitrates, dry diazonium salts, azides, and alkynes of heavy metals are all explosive substances that require special attention when used and handled. When distilling ether containing peroxides, there is a risk of explosion; the peroxides must be removed in advance. If peroxides are present, an acidic solution of ferrous sulfate can be added to remove them. Aromatic polynitro compounds should not be dried in an oven. Mixing ethanol with concentrated nitric acid can cause an extremely violent explosion ； (2) Incorrect instrument setup or operational errors can sometimes cause explosions. If distillation or heating under reflux is carried out at atmospheric pressure, the apparatus must be in communication with the atmosphere. When distilling, be careful not to evaporate the material completely. During vacuum operations, glass instruments that are not resistant to external pressure (such as flat-bottom flasks and Erlenmeyer flasks) must not be used. (3) Gases such as hydrogen, acetylene, and ethylene oxide, when mixed with air in certain proportions, form explosive mixtures that can explode upon contact with an open flame. Therefore, open flames must be strictly prohibited when using the aforementioned substances. For synthesis reactions that generate a large amount of heat, add the materials slowly and carefully while ensuring proper cooling. Also, take precautions to prevent accidents caused by leakage from the stopcock of the dropping funnel. 3. Prevention and handling of poisoning incidents: Many reagents used in experiments are toxic. Toxic substances often cause poisoning through inhalation, skin absorption, accidental ingestion, and other means. When handling irritating, malodorous, and toxic chemicals such as H2S, NO2, Cl2, Br2, CO, SO2, SO3, HCl, HF, concentrated nitric acid, fuming sulfuric acid, concentrated hydrochloric acid, acetyl chloride, etc., it must be done in a fume hood. After the fume hood is turned on, do not stick your head inside it, and ensure good ventilation in the laboratory. During experiments, direct hand contact with chemical substances should be avoided; in particular, it is strictly prohibited to touch highly toxic substances with bare hands. Organic substances that come into contact with the skin should be immediately washed off with plenty of water and soap; organic solvents should not be used, as this will only increase the rate at which chemicals penetrate the skin. Organic matter spilled on the tabletop or floor should be removed promptly. If a mercury thermometer is accidentally broken, the mercury that spills on the floor should be collected as much as possible, and sulfur powder should be spread over the spilled area. The highly toxic substances used in the experiments are kept under the responsibility of the technical leaders of each research team, distributed in appropriate amounts to the users, and the remaining amount is collected back. Containers used for experiments with toxic substances must be labeled, and they should be cleaned promptly after use. Workbenches and sinks that are frequently used for experiments with toxic substances also need to be labeled. Toxic residues remaining after experiments must be disposed of in accordance with the laboratory’s regulations; they must not be discarded carelessly. In experiments involving the handling of toxic substances, if symptoms such as a burning sensation in the throat, discoloration or cyanosis of the lips, stomach cramps, nausea and vomiting, palpitations, or dizziness occur, it may be due to poisoning. After providing the following first aid measures depending on the cause of poisoning, take the victim to the hospital for treatment immediately without delay. (a) Poisoning by solid or liquid toxins: Spit out the toxic substance immediately if it is still in the mouth, and rinse the mouth with plenty of water. If someone swallows alkali, they should first drink plenty of water and then some milk. If acid is swallowed, drink water first, then take an Mg(OH)2 emulsion, and finally drink some milk. Do not use emetics, nor take carbonates or bicarbonates. Those poisoned by heavy metal salts should drink a glass of an aqueous solution containing a few grams of MgSO4 and seek medical attention immediately. Do not take emetics, as this may cause danger or complicate the condition. Those poisoned by arsenic and mercury compounds must seek medical attention immediately. (b) Persons poisoned by inhaling gases or vapors: Immediately move them outdoors, loosen their collars and buttons, and let them breathe fresh air. Artificial respiration should be performed on shock victims, but not by mouth-to-mouth method. Take them to the hospital immediately for emergency treatment. 4. Prevention and handling of electric shock accidents in laboratories. Electric furnaces, heating mantles, electric stirrers, etc. are commonly used in experiments. When using such electrical devices, it is necessary to prevent direct contact between the human body and the conductive parts of the devices, as well as contact between the metal wires of the asbestos mesh and the resistance wires of the electric furnaces ； Do not touch electrical plugs with wet hands or while holding wet objects ； It is strictly prohibited to drop liquids such as water into the electric heating jacket to prevent electrical short circuits. To prevent electric shock, the metal casings of devices and apparatuses should be connected to a ground wire. After the experiment, turn off the instrument’s switch first, and then unplug the power connector. To check whether electrical equipment is leaking electricity, a voltage tester should be used; any device that shows signs of leakage must not be used. First aid measures in case of electric shock: ① Turn off the power supply ； ②Use a dry stick to separate the wire from the victim ； ③Separate the victim from the ground; when providing first aid, the rescuer must take safety measures to prevent electric shock, and their hands and feet must be insulated. Perform artificial respiration if necessary and transport the person to the hospital for treatment. 5. First aid knowledge for other laboratory accidents (1) Glass cuts: In cases of minor injuries, the blood should be promptly squeezed out; glass shards should be removed using sterilized forceps. The wound should then be washed with distilled water, treated with iodine, and covered with a band-aid or wrap ； For large wounds, the area above the wound should be tightly bandaged immediately to stop the bleeding, and the victim should be rushed to the hospital. (2) Burns: When burned by flames, steam, red-hot glass, iron objects, etc., the wound should be immediately rinsed or soaked in plenty of water to rapidly lower the temperature and prevent thermal burns. If blisters form, they should not be popped; instead, they should be covered with gauze and the person should be taken to the hospital for treatment. For minor burns, apply some cod liver oil, burn ointment, or ten-thousand-flower oil to the affected area and then bandage it. If blisters form on the skin (second-degree burn), do not puncture the blisters to prevent infection ； If the skin at the wound is brown or black (third-degree burn), it should be gently covered with dry, sterile gauze, and the patient should be taken to the hospital immediately for treatment. (3) Burns caused by acids, alkalis, or bromine solutions: (a) In the event of skin burns from acids, rinse immediately with plenty of flowing water. When the skin is contaminated with concentrated sulfuric acid, do not rinse it with water first, as this can cause intense heat release upon hydration of the sulfuric acid and worsen the injury; instead, use a dry cloth to absorb the concentrated sulfuric acid first, and then rinse with water. After thorough rinsing, neutralize the area using a 2–5% sodium bicarbonate solution or soapy water, and finally rinse again with water and apply Vaseline. (b) In the case of alkali burns, rinse immediately with plenty of flowing water, then wash further with 2% acetic acid or a 3% boric acid solution, rinse again with water, and apply Vaseline as a medication. (c) In the event of phenol burns, wipe the area several times with 30% alcohol immediately, then rinse thoroughly with plenty of water. After that, apply a saturated solution of sodium sulfate for 4–6 hours. Since diluting phenol with water at a ratio of 1:1 or 2:1 can instantly worsen skin damage and increase phenol absorption, it is not advisable to rinse the contaminated area with water first. After the aforementioned burns, if blisters form on the wound site, it is not advisable to pop them. Those with serious injuries were rushed to the medical clinic after preliminary treatment. (4) Acid, alkali, or other foreign substances getting into the eyes: (a) If acid gets into the eyes, immediately rinse with plenty of water, then rinse with a 1% sodium bicarbonate solution. (b) If it is an alkaline solution, rinse immediately with plenty of water, followed by rinsing with a 1% boric acid solution. Keep the eyelids open while washing the eyes; someone can help lift them, and the rinsing should continue for 15 minutes. Those seriously injured were taken to the hospital for treatment immediately after preliminary first aid. (c) If foreign objects such as wood shavings or dust particles are present, another person can lift the eyelids and gently remove the objects using a disinfected cotton swab, or the person can be allowed to cry so that the foreign objects are expelled; after that, a few drops of cod liver oil can be applied. It is quite dangerous if glass shards get into the eyes. At this time, try to stay calm. Never rub or wipe it with your hand, and don’t let anyone flip your eyelid. Try not to move your eyeball; allow tears to flow freely. Sometimes, debris will be washed out along with the tears. After gently covering the eyes with gauze, the injured person should be rushed to the hospital for treatment immediately. (5) In case of strongly acidic corrosive poisons, drink plenty of water first, then consume aluminum hydroxide paste and egg whites ； For strongly alkaline poisons, it is best to drink a large amount of water first, and then consume vinegar, acidic fruit juices, or egg whites. In both acidosis and alkalosis, milk should be given for infusion; do not take emetics. (6) Mercury can easily enter the body through the respiratory tract, and it can also be absorbed directly through the skin, leading to cumulative poisoning. Signs of severe poisoning include a metallic taste in the mouth and an odor in the exhaled breath ； Saliva dripping; black color from mercury sulfide on gums and lips ； Enlarged lymph nodes and salivary glands. In the event of accidental poisoning, one should be taken to the hospital for emergency treatment. In cases of acute poisoning, gastric lavage is usually performed using charcoal or emetics, or protein is administered (such as 1 liter of milk mixed with 3 egg whites) along with castor oil to induce vomiting and facilitate detoxification.