There are many toxic chemical reagents in laboratories, such as DMSO, ethidium bromide, and phenol. These reagents are essential experimental materials when needed, but improper handling can cause harm to the human body. Inhaling the vapors of these reagents can also irritate and damage the respiratory tract.
Toxins enter the human body mainly through the following pathways:
- Absorption through the skin and mucous membranes
- Inhalation through the respiratory tract
- Ingestion through the gastrointestinal tract
- Entry through the eyes, ears, pleural cavity, rectum, etc.
- Entry through subcutaneous injection, intravenous injection, etc.
Hazards and Protective Measures for Common Reagents
- Dimethyl Sulfoxide (DMSO)
Uses and Hazards: DMSO is a sulfur-containing organic compound with the molecular formula (CH₃)₂SO. It is a colorless, odorless, transparent liquid at room temperature, and a hygroscopic flammable liquid. It has the characteristics of high polarity, high boiling point, good thermal stability, aprotic property, and miscibility with water. It is soluble in most organic solvents such as ethanol, propanol, benzene, and chloroform, and is known as the “universal solvent” with a wide range of uses. Since it can lower the freezing point of cells, reduce the formation of ice crystals, and mitigate cell damage caused by free radicals, it is often used for cell cryopreservation. DMSO has severe toxic effects: it interacts with hydrophobic groups of proteins, leading to protein denaturation, and exhibits vascular toxicity as well as hepatotoxicity and nephrotoxicity.
Protective Measures: Prevent volatilization during use. Prepare 1%-5% ammonia water for standby. If DMSO comes into contact with the skin, rinse thoroughly with plenty of water and then wash with dilute ammonia water.
- Polyethylene Glycol (PEG)
Uses and Hazards: Often used for cell fusion. Damage can occur through inhalation, ingestion, or skin absorption.
Protective Measures: Must wear appropriate personal protective equipment (PPE), including a lab coat, gloves, and goggles, to reduce the risk of skin contact and inhalation.
- Ultraviolet (UV) Light
Uses and Hazards: Used for sterilization and disinfection, as well as DNA observation. Common UV light sources in laboratories include portable UV lamps and UV transilluminators. UV light can damage the retinal of the eyes; observation is only allowed through filters or safety glass that absorb harmful wavelengths. UV light can induce mutations and cause cancer.
Protective Measures: Do not observe unshielded UV light sources with the naked eye. Wear appropriate protective gloves when operating under UV light.
- Trizol
Uses and Hazards: A reagent used for nucleic acid extraction (including RNA and DNA). Although it is not a direct carcinogen, Trizol contains toxic phenol. If the skin accidentally comes into contact with Trizol, immediately rinse with plenty of detergent and water. If discomfort persists, consult a doctor.
Protective Measures: Follow safe operating procedures during use to minimize chemical contact and inhalation. Ensure operations are conducted in a fume hood.
- Phenol (C₆H₆O)
Uses and Hazards: Mainly used for cell lysis to depolymerize proteins and nucleic acids in cells for release. It is a highly toxic substance that can be absorbed through the respiratory tract, skin, and digestive tract. Poisoning can cause headache, dizziness, collapse, difficulty breathing, loss of consciousness, and even death.
Protective Measures: If it accidentally comes into contact with the eyes or skin, rinse immediately with plenty of water and seek medical treatment.
- Trichloroacetic Acid (TCA)
Uses and Hazards: A precipitant for macromolecules, used for concentration or desalting of protein samples. It has a slight special pungent odor and strong corrosiveness. TCA can also effectively disrupt cell membranes and nuclear membranes, and purify DNA to make it suitable for subsequent molecular biology experiments such as PCR, restriction enzyme digestion, and sequencing. Ingestion or inhalation can cause poisoning; it is highly irritating and corrosive to the skin and tissues.
Protective Measures: Operators must wear protective gear to prevent contact with the human body. If it accidentally comes into contact with the eyes or skin, rinse immediately with plenty of water and seek medical treatment.
- Diethyl Pyrocarbonate (DEPC)
Uses and Hazards: DEPC is used to dissolve RNA, inactivate various proteins, and is a strong inhibitor of RNase. It is a potential carcinogen. DEPC reacts with amines and sulfhydryl groups, so reagents containing Tris and DTT cannot be treated with DEPC.
Protective Measures: Operate in a fume hood and avoid skin contact. DEPC itself is not highly toxic, but it is highly toxic when inhaled; a mask must be worn during use. If it accidentally gets on the hands, immediately rinse with plenty of water.
- Ethidium Bromide (EB)
Uses and Hazards: A fluorescent dye often used for nucleic acid staining in agarose gel electrophoresis to visualize DNA in agarose and polyacrylamide gels. However, EB is a strong mutagen with high carcinogenicity and evaporates at 60-70°C. Therefore, extreme caution is required when using it, and appropriate safety measures must be taken to reduce exposure risk.
Protective Measures: When handling EB, wear appropriate PPE including a lab coat, gloves, and goggles to reduce skin contact and inhalation risks. Due to the toxicity of ethidium bromide, solutions containing EB must be purified before disposal after experiments to avoid environmental pollution and harm to human health.
- Bromophenol Blue
Uses and Hazards: 1% bromophenol blue is often used as an indicator dye in electrophoresis. Skin absorption can cause damage.
Protective Measures: Prepare solutions in a fume hood and wear appropriate PPE, including gloves and goggles.
- Dithiothreitol (DTT)
Uses and Hazards: A small-molecule reducing agent often used to reduce disulfide bonds in proteins and prevent the formation of intra- or intermolecular disulfide bonds between cysteines in proteins. It emits an unpleasant odor. It can harm health through inhalation, ingestion, or skin absorption.
Protective Measures: When using solid DTT or high-concentration stock solutions, wear gloves and goggles, and operate in a fume hood.
- Coomassie Brilliant Blue
Uses and Hazards: Its concentration is proportional to protein concentration within a certain range, so it is used for quantitative determination of proteins. Damage can occur through inhalation, ingestion, or skin absorption.
Protective Measures: Follow safe operating procedures during use to minimize chemical contact and inhalation. Wear appropriate PPE, including gloves and goggles.
- Acrylamide
Uses and Hazards: A white crystalline chemical substance, and a raw material for producing polyacrylamide. Acrylamide is a moderately toxic substance that can enter the human body through skin absorption or the respiratory tract. Its main hazards include neurotoxicity, as well as reproductive and developmental toxicity. Neurotoxic effects manifest as degenerative changes in the peripheral nerves and brain regions involved in learning, memory, and other cognitive functions. Experiments also show that acrylamide is a potential carcinogen with cumulative toxicity and is difficult to excrete from the body.
Protective Measures: Avoid inhaling vapors of unpolymerized acrylamide during operation. Wear appropriate PPE, including a respirator and gloves, to reduce exposure risk. Ensure operations are conducted in a well-ventilated laboratory.
- N,N,N’,N’-Tetramethylethylenediamine (TEMED)
Uses and Hazards: TEMED is a colorless, transparent liquid with a slight fishy odor. It is a strong neurotoxin that can cause respiratory irritation and nervous system damage. In molecular biology, it is used to prepare SDS-PAGE gels: it catalyzes APS to generate free radicals, thereby accelerating the polymerization of polyacrylamide gels, and acts as a coagulant.
Protective Measures: Prevent volatilization during use. Prepare 1%-5% ammonia water for standby. If it comes into contact with the skin, rinse thoroughly with plenty of water and then wash with dilute ammonia water. Avoid direct contact with the skin and eyes; wear appropriate gloves and safety goggles. In addition, handle TEMED with care to reduce volatile exposure, prevent accidental inhalation, operate quickly, and store it in a sealed container.
- Sodium Dodecyl Sulfate (SDS)
Uses and Hazards: SDS is an anionic surfactant with strong destructive properties. It can dissolve almost all proteins and disrupt their native conformation. SDS binds to protein molecules at a ratio of 1.4:1, effectively masking the inherent charge of proteins. SDS is toxic and an irritant, posing a risk of severe eye damage. It can harm health through inhalation, ingestion, or skin absorption.
Protective Measures: Wear appropriate gloves and safety goggles. Operate in a chemical fume hood to avoid inhaling its powder.
- Ammonium Persulfate (APS)
Uses and Hazards: Used in Western Blot (WB) gel preparation to generate free radicals, which initiate the polymerization of acrylamide. APS is highly hazardous to mucous membranes, upper respiratory tract tissues, eyes, and skin; inhalation can be fatal.
Protective Measures: Wear appropriate gloves, safety goggles, and a protective suit during operation. Always work in a fume hood and wash hands immediately after operation.
- Phenylmethylsulfonyl Fluoride (PMSF)
Uses and Hazards: PMSF is a highly toxic cholinesterase inhibitor that inhibits the activity of various proteases. To prevent protein degradation and improve yield, it is generally added during protein extraction. However, it is highly destructive to the respiratory mucosa, eyes, and skin. Fatal harm can occur through inhalation, ingestion, or skin absorption.
Protective Measures: Wear appropriate gloves and safety glasses; always use it in a chemical fume hood. In case of contact with the human body, immediately rinse the eyes or skin with plenty of water and discard contaminated work clothes.
- Sodium Azide (NaN₃)
Uses and Hazards: Sodium azide is extremely toxic; it can block the cytochrome electron transport system. Solutions containing sodium azide must be clearly labeled. It can harm health through inhalation, ingestion, or skin absorption.
Protective Measures: Wear appropriate gloves and safety goggles; operate with extra caution.
- Silver Nitrate (AgNO₃)
Uses and Hazards: Used for protein staining (silver staining method) after electrophoresis. Silver nitrate is a strong oxidant with corrosiveness (black spots appear on the skin upon contact) and contamination risks; it can cause skin and eye burns. Ingestion of silver nitrate can cause severe abdominal pain, vomiting, bloody stools, and even gastrointestinal perforation. The lethal dose for adults is approximately 10 grams. The median lethal dose (mouse, oral) is 50 mg/kg; it can explode when in contact with alcohol.
Protective Measures: Avoid inhalation; wear appropriate gloves and safety goggles. Operate in a fume hood and keep away from heat sources, sparks, and open flames. If it accidentally comes into contact with the eyes or skin, rinse immediately with plenty of water and seek medical treatment.
- Glacial Acetic Acid (CH₃COOH)
Uses and Hazards: Mixed with ethanol to form a protein fixation solution in silver staining. Glacial acetic acid is highly corrosive and a flammable liquid. Inhalation irritates the nose, throat, and respiratory tract; it has a strong irritating effect on the eyes. Skin contact can cause erythema in mild cases and chemical burns in severe cases. Ingestion of concentrated acetic acid can cause erosion of the mouth and digestive tract, and severe cases may lead to death from shock. It is flammable, and its vapor can form an explosive mixture with air.
Protective Measures: Avoid inhalation; wear appropriate gloves and safety goggles. Operate in a fume hood and keep away from heat sources, sparks, and open flames. If it accidentally comes into contact with the eyes or skin, rinse immediately with plenty of water and seek medical treatment.
- Xylene
Uses and Hazards: Flammable; high concentrations have an anesthetic effect. Damage can occur through inhalation, ingestion, or skin absorption.
Protective Measures: Avoid inhalation; wear appropriate gloves and safety goggles. Operate in a fume hood and keep away from heat sources, sparks, and open flames.
- Paraformaldehyde (POM)
Uses and Hazards: Used for tissue fixation; it is a highly toxic volatile substance. It is easily absorbed through the skin and causes severe damage to the skin, eyes, mucous membranes, and upper respiratory tract.
Protective Measures: Avoid inhalation; wear appropriate gloves and safety goggles. Operate in a fume hood.
- Formaldehyde (HCHO)
Uses and Hazards: Formaldehyde has antiseptic and bactericidal properties; it is used for immersing biological specimens and disinfecting seeds. It is highly toxic, volatile, and a carcinogen. It is easily absorbed through the skin and irritates and damages the eyes, mucous membranes, and upper respiratory tract.
Protective Measures: Avoid inhaling its volatile mist. Wear appropriate gloves and safety glasses. Always operate in a chemical fume hood. Keep away from heat sources, sparks, and open flames.
- Chloroform (Trichloromethane, CHCl₃)
Uses and Hazards: Chloroform can be used as an extractant for separating and extracting organic substances from biological samples, and as an inhibitor for suppressing the activity of certain enzymes in biological reactions. It is a volatile organic solvent; long-term or high-concentration exposure may harm health. It is toxic to the central nervous system, irritates the skin, eyes, mucous membranes, and respiratory tract, and is a carcinogen that can damage the liver and kidneys. It is volatile, so inhalation of its vapor should be avoided.
Protective Measures: Take appropriate safety measures during use; wear appropriate gloves and safety goggles. Operate in a fume hood.
- Triton X-100
Uses and Hazards: Triton X-100 is a relatively mild detergent, often used as an additive to maintain protein stability (especially membrane proteins). It can increase the permeability of eukaryotic cell membranes. It causes severe eye irritation and burns. Damage can occur through inhalation, ingestion, or skin contact.
Protective Measures: Take appropriate safety measures; wear appropriate gloves and safety goggles. Operate in a fume hood.
- Giemsa
Uses and Hazards: Giemsa stain is suitable for staining blood smears, blood cells, plasmodia, rickettsiae, as well as bone marrow cells and spinal cord cells. Giemsa stain is toxic; inhalation by the human body can cause permanent blindness or even death.
Protective Measures: Wear appropriate gloves and safety goggles. Operate in a chemical fume hood to avoid inhaling its powder.
- Isotopes
Uses and Hazards: Isotope labeling (also called isotope tracing) is used to track the movement and transformation of substances. Isotopes can be divided into stable isotopes and radioactive isotopes. Stable isotopes do not decay, have no radioactivity, and do not cause adverse effects on health. Radioactive isotopes have a certain half-life, are unstable, and have radioactivity, which is harmful to the human body.
Protective Measures: Take necessary radioactive protection and safety measures; avoid severe reactions such as high temperature and high pressure as much as possible.