R-phrases, also known as risk phrases, specify the particular danger(s) of a hazardous substance. The European Union (EU) currently requires that R-phrases appear on each label and MSDS data sheet for hazardous substances; however, both risk phrases and safety phrases (also known as S-phrases) are being phased out under the implementation of the Globally Harmonized System of Classification and Labeling of Chemicals (GHS).
To learn more about safety phrases and to see a table of the safety phrases, please click here.
R-phrases consist of the letter R followed by a number, or a sequence of numbers. The precise meaning of each of these appears in the table below.
| Single Risk Phrases (R-Phrases) | |
| R1: | Explosive when dry. |
| R2: | Risk of explosion by shock, friction, fire or other sources of ignition. |
| R3: | $129,336 per violation |
| R4: | Extreme risk of explosion by shock, friction, fire or other sources of ignition. |
| R5: | Heating may cause an explosion. |
| R6: | Explosive with or without contact with air. |
| R7: | May cause fire. |
| R8: | Contact with combustible material may cause fire. |
| R9: | Explosive when mixed with combustible material. |
| R10: | Flammable |
| R11: | Highly flammable |
| R12: | Extremely flammable |
| R13 (Obsolete): | Extremely flammable liquid gas. |
| R14: | Reacts violently with water. |
| R15: | Contact with water liberates extremely flammable gases. |
| R16: | Explosive when mixed with oxidizing substances. |
| R17: | Spontaneously flammable in air. |
| R18: | In use, may form flammable/explosive vapor-air mixture. |
| R19: | May form explosive peroxides. |
| R20: | Harmful by inhalation. |
| R21: | Harmful in contact with skin. |
| R22: | Harmful if swallowed. |
| R23: | Toxic by inhalation. |
| R24: | Toxic in contact with skin. |
| R25: | Toxic if swallowed. |
| R26: | Very toxic by inhalation. |
| R27: | Very toxic in contact with skin |
| R28: | Very toxic if swallowed. |
| R29: | Contact with water liberates toxic gas. |
| R30: | Can become highly flammable in use. |
| R31: | Contact with acids liberates toxic gas. |
| R32: | Contact with acids liberates very toxic gas. |
| R33: | Danger of cumulative effects. |
| R34: | Causes burns. |
| R35: | Causes severe burns. |
| R36: | Irritating to eyes. |
| R37: | Irritating to respiratory system. |
| R38: | Irritating to skin. |
| R39: | Danger of very serious irreversible effects. |
| R40: | Possible risk of cancer. |
| R41: | Risk of serious damage to eyes. |
| R42: | May cause sensitization by inhalation. |
| R43: | May cause sensitization by skin contact. |
| R44: | Risk of explosion if heated under confinement. |
| R45: | May cause cancer. |
| R46: | May cause heritable genetic damage. |
| R47 (obsolete): | May cause birth defects. |
| R48: | Danger of serious damage to health by prolonged exposure. |
| R49: | May cause cancer by inhalation. |
| R50: | Very toxic to aquatic organisms. |
| R51: | Toxic to aquatic organisms. |
| R52: | Harmful to aquatic organisms. |
| R53: | May cause long-term adverse effects in the aquatic environment. |
| R54: | Toxic to flora. |
| R55: | Toxic to fauna. |
| R56: | Toxic to soil organisms. |
| R57: | Toxic to bees. |
| R58: | May cause long-term adverse effects in the environment. |
| R59: | Dangerous for the ozone layer. |
| R60: | May impair fertility. |
| R61: | May cause harm to the unborn child. |
| R62: | Possible risk of impaired fertility. |
| R63: | Possible risk of harm to the unborn child. |
| R64: | May cause harm to breastfed babies. |
| R65: | Harmful: may cause lung damage if swallowed. |
| R66: | Repeated exposure may cause skin dryness or cracking. |
| R67: | Vapors may cause drowsiness and dizziness. |
| R68: | Possible risks of irreversible effects. |
| Combinations of R-Phrases | |
| R14/15: | Reacts violently with water, liberating extremely flammable gases. |
| R15/29: | Contact with water liberates toxic, extremely flammable gas. |
| R20/21: | Harmful by inhalation and in contact with skin. |
| R21/22: | Harmful in contact with skin and if swallowed. |
| R20/22: | Harmful by inhalation and if swallowed. |
| R20/21/22: | Harmful by inhalation, in contact with skin and if swallowed. |
| R21/22: | Harmful in contact with skin and if swallowed. |
| R23/24: | Toxic by inhalation and in contact with skin. |
| R24/25: | Toxic in contact with skin and if swallowed. |
| R23/25: | Toxic by inhalation and if swallowed. |
| R23/24/25: | Toxic by inhalation, in contact with skin and if swallowed. |
| R24/25: | Toxic in contact with skin and if swallowed. |
| R26/27: | Very toxic by inhalation and in contact with skin. |
| R27/28: | Very toxic in contact with skin and if swallowed. |
| R26/28: | Very toxic by inhalation and if swallowed. |
| R26/27/28: | Very toxic by inhalation, in contact with skin and if swallowed. |
| R36/37: | Irritating to eyes and respiratory system. |
| R37/38: | Irritating to respiratory system and skin. |
| R36/38: | Irritating to eyes and skin. |
| R36/37/38: | Irritating to eyes, respiratory system and skin. |
| R39/23: | Toxic: danger of very serious irreversible effects through inhalation. |
| R39/24: | Toxic: danger of very serious irreversible effects in contact with skin. |
| R39/25: | Toxic: danger of very serious irreversible effects if swallowed. |
| R39/23/24: | Toxic: danger of very serious irreversible effects through inhalation and in contact with skin. |
| R39/23/25: | Toxic: danger of very serious irreversible effects through inhalation and if swallowed. |
| R39/24/25: | Toxic: danger of very serious irreversible effects in contact with skin and if swallowed. |
| R39/23/24/25: | Toxic: danger of very serious irreversible effects through inhalation, in contact with skin and if swallowed. |
| R39/26: | Very toxic: danger of very serious irreversible effects through inhalation. |
| R39/27: | Very toxic: danger of very serious irreversible effects in contact with skin. |
| R39/28: | Very toxic: danger of very serious irreversible effects if swallowed. |
| R39/26/27: | Very toxic: danger of very serious irreversible effects through inhalation and in contact with skin. |
| R39/26/28: | Very toxic: danger of very serious irreversible effects through inhalation and if swallowed. |
| R39/27/28: | Very toxic: danger of very serious irreversible effects in contact with skin and if swallowed. |
| R39/26/27/28: | Very toxic: danger of very serious irreversible effects through inhalation, in contact with skin and if swallowed. |
| R42/43: | May cause sensitization by inhalation and skin contact. |
| R48/20: | Harmful: danger of serious damage to health by prolonged exposure through inhalation. |
| R48/21: | Harmful: danger of serious damage to health by prolonged exposure in contact with skin. |
| R48/22: | Harmful: danger of serious damage to health by prolonged exposure if swallowed. |
| R48/20/21: | Harmful: danger of serious damage to health by prolonged exposure through inhalation and in contact with skin. |
| R48/20/22: | Harmful: danger of serious damage to health by prolonged exposure through inhalation and if swallowed. |
| R48/21/22: | Harmful: danger of serious damage to health by prolonged exposure in contact with skin and if swallowed. |
| R48/20/21/22: | Harmful: danger of serious damage to health by prolonged exposure through inhalation, in contact with skin and if swallowed. |
| R48/23: | Toxic: danger of serious damage to health by prolonged exposure through inhalation. |
| R48/24: | Toxic: danger of serious damage to health by prolonged exposure in contact with skin. |
| R48/25: | Toxic: danger of serious damage to health by prolonged exposure if swallowed. |
| R48/23/24: | Toxic: danger of serious damage to health by prolonged exposure through inhalation and in contact with skin. |
| R48/23/25: | Toxic: danger of serious damage to health by prolonged exposure through inhalation and if swallowed. |
| R48/24/25: | Toxic: danger of serious damage to health by prolonged exposure in contact with skin and if swallowed. |
| R48/23/24/25: | Toxic: danger of serious damage to health by prolonged exposure through inhalation, in contact with skin and if swallowed. |
| R50/53: | Very toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment. |
| R51/53: | Toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment. |
| R52/53: | Harmful to aquatic organisms, may cause long-term adverse effects in the aquatic environment. |
| R68/20: | Harmful: possible risk of irreversible effects through inhalation. |
| R68/21: | Harmful: possible risk of irreversible effects in contact with skin. |
| R68/22: | Harmful: possible risk of irreversible effects if swallowed. |
| R68/20/21: | Harmful: possible risk of irreversible effects through inhalation and in contact with skin. |
| R68/20/22: | Harmful: possible risk of irreversible effects through inhalation and if swallowed. |
| R68/21/22: | Harmful: possible risk of irreversible effects in contact with skin and if swallowed. |
| R68/20/21/22: | Harmful: possible risk of irreversible effects through inhalation, in contact with skin and if swallowed. |
To contact MSDS Authoring Services regarding any additional questions about R-Phrases, click here.