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GHS Classification Criteria

By Little Pro on 2016-05-09 Views:  Update:2017-02-02

GHS classification criteria are used to determine the nature and the relative severity of the hazard of a chemical substance or mixture.  In this article, we have summarized GHS classification criteria (in GHS rev. 6) for all 29 hazard classes, including 17 physical hazards, 10 health hazards and 2 environmental hazards (see all GHS hazard classes). 

For a substance, you can refer to the table below to determine its GHS classification. For a mixture, it is recommended that you read this article (GHS mixture classification) first.

It should be noted that GHS allows each country to choose their own concentration limits for certain hazard categories. The classification critiera below works for most of countries, but not all countries.

Physical Hazards (17 Hazard Classes)

Explosives

Explosives can be classified as unstable explosives or stable explosives. For stable explosives, there are 6 divisions under GHS (see the table below).

Division Characteristics
1.1 Mass explosion hazard
1.2 Projection hazard
1.3 Fire hazard or minor projection hazard
1.4 No significant hazard
1.5 Very insensitive substances with mass explosion hazard
1.6 Extremely insensitive substances with no mass explosion hazard

Classification as an explosive and allocation to a division is a three-step process

  • Ascertain if the material has explosive effects (Test Series 1 of UN TDG);
  • Acceptance procedure (Test Series 2 to 4 of TDG);
  • Assignment to one of six hazard divisions (Test Series 5 to 7 of UN TDG). 

Explosive properties are usually associated with certain chemical groups (see picture below) that can react to give very rapid increases in temperature or pressure. GHS allows you to classify a substance as non-explosive if there are no functional groups associated with explosive properties in the molecule. If a substance is identified to be a potential explosive, acceptance procedure/testing must be followed to determine right division.

explosive functional group

Flammable Gases (Including Unstable Gases)

The table below summarizes GHS classification criteria for flammable gases (including pyrophoric gases and chemically unstable gases).

Type Category GHS Classification Criteria
Flammable gases Category 1 Gases, which at 20°C (68°F) and a standard pressure of 101.3 kPa (14.7 psi) that: (a) are ignitable when in a mixture of 13% or less by volume in air; or (b) have a flammable range with air of at least 12 percentage points regardless of the lower flammable limit.
Flammable gases Category 2 Gases, other than those of Category 1, which, at 20°C (68°F) and a standard pressure of 101.3 kPa (14.7 psi), have a flammable range while mixed in air.
 Pyrophoric gases Category 1 Flammable gases that ignite spontaneously in air at a temperature of 54°C or below
Chemically unstable gases Category A Flammable gases, which are chemically unstable at 20°C (68°F) and a standard pressure of 101.3 kPa
Chemically unstable gases Category B Flammable gases, which are chemically unstable at a temperature higher than 20°C (68°F) or a pressure greater than 101.3 kPa

Aerosols

Aerosols are any gas compressed, liquefied or dissolved under pressure within a non-refillable container made of metal, glass or plastic, with or without a liquid, paste or powder. Aerosols should be considered for classification as either a Category 1 or Category 2 Flammable Aerosol if they contain any component classified as flammable according to the GHS criteria for flammable liquids, flammable gases, or flammable solids.

Type Category GHS Classification Criteria
Aerosols Category 3 The concentration of the flammable components ≤ 1% and the heat of combustion is < 20 kJ/g or other spray/foam aerosols.
Aerosols Category 1 The concentration of the flammable components >85% and the heat of combustion is ≥ 30 kJ/g.
Spray Aerosols Category 1 Ignition occurs at a distance >=75cm in an ignition test.
Spray Aerosols Category 2 Ignition occurs at a distance <75cm in an ignition test. However, the heat of combustion is >20kJ/g or ignition distance is >=15cm or the space ignition test shows that the time equivalent <=300s/m3 or the deflation density <300g/m3;
Foam Aerosols Category 1 In the foam test, the flame height is >=20cm and the flame duration >=2s; or the flame height is >=4cm and the flame duration >=7s.
Foam Aerosols Category 2 In the foam test, the flame height is >=4cm and the flame duration >=2s.

Oxidizing Gases

Category GHS Classification Criteria
Category 1 Gases that cause or contribute to the combustion of other material more than air does. Usually test is not needed. Calculation of oxidizing power can be done according to ISO 10156:2012.

Gases Under Pressure

GHS classification criteria gases under pressure

Flammable Liquids

GHS classification criteria flammable liquids

Flammable Solids

GHS classification criteria flammable solids

Self-reactive Substances

Type GHS Classification Criteria
A Any self-reactive substance or mixture which can detonate or deflagrate rapidly, as packaged;
B Any self-reactive substance or mixture possessing explosive properties and which, as packaged, neither detonates nor deflagrates rapidly, but is liable to undergo a thermal explosion in that package;
C Self-reactive substance or mixture possessing explosive properties when the substance or mixture as packaged cannot detonate or deflagrate rapidly or undergo a thermal explosion;
D Self-reactive substance or mixture which in laboratory testing either detonates partially, does not deflagrate rapidly and shows no violent effect when heated under confinement; does not detonate at all, deflagrates slowly and shows no violent effect when heated under confinement; or does not detonate or deflagrate at all and shows a medium effect when heated under confinement;
E Self-reactive substance or mixture which, in laboratory testing, neither detonates nor deflagrates at all and shows low or no effect when heated under confinement;
F Self-reactive substance or mixture which, in laboratory testing, neither detonates in the cavitated state nor deflagrates at all and shows only a low or no effect when heated under confinement;
G Self-reactive substance or mixture which, in laboratory testing, neither detonates in the cavitated state nor deflagrates at all and shows no effect when heated under confinement and no explosive powder, provided that it is thermally stable and, for liquid mixtures, a diluent having a boiling point greater than or equal to 150°C is used for desensitization;

Pyrophoric Solids

Category GHS Classification Criteria
Category 1 The solid ignites within 5 mins of coming into contact with air.

Pyrophoric Liquids

Category GHS Classification Criteria
Category 1 The liquid ignites within 5 mins when added to an inert carrier or exposed to air, or it ignites or chars a filter paper on contact with air within 5 mins.

Self-heating Substances and Mixtures

GHS classification criteria self-heating substances

Substances which on Contact with Water Emit Flammable Gases

GHS classification criteria water-reactive substances

Oxidizing Liquids

GHS classification criteria oxidising liquids

It shall be noted that above ignition test is not necessary to determine whether or not a substance or mixture is oxidizing; examination of its structural formula may provide predictive information. Organic peroxides, for instance, are generally considered as oxidizing. However, the following substances are not considered as oxidizing:

  • Organic substance or mixture that does not contain oxygen, flourine or chlorine; or
  • The substance or mixture contains oxygen, flourine or chlorine and there elements are bonded only to hydrogen or carbon;
  • Inorganic substances that do not contain oxygen or halogen items.

Oxidizing Solids

GHS classification criteria oxidising solids

It shall be noted that above ignition test is not necessary to determine whether or not a substance or mixture is oxidizing; examination of its structural formula may provide predictive information. Organic peroxides, for instance, are generally considered as oxidizing. However, the following substances are not considered as oxidizing:

  • Organic substance or mixture that does not contain oxygen, flourine or chlorine; or
  • The substance or mixture contains oxygen, flourine or chlorine and there elements are bonded only to hydrogen or carbon;
  • Inorganic substances that do not contain oxygen or halogen items.

Organic Peroxides

Type GHS Classification Criteria
A Any organic peroxide which, as packaged, can detonate or deflagrate rapidly.
B Any organic peroxide possessing explosive properties and which, as packaged, neither detonates nor deflagrates rapidly, but is liable to undergo a thermal explosion in that package.
C Any organic peroxide possessing explosive properties when the substance or mixture as packaged cannot detonate or deflagrate rapidly or undergo a thermal explosion;
D Any organic peroxide which in laboratory testing:
  • Detonates partially, does not deflagrate rapidly and shows no violent effect when heated under confinement; or
  • Does not detonate at all, deflagrates slowly and shows no violent effect when heated under confinement; or
  • Does not detonate or deflagrate at all and shows a medium effect when heated under confinement.
E Any organic peroxide which, in laboratory testing, neither detonates nor deflagrates at all and shows low or no effect when heated under confinement.
F Any organic peroxide which, in laboratory testing, neither detonates in the cavitated state nor deflagrates at all and shows only a low or no effect when heated under confinement as well as low or no explosive power.
G Any organic peroxide which, in laboratory testing, neither detonates in the cavitated state nor deflagrates at all and shows no effect when heated under confinement nor any explosive power, provided that it is thermally stable (self-accelerating decomposition temperature is 60°C or higher for a 50 kg package).

Corrosive to Metals

Category GHS Classification Criteria
Category 1 Corrosion rate on steel or aluminum surfaces exceeds 6.25 mm per year at a test temperature of 55°C.

Desensitized Explosives

GHS classification criteria de-sensitized explosives

 

Health Hazards (10 Hazard Classes)

Acute Toxicity

Substances are assigned to one of the five toxicity categories on the basis of LD50 (oral, dermal) or LC50 (inhalation).from acute toxicity studies. Some countries/region (i.e, EU) have not adopted acute toxicity category 5.

GHS classification criteria acute toxicity

Skin Irritation/Corrosion

Category 1 Corrosive Category 2 Irritant Category 3 Mild Irritant

For substances and tested mixtures:

• Human experience showing irreversible damage to the skin;

• Structure/activity or structure property relationship to a substance or mixture already classified as corrosive;

• pH extremes of <=2 and >=11.5 including acid/alkali reserve capacity;

• Positive results in a valid and accepted in vitro skin corrosion test; or

• Animal experience or test data that indicate that the substance/mixture causes irreversible damage to the skin following exposure of up to 4 hours.

For mixtures where substances can be added:

• Classify as corrosive if the sum of the concentrations of corrosive substances in the mixture is ≥ 5% (for substances with additivity); or

For mixtures where substances cannot be added: ≥ 1%.

For substances and tested mixtures:

• Human experience or data showing reversible damage to the skin following exposure of up to 4 hours;

• Structure/activity or structure property relationship to a substance or mixture already classified as an irritant;

• Positive results in a valid and accepted in vitro skin irritation test; or

• Animal experience or test data that indicate that the substance/mixture causes reversible damage to the skin following exposure of up to 4 hours, mean value of ≥ 2.3 < 4.0 for erythema/eschar or for oedema, or inflammation that persists to the end of the observation period, in 2 of 3 tested animals.

For mixtures where substances can be added:

• The sum of concentrations of corrosive substances in the mixture is ≥ 1% but ≤ 5%;

• The sum of the concentrations of irritant substances is > 10%; or

• The sum of (10 × the concentrations of corrosive ingredients) + (the concentrations of irritant ingredients) is ≥ 10%;

or For mixtures where substances cannot be added: ≥ 3%..

For substances and tested mixtures:

• Animal experience or test data that indicates that the substance/mixture causes reversible damage to the skin following exposure of up to 4 hours, mean value of ≥ 1.5 < 2.3 for erythema/eschar in 2 of 3 tested animals.

For mixtures where substances can be added:

• The sum of the concentrations of irritant substances in the mixture is ≥ 1% but ≤ 10%;

For mixtures where substances cannot be added:

• The sum of the concentrations of mild irritant substances is ≥ 10%;

• The sum of (10 × the concentrations of corrosive substances) + (the concentrations of irritant substances) is ≥ 1% but ≤ 10%; or

• The sum of (10 × the concentrations of corrosive substances) + (the concentrations of irritant substances) + (the concentrations of mild irritant substances ) is ≥ 10%.

More info about additive hazards and non-additive hazards can be found here.

Serious Eye Damage/Eye Irritation

Category 1 Corrosive Category 2A Irritant Category 2B Mild Irritant

For substances and tested mixtures

• Classification as corrosive to skin;

• Human experience or data showing damage to the eye which is not fully reversible within 21 days;

• Structure/activity or structure property relationship to a substance or mixture already classified as corrosive;

• pH extremes of < 2 and > 11.5 including buffering capacity;

• Positive results in a valid and accepted in vitro test to assess serious damage to eyes; or

• Animal experience or test data that the substance or mixture produces either

(1) in at least one animal, effects on the cornea, iris or conjunctiva that are not expected to reverse or have not reversed; or

(2) in at least 2 of 3 tested animals a positive response of corneal opacity ≥ 3 and/or iritis > 1.5.

For mixtures where substances can be added:

• Classify as Category 1 if the sum of the concentrations of substances classified as corrosive to the skin and/or eye Category 1 substances in the mixture is ≥ 3%;or

For mixtures where substances cannot be added: ≥ 1.

For substances and tested mixtures

• Classification as severe skin irritant;

• Human experience or data showing production of changes in the eye which are fully reversible within 21 days;

• Structure/activity or structure property relationship to a substance or mixture already classified as an eye irritant;

• Positive results in a valid and accepted in vitro eye irritation test; or

• Animal experience or test data that indicate that the substance/mixture produces a positive response in at least 2 of 3 tested animals of: corneal opacity ≥ 1, iritis ≥ 1, or conjunctival edema (chemosis) ≥ 2.

For mixtures where substances can be added:

• The sum of the concentrations of skin and/or eye Category 1 substances in the mixture is ≥ 1% but ≤ 3%; the sum of the concentrations of eye irritant substances is ≥ 10%; or

• The sum of (10 × the concentrations of skin and/or eye category 1 substances) + (the concentrations of eye irritants) is ≥ 10%;or

For mixtures where substances cannot be added:

• The sum of the concentrations of eye irritant ingredients is 3%.

For substances and tested mixtures;

• Human experience or data showing production of mild eye irritation;

• Animal experience or test data that indicate that the lesions are fully reversible within 7 days.

For mixtures where substances can be added:

• The sum of the concentrations of skin and/or eye Category 1 substances in the mixture is ≥ 1% but ≤ 3%;

• The sum of concentrations of eye irritant substances is ≥ 10%; or

• The sum of (10 × the concentrations of skin and/or eye category 1 substances) + (the concentrations of eye irritants) is ≥ 10%; or

For mixtures where substances cannot be added:

• The sum of the concentrations of eye irritant ingredients is ≥ 3%.

Respiratory or Skin Sensitization

Category 1 Skin Sensitization Category 1 Respiratory Sensitization

For substances and tested mixtures:

• If there is evidence in humans that the individual substance can induce sensitization by skin contact in a substantial number of persons, or where there are positive results from an appropriate animal test.

• If any individual skin sensitizer in the mixture has a concentration of:  Subcategory 1B≥ 1.0% Solid/Liquid/Gas or Subcategory 1A≥ 0.1% Solid/Liquid/Gas

For substances and tested mixtures:

• If there is human evidence that the individual substance induces specific respiratory hypersensitivity, and/or Where there are positive results from an appropriate animal test.

• If any individual respiratory sensitizer in the mixture has a concentration of: ≥ 1.0% Solid/Liquid and ≥ 0.2% Gas

Germ Cell Mutagenicity

Category Criteria
Category 1A Chemicals known to induce or regarded as if they induce heritable mutations in human germ cells

Known to induce heritable mutations –positive evidence from human epidemiological studies.

Mixtures containing ≥ 0.1% of such a category 1A mutagen.

Category 1B Chemicals known to induce or regarded as if they induce heritable mutations in human germ cells

Regard as if they induce heritable mutations – positive results from in vivo heritable germ cell or somatic cell mammalian mutagenicity tests, or positive results showing mutagenic effects in the germ cells of humans without demonstration of transmission to progeny.

Mixtures containing ≥ 0.1% of such a category 1B mutagen.

Category 2 Chemicals that may induce heritable mutations in human germ cells

Positive evidence obtained from in vivo somatic cell mutagenicity or somatic cell genotoxicity tests in mammals and in some cases with support from in vitro experiments

Mixtures containing ≥ 1% of such a category 2 mutagen.

Carcinogenicity

Category Criteria
Category 1A Chemicals known to have carcinogenic potential to humans - largely based on human evidence

Mixtures containing ≥ 0.1% of such a category 1A carcinogen.

Category 1B Chemicals presumed to have carcinogenic potential to humans - largely based on animal evidence.

Mixtures containing ≥ 0.1% of such a category 1B carcinogen.

Category 2 Suspected human carcinogen - evidence from human and/or animal studies is limited

Mixtures containing ≥ 0.1% of such a category 2 carcinogen. (Note: Some countries have different concentration limits. For example, EU's concentration limit for category 2 carcinogen is 1%).

Reproductive Toxicity

Category Criteria
Category 1A Known human reproductive toxicants

Mixtures containing ≥ 0.1% or ≥ 0.3 % of such a substance. (EU's value is 0.3%).

Category 1B  Presumed human reproductive toxicants - largly based on animal studies

Mixtures containing ≥ 0.1% or ≥ 0.3 % of such a substance. (EU's value is 0.3%. USA's value is 0.1%)

Comparison of concentration limits for reproductive toxicity

Category 2 Suspected human reproductive toxicant - Evidence from animal and/or human studies is limited

Mixtures containing ≥ 0.1% or ≥ 3 % of such a substance. (EU's value is 3% while USA's value is 0.1%).

Effects on via lactation Effects on via lactation

Toxicants which may interfere with lactation or which may be present in breast milk and may cause harm to breast-fed children 

Mixtures containing ≥ 0.1% or ≥ 0.3 % of such a substance.

Target Organ Systemic Toxicity - Single Exposure

This provide a means of classifying substances that produce specific, non lethal target organ/systemic toxicity arising from a single exposure. Guidance value (LD50, LC50) from acute toxicity studies are used to determine specific hazard category.

GHS STOT Single Exposure

For mixture, please refer to the table below:

STOT Concentration Limit GHS

Target Organ Systemic Toxicity - Repeated Exposure

This provides a means of classifying substances that produce specific target organ/systemic toxicity arising from repeated exposure that is not specifically addressed elsewhere in the harmonised classification system (GHS).

Standard 90d repeated dose toxicity study serves as the most important study to determine the classification of the specific target organ toxicity of a chemical substance. Since toxicity depends on doses, GHS uses guidance value C to determine the hazard category of specific target organ/systemic toxicity. Guidance value C is defined as test concentration at which there is evidence of significant toxicity and it is not NOAEL.  Guidance value C is usually bigger than NOAEL. Some effects such as body weight change are not regarded as significant toxicity. 

Repeated dose toxicity studies of greater or lesser duration can be used to derive equivalent guidance value by extrapolation. 

Category Classification Criteria and Guidance Value
Category 1

Reliable evidence on the substance or mixture (including bridging) of an adverse effect on specific organ/systems or systemic toxicity in humans or animals. May be named for specific organ/system.

For tested substances and mixtures:

  • Guidance value C (oral, rat) ≤ 10 mg/kg bw/d
  • Guidance value C (dermal, rat or rabbit) ≤20 mg/kg bw/d
  • Guidance value C (inhalation, rat, gas) ≤ 50ppm/6h/d
  • Guidance value C (inhalation, rat, vapour) ≤ 0.2 mg/l/6h/d
  • Guidance value C (inhalation, rat, dust/mist/fume) ≤ 0.02mg/l/6h/d

Mixture that lacks sufficient data, but contains Category 1 ingredient: ≥ 1 to ≤ 10% for some authorities; and ≥ 10% for all authorities.

Category 2

Evidence on the substance or mixture (including bridging) of an adverse effect on specific organ/systems or systemic toxicity from animal studies or humans. May be named for specific organ/system.

For substances and tested mixtures:

  • 10<Guidance value C (oral, rat) ≤ 100 mg/kg bw/d
  • 20<Guidance value C (dermal, rat or rabbit) ≤200 mg/kg bw/d
  • 50<Guidance value C (inhalation, rat, gas) ≤ 250ppm/6h/d
  • 0.2<Guidance value C (inhalation, rat, vapour) ≤ 1 mg/l/6h/d
  • 0.02<Guidance value C (inhalation, rat, dust/mist/fume) ≤ 0.2mg/l/6h/d

Mixture that lacks sufficient data, but contains Category 1 ingredient: ≥ 1.0 but ≤ 10% for some authorities and/or contains Category 2 ingredient: ≥ 1.0 or ≥ 10%.

Aspiration Toxicity

GHS classification criteria aspiration toxicity

For mixture, please refer to the table below:

Category Criteria
Category 1

Contains >=10% category 1 ingredient and has a kinematic viscosity<=20.5mm2/s (measured at 40 celcius degrees); 

Category 2 Contains >=10% category 2 ingredient and has a kinematic viscosity<=14mm2/s (measured at 40 celcius degrees); 
Environmental Hazards (2 Hazard Classes)

Hazardous to Aquatic Environment (Acute/Chronic)

The picture below summarizes environmental hazard classification based on aquatic toxicity data. Lower LC50/EC50/NOEC indicates higher toxicity. Please note that degradation and bio-concentration shall also be taken into account.

GHS classification criteria environmental hazard

For mixture, please refer to the table below. If you do not know what M-factor is and how it is used for environmental hazard classification, please click here.

Concentration limit aquatic hazard

The value of multiplying factor (M-factor) can be found in the table below:

GHS M factor

Hazardous to the Ozone Layer

Category Criteria
Category 1

Any of the controlled substances in the annexes to the Montreal Protocol; or any mixture containing at least 1 ingredient listed in the annexes to the Montreal protocal, at a concentration>=0.1%;

Reference and More Reading

 

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