463 

Occupational Safety and Health Admin., Labor § 1910.1200 

of a currently effective determination 

by the Assistant Secretary of Labor 

that such program is compatible with 

the requirements of this section. Such 

determinations currently are in effect 

only in the States of Alabama, Arkansas, California, Kansas, Kentucky, 

Florida, Mississippi, New Hampshire, 

New York, North Carolina, Texas, Tennessee, Oregon, Idaho, Arizona, Colorado, Louisiana, Nebraska, Washington, Maryland, North Dakota, 

South Carolina, and Georgia. 

[39 FR 23502, June 27, 1974, as amended at 43 

FR 49746, Oct. 24, 1978; 43 FR 51759, Nov. 7, 

1978; 49 FR 18295, Apr. 30, 1984; 58 FR 35309, 

June 30, 1993. Redesignated at 61 FR 31430, 

June 20, 1996] 

§ 1910.1200 Hazard communication. 

(a) Purpose. (1) The purpose of this 

section is to ensure that the hazards of 

all chemicals produced or imported are 

classified, and that information concerning the classified hazards is transmitted to employers and employees. 

The requirements of this section are 

intended to be consistent with the provisions of the United Nations Globally 

Harmonized System of Classification 

and Labelling of Chemicals (GHS), Revision 3. The transmittal of information is to be accomplished by means of 

comprehensive hazard communication 

programs, which are to include container labeling and other forms of 

warning, safety data sheets and employee training. 

(2) This occupational safety and 

health standard is intended to address 

comprehensively the issue of 

classifying the potential hazards of 

chemicals, and communicating information concerning hazards and appropriate protective measures to employees, and to preempt any legislative or 

regulatory enactments of a state, or 

political subdivision of a state, pertaining to this subject. Classifying the 

potential hazards of chemicals and 

communicating information concerning hazards and appropriate protective measures to employees, may include, for example, but is not limited 

to, provisions for: developing and maintaining a written hazard communication program for the workplace, including lists of hazardous chemicals 

present; labeling of containers of 

chemicals in the workplace, as well as 

of containers of chemicals being 

shipped to other workplaces; preparation and distribution of safety data 

sheets to employees and downstream 

employers; and development and implementation of employee training programs regarding hazards of chemicals 

and protective measures. Under section 

18 of the Act, no state or political subdivision of a state may adopt or enforce any requirement relating to the 

issue addressed by this Federal standard, except pursuant to a Federally-approved state plan. 

(b) Scope and application. (1) This section requires chemical manufacturers 

or importers to classify the hazards of 

chemicals which they produce or import, and all employers to provide information to their employees about the 

hazardous chemicals to which they are 

exposed, by means of a hazard communication program, labels and other 

forms of warning, safety data sheets, 

and information and training. In addition, this section requires distributors 

to transmit the required information 

to employers. (Employers who do not 

produce or import chemicals need only 

focus on those parts of this rule that 

deal with establishing a workplace program and communicating information 

to their workers.) 

(2) This section applies to any chemical which is known to be present in 

the workplace in such a manner that 

employees may be exposed under normal conditions of use or in a foreseeable emergency. 

(3) This section applies to laboratories only as follows: 

(i) Employers shall ensure that labels 

on incoming containers of hazardous 

chemicals are not removed or defaced; 

(ii) Employers shall maintain any 

safety data sheets that are received 

with incoming shipments of hazardous 

chemicals, and ensure that they are 

readily accessible during each 

workshift to laboratory employees 

when they are in their work areas; 

(iii) Employers shall ensure that laboratory employees are provided information and training in accordance 

with paragraph (h) of this section, except for the location and availability of 

464 

§ 1910.1200 29 CFR Ch. XVII (7–1–13 Edition) 

the written hazard communication program under paragraph (h)(2)(iii) of this 

section; and, 

(iv) Laboratory employers that ship 

hazardous chemicals are considered to 

be either a chemical manufacturer or a 

distributor under this rule, and thus 

must ensure that any containers of 

hazardous chemicals leaving the laboratory are labeled in accordance with 

paragraph (f) of this section, and that a 

safety data sheet is provided to distributors and other employers in accordance with paragraphs (g)(6) and 

(g)(7) of this section. 

(4) In work operations where employees only handle chemicals in sealed 

containers which are not opened under 

normal conditions of use (such as are 

found in marine cargo handling, 

warehousing, or retail sales), this section applies to these operations only as 

follows: 

(i) Employers shall ensure that labels 

on incoming containers of hazardous 

chemicals are not removed or defaced; 

(ii) Employers shall maintain copies 

of any safety data sheets that are received with incoming shipments of the 

sealed containers of hazardous chemicals, shall obtain a safety data sheet as 

soon as possible for sealed containers 

of hazardous chemicals received without a safety data sheet if an employee 

requests the safety data sheet, and 

shall ensure that the safety data sheets 

are readily accessible during each work 

shift to employees when they are in 

their work area(s); and, 

(iii) Employers shall ensure that employees are provided with information 

and training in accordance with paragraph (h) of this section (except for the 

location and availability of the written 

hazard communication program under 

paragraph (h)(2)(iii) of this section), to 

the extent necessary to protect them 

in the event of a spill or leak of a hazardous chemical from a sealed container. 

(5) This section does not require labeling of the following chemicals: 

(i) Any pesticide as such term is defined in the Federal Insecticide, Fungicide, and Rodenticide Act (7 U.S.C. 

136 et seq.), when subject to the labeling 

requirements of that Act and labeling 

regulations issued under that Act by 

the Environmental Protection Agency; 

(ii) Any chemical substance or mixture as such terms are defined in the 

Toxic Substances Control Act (15 

U.S.C. 2601 et seq.), when subject to the 

labeling requirements of that Act and 

labeling regulations issued under that 

Act by the Environmental Protection 

Agency. 

(iii) Any food, food additive, color additive, drug, cosmetic, or medical or 

veterinary device or product, including 

materials intended for use as ingredients in such products (e.g. flavors and 

fragrances), as such terms are defined 

in the Federal Food, Drug, and Cosmetic Act (21 U.S.C. 301 et seq.) or the 

Virus-Serum-Toxin Act of 1913 (21 

U.S.C. 151 et seq.), and regulations 

issued under those Acts, when they are 

subject to the labeling requirements 

under those Acts by either the Food 

and Drug Administration or the Department of Agriculture; 

(iv) Any distilled spirits (beverage alcohols), wine, or malt beverage intended for nonindustrial use, as such 

terms are defined in the Federal Alcohol Administration Act (27 U.S.C. 201 et 

seq.) and regulations issued under that 

Act, when subject to the labeling requirements of that Act and labeling 

regulations issued under that Act by 

the Bureau of Alcohol, Tobacco, Firearms and Explosives; 

(v) Any consumer product or hazardous substance as those terms are defined in the Consumer Product Safety 

Act (15 U.S.C. 2051 et seq.) and Federal 

Hazardous Substances Act (15 U.S.C. 

1261 et seq.) respectively, when subject 

to a consumer product safety standard 

or labeling requirement of those Acts, 

or regulations issued under those Acts 

by the Consumer Product Safety Commission; and, 

(vi) Agricultural or vegetable seed 

treated with pesticides and labeled in 

accordance with the Federal Seed Act 

(7 U.S.C. 1551 et seq.) and the labeling 

regulations issued under that Act by 

the Department of Agriculture. 

(6) This section does not apply to: (i) 

Any hazardous waste as such term is 

defined by the Solid Waste Disposal 

Act, as amended by the Resource Conservation and Recovery Act of 1976, as 

amended (42 U.S.C. 6901 et seq.), when 

subject to regulations issued under 

465 

Occupational Safety and Health Admin., Labor § 1910.1200 

that Act by the Environmental Protection Agency; 

(ii) Any hazardous substance as such 

term is defined by the Comprehensive 

Environmental Response, Compensation and Liability Act (CERCLA) (42 

U.S.C. 9601 et seq.) when the hazardous 

substance is the focus of remedial or 

removal action being conducted under 

CERCLA in accordance with Environmental Protection Agency regulations. 

(iii) Tobacco or tobacco products; 

(iv) Wood or wood products, including 

lumber which will not be processed, 

where the chemical manufacturer or 

importer can establish that the only 

hazard they pose to employees is the 

potential for flammability or combustibility (wood or wood products which 

have been treated with a hazardous 

chemical covered by this standard, and 

wood which may be subsequently sawed 

or cut, generating dust, are not exempted); 

(v) Articles (as that term is defined 

in paragraph (c) of this section); 

(vi) Food or alcoholic beverages 

which are sold, used, or prepared in a 

retail establishment (such as a grocery 

store, restaurant, or drinking place), 

and foods intended for personal consumption by employees while in the 

workplace; 

(vii) Any drug, as that term is defined in the Federal Food, Drug, and 

Cosmetic Act (21 U.S.C. 301 et seq.), 

when it is in solid, final form for direct 

administration to the patient (e.g., tablets or pills); drugs which are packaged 

by the chemical manufacturer for sale 

to consumers in a retail establishment 

(e.g., over-the-counter drugs); and 

drugs intended for personal consumption by employees while in the workplace (e.g., first aid supplies); 

(viii) Cosmetics which are packaged 

for sale to consumers in a retail establishment, and cosmetics intended for 

personal consumption by employees 

while in the workplace; 

(ix) Any consumer product or hazardous substance, as those terms are 

defined in the Consumer Product Safety Act (15 U.S.C. 2051 et seq.) and Federal Hazardous Substances Act (15 

U.S.C. 1261 et seq.) respectively, where 

the employer can show that it is used 

in the workplace for the purpose intended by the chemical manufacturer 

or importer of the product, and the use 

results in a duration and frequency of 

exposure which is not greater than the 

range of exposures that could reasonably be experienced by consumers when 

used for the purpose intended; 

(x) Nuisance particulates where the 

chemical manufacturer or importer 

can establish that they do not pose any 

physical or health hazard covered 

under this section; 

(xi) Ionizing and nonionizing radiation; and, 

(xii) Biological hazards. 

(c) Definitions. Article means a manufactured item other than a fluid or particle: (i) which is formed to a specific 

shape or design during manufacture; 

(ii) which has end use function(s) dependent in whole or in part upon its 

shape or design during end use; and (iii) 

which under normal conditions of use 

does not release more than very small 

quantities, e.g., minute or trace 

amounts of a hazardous chemical (as 

determined under paragraph (d) of this 

section), and does not pose a physical 

hazard or health risk to employees. 

Assistant Secretary means the Assistant Secretary of Labor for Occupational Safety and Health, U.S. Department of Labor, or designee. 

Chemical means any substance, or 

mixture of substances. 

Chemical manufacturer means an employer with a workplace where chemical(s) are produced for use or distribution. 

Chemical name means the scientific 

designation of a chemical in accordance with the nomenclature system developed by the International Union of 

Pure and Applied Chemistry (IUPAC) 

or the Chemical Abstracts Service 

(CAS) rules of nomenclature, or a name 

that will clearly identify the chemical 

for the purpose of conducting a hazard 

classification. 

Classification means to identify the 

relevant data regarding the hazards of 

a chemical; review those data to ascertain the hazards associated with the 

chemical; and decide whether the 

chemical will be classified as hazardous 

according to the definition of hazardous chemical in this section. In addition, classification for health and 

physical hazards includes the determination of the degree of hazard, where 

466 

§ 1910.1200 29 CFR Ch. XVII (7–1–13 Edition) 

appropriate, by comparing the data 

with the criteria for health and physical hazards. 

Commercial account means an arrangement whereby a retail distributor 

sells hazardous chemicals to an employer, generally in large quantities 

over time and/or at costs that are 

below the regular retail price. 

Common name means any designation 

or identification such as code name, 

code number, trade name, brand name 

or generic name used to identify a 

chemical other than by its chemical 

name. 

Container means any bag, barrel, bottle, box, can, cylinder, drum, reaction 

vessel, storage tank, or the like that 

contains a hazardous chemical. For 

purposes of this section, pipes or piping 

systems, and engines, fuel tanks, or 

other operating systems in a vehicle, 

are not considered to be containers. 

Designated representative means any 

individual or organization to whom an 

employee gives written authorization 

to exercise such employee’s rights 

under this section. A recognized or certified collective bargaining agent shall 

be treated automatically as a designated representative without regard 

to written employee authorization. 

Director means the Director, National 

Institute for Occupational Safety and 

Health, U.S. Department of Health and 

Human Services, or designee. 

Distributor means a business, other 

than a chemical manufacturer or importer, which supplies hazardous 

chemicals to other distributors or to 

employers. 

Employee means a worker who may be 

exposed to hazardous chemicals under 

normal operating conditions or in foreseeable emergencies. Workers such as 

office workers or bank tellers who encounter hazardous chemicals only in 

non-routine, isolated instances are not 

covered. 

Employer means a person engaged in a 

business where chemicals are either 

used, distributed, or are produced for 

use or distribution, including a contractor or subcontractor. 

Exposure or exposed means that an 

employee is subjected in the course of 

employment to a chemical that is a 

physical or health hazard, and includes 

potential (e.g. accidental or possible) 

exposure. ‘‘Subjected’’ in terms of 

health hazards includes any route of 

entry (e.g. inhalation, ingestion, skin 

contact or absorption.) 

Foreseeable emergency means any potential occurrence such as, but not limited to, equipment failure, rupture of 

containers, or failure of control equipment which could result in an uncontrolled release of a hazardous chemical 

into the workplace. 

Hazard category means the division of 

criteria within each hazard class, e.g., 

oral acute toxicity and flammable liquids include four hazard categories. 

These categories compare hazard severity within a hazard class and should 

not be taken as a comparison of hazard 

categories more generally. 

Hazard class means the nature of the 

physical or health hazards, e.g., flammable solid, carcinogen, oral acute toxicity. 

Hazard not otherwise classified (HNOC) 

means an adverse physical or health effect identified through evaluation of 

scientific evidence during the classification process that does not meet the 

specified criteria for the physical and 

health hazard classes addressed in this 

section. This does not extend coverage 

to adverse physical and health effects 

for which there is a hazard class addressed in this section, but the effect 

either falls below the cut-off value/concentration limit of the hazard class or 

is under a GHS hazard category that 

has not been adopted by OSHA (e.g., 

acute toxicity Category 5). 

Hazard statement means a statement 

assigned to a hazard class and category 

that describes the nature of the hazard(s) of a chemical, including, where 

appropriate, the degree of hazard. 

Hazardous chemical means any chemical which is classified as a physical 

hazard or a health hazard, a simple asphyxiant, combustible dust, pyrophoric 

gas, or hazard not otherwise classified. 

Health hazard means a chemical 

which is classified as posing one of the 

following hazardous effects: acute toxicity (any route of exposure); skin corrosion or irritation; serious eye damage or eye irritation; respiratory or 

skin sensitization; germ cell mutagenicity; carcinogenicity; reproductive 

toxicity; specific target organ toxicity 

467 

Occupational Safety and Health Admin., Labor § 1910.1200 

(single or repeated exposure); or aspiration hazard. The criteria for determining whether a chemical is classified 

as a health hazard are detailed in Appendix A to §1910.1200—Health Hazard 

Criteria. 

Immediate use means that the hazardous chemical will be under the control of and used only by the person who 

transfers it from a labeled container 

and only within the work shift in 

which it is transferred. 

Importer means the first business 

with employees within the Customs 

Territory of the United States which 

receives hazardous chemicals produced 

in other countries for the purpose of 

supplying them to distributors or employers within the United States. 

Label means an appropriate group of 

written, printed or graphic information 

elements concerning a hazardous chemical that is affixed to, printed on, or attached to the immediate container of a 

hazardous chemical, or to the outside 

packaging. 

Label elements means the specified 

pictogram, hazard statement, signal 

word and precautionary statement for 

each hazard class and category. 

Mixture means a combination or a solution composed of two or more substances in which they do not react. 

Physical hazard means a chemical 

that is classified as posing one of the 

following hazardous effects: explosive; 

flammable (gases, aerosols, liquids, or 

solids); oxidizer (liquid, solid or gas); 

self-reactive; pyrophoric (liquid or 

solid); self-heating; organic peroxide; 

corrosive to metal; gas under pressure; 

or in contact with water emits flammable gas. See Appendix B to 

§1910.1200—Physical Hazard Criteria. 

Pictogram means a composition that 

may include a symbol plus other graphic elements, such as a border, background pattern, or color, that is intended to convey specific information 

about the hazards of a chemical. Eight 

pictograms are designated under this 

standard for application to a hazard 

category. 

Precautionary statement means a 

phrase that describes recommended 

measures that should be taken to minimize or prevent adverse effects resulting from exposure to a hazardous 

chemical, or improper storage or handling. 

Produce means to manufacture, process, formulate, blend, extract, generate, emit, or repackage. 

Product identifier means the name or 

number used for a hazardous chemical 

on a label or in the SDS. It provides a 

unique means by which the user can 

identify the chemical. The product 

identifier used shall permit cross-references to be made among the list of 

hazardous chemicals required in the 

written hazard communication program, the label and the SDS. 

Pyrophoric gas means a chemical in a 

gaseous state that will ignite spontaneously in air at a temperature of 130 degrees F (54.4 degrees C) or below. 

Responsible party means someone who 

can provide additional information on 

the hazardous chemical and appropriate emergency procedures, if necessary. 

Safety data sheet (SDS) means written 

or printed material concerning a hazardous chemical that is prepared in accordance with paragraph (g) of this section. 

Signal word means a word used to indicate the relative level of severity of 

hazard and alert the reader to a potential hazard on the label. The signal 

words used in this section are ‘‘danger’’ 

and ‘‘warning.’’ ‘‘Danger’’ is used for 

the more severe hazards, while ‘‘warning’’ is used for the less severe. 

Simple asphyxiant means a substance 

or mixture that displaces oxygen in the 

ambient atmosphere, and can thus 

cause oxygen deprivation in those who 

are exposed, leading to unconsciousness and death. 

Specific chemical identity means the 

chemical name, Chemical Abstracts 

Service (CAS) Registry Number, or any 

other information that reveals the precise chemical designation of the substance. 

Substance means chemical elements 

and their compounds in the natural 

state or obtained by any production 

process, including any additive necessary to preserve the stability of the 

product and any impurities deriving 

from the process used, but excluding 

any solvent which may be separated 

without affecting the stability of the 

substance or changing its composition. 

468 

§ 1910.1200 29 CFR Ch. XVII (7–1–13 Edition) 

Trade secret means any confidential 

formula, pattern, process, device, information or compilation of information 

that is used in an employer’s business, 

and that gives the employer an opportunity to obtain an advantage over 

competitors who do not know or use it. 

Appendix E to §1910.1200—Definition of 

Trade Secret, sets out the criteria to 

be used in evaluating trade secrets. 

Use means to package, handle, react, 

emit, extract, generate as a byproduct, 

or transfer. 

Work area means a room or defined 

space in a workplace where hazardous 

chemicals are produced or used, and 

where employees are present. 

Workplace means an establishment, 

job site, or project, at one geographical 

location containing one or more work 

areas. 

(d) Hazard classification. (1) Chemical 

manufacturers and importers shall 

evaluate chemicals produced in their 

workplaces or imported by them to 

classify the chemicals in accordance 

with this section. For each chemical, 

the chemical manufacturer or importer 

shall determine the hazard classes, 

and, where appropriate, the category of 

each class that apply to the chemical 

being classified. Employers are not required to classify chemicals unless 

they choose not to rely on the classification performed by the chemical 

manufacturer or importer for the 

chemical to satisfy this requirement. 

(2) Chemical manufacturers, importers or employers classifying chemicals 

shall identify and consider the full 

range of available scientific literature 

and other evidence concerning the potential hazards. There is no requirement to test the chemical to determine 

how to classify its hazards. Appendix A 

to §1910.1200 shall be consulted for classification of health hazards, and Appendix B to §1910.1200 shall be consulted for the classification of physical 

hazards. 

(3) Mixtures. (i) Chemical manufacturers, importers, or employers evaluating chemicals shall follow the procedures described in Appendices A and B 

to §1910.1200 to classify the hazards of 

the chemicals, including determinations regarding when mixtures of the 

classified chemicals are covered by this 

section. 

(ii) When classifying mixtures they 

produce or import, chemical manufacturers and importers of mixtures may 

rely on the information provided on 

the current safety data sheets of the 

individual ingredients, except where 

the chemical manufacturer or importer 

knows, or in the exercise of reasonable 

diligence should know, that the safety 

data sheet misstates or omits information required by this section. 

(e) Written hazard communication program. (1) Employers shall develop, implement, and maintain at each workplace, a written hazard communication 

program which at least describes how 

the criteria specified in paragraphs (f), 

(g), and (h) of this section for labels 

and other forms of warning, safety data 

sheets, and employee information and 

training will be met, and which also includes the following: 

(i) A list of the hazardous chemicals 

known to be present using a product 

identifier that is referenced on the appropriate safety data sheet (the list 

may be compiled for the workplace as a 

whole or for individual work areas); 

and, 

(ii) The methods the employer will 

use to inform employees of the hazards 

of non-routine tasks (for example, the 

cleaning of reactor vessels), and the 

hazards associated with chemicals contained in unlabeled pipes in their work 

areas. 

(2) Multi-employer workplaces. Employers who produce, use, or store hazardous chemicals at a workplace in 

such a way that the employees of other 

employer(s) may be exposed (for example, employees of a construction contractor working on-site) shall additionally ensure that the hazard communication programs developed and implemented under this paragraph (e) include the following: 

(i) The methods the employer will 

use to provide the other employer(s) 

on-site access to safety data sheets for 

each hazardous chemical the other employer(s)’ employees may be exposed to 

while working; 

(ii) The methods the employer will 

use to inform the other employer(s) of 

any precautionary measures that need 

to be taken to protect employees during the workplace’s normal operating 

469 

Occupational Safety and Health Admin., Labor § 1910.1200 

conditions and in foreseeable emergencies; and, 

(iii) The methods the employer will 

use to inform the other employer(s) of 

the labeling system used in the workplace. 

(3) The employer may rely on an existing hazard communication program 

to comply with these requirements, 

provided that it meets the criteria established in this paragraph (e). 

(4) The employer shall make the 

written hazard communication program available, upon request, to employees, their designated representatives, the Assistant Secretary and the 

Director, in accordance with the requirements of 29 CFR 1910.20 (e). 

(5) Where employees must travel between workplaces during a workshift, 

i.e., their work is carried out at more 

than one geographical location, the 

written hazard communication program may be kept at the primary 

workplace facility. 

(f) Labels and other forms of warning— 

(1) Labels on shipped containers. The 

chemical manufacturer, importer, or 

distributor shall ensure that each container of hazardous chemicals leaving 

the workplace is labeled, tagged, or 

marked. Hazards not otherwise classified do not have to be addressed on the 

container. Where the chemical manufacturer or importer is required to 

label, tag or mark the following information shall be provided: 

(i) Product identifier; 

(ii) Signal word; 

(iii) Hazard statement(s); 

(iv) Pictogram(s); 

(v) Precautionary statement(s); and, 

(vi) Name, address, and telephone 

number of the chemical manufacturer, 

importer, or other responsible party. 

(2) The chemical manufacturer, importer, or distributor shall ensure that 

the information provided under paragraphs (f)(1)(i) through (v) of this section is in accordance with Appendix C 

to §1910.1200, for each hazard class and 

associated hazard category for the hazardous chemical, prominently displayed, and in English (other languages 

may also be included if appropriate). 

(3) The chemical manufacturer, importer, or distributor shall ensure that 

the information provided under paragraphs (f)(1)(ii) through (iv) of this section is located together on the label, 

tag, or mark. 

(4) Solid materials. (i) For solid metal 

(such as a steel beam or a metal casting), solid wood, or plastic items that 

are not exempted as articles due to 

their downstream use, or shipments of 

whole grain, the required label may be 

transmitted to the customer at the 

time of the initial shipment, and need 

not be included with subsequent shipments to the same employer unless the 

information on the label changes; 

(ii) The label may be transmitted 

with the initial shipment itself, or with 

the safety data sheet that is to be provided prior to or at the time of the first 

shipment; and, 

(iii) This exception to requiring labels on every container of hazardous 

chemicals is only for the solid material 

itself, and does not apply to hazardous 

chemicals used in conjunction with, or 

known to be present with, the material 

and to which employees handling the 

items in transit may be exposed (for 

example, cutting fluids or pesticides in 

grains). 

(5) Chemical manufacturers, importers, or distributors shall ensure that 

each container of hazardous chemicals 

leaving the workplace is labeled, 

tagged, or marked in accordance with 

this section in a manner which does 

not conflict with the requirements of 

the Hazardous Materials Transportation Act (49 U.S.C. 1801 et seq.) and 

regulations issued under that Act by 

the Department of Transportation. 

(6) Workplace labeling. Except as 

provided in paragraphs (f)(7) and (f)(8) 

of this section, the employer shall ensure that each container of hazardous 

chemicals in the workplace is labeled, 

tagged or marked with either: 

(i) The information specified under 

paragraphs (f)(1)(i) through (v) of this 

section for labels on shipped containers; or, 

(ii) Product identifier and words, pictures, symbols, or combination thereof, 

which provide at least general information regarding the hazards of the 

chemicals, and which, in conjunction 

with the other information immediately available to employees under 

the hazard communication program, 

470 

§ 1910.1200 29 CFR Ch. XVII (7–1–13 Edition) 

will provide employees with the specific information regarding the physical and health hazards of the hazardous chemical. 

(7) The employer may use signs, placards, process sheets, batch tickets, operating procedures, or other such written materials in lieu of affixing labels 

to individual stationary process containers, as long as the alternative 

method identifies the containers to 

which it is applicable and conveys the 

information required by paragraph 

(f)(6) of this section to be on a label. 

The employer shall ensure the written 

materials are readily accessible to the 

employees in their work area throughout each work shift. 

(8) The employer is not required to 

label portable containers into which 

hazardous chemicals are transferred 

from labeled containers, and which are 

intended only for the immediate use of 

the employee who performs the transfer. For purposes of this section, drugs 

which are dispensed by a pharmacy to 

a health care provider for direct administration to a patient are exempted 

from labeling. 

(9) The employer shall not remove or 

deface existing labels on incoming containers of hazardous chemicals, unless 

the container is immediately marked 

with the required information. 

(10) The employer shall ensure that 

workplace labels or other forms of 

warning are legible, in English, and 

prominently displayed on the container, or readily available in the work 

area throughout each work shift. Employers having employees who speak 

other languages may add the information in their language to the material 

presented, as long as the information is 

presented in English as well. 

(11) Chemical manufacturers, importers, distributors, or employers who become newly aware of any significant 

information regarding the hazards of a 

chemical shall revise the labels for the 

chemical within six months of becoming aware of the new information, and 

shall ensure that labels on containers 

of hazardous chemicals shipped after 

that time contain the new information. 

If the chemical is not currently produced or imported, the chemical manufacturer, importer, distributor, or employer shall add the information to the 

label before the chemical is shipped or 

introduced into the workplace again. 

(g) Safety data sheets. (1) Chemical 

manufacturers and importers shall obtain or develop a safety data sheet for 

each hazardous chemical they produce 

or import. Employers shall have a safety data sheet in the workplace for each 

hazardous chemical which they use. 

(2) The chemical manufacturer or importer preparing the safety data sheet 

shall ensure that it is in English (although the employer may maintain 

copies in other languages as well), and 

includes at least the following section 

numbers and headings, and associated 

information under each heading, in the 

order listed (See Appendix D to 

§1910.1200—Safety Data Sheets, for the 

specific content of each section of the 

safety data sheet): 

(i) Section 1, Identification; 

(ii) Section 2, Hazard(s) identification; 

(iii) Section 3, Composition/information on ingredients; 

(iv) Section 4, First-aid measures; 

(v) Section 5, Fire-fighting measures; 

(vi) Section 6, Accidental release 

measures; 

(vii) Section 7, Handling and storage; 

(viii) Section 8, Exposure controls/ 

personal protection; 

(ix) Section 9, Physical and chemical 

properties; 

(x) Section 10, Stability and reactivity; 

(xi) Section 11, Toxicological information; 

(xii) Section 12, Ecological information; 

(xiii) Section 13, Disposal considerations; 

(xiv) Section 14, Transport information; 

(xv) Section 15, Regulatory information; and 

(xvi) Section 16, Other information, 

including date of preparation or last 

revision. 

NOTE 1 TO PARAGRAPH (g)(2): To be consistent with the GHS, an SDS must also include the headings in paragraphs (g)(2)(xii) 

through (g)(2)(xv) in order. 

NOTE 2 TO PARAGRAPH (g)(2): OSHA will not 

be enforcing information requirements in 

sections 12 through 15, as these areas are not 

under its jurisdiction. 

471 

Occupational Safety and Health Admin., Labor § 1910.1200 

(3) If no relevant information is 

found for any sub-heading within a section on the safety data sheet, the 

chemical manufacturer, importer or 

employer preparing the safety data 

sheet shall mark it to indicate that no 

applicable information was found. 

(4) Where complex mixtures have 

similar hazards and contents (i.e. the 

chemical ingredients are essentially 

the same, but the specific composition 

varies from mixture to mixture), the 

chemical manufacturer, importer or 

employer may prepare one safety data 

sheet to apply to all of these similar 

mixtures. 

(5) The chemical manufacturer, importer or employer preparing the safety data sheet shall ensure that the information provided accurately reflects 

the scientific evidence used in making 

the hazard classification. If the chemical manufacturer, importer or employer preparing the safety data sheet 

becomes newly aware of any significant 

information regarding the hazards of a 

chemical, or ways to protect against 

the hazards, this new information shall 

be added to the safety data sheet within three months. If the chemical is not 

currently being produced or imported, 

the chemical manufacturer or importer 

shall add the information to the safety 

data sheet before the chemical is introduced into the workplace again. 

(6)(i) Chemical manufacturers or importers shall ensure that distributors 

and employers are provided an appropriate safety data sheet with their initial shipment, and with the first shipment after a safety data sheet is updated; 

(ii) The chemical manufacturer or 

importer shall either provide safety 

data sheets with the shipped containers 

or send them to the distributor or employer prior to or at the time of the 

shipment; 

(iii) If the safety data sheet is not 

provided with a shipment that has been 

labeled as a hazardous chemical, the 

distributor or employer shall obtain 

one from the chemical manufacturer or 

importer as soon as possible; and, 

(iv) The chemical manufacturer or 

importer shall also provide distributors 

or employers with a safety data sheet 

upon request. 

(7)(i) Distributors shall ensure that 

material data sheets, and updated information, are provided to other distributors and employers with their initial shipment and with the first shipment after a safety data sheet is updated; 

(ii) The distributor shall either provide safety data sheets with the 

shipped containers, or send them to the 

other distributor or employer prior to 

or at the time of the shipment; 

(iii) Retail distributors selling hazardous chemicals to employers having 

a commercial account shall provide a 

safety data sheet to such employers 

upon request, and shall post a sign or 

otherwise inform them that a material 

safety data sheet is available; 

(iv) Wholesale distributors selling 

hazardous chemicals to employers 

over-the-counter may also provide 

safety data sheets upon the request of 

the employer at the time of the overthe-counter purchase, and shall post a 

sign or otherwise inform such employers that a material safety data sheet is 

available; 

(v) If an employer without a commercial account purchases a hazardous 

chemical from a retail distributor not 

required to have safety data sheets on 

file (i.e., the retail distributor does not 

have commercial accounts and does not 

use the materials), the retail distributor shall provide the employer, 

upon request, with the name, address, 

and telephone number of the chemical 

manufacturer, importer, or distributor 

from which a safety data sheet can be 

obtained; 

(vi) Wholesale distributors shall also 

provide safety data sheets to employers 

or other distributors upon request; and, 

(vii) Chemical manufacturers, importers, and distributors need not provide safety data sheets to retail distributors that have informed them that 

the retail distributor does not sell the 

product to commercial accounts or 

open the sealed container to use it in 

their own workplaces. 

(8) The employer shall maintain in 

the workplace copies of the required 

safety data sheets for each hazardous 

chemical, and shall ensure that they 

are readily accessible during each work 

shift to employees when they are in 

their work area(s). (Electronic access 

472 

§ 1910.1200 29 CFR Ch. XVII (7–1–13 Edition) 

and other alternatives to maintaining 

paper copies of the safety data sheets 

are permitted as long as no barriers to 

immediate employee access in each 

workplace are created by such options.) 

(9) Where employees must travel between workplaces during a workshift, 

i.e., their work is carried out at more 

than one geographical location, the 

safety data sheets may be kept at the 

primary workplace facility. In this situation, the employer shall ensure that 

employees can immediately obtain the 

required information in an emergency. 

(10) Safety data sheets may be kept 

in any form, including operating procedures, and may be designed to cover 

groups of hazardous chemicals in a 

work area where it may be more appropriate to address the hazards of a process rather than individual hazardous 

chemicals. However, the employer 

shall ensure that in all cases the required information is provided for each 

hazardous chemical, and is readily accessible during each work shift to employees when they are in their work 

area(s). 

(11) Safety data sheets shall also be 

made readily available, upon request, 

to designated representatives, the Assistant Secretary, and the Director, in 

accordance with the requirements of 

§1910.1020(e). 

(h) Employee information and training. 

(1) Employers shall provide employees 

with effective information and training 

on hazardous chemicals in their work 

area at the time of their initial assignment, and whenever a new chemical 

hazard the employees have not previously been trained about is introduced into their work area. Information and training may be designed to 

cover categories of hazards (e.g., flammability, carcinogenicity) or specific 

chemicals. Chemical-specific information must always be available through 

labels and safety data sheets. 

(2) Information. Employees shall be 

informed of: 

(i) The requirements of this section; 

(ii) Any operations in their work area 

where hazardous chemicals are present; 

and, 

(iii) The location and availability of 

the written hazard communication program, including the required list(s) of 

hazardous chemicals, and safety data 

sheets required by this section. 

(3) Training. Employee training shall 

include at least: 

(i) Methods and observations that 

may be used to detect the presence or 

release of a hazardous chemical in the 

work area (such as monitoring conducted by the employer, continuous 

monitoring devices, visual appearance 

or odor of hazardous chemicals when 

being released, etc.); 

(ii) The physical, health, simple asphyxiation, combustible dust, and 

pyrophoric gas hazards, as well as hazards not otherwise classified, of the 

chemicals in the work area; 

(iii) The measures employees can 

take to protect themselves from these 

hazards, including specific procedures 

the employer has implemented to protect employees from exposure to hazardous chemicals, such as appropriate 

work practices, emergency procedures, 

and personal protective equipment to 

be used; and, 

(iv) The details of the hazard communication program developed by the employer, including an explanation of the 

labels received on shipped containers 

and the workplace labeling system 

used by their employer; the safety data 

sheet, including the order of information and how employees can obtain and 

use the appropriate hazard information. 

(i) Trade secrets. (1) The chemical 

manufacturer, importer, or employer 

may withhold the specific chemical 

identity, including the chemical name, 

other specific identification of a hazardous chemical, or the exact percentage (concentration) of the substance in 

a mixture, from the safety data sheet, 

provided that: 

(i) The claim that the information 

withheld is a trade secret can be supported; 

(ii) Information contained in the 

safety data sheet concerning the properties and effects of the hazardous 

chemical is disclosed; 

(iii) The safety data sheet indicates 

that the specific chemical identity and/ 

or percentage of composition is being 

withheld as a trade secret; and, 

(iv) The specific chemical identity 

and percentage is made available to 

health professionals, employees, and 

473 

Occupational Safety and Health Admin., Labor § 1910.1200 

designated representatives in accordance with the applicable provisions of 

this paragraph (i). 

(2) Where a treating physician or 

nurse determines that a medical emergency exists and the specific chemical 

identity and/or specific percentage of 

composition of a hazardous chemical is 

necessary for emergency or first-aid 

treatment, the chemical manufacturer, 

importer, or employer shall immediately disclose the specific chemical 

identity or percentage composition of a 

trade secret chemical to that treating 

physician or nurse, regardless of the 

existence of a written statement of 

need or a confidentiality agreement. 

The chemical manufacturer, importer, 

or employer may require a written 

statement of need and confidentiality 

agreement, in accordance with the provisions of paragraphs (i)(3) and (4) of 

this section, as soon as circumstances 

permit. 

(3) In non-emergency situations, a 

chemical manufacturer, importer, or 

employer shall, upon request, disclose 

a specific chemical identity or percentage composition, otherwise permitted 

to be withheld under paragraph (i)(1) of 

this section, to a health professional 

(i.e. physician, industrial hygienist, 

toxicologist, epidemiologist, or occupational health nurse) providing medical 

or other occupational health services 

to exposed employee(s), and to employees or designated representatives, if: 

(i) The request is in writing; 

(ii) The request describes with reasonable detail one or more of the following occupational health needs for 

the information: 

(A) To assess the hazards of the 

chemicals to which employees will be 

exposed; 

(B) To conduct or assess sampling of 

the workplace atmosphere to determine employee exposure levels; 

(C) To conduct pre-assignment or 

periodic medical surveillance of exposed employees; 

(D) To provide medical treatment to 

exposed employees; 

(E) To select or assess appropriate 

personal protective equipment for exposed employees; 

(F) To design or assess engineering 

controls or other protective measures 

for exposed employees; and, 

(G) To conduct studies to determine 

the health effects of exposure. 

(iii) The request explains in detail 

why the disclosure of the specific 

chemical identity or percentage composition is essential and that, in lieu 

thereof, the disclosure of the following 

information to the health professional, 

employee, or designated representative, would not satisfy the purposes described in paragraph (i)(3)(ii) of this 

section: 

(A) The properties and effects of the 

chemical; 

(B) Measures for controlling workers’ 

exposure to the chemical; 

(C) Methods of monitoring and analyzing worker exposure to the chemical; and, 

(D) Methods of diagnosing and treating harmful exposures to the chemical; 

(iv) The request includes a description of the procedures to be used to 

maintain the confidentiality of the disclosed information; and, 

(v) The health professional, and the 

employer or contractor of the services 

of the health professional (i.e. downstream employer, labor organization, 

or individual employee), employee, or 

designated representative, agree in a 

written confidentiality agreement that 

the health professional, employee, or 

designated representative, will not use 

the trade secret information for any 

purpose other than the health need(s) 

asserted and agree not to release the 

information under any circumstances 

other than to OSHA, as provided in 

paragraph (i)(6) of this section, except 

as authorized by the terms of the 

agreement or by the chemical manufacturer, importer, or employer. 

(4) The confidentiality agreement authorized by paragraph (i)(3)(iv) of this 

section: 

(i) May restrict the use of the information to the health purposes indicated in the written statement of need; 

(ii) May provide for appropriate legal 

remedies in the event of a breach of the 

agreement, including stipulation of a 

reasonable pre-estimate of likely damages; and, 

(iii) May not include requirements 

for the posting of a penalty bond. 

(5) Nothing in this standard is meant 

to preclude the parties from pursuing 

474 

§ 1910.1200 29 CFR Ch. XVII (7–1–13 Edition) 

non-contractual remedies to the extent 

permitted by law. 

(6) If the health professional, employee, or designated representative receiving the trade secret information 

decides that there is a need to disclose 

it to OSHA, the chemical manufacturer, importer, or employer who provided the information shall be informed by the health professional, employee, or designated representative 

prior to, or at the same time as, such 

disclosure. 

(7) If the chemical manufacturer, importer, or employer denies a written request for disclosure of a specific chemical identity or percentage composition, the denial must: 

(i) Be provided to the health professional, employee, or designated representative, within thirty days of the 

request; 

(ii) Be in writing; 

(iii) Include evidence to support the 

claim that the specific chemical identity or percent of composition is a 

trade secret; 

(iv) State the specific reasons why 

the request is being denied; and, 

(v) Explain in detail how alternative 

information may satisfy the specific 

medical or occupational health need 

without revealing the trade secret. 

(8) The health professional, employee, or designated representative 

whose request for information is denied 

under paragraph (i)(3) of this section 

may refer the request and the written 

denial of the request to OSHA for consideration. 

(9) When a health professional, employee, or designated representative refers the denial to OSHA under paragraph (i)(8) of this section, OSHA shall 

consider the evidence to determine if: 

(i) The chemical manufacturer, importer, or employer has supported the 

claim that the specific chemical identity or percentage composition is a 

trade secret; 

(ii) The health professional, employee, or designated representative 

has supported the claim that there is a 

medical or occupational health need 

for the information; and, 

(iii) The health professional, employee or designated representative has 

demonstrated adequate means to protect the confidentiality. 

(10)(i) If OSHA determines that the 

specific chemical identity or percentage composition requested under paragraph (i)(3) of this section is not a 

‘‘bona fide’’ trade secret, or that it is a 

trade secret, but the requesting health 

professional, employee, or designated 

representative has a legitimate medical or occupational health need for the 

information, has executed a written 

confidentiality agreement, and has 

shown adequate means to protect the 

confidentiality of the information, the 

chemical manufacturer, importer, or 

employer will be subject to citation by 

OSHA. 

(ii) If a chemical manufacturer, importer, or employer demonstrates to 

OSHA that the execution of a confidentiality agreement would not provide 

sufficient protection against the potential harm from the unauthorized disclosure of a trade secret, the Assistant 

Secretary may issue such orders or impose such additional limitations or 

conditions upon the disclosure of the 

requested chemical information as may 

be appropriate to assure that the occupational health services are provided 

without an undue risk of harm to the 

chemical manufacturer, importer, or 

employer. 

(11) If a citation for a failure to release trade secret information is contested by the chemical manufacturer, 

importer, or employer, the matter will 

be adjudicated before the Occupational 

Safety and Health Review Commission 

in accordance with the Act’s enforcement scheme and the applicable Commission rules of procedure. In accordance with the Commission rules, when 

a chemical manufacturer, importer, or 

employer continues to withhold the information during the contest, the Administrative Law Judge may review 

the citation and supporting documentation ‘‘in camera’’ or issue appropriate orders to protect the confidentiality of such matters. 

(12) Notwithstanding the existence of 

a trade secret claim, a chemical manufacturer, importer, or employer shall, 

upon request, disclose to the Assistant 

Secretary any information which this 

section requires the chemical manufacturer, importer, or employer to make 

available. Where there is a trade secret 

claim, such claim shall be made no 

475 

Occupational Safety and Health Admin., Labor § 1910.1200 

later than at the time the information 

is provided to the Assistant Secretary 

so that suitable determinations of 

trade secret status can be made and 

the necessary protections can be implemented. 

(13) Nothing in this paragraph shall 

be construed as requiring the disclosure under any circumstances of process information which is a trade secret. 

(j) Effective dates. (1) Employers shall 

train employees regarding the new 

label elements and safety data sheets 

format by December 1, 2013. 

(2) Chemical manufacturers, importers, distributors, and employers shall 

be in compliance with all modified provisions of this section no later than 

June 1, 2015, except: 

(i) After December 1, 2015, the distributor shall not ship containers labeled by the chemical manufacturer or 

importer unless the label has been 

modified to comply with paragraph 

(f)(1) of this section. 

(ii) All employers shall, as necessary, 

update any alternative workplace labeling used under paragraph (f)(6) of 

this section, update the hazard communication program required by paragraph (h)(1), and provide any additional 

employee training in accordance with 

paragraph (h)(3) for newly identified 

physical or health hazards no later 

than June 1, 2016. 

(3) Chemical manufacturers, importers, distributors, and employers may 

comply with either §1910.1200 revised as 

of October 1, 2011, or the current 

version of this standard, or both during 

the transition period. 

APPENDIX A TO §1910.1200—HEALTH HAZARD

CRITERIA (MANDATORY) 

A.0 GENERAL CLASSIFICATION 

CONSIDERATIONS 

A.0.1 CLASSIFICATION

A.0.1.1 The term ‘‘hazard classification’’ 

is used to indicate that only the intrinsic 

hazardous properties of chemicals are considered. Hazard classification incorporates 

three steps: 

(a) Identification of relevant data regarding the hazards of a chemical; 

(b) Subsequent review of those data to ascertain the hazards associated with the 

chemical; 

(c) Determination of whether the chemical 

will be classified as hazardous and the degree 

of hazard. 

A.0.1.2 For many hazard classes, the criteria are semi-quantitative or qualitative 

and expert judgment is required to interpret 

the data for classification purposes. 

A.0.2 AVAILABLE DATA, TEST METHODS AND

TEST DATA QUALITY

A.0.2.1 There is no requirement for testing chemicals. 

A.0.2.2 The criteria for determining 

health hazards are test method neutral, i.e., 

they do not specify particular test methods, 

as long as the methods are scientifically 

validated. 

A.0.2.3 The term ‘‘scientifically validated’’ refers to the process by which the reliability and the relevance of a procedure are 

established for a particular purpose. Any 

test that determines hazardous properties, 

which is conducted according to recognized 

scientific principles, can be used for purposes 

of a hazard determination for health hazards. 

Test conditions need to be standardized so 

that the results are reproducible with a 

given substance, and the standardized test 

yields ‘‘valid’’ data for defining the hazard 

class of concern. 

A.0.2.4 Existing test data are acceptable 

for classifying chemicals, although expert 

judgment also may be needed for classification purposes. 

A.0.2.5 The effect of a chemical on biological systems is influenced, by the physicochemical properties of the substance and/or 

ingredients of the mixture and the way in 

which ingredient substances are biologically 

available. A chemical need not be classified 

when it can be shown by conclusive experimental data from scientifically validated 

test methods that the chemical is not biologically available. 

A.0.2.6 For classification purposes, epidemiological data and experience on the effects 

of chemicals on humans (e.g., occupational 

data, data from accident databases) shall be 

taken into account in the evaluation of 

human health hazards of a chemical. 

A.0.3 CLASSIFICATION BASED ON WEIGHT OF

EVIDENCE

A.0.3.1 For some hazard classes, classification results directly when the data satisfy the criteria. For others, classification of 

a chemical shall be determined on the basis 

of the total weight of evidence using expert 

judgment. This means that all available information bearing on the classification of 

hazard shall be considered together, including the results of valid in vitro tests, relevant 

animal data, and human experience such as 

epidemiological and clinical studies and 

well-documented case reports and observations. 

A.0.3.2 The quality and consistency of the 

data shall be considered. Information on 

476 

§ 1910.1200 29 CFR Ch. XVII (7–1–13 Edition) 

chemicals related to the material being classified shall be considered as appropriate, as 

well as site of action and mechanism or 

mode of action study results. Both positive 

and negative results shall be considered together in a single weight-of-evidence determination. 

A.0.3.3 Positive effects which are consistent with the criteria for classification, 

whether seen in humans or animals, shall 

normally justify classification. Where evidence is available from both humans and animals and there is a conflict between the findings, the quality and reliability of the evidence from both sources shall be evaluated 

in order to resolve the question of classification. Reliable, good quality human data 

shall generally have precedence over other 

data. However, even well-designed and conducted epidemiological studies may lack a 

sufficient number of subjects to detect relatively rare but still significant effects, or to 

assess potentially confounding factors. 

Therefore, positive results from well-conducted animal studies are not necessarily negated by the lack of positive human experience but require an assessment of the 

robustness, quality and statistical power of 

both the human and animal data. 

A.0.3.4 Route of exposure, mechanistic information, and metabolism studies are pertinent to determining the relevance of an effect in humans. When such information 

raises doubt about relevance in humans, a 

lower classification may be warranted. When 

there is scientific evidence demonstrating 

that the mechanism or mode of action is not 

relevant to humans, the chemical should not 

be classified. 

A.0.3.5 Both positive and negative results 

are considered together in the weight of evidence determination. However, a single positive study performed according to good scientific principles and with statistically and 

biologically significant positive results may 

justify classification. 

A.0.4 CONSIDERATIONS FOR THE

CLASSIFICATION OF MIXTURES

A.0.4.1 For most hazard classes, the recommended process of classification of mixtures is based on the following sequence: 

(a) Where test data are available for the 

complete mixture, the classification of the 

mixture will always be based on those data; 

(b) Where test data are not available for 

the mixture itself, the bridging principles 

designated in each health hazard chapter of 

this appendix shall be considered for classification of the mixture; 

(c) If test data are not available for the 

mixture itself, and the available information 

is not sufficient to allow application of the 

above-mentioned bridging principles, then 

the method(s) described in each chapter for 

estimating the hazards based on the information known will be applied to classify the 

mixture (e.g., application of cut-off values/ 

concentration limits). 

A.0.4.2 An exception to the above order or 

precedence is made for Carcinogenicity, 

Germ Cell Mutagenicity, and Reproductive 

Toxicity. For these three hazard classes, 

mixtures shall be classified based upon information on the ingredient substances, unless 

on a case-by-case basis, justification can be 

provided for classifying based upon the mixture as a whole. See chapters A.5, A.6, and 

A.7 for further information on case-by-case 

bases. 

A.0.4.3 Use of cut-off values/concentration 

limits. 

A.0.4.3.1 When classifying an untested 

mixture based on the hazards of its ingredients, cut-off values/concentration limits for 

the classified ingredients of the mixture are 

used for several hazard classes. While the 

adopted cut-off values/concentration limits 

adequately identify the hazard for most mixtures, there may be some that contain hazardous ingredients at lower concentrations 

than the specified cut-off values/concentration limits that still pose an identifiable 

hazard. There may also be cases where the 

cut-off value/concentration limit is considerably lower than the established non-hazardous level for an ingredient. 

A.0.4.3.2 If the classifier has information 

that the hazard of an ingredient will be evident (i.e., it presents a health risk) below the 

specified cut-off value/concentration limit, 

the mixture containing that ingredient shall 

be classified accordingly. 

A.0.4.3.3 In exceptional cases, conclusive 

data may demonstrate that the hazard of an 

ingredient will not be evident (i.e., it does 

not present a health risk) when present at a 

level above the specified cut-off value/concentration limit(s). In these cases the mixture may be classified according to those 

data. The data must exclude the possibility 

that the ingredient will behave in the mixture in a manner that would increase the 

hazard over that of the pure substance. Furthermore, the mixture must not contain ingredients that would affect that determination. 

A.0.4.4 Synergistic or antagonistic effects. 

When performing an assessment in accordance with these requirements, the evaluator 

must take into account all available information about the potential occurrence of 

synergistic effects among the ingredients of 

the mixture. Lowering classification of a 

mixture to a less hazardous category on the 

basis of antagonistic effects may be done 

only if the determination is supported by 

sufficient data. 

477 

Occupational Safety and Health Admin., Labor § 1910.1200 

A.0.5 BRIDGING PRINCIPLES FOR THE CLASSIFICATION OF MIXTURES WHERE TEST DATA

ARE NOT AVAILABLE FOR THE COMPLETE

MIXTURE

A.0.5.1 Where the mixture itself has not 

been tested to determine its toxicity, but 

there are sufficient data on both the individual ingredients and similar tested mixtures to adequately characterize the hazards 

of the mixture, these data shall be used in 

accordance with the following bridging principles, subject to any specific provisions for 

mixtures for each hazard class. These principles ensure that the classification process 

uses the available data to the greatest extent possible in characterizing the hazards of 

the mixture. 

A.0.5.1.1 Dilution. 

For mixtures classified in accordance with 

A.1 through A.10 of this Appendix, if a tested 

mixture is diluted with a diluent that has an 

equivalent or lower toxicity classification 

than the least toxic original ingredient, and 

which is not expected to affect the toxicity 

of other ingredients, then: 

(a) The new diluted mixture shall be classified as equivalent to the original tested mixture; or 

(b) For classification of acute toxicity in 

accordance with A.1 of this Appendix, paragraph A.1.3.6 (the additivity formula) shall 

be applied. 

A.0.5.1.2 Batching. 

For mixtures classified in accordance with 

A.1 through A.10 of this Appendix, the toxicity of a tested production batch of a mixture can be assumed to be substantially 

equivalent to that of another untested production batch of the same mixture, when 

produced by or under the control of the same 

chemical manufacturer, unless there is reason 

to believe there is significant variation such 

that the toxicity of the untested batch has 

changed. If the latter occurs, a new classification is necessary. 

A.0.5.1.3 Concentration of mixtures. 

For mixtures classified in accordance with 

A.1, A.2, A.3, A.8, A.9, or A.10 of this Appendix, if a tested mixture is classified in Category 1, and the concentration of the ingredients of the tested mixture that are in Category 1 is increased, the resulting untested 

mixture shall be classified in Category 1. 

A.0.5.1.4 Interpolation within one toxicity 

category. 

For mixtures classified in accordance with 

A.1, A.2, A.3, A.8, A.9, or A.10 of this Appendix, for three mixtures (A, B and C) with 

identical ingredients, where mixtures A and 

B have been tested and are in the same toxicity category, and where untested mixture 

C has the same toxicologically active ingredients as mixtures A and B but has concentrations of toxicologically active ingredients intermediate to the concentrations in 

mixtures A and B, then mixture C is assumed 

to be in the same toxicity category as A and 

B. 

A.0.5.1.5 Substantially similar mixtures. 

For mixtures classified in accordance with 

A.1 through A.10 of this Appendix, given the 

following set of conditions: 

(a) Where there are two mixtures: 

(i) A + B; 

(ii) C + B; 

(b) The concentration of ingredient B is essentially the same in both mixtures; 

(c) The concentration of ingredient A in 

mixture (i) equals that of ingredient C in 

mixture (ii); 

(d) And data on toxicity for A and C are 

available and substantially equivalent; i.e., 

they are in the same hazard category and are 

not expected to affect the toxicity of B; then 

If mixture (i) or (ii) is already classified 

based on test data, the other mixture can be 

assigned the same hazard category. 

A.0.5.1.6 Aerosols. 

For mixtures classified in accordance with 

A.1, A.2, A.3, A.4, A.8, or A.9 of this Appendix, an aerosol form of a mixture shall be 

classified in the same hazard category as the 

tested, non-aerosolized form of the mixture, 

provided the added propellant does not affect 

the toxicity of the mixture when spraying. 

A.1 ACUTE TOXICITY 

A.1.1 DEFINITION

Acute toxicity refers to those adverse effects 

occurring following oral or dermal administration of a single dose of a substance, or 

multiple doses given within 24 hours, or an 

inhalation exposure of 4 hours. 

A.1.2 CLASSIFICATION CRITERIA FOR

SUBSTANCES

A.1.2.1 Substances can be allocated to one 

of four toxicity categories based on acute 

toxicity by the oral, dermal or inhalation 

route according to the numeric cut-off criteria as shown in Table A.1.1. Acute toxicity 

values are expressed as (approximate) LD50 

(oral, dermal) or LC50 (inhalation) values or 

as acute toxicity estimates (ATE). See the 

footnotes following Table A.1.1 for further 

explanation on the application of these values. 

TABLE A.1.1—ACUTE TOXICITY HAZARD CATEGORIES AND ACUTE TOXICITY ESTIMATE (ATE) VALUES

DEFINING THE RESPECTIVE CATEGORIES

Exposure route Category 1 Category 2 Category 3 Category 4 

Oral (mg/kg bodyweight) 

478 

§ 1910.1200 29 CFR Ch. XVII (7–1–13 Edition) 

TABLE A.1.1—ACUTE TOXICITY HAZARD CATEGORIES AND ACUTE TOXICITY ESTIMATE (ATE) VALUES

DEFINING THE RESPECTIVE CATEGORIES—Continued 

Exposure route Category 1 Category 2 Category 3 Category 4 

see: Note (a) ................... ≤ 5 >5 and ≤ 50 ................ >50 and ≤ 300 ............ >300 and ≤ 2000. 

Note (b) 

Dermal (mg/kg bodyweight) 

see: Note (a) ................... ≤ 50 >50 and ≤ 200 ............ >200 and ≤ 1000 ........ >1000 and ≤ 2000. 

Note (b) 

Inhalation—Gases (ppmV) 

see: Note (a) ................... ≤ 100 >100 and ≤ 500 .......... >500 and ≤ 2500 ........ >2500 and ≤ 20000. 

Note (b) 

Note (c) 

Inhalation—Vapors (mg/l) 

see: Note (a) ................... ≤ 0.5 >0.5 and ≤ 2.0 ............ >2.0 and ≤ 10.0 .......... >10.0 and ≤ 20.0. 

Note (b) 

Note (c) 

Note (d) 

Inhalation—Dusts and Mists (mg/l) 

see: Note (a) ................... ≤ 0.05 >0.05 and ≤ 0.5 .......... >0.5 and ≤ 1.0 ............ >1.0 and ≤ 5.0. 

Note (b) 

Note (c) 

Note: Gas concentrations are expressed in parts per million per volume (ppmV). 

Notes to Table A.1.1: 

(a) The acute toxicity estimate (ATE) for the classification of a substance is derived using the LD50/LC50 where available; 

(b) The acute toxicity estimate (ATE) for the classification of a substance or ingredient in a mixture is derived using: 

(i) the LD50/LC50 where available. Otherwise, 

(ii) the appropriate conversion value from Table 1.2 that relates to the results of a range test, or 

(iii) the appropriate conversion value from Table 1.2 that relates to a classification category; 

(c) Inhalation cut-off values in the table are based on 4 hour testing exposures. Conversion of existing inhalation toxicity data 

which has been generated according to 1 hour exposure is achieved by dividing by a factor of 2 for gases and vapors and 4 for 

dusts and mists; 

(d) For some substances the test atmosphere will be a vapor which consists of a combination of liquid and gaseous phases. 

For other substances the test atmosphere may consist of a vapor which is nearly all the gaseous phase. In these latter cases, 

classification is based on ppmV as follows: Category 1 (100 ppmV), Category 2 (500 ppmV), Category 3 (2500 ppmV), Category 

4 (20000 ppmV). 

The terms ‘‘dust’’, ‘‘mist’’ and ‘‘vapor’’ are defined as follows: 

(i) Dust: solid particles of a substance or mixture suspended in a gas (usually air); 

(ii) Mist: liquid droplets of a substance or mixture suspended in a gas (usually air); 

(iii) Vapor: the gaseous form of a substance or mixture released from its liquid or solid state. 

A.1.2.3 The preferred test species for evaluation of acute toxicity by the oral and inhalation routes is the rat, while the rat or 

rabbit are preferred for evaluation of acute 

dermal toxicity. Test data already generated 

for the classification of chemicals under existing systems should be accepted when reclassifying these chemicals under the harmonized system. When experimental data for 

acute toxicity are available in several animal species, scientific judgment should be 

used in selecting the most appropriate LD50

value from among scientifically validated 

tests. 

A.1.3 CLASSIFICATION CRITERIA FOR

MIXTURES

A.1.3.1 The approach to classification of 

mixtures for acute toxicity is tiered, and is 

dependent upon the amount of information 

available for the mixture itself and for its ingredients. The flow chart of Figure A.1.1 indicates the process that must be followed: 

479 

Occupational Safety and Health Admin., Labor § 1910.1200 

A.1.3.2 Classification of mixtures for 

acute toxicity may be carried out for each 

route of exposure, but is only required for 

one route of exposure as long as this route is 

followed (estimated or tested) for all ingredients and there is no relevant evidence to suggest acute toxicity by multiple routes. When 

there is relevant evidence of acute toxicity 

by multiple routes of exposure, classification 

is to be conducted for all appropriate routes 

of exposure. All available information shall 

be considered. The pictogram and signal 

word used shall reflect the most severe hazard category; and all relevant hazard statements shall be used. 

A.1.3.3 For purposes of classifying the 

hazards of mixtures in the tiered approach: 

(a) The ‘‘relevant ingredients’’ of a mixture 

are those which are present in concentrations ≥1% (weight/weight for solids, liquids, 

dusts, mists and vapors and volume/volume 

for gases). If there is reason to suspect that 

an ingredient present at a concentration <1% 

will affect classification of the mixture for 

acute toxicity, that ingredient shall also be 

considered relevant. Consideration of ingredients present at a concentration <1% is particularly important when classifying untested mixtures which contain ingredients that 

are classified in Category 1 and Category 2; 

(b) Where a classified mixture is used as an 

ingredient of another mixture, the actual or 

derived acute toxicity estimate (ATE) for 

that mixture is used when calculating the 

classification of the new mixture using the 

formulas in A.1.3.6.1 and A.1.3.6.2.4. 

(c) If the converted acute toxicity point estimates for all ingredients of a mixture are 

within the same category, then the mixture 

should be classified in that category. 

(d) When only range data (or acute toxicity 

hazard category information) are available 

for ingredients in a mixture, they may be 

converted to point estimates in accordance 

with Table A.1.2 when calculating the classification of the new mixture using the formulas in A.1.3.6.1 and A.1.3.6.2.4. 

A.1.3.4 CLASSIFICATION OF MIXTURES WHERE

ACUTE TOXICITY TEST DATA ARE AVAILABLE

FOR THE COMPLETE MIXTURE

Where the mixture itself has been tested to 

determine its acute toxicity, it is classified 

according to the same criteria as those used 

for substances, presented in Table A.1.1. If 

test data for the mixture are not available, 

the procedures presented below must be followed. 

A.1.3.5 CLASSIFICATION OF MIXTURES WHERE

ACUTE TOXICITY TEST DATA ARE NOT

AVAILABLE FOR THE COMPLETE MIXTURE: 

BRIDGING PRINCIPLES

A.1.3.5.1 Where the mixture itself has not 

been tested to determine its acute toxicity, 

but there are sufficient data on both the individual ingredients and similar tested mixtures to adequately characterize the hazards 

of the mixture, these data will be used in accordance with the following bridging principles as found in paragraph A.0.5 of this Appendix: Dilution, Batching, Concentration of 

mixtures, Interpolation within one toxicity 

category, Substantially similar mixtures, 

and Aerosols. 


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A.1.3.6 CLASSIFICATION OF MIXTURES BASED

ON INGREDIENTS OF THE MIXTURE

(ADDITIVITY FORMULA) 

A.1.3.6.1 Data available for all ingredients. 

The acute toxicity estimate (ATE) of ingredients is considered as follows: 

(a) Include ingredients with a known acute 

toxicity, which fall into any of the acute 

toxicity categories, or have an oral or dermal LD50 greater than 2000 but less than or 

equal to 5000 mg/kg body weight (or the 

equivalent dose for inhalation); 

(b) Ignore ingredients that are presumed 

not acutely toxic (e.g., water, sugar); 

(c) Ignore ingredients if the data available 

are from a limit dose test (at the upper 

threshold for Category 4 for the appropriate 

route of exposure as provided in Table A.1.1) 

and do not show acute toxicity. 

Ingredients that fall within the scope of 

this paragraph are considered to be ingredients with a known acute toxicity estimate 

(ATE). See note (b) to Table A.1.1 and paragraph A.1.3.3 for appropriate application of 

available data to the equation below, and 

paragraph A.1.3.6.2.4. 

The ATE of the mixture is determined by 

calculation from the ATE values for all relevant ingredients according to the following 

formula below for oral, dermal or inhalation 

toxicity: 

Where: 

Ci = concentration of ingredient i 

n ingredients and i is running from 1 to n 

ATEi = acute toxicity estimate of ingredient 

i. 

A.1.3.6.2 Data are not available for one or 

more ingredients of the mixture. 

A.1.3.6.2.1 Where an ATE is not available 

for an individual ingredient of the mixture, 

but available information provides a derived 

conversion value, the formula in A.1.3.6.1 

may be applied. This information may include evaluation of: 

(a) Extrapolation between oral, dermal and 

inhalation acute toxicity estimates. Such an 

evaluation requires appropriate 

pharmacodynamic and pharmacokinetic 

data; 

(b) Evidence from human exposure that indicates toxic effects but does not provide lethal dose data; 

(c) Evidence from any other toxicity tests/ 

assays available on the substance that indicates toxic acute effects but does not necessarily provide lethal dose data; or 

(d) Data from closely analogous substances 

using structure/activity relationships. 

A.1.3.6.2.2 This approach requires substantial supplemental technical information, and 

a highly trained and experienced expert, to 

reliably estimate acute toxicity. If sufficient 

information is not available to reliably estimate acute toxicity, proceed to the provisions of A.1.3.6.2.3. 

A.1.3.6.2.3 In the event that an ingredient 

with unknown acute toxicity is used in a 

mixture at a concentration ≥1%, and the 

mixture has not been classified based on 

testing of the mixture as a whole, the mixture cannot be attributed a definitive acute 

toxicity estimate. In this situation the mixture is classified based on the known ingredients only. (Note: A statement that × percent 

of the mixture consists of ingredient(s) of 

unknown toxicity is required on the label 

and safety data sheet in such cases; see Appendix C to this section, Allocation of Label 

Elements and Appendix D to this section, 

Safety Data Sheets.) 

Where an ingredient with unknown acute 

toxicity is used in a mixture at a concentration ≥1%, and the mixture is not classified 

based on testing of the mixture as a whole, 

a statement that X% of the mixture consists 

of ingredient(s) of unknown acute toxicity is 

required on the label and safety data sheet in 

such cases; see Appendix C to this section, 

Allocation of Label Elements and Appendix 

D to this section, Safety Data Sheets.) 

A.1.3.6.2.4 If the total concentration of the 

relevant ingredient(s) with unknown acute 

toxicity is ≤10% then the formula presented 

in A.1.3.6.1 must be used. If the total concentration of the relevant ingredient(s) with 

unknown acute toxicity is >10%, the formula 

presented in A.1.3.6.1 is corrected to adjust 

for the percentage of the unknown ingredient(s) as follows: 


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TABLE A.1.2—CONVERSION FROM EXPERIMENTALLY OBTAINED ACUTE TOXICITY RANGE VALUES (OR

ACUTE TOXICITY HAZARD CATEGORIES) TO ACUTE TOXICITY POINT ESTIMATES FOR USE IN THE

FORMULAS FOR THE CLASSIFICATION OF MIXTURES

Exposure routes 

Classification category or experimentally obtained acute toxicity range estimate Converted 

acute toxicity 

point estimate 

Oral (mg/kg bodyweight ) ............................................. 0 <Category 1 ≤5 ......................................................... 0 .5 

5 <Category 2 ≤50 ....................................................... 5 

50 <Category 3 ≤300 ................................................... 100 

300 <Category 4 ≤2000 ............................................... 500 

Dermal (mg/kg bodyweight) .......................................... 0 <Category 1 ≤50 ....................................................... 5 

50 <Category 2 ≤200 ................................................... 50 

200 <Category 3 ≤1000 ............................................... 300 

1000 <Category 4 ≤2000 ............................................. 1100 

Gases (ppmV) ............................................................... 0 <Category 1 ≤100 ..................................................... 10 

100 <Category 2 ≤500 ................................................. 100 

500 <Category 3 ≤2500 ............................................... 700 

2500 <Category 4 ≤20000 ........................................... 4500 

Vapors (mg/l) ................................................................ 0 <Category 1 ≤0.5 ...................................................... 0 .05 

0.5 <Category 2 ≤2.0 ................................................... 0 .5 

2.0 <Category 3 ≤10.0 ................................................. 3 

10.0 <Category 4 ≤20.0 ............................................... 11 

Dust/mist (mg/l) ............................................................. 0 <Category 1 ≤0.05 .................................................... 0 .005 

0.05 <Category 2 ≤0.5 ................................................. 0 .05 

0.5 <Category 3 ≤1.0 ................................................... 0 .5 

1.0 <Category 4 ≤5.0 ................................................... 1 .5 

Note: Gas concentrations are expressed in parts per million per volume (ppmV). 

A.2 SKIN CORROSION/IRRITATION 

A.2.1 DEFINITIONS AND GENERAL

CONSIDERATIONS

A.2.1.1 Skin corrosion is the production of 

irreversible damage to the skin; namely, 

visible necrosis through the epidermis and 

into the dermis, following the application of 

a test substance for up to 4 hours. Corrosive 

reactions are typified by ulcers, bleeding, 

bloody scabs, and, by the end of observation 

at 14 days, by discoloration due to blanching 

of the skin, complete areas of alopecia, and 

scars. Histopathology should be considered 

to evaluate questionable lesions. 

Skin irritation is the production of reversible damage to the skin following the application of a test substance for up to 4 hours. 

A.2.1.2 Skin corrosion/irritation shall be 

classified using a tiered approach as detailed 

in figure A.2.1. Emphasis shall be placed 

upon existing human data (See A.0.2.6), followed by other sources of information. Classification results directly when the data satisfy the criteria in this section. In case the 

criteria cannot be directly applied, classification of a substance or a mixture is made 

on the basis of the total weight of evidence 

(See A.0.3.1). This means that all available 

information bearing on the determination of 

skin corrosion/irritation is considered together, including the results of appropriate 

scientifically validated in-vitro tests, relevant animal data, and human data such as 

epidemiological and clinical studies and 

well-documented case reports and observations. 

A.2.2 CLASSIFICATION CRITERIA FOR

SUBSTANCES USING ANIMAL TEST DATA

A.2.2.1 CORROSION

A.2.2.1.1 A corrosive substance is a chemical that produces destruction of skin tissue, 

namely, visible necrosis through the epidermis and into the dermis, in at least 1 of 3 

tested animals after exposure up to a 4-hour 

duration. Corrosive reactions are typified by 

ulcers, bleeding, bloody scabs and, by the end 

of observation at 14 days, by discoloration 

due to blanching of the skin, complete areas 

of alopecia and scars. Histopathology should 

be considered to discern questionable lesions. 

A.2.2.1.2 Three sub-categories of Category 

1 are provided in Table A.2.1, all of which 

shall be regulated as Category 1. 


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TABLE A.2.1—SKIN CORROSION CATEGORY AND SUB-CATEGORIES

Category 1: corrosive Corrosive sub-categories 

Corrosive in ≥1 of 3 animals 

Exposure Observation 

1A ........................................... ≤3 min .................................... ≤1 h. 

1B ........................................... >3 min ≤1 h ............................ ≤14 days. 

1C ........................................... >1 h ≤4 h ............................... ≤14 days. 

A.2.2.2 IRRITATION

A.2.2.2.1 A single irritant category (Category 2) is presented in the Table A.2.2. The 

major criterion for the irritant category is 

that at least 2 tested animals have a mean 

score of ≥2.3 ≤4.0. 

TABLE A.2.2—SKIN IRRITATION CATEGORY

Criteria 

Irritant (Category 2) ........ (1) Mean value of ≥2.3 ≤4.0 for erythema/eschar or for edema in at least 2 of 3 tested animals from 

gradings at 24, 48 and 72 hours after patch removal or, if reactions are delayed, from grades on 3 

consecutive days after the onset of skin reactions; or 

(2) Inflammation that persists to the end of the observation period normally 14 days in at least 2 animals, particularly taking into account alopecia (limited area), hyperkeratosis, hyperplasia, and scaling; or 

(3) In some cases where there is pronounced variability of response among animals, with very definite positive effects related to chemical exposure in a single animal but less than the criteria 

above. 

A.2.2.2.2 Animal irritant responses within 

a test can be quite variable, as they are with 

corrosion. A separate irritant criterion accommodates cases when there is a significant irritant response but less than the 

mean score criterion for a positive test. For 

example, a substance might be designated as 

an irritant if at least 1 of 3 tested animals 

shows a very elevated mean score throughout the study, including lesions persisting at 

the end of an observation period of normally 

14 days. Other responses could also fulfil this 

criterion. However, it should be ascertained 

that the responses are the result of chemical 

exposure. Addition of this criterion increases 

the sensitivity of the classification system. 

A.2.2.2.3 Reversibility of skin lesions is 

another consideration in evaluating irritant 

responses. When inflammation persists to 

the end of the observation period in 2 or 

more test animals, taking into consideration 

alopecia (limited area), hyperkeratosis, 

hyperplasia and scaling, then a chemical 

should be considered to be an irritant. 

A.2.3 CLASSIFICATION CRITERIA FOR

SUBSTANCES USING OTHER DATA ELEMENTS

A.2.3.1 Existing human and animal data 

including information from single or repeated exposure should be the first line of 

analysis, as they give information directly 

relevant to effects on the skin. If a substance 

is highly toxic by the dermal route, a skin 

corrosion/irritation study may not be practicable since the amount of test substance to 

be applied would considerably exceed the 

toxic dose and, consequently, would result in 

the death of the animals. When observations 

are made of skin corrosion/irritation in 

acute toxicity studies and are observed up 

through the limit dose, these data may be 

used for classification provided that the dilutions used and species tested are equivalent. 

In vitro alternatives that have been scientifically validated shall be used to make classification decisions. Solid substances (powders) may become corrosive or irritant when 

moistened or in contact with moist skin or 

mucous membranes. Likewise, pH extremes 

like ≤2 and ≥11.5 may indicate skin effects, 

especially when associated with significant 

buffering capacity. Generally, such substances are expected to produce significant 

effects on the skin. In the absence of any 

other information, a substance is considered 

corrosive (Skin Category 1) if it has a pH ≤2 

or a pH ≥11.5. However, if consideration of alkali/acid reserve suggests the substance or 

mixture may not be corrosive despite the low 

or high pH value, then further evaluation 

may be necessary. In some cases enough information may be available from structurally related compounds to make classification decisions. 

A.2.3.2 A tiered approach to the evaluation 

of initial information shall be used (Figure 

A.2.1) recognizing that all elements may not 

be relevant in certain cases. 

A.2.3.3 The tiered approach explains how 

to organize information on a substance and 

to make a weight-of-evidence decision about 

hazard assessment and hazard classification. 

A.2.3.4 All the above information that is 

available on a substance shall be evaluated. 

Although information might be gained from 

483 

Occupational Safety and Health Admin., Labor § 1910.1200 

the evaluation of single parameters within a 

tier, there is merit in considering the totality of existing information and making an 

overall weight of evidence determination. 

This is especially true when there is information available on some but not all parameters. Emphasis shall be placed upon existing 

human experience and data, followed by animal experience and testing data, followed by 

other sources of information, but case-bycase determinations are necessary. 


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§ 1910.1200 29 CFR Ch. XVII (7–1–13 Edition) 

A.2.4 CLASSIFICATION CRITERIA FOR

MIXTURES

A.2.4.1 CLASSIFICATION OF MIXTURES WHEN

DATA ARE AVAILABLE FOR THE COMPLETE

MIXTURE

A.2.4.1.1 The mixture shall be classified 

using the criteria for substances (See A.2.3). 

A.2.4.2 CLASSIFICATION OF MIXTURES WHEN

DATA ARE NOT AVAILABLE FOR THE COMPLETE MIXTURE: BRIDGING PRINCIPLES

A.2.4.2.1 Where the mixture itself has not 

been tested to determine its skin corrosion/ 

irritation, but there are sufficient data on 

both the individual ingredients and similar 

tested mixtures to adequately characterize 

the hazards of the mixture, these data will 

be used in accordance with the following 

bridging principles, as found in paragraph 

A.0.5 of this Appendix: Dilution, Batching, 

Concentration of mixtures, Interpolation 

within one toxicity category, Substantially 

similar mixtures, and Aerosols. 

A.2.4.3 CLASSIFICATION OF MIXTURES WHEN

DATA ARE AVAILABLE FOR ALL INGREDIENTS

OR ONLY FOR SOME INGREDIENTS OF THE

MIXTURE

A.2.4.3.1 For purposes of classifying the 

skin corrosion/irritation hazards of mixtures 

in the tiered approach: 

The ‘‘relevant ingredients’’ of a mixture 

are those which are present in concentrations ≥1% (weight/weight for solids, liquids, 

dusts, mists and vapors and volume/volume 

for gases.) If the classifier has reason to suspect that an ingredient present at a concentration <1% will affect classification of 

the mixture for skin corrosion/irritation, 

that ingredient shall also be considered relevant. 

A.2.4.3.2 In general, the approach to classification of mixtures as irritant or corrosive 

to skin when data are available on the ingredients, but not on the mixture as a whole, is 

based on the theory of additivity, such that 

each corrosive or irritant ingredient contributes to the overall irritant or corrosive properties of the mixture in proportion to its potency and concentration. A weighting factor 

of 10 is used for corrosive ingredients when 

they are present at a concentration below 

the concentration limit for classification 

with Category 1, but are at a concentration 

that will contribute to the classification of 

the mixture as an irritant. The mixture is 

classified as corrosive or irritant when the 

sum of the concentrations of such ingredients exceeds a cut-off value/concentration 

limit. 

A.2.4.3.3 Table A.2.3 below provides the 

cut-off value/concentration limits to be used 

to determine if the mixture is considered to 

be an irritant or a corrosive to the skin. 

A.2.4.3.4 Particular care shall be taken 

when classifying certain types of chemicals 

such as acids and bases, inorganic salts, 

aldehydes, phenols, and surfactants. The approach explained in A.2.4.3.1 and A.2.4.3.2 

might not work given that many of such substances are corrosive or irritant at concentrations <1%. For mixtures containing 

strong acids or bases the pH should be used 

as classification criteria since pH will be a 

better indicator of corrosion than the concentration limits of Table A.2.3. A mixture 


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Occupational Safety and Health Admin., Labor § 1910.1200 

containing corrosive or irritant ingredients 

that cannot be classified based on the 

additivity approach shown in Table A.2.3, 

due to chemical characteristics that make 

this approach unworkable, should be classified as Skin Category 1 if it contains ≥1% of 

a corrosive ingredient and as Skin Category 

2 when it contains ≥3% of an irritant ingredient. Classification of mixtures with ingredients for which the approach in Table A.2.3 

does not apply is summarized in Table A.2.4 

below. 

A.2.4.3.5 On occasion, reliable data may 

show that the skin corrosion/irritation of an 

ingredient will not be evident when present 

at a level above the generic concentration 

cut-off values mentioned in Tables A.2.3 and 

A.2.4. In these cases the mixture could be 

classified according to those data (See Use of 

cut-off values/concentration limits, paragraph 

A.0.4.3 of this Appendix). 

A.2.4.3.6 If there are data showing that 

(an) ingredient(s) may be corrosive or irritant at a concentration of <1% (corrosive) or 

<3% (irritant), the mixture shall be classified 

accordingly (See Use of cut-off values/concentration limits, paragraph A.0.4.3 of this Appendix). 

TABLE A.2.3—CONCENTRATION OF INGREDIENTS OF A MIXTURE CLASSIFIED AS SKIN CATEGORY 1 OR

2 THAT WOULD TRIGGER CLASSIFICATION OF THE MIXTURE AS HAZARDOUS TO SKIN

[Category 1 or 2] 

Sum of ingredients classified as: 

Concentration triggering classification of a mixture as: 

Skin corrosive Skin irritant 

Category 1 Category 2 

Skin Category 1 ......................................................................................................... ≥5% ≥1% but <5%. 

Skin Category 2 ......................................................................................................... ................................ ≥10%. 

(10 × Skin Category 1) + Skin Category 2 ............................................................... ................................ ≥10%. 

TABLE A.2.4—CONCENTRATION OF INGREDIENTS OF A MIXTURE FOR WHICH THE ADDITIVITY APPROACH DOES NOT APPLY, THAT WOULD TRIGGER CLASSIFICATION OF THE MIXTURE AS HAZARDOUS TO SKIN

Ingredient: Concentration: 

Mixture 

classified as: 

Skin 

Acid with pH ≤2 ......................................................................................................... ≥1% Category 1. 

Base with pH ≥11.5 ................................................................................................... ≥1% Category 1. 

Other corrosive (Category 1) ingredients for which additivity does not apply .......... ≥1% Category 1. 

Other irritant (Category 2) ingredients for which additivity does not apply, including acids and bases.≥3% Category 2. 

A.3 SERIOUS EYE DAMAGE/EYE 

IRRITATION 

A.3.1 DEFINITIONS AND GENERAL

CONSIDERATIONS

A.3.1.1 Serious eye damage is the production of tissue damage in the eye, or serious 

physical decay of vision, following application of a test substance to the anterior surface of the eye, which is not fully reversible 

within 21 days of application. 

Eye irritation is the production of changes 

in the eye following the application of test 

substance to the anterior surface of the eye, 

which are fully reversible within 21 days of 

application. 

A.3.1.2 Serious eye damage/eye irritation 

shall be classified using a tiered approach as 

detailed in Figure A.3.1. Emphasis shall be 

placed upon existing human data (See 

A.0.2.6), followed by animal data, followed by 

other sources of information. Classification 

results directly when the data satisfy the 

criteria in this section. In case the criteria 

cannot be directly applied, classification of a 

substance or a mixture is made on the basis 

of the total weight of evidence (See A.0.3.1). 

This means that all available information 

bearing on the determination of serious eye 

damage/eye irritation is considered together, 

including the results of appropriate scientifically validated in vitro tests, relevant animal data, and human data such as epidemiological and clinical studies and well-documented case reports and observations. 

A.3.2 CLASSIFICATION CRITERIA FOR

SUBSTANCES USING ANIMAL TEST DATA

A.3.2.1 Irreversible effects on the eye/serious damage to eyes (Category 1). 

A single hazard category is provided in 

Table A.3.1, for substances that have the potential to seriously damage the eyes. Category 1, irreversible effects on the eye, includes the criteria listed below. These observations include animals with grade 4 cornea 

486 

§ 1910.1200 29 CFR Ch. XVII (7–1–13 Edition) 

lesions and other severe reactions (e.g. destruction of cornea) observed at any time 

during the test, as well as persistent corneal 

opacity, discoloration of the cornea by a dye 

substance, adhesion, pannus, and interference with the function of the iris or other 

effects that impair sight. In this context, 

persistent lesions are considered those which 

are not fully reversible within an observation period of normally 21 days. Category 1 

also contains substances fulfilling the criteria of corneal opacity ≥3 and/or iritis >1.5 

detected in a Draize eye test with rabbits, 

because severe lesions like these usually do 

not reverse within a 21-day observation period. 

TABLE A.3.1—IRREVERSIBLE EYE EFFECTS

A substance is classified as Serious Eye Damage Category 1 (irreversible effects on the eye) 

when it produces: 

(a) at least in one tested animal, effects on the cornea, iris or conjunctiva that are not 

expected to reverse or have not fully reversed within an observation period of normally 21 days; and/or 

(b) at least in 2 of 3 tested animals, a positive response of: 

(i) corneal opacity ≥3; and/or 

(ii) iritis >1.5; 

calculated as the mean scores following grading at 24, 48 and 72 hours 

after instillation of the substance. 

A.3.2.2 Reversible effects on the eye (Category 2). A single category is provided in Table A.3.2 

for substances that have the potential to induce reversible eye irritation. 

TABLE A.3.2—REVERSIBLE EYE EFFECTS

A substance is classified as Eye irritant Category 2A (irritating to eyes) when it produces in at 

least in 2 of 3 tested animals a positive response of: 

(i) corneal opacity ≥1; and/or 

(ii) iritis ≥1; and/or 

(iii) conjunctival redness ≥2; and/or 

(iv) conjunctival edema (chemosis) ≥2 

calculated as the mean scores following grading at 24, 48 and 72 hours after instillation of the substance, and which fully reverses within an observation period of normally 21 days. 

An eye irritant is considered mildly irritating to eyes (Category 2B) when the effects listed 

above are fully reversible within 7 days of observation. 

A.3.2.3 For those chemicals where there is 

pronounced variability among animal responses, this information may be taken into 

account in determining the classification. 

A.3.3 CLASSIFICATION CRITERIA FOR

SUBSTANCES USING OTHER DATA ELEMENTS

A.3.3.1 Existing human and animal data 

should be the first line of analysis, as they 

give information directly relevant to effects 

on the eye. Possible skin corrosion shall be 

evaluated prior to consideration of serious 

eye damage/eye irritation in order to avoid 

testing for local effects on eyes with skin 

corrosive substances. In vitro alternatives 

that have been scientifically validated and 

accepted shall be used to make classification 

decisions. Likewise, pH extremes like ≤2 and 

≥11.5, may indicate serious eye damage, especially when associated with significant 

buffering capacity. Generally, such substances are expected to produce significant 

effects on the eyes. In the absence of any 

other information, a mixture/substance is 

considered to cause serious eye damage (Eye 

Category 1) if it has a pH ≤2 or ≥11.5. However, if consideration of acid/alkaline reserve 

suggests the substance may not have the potential to cause serious eye damage despite 

the low or high pH value, then further evaluation may be necessary. In some cases 

enough information may be available from 

structurally related compounds to make 

classification decisions. 

A.3.3.2 A tiered approach to the evaluation of initial information shall be used 

487 

Occupational Safety and Health Admin., Labor § 1910.1200 

where applicable, recognizing that all elements may not be relevant in certain cases 

(Figure A.3.1). 

A.3.3.3 The tiered approach explains how 

to organize existing information on a substance and to make a weight-of-evidence decision, where appropriate, about hazard assessment and hazard classification. 

A.3.3.4 All the above information that is 

available on a substance shall be evaluated. 

Although information might be gained from 

the evaluation of single parameters within a 

tier, consideration should be given to the totality of existing information and making an 

overall weight-of-evidence determination. 

This is especially true when there is conflict 

in information available on some parameters. 


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§ 1910.1200 29 CFR Ch. XVII (7–1–13 Edition) 

A.3.4 CLASSIFICATION CRITERIA FOR

MIXTURES

A.3.4.1 CLASSIFICATION OF MIXTURES WHEN

DATA ARE AVAILABLE FOR THE COMPLETE

MIXTURE

A.3.4.1.1 The mixture will be classified 

using the criteria for substances. 

A.3.4.1.2 Unlike other hazard classes, 

there are alternative tests available for skin 

corrosivity of certain types of chemicals 

that can give an accurate result for classification purposes, as well as being simple and 

relatively inexpensive to perform. When considering testing of the mixture, chemical 

manufacturers are encouraged to use a tiered 

weight of evidence strategy as included in 

the criteria for classification of substances 

for skin corrosion and serious eye damage 

and eye irritation to help ensure an accurate 

classification, as well as avoid unnecessary 

animal testing. In the absence of any other 

information, a mixture is considered to 

cause serious eye damage (Eye Category 1) if 

it has a pH ≤2 or ≥11.5. However, if consideration of acid/alkaline reserve suggests the 

substance or mixture may not have the potential to cause serious eye damage despite 

the low or high pH value, then further evaluation may be necessary. 

A.3.4.2 CLASSIFICATION OF MIXTURES WHEN

DATA ARE NOT AVAILABLE FOR THE COMPLETE MIXTURE: BRIDGING PRINCIPLES

A.3.4.2.1 Where the mixture itself has not 

been tested to determine its skin corrosivity 

or potential to cause serious eye damage or 

eye irritation, but there are sufficient data 

on both the individual ingredients and similar tested mixtures to adequately characterize the hazards of the mixture, these data 

will be used in accordance with the following 

bridging principles, as found in paragraph 

A.0.5 of this Appendix: Dilution, Batching, 

Concentration of mixtures, Interpolation 

within one toxicity category, Substantially 

similar mixtures, and Aerosols. 

A.3.4.3 CLASSIFICATION OF MIXTURES WHEN

DATA ARE AVAILABLE FOR ALL INGREDIENTS

OR ONLY FOR SOME INGREDIENTS OF THE

MIXTURE

A.3.4.3.1 For purposes of classifying the 

eye corrosion/irritation hazards of mixtures 

in the tiered approach: 

The ‘‘relevant ingredients’’ of a mixture 

are those which are present in concentrations ≥1% (weight/weight for solids, liquids, 

dusts, mists and vapors and volume/volume 

for gases.) If the classifier has reason to suspect that an ingredient present at a concentration <1% will affect classification of 

the mixture for eye corrosion/irritation, that 

ingredient shall also be considered relevant. 

A.3.4.3.2 In general, the approach to classification of mixtures as seriously damaging 

to the eye or eye irritant when data are 

available on the ingredients, but not on the 

mixture as a whole, is based on the theory of 

additivity, such that each corrosive or irritant ingredient contributes to the overall irritant or corrosive properties of the mixture 

in proportion to its potency and concentration. A weighting factor of 10 is used for corrosive ingredients when they are present at a 

concentration below the concentration limit 

for classification with Category 1, but are at 

a concentration that will contribute to the 

classification of the mixture as an irritant. 

The mixture is classified as seriously damaging to the eye or eye irritant when the 

sum of the concentrations of such ingredients exceeds a threshold cut-off value/concentration limit. 

A.3.4.3.3 Table A.3.3 provides the cut-off 

value/concentration limits to be used to determine if the mixture should be classified as 

seriously damaging to the eye or an eye irritant. 

A.3.4.3.4 Particular care must be taken 

when classifying certain types of chemicals 

such as acids and bases, inorganic salts, 

aldehydes, phenols, and surfactants. The approach explained in A.3.4.3.1 and A.3.4.3.2 

might not work given that many of such substances are corrosive or irritant at concentrations <1%. For mixtures containing 

strong acids or bases, the pH should be used 

as classification criteria (See A.3.4.1) since 

pH will be a better indicator of serious eye 

damage than the concentration limits of 

Table A.3.3. A mixture containing corrosive 

or irritant ingredients that cannot be classified based on the additivity approach applied 

in Table A.3.3 due to chemical characteristics that make this approach unworkable, 

should be classified as Eye Category 1 if it 

contains ≥1% of a corrosive ingredient and as 

Eye Category 2 when it contains ≥3% of an 

irritant ingredient. Classification of mixtures with ingredients for which the approach in Table A.3.3 does not apply is summarized in Table A.3.4. 

A.3.4.3.5 On occasion, reliable data may 

show that the reversible/irreversible eye effects of an ingredient will not be evident 

when present at a level above the generic 

cut-off values/concentration limits mentioned in Tables A.3.3 and A.3.4. In these 

cases the mixture could be classified according to those data (See also A.0.4.3 Use of cutoff values/concentration limits’’). On occasion, 

when it is expected that the skin corrosion/ 

irritation or the reversible/irreversible eye 

effects of an ingredient will not be evident 

when present at a level above the generic 

concentration/cut-off levels mentioned in 

Tables A.3.3 and A.3.4, testing of the mixture 

may be considered. In those cases, the tiered 

weight of evidence strategy should be applied as referred to in section A.3.3, Figure 

A.3.1 and explained in detail in this chapter. 

489 

Occupational Safety and Health Admin., Labor § 1910.1200 

A.3.4.3.6 If there are data showing that 

(an) ingredient(s) may be corrosive or irritant at a concentration of <1% (corrosive) or 

<3% (irritant), the mixture should be classified accordingly (See also paragraph A.0.4.3, 

Use of cut-off values/concentration limits). 

TABLE A.3.3—CONCENTRATION OF INGREDIENTS OF A MIXTURE CLASSIFIED AS SKIN CATEGORY 1 

AND/OR EYE CATEGORY 1 OR 2 THAT WOULD TRIGGER CLASSIFICATION OF THE MIXTURES AS

HAZARDOUS TO THE EYE

Sum of ingredients classified as: 

Concentration triggering classification of a mixture as: 

Irreversible eye effects Reversible eye effects 

Category 1 Category 2 

Eye or Skin Category 1 ....................................................... ≥3% ≥1% but <3%. 

Eye Category 2 .................................................................... ................................................ ≥10%. 

(10 × Eye Category 1) + Eye Category 2 ........................... ................................................ ≥10%. 

Skin Category 1 + Eye Category 1 ..................................... ≥3% ≥1% but <3%. 

10 × (Skin Category 1 + Eye Category 1) + Eye Category 

2.

................................................ ≥10%. 

Note: A mixture may be classified as Eye Category 2B in cases when all relevant ingredients are classified as Eye Category 

2B. 

TABLE A.3.4—CONCENTRATION OF INGREDIENTS OF A MIXTURE FOR WHICH THE ADDITIVITY APPROACH DOES NOT APPLY, THAT WOULD TRIGGER CLASSIFICATION OF THE MIXTURE AS HAZARDOUS TO THE EYE

Ingredient Concentration 

Mixture classified as: Eye 

Acid with pH ≤2 ........................................................................................................... ≥1% Category 1. 

Base with pH ≥11.5 ..................................................................................................... ≥1% Category 1. 

Other corrosive (Category 1) ingredients for which additivity does not apply ............ ≥1% Category 1. 

Other irritant (Category 2) ingredients for which additivity does not apply, including 

acids and bases.

≥3% Category 2. 

A.4 RESPIRATORY OR SKIN 

SENSITIZATION 

A.4.1 DEFINITIONS AND GENERAL

CONSIDERATIONS

A.4.1.1 Respiratory sensitizer means a 

chemical that will lead to hypersensitivity 

of the airways following inhalation of the 

chemical. 

Skin sensitizer means a chemical that will 

lead to an allergic response following skin 

contact. 

A.4.1.2 For the purpose of this chapter, 

sensitization includes two phases: the first 

phase is induction of specialized 

immunological memory in an individual by 

exposure to an allergen. The second phase is 

elicitation, i.e., production of a cell-mediated or antibody-mediated allergic response 

by exposure of a sensitized individual to an 

allergen. 

A.4.1.3 For respiratory sensitization, the 

pattern of induction followed by elicitation 

phases is shared in common with skin sensitization. For skin sensitization, an induction phase is required in which the immune 

system learns to react; clinical symptoms 

can then arise when subsequent exposure is 

sufficient to elicit a visible skin reaction 

(elicitation phase). As a consequence, predictive tests usually follow this pattern in 

which there is an induction phase, the response to which is measured by a standardized elicitation phase, typically involving a 

patch test. The local lymph node assay is the 

exception, directly measuring the induction 

response. Evidence of skin sensitization in 

humans normally is assessed by a diagnostic 

patch test. 

A.4.1.4 Usually, for both skin and respiratory sensitization, lower levels are necessary for elicitation than are required for 

induction. 

A.4.1.5 The hazard class ‘‘respiratory or 

skin sensitization’’ is differentiated into: 

(a) Respiratory sensitization; and 

(b) Skin sensitization. 

A.4.2 CLASSIFICATION CRITERIA FOR

SUBSTANCES

A.4.2.1 RESPIRATORY SENSITIZERS

A.4.2.1.1 Hazard Categories. 

A.4.2.1.1.1 Effects seen in either humans 

or animals will normally justify classification in a weight of evidence approach for respiratory sensitizers. Substances may be allocated to one of the two sub-categories 1A or 

1B using a weight of evidence approach in accordance with the criteria given in Table 

A.4.1 and on the basis of reliable and good 

490 

§ 1910.1200 29 CFR Ch. XVII (7–1–13 Edition) 

1At this writing, recognized and validated 

animal models for the testing of respiratory 

hypersensitivity are not available. Under certain circumstances, data from animal studies 

may provide valuable information in a weight of 

evidence assessment. 

2At this writing, recognized and validated 

animal models for the testing of respiratory 

hypersensitivity are not available. Under certain circumstances, data from animal studies 

may provide valuable information in a weight of 

evidence assessment. 3 The mechanisms by which substances induce 

symptoms of asthma are not yet fully known. 

For preventive measures, these substances are 

considered respiratory sensitizers. However, if 

on the basis of the evidence, it can be demonstrated that these substances induce symptoms of asthma by irritation only in people with 

bronchial hyperactivity, they should not be considered as respiratory sensitizers. 

quality evidence from human cases or epidemiological studies and/or observations from 

appropriate studies in experimental animals. 

A.4.2.1.1.2 Where data are not sufficient 

for sub-categorization, respiratory sensitizers shall be classified in Category 1. 

TABLE A.4.1—HAZARD CATEGORY AND SUB-CATEGORIES FOR RESPIRATORY SENSITIZERS

Category 1 Respiratory sensitizer 

A substance is classified as a respiratory sensitizer. 

(a) if there is evidence in humans that the substance can lead to specific respiratory hypersensitivity and/or 

(b) if there are positive results from an appropriate animal test.1

Sub-category 1A ....................... Substances showing a high frequency of occurrence in humans; or a probability of occurrence 

of a high sensitization rate in humans based on animal or other tests.1 Severity of reaction 

may also be considered. 

Sub-category 1B ....................... Substances showing a low to moderate frequency of occurrence in humans; or a probability of 

occurrence of a low to moderate sensitization rate in humans based on animal or other 

tests.1 Severity of reaction may also be considered. 

A.4.2.1.2 Human evidence. 

A.4.2.1.2.1 Evidence that a substance can 

lead to specific respiratory hypersensitivity 

will normally be based on human experience. 

In this context, hypersensitivity is normally 

seen as asthma, but other hypersensitivity 

reactions such as rhinitis/conjunctivitis and 

alveolitis are also considered. The condition 

will have the clinical character of an allergic 

reaction. However, immunological mechanisms do not have to be demonstrated. 

A.4.2.1.2.2 When considering the human 

evidence, it is necessary that in addition to 

the evidence from the cases, the following be 

taken into account: 

(a) The size of the population exposed; 

(b) The extent of exposure. 

A.4.2.1.2.3 The evidence referred to above 

could be: 

(a) Clinical history and data from appropriate lung function tests related to exposure to the substance, confirmed by other 

supportive evidence which may include: 

(i) In vivo immunological test (e.g., skin 

prick test); 

(ii) In vitro immunological test (e.g., serological analysis); 

(iii) Studies that may indicate other specific hypersensitivity reactions where 

immunological mechanisms of action have 

not been proven, e.g., repeated low-level irritation, pharmacologically mediated effects; 

(iv) A chemical structure related to substances known to cause respiratory hypersensitivity; 

(b) Data from positive bronchial challenge 

tests with the substance conducted according to accepted guidelines for the determination of a specific hypersensitivity reaction. 

A.4.2.1.2.4 Clinical history should include 

both medical and occupational history to determine a relationship between exposure to a 

specific substance and development of respiratory hypersensitivity. Relevant information includes aggravating factors both in the 

home and workplace, the onset and progress 

of the disease, family history and medical 

history of the patient in question. The medical history should also include a note of 

other allergic or airway disorders from childhood and smoking history. 

A.4.2.1.2.5 The results of positive bronchial challenge tests are considered to provide sufficient evidence for classification on 

their own. It is, however, recognized that in 

practice many of the examinations listed 

above will already have been carried out. 

A.4.2.1.3 Animal studies. 

A.4.2.1.3.1 Data from appropriate animal 

studies 2 which may be indicative of the potential of a substance to cause sensitization 

by inhalation in humans 3 may include: 

(a) Measurements of Immunoglobulin E 

(IgE) and other specific immunological parameters, for example in mice 

(b) Specific pulmonary responses in guinea 

pigs. 

A.4.2.2 SKIN SENSITIZERS

A.4.2.2.1 Hazard categories. 

491 

Occupational Safety and Health Admin., Labor § 1910.1200 

4 Test methods for skin sensitization are described in OECD Guideline 406 (the Guinea Pig 

Maximization test and the Buehler guinea pig 

test) and Guideline 429 (Local Lymph Node 

Assay). Other methods may be used provided 

that they are scientifically validated. The 

Mouse Ear Swelling Test (MEST), appears to be 

a reliable screening test to detect moderate to 

strong sensitizers, and can be used, in accordance with professional judgment, as a first stage 

in the assessment of skin sensitization potential. 

A.4.2.2.1.1 Effects seen in either humans 

or animals will normally justify classification in a weight of evidence approach for 

skin sensitizers. Substances may be allocated to one of the two sub-categories 1A or 

1B using a weight of evidence approach in accordance with the criteria given in Table 

A.4.2 and on the basis of reliable and good 

quality evidence from human cases or epidemiological studies and/or observations from 

appropriate studies in experimental animals 

according to the guidance values provided in 

A.4.2.2.2.1 and A.4.2.2.3.2 for sub-category 1A 

and in A.4.2.2.2.2 and A.4.2.2.3.3 for sub-category 1B. 

A.4.2.2.1.2 Where data are not sufficient 

for sub-categorization, skin sensitizers shall 

be classified in Category 1. 

TABLE A.4.2—HAZARD CATEGORY AND SUB-CATEGORIES FOR SKIN SENSITIZERS

Category 1 Skin sensitizer 

A substance is classified as a skin sensitizer. 

(a) if there is evidence in humans that the substance can lead to sensitization by skin contact 

in a substantial number of persons, or 

(b) if there are positive results from an appropriate animal test. 

Sub-category 1A ....................... Substances showing a high frequency of occurrence in humans and/or a high potency in animals can be presumed to have the potential to produce significant sensitization in humans. 

Severity of reaction may also be considered. 

Sub-category 1B ....................... Substances showing a low to moderate frequency of occurrence in humans and/or a low to 

moderate potency in animals can be presumed to have the potential to produce sensitization 

in humans. Severity of reaction may also be considered. 

A.4.2.2.2 Human evidence. 

A.4.2.2.2.1 Human evidence for sub-category 1A may include: 

(a) Positive responses at ≤500 μg/cm2

(Human Repeat Insult Patch Test (HRIPT), 

Human Maximization Test (HMT)—induction 

threshold); 

(b) Diagnostic patch test data where there 

is a relatively high and substantial incidence 

of reactions in a defined population in relation to relatively low exposure; 

(c) Other epidemiological evidence where 

there is a relatively high and substantial incidence of allergic contact dermatitis in relation to relatively low exposure. 

A.4.2.2.2.2 Human evidence for sub-category 1B may include: 

(a) Positive responses at >500 μg/cm2

(HRIPT, HMT—induction threshold); 

(b) Diagnostic patch test data where there 

is a relatively low but substantial incidence 

of reactions in a defined population in relation to relatively high exposure; 

(c) Other epidemiological evidence where 

there is a relatively low but substantial incidence of allergic contact dermatitis in relation to relatively high exposure. 

A.4.2.2.3 Animal studies 

A.4.2.2.3.1 For Category 1, when an adjuvant type test method for skin sensitization 

is used, a response of at least 30% of the animals is considered as positive. For a non-adjuvant Guinea pig test method a response of 

at least 15% of the animals is considered 

positive. For Category 1, a stimulation index 

of three or more is considered a positive response in the local lymph node assay.4

A.4.2.2.3.2 Animal test results for sub-category 1A can include data with values indicated in Table A.4.3 below: 

TABLE A.4.3—ANIMAL TEST RESULTS FOR SUB-CATEGORY 1A 

Assay Criteria 

Local lymph node assay ............................. EC3 value ≤2%. 

Guinea pig maximization test ...................... ≥30% responding at ≤0.1% intradermal induction dose or 

≥60% responding at >0.1% to ≤1% intradermal induction dose. 

Buehler assay ............................................. ≥15% responding at ≤0.2% topical induction dose or 

≥60% responding at >0.2% to ≤20% topical induction dose. 

Note: EC3 refers to the estimated concentration of test chemical required to induce a stimulation index of 3 in the local lymph 

node assay. 

492 

§ 1910.1200 29 CFR Ch. XVII (7–1–13 Edition) 

A.4.2.2.3.3 Animal test results for sub-category 1B can include data with values indicated in Table A.4.4 below: 

TABLE A.4.4—ANIMAL TEST RESULTS FOR SUB-CATEGORY 1B 

Assay Criteria 

Local lymph node assay ............................. EC3 value >2%. 

Guinea pig maximization test ...................... ≥30% to <60% responding at >0.1% to ≤1% intradermal induction dose or 

≥30% responding at >1% intradermal induction dose. 

Buehler assay ............................................. ≥15% to <60% responding at >0.2% to ≤20% topical induction dose or 

≥15% responding at >20% topical induction dose. 

Note: EC3 refers to the estimated concentration of test chemical required to induce a stimulation index of 3 in the local lymph 

node assay. 

A.4.2.2.4 Specific considerations. 

A.4.2.2.4.1 For classification of a substance, evidence shall include one or more of 

the following using a weight of evidence approach: 

(a) Positive data from patch testing, normally obtained in more than one dermatology clinic; 

(b) Epidemiological studies showing allergic contact dermatitis caused by the substance. Situations in which a high proportion of those exposed exhibit characteristic 

symptoms are to be looked at with special 

concern, even if the number of cases is small; 

(c) Positive data from appropriate animal 

studies; 

(d) Positive data from experimental studies in man (See paragraph A.0.2.6 of this Appendix); 

(e) Well documented episodes of allergic 

contact dermatitis, normally obtained in 

more than one dermatology clinic; 

(f) Severity of reaction. 

A.4.2.2.4.2 Evidence from animal studies is 

usually much more reliable than evidence 

from human exposure. However, in cases 

where evidence is available from both 

sources, and there is conflict between the results, the quality and reliability of the evidence from both sources must be assessed in 

order to resolve the question of classification on a case-by-case basis. Normally, 

human data are not generated in controlled 

experiments with volunteers for the purpose 

of hazard classification but rather as part of 

risk assessment to confirm lack of effects 

seen in animal tests. Consequently, positive 

human data on skin sensitization are usually 

derived from case-control or other, less defined studies. Evaluation of human data 

must, therefore, be carried out with caution 

as the frequency of cases reflect, in addition 

to the inherent properties of the substances, 

factors such as the exposure situation, bioavailability, individual predisposition and 

preventive measures taken. Negative human 

data should not normally be used to negate 

positive results from animal studies. For 

both animal and human data, consideration 

should be given to the impact of vehicle. 

A.4.2.2.4.3 If none of the above-mentioned 

conditions are met, the substance need not 

be classified as a skin sensitizer. However, a 

combination of two or more indicators of 

skin sensitization, as listed below, may alter 

the decision. This shall be considered on a 

case-by-case basis. 

(a) Isolated episodes of allergic contact 

dermatitis; 

(b) Epidemiological studies of limited 

power, e.g., where chance, bias or confounders have not been ruled out fully with 

reasonable confidence; 

(c) Data from animal tests, performed according to existing guidelines, which do not 

meet the criteria for a positive result described in A.4.2.2.3, but which are sufficiently 

close to the limit to be considered significant; 

(d) Positive data from non-standard methods; 

(e) Positive results from close structural 

analogues. 

A.4.2.2.4.4 Immunological contact urticaria. 

A.4.2.2.4.4.1 Substances meeting the criteria for classification as respiratory sensitizers may, in addition, cause immunological 

contact urticaria. Consideration shall be 

given to classifying these substances as skin 

sensitizers. 

A.4.2.2.4.4.2 Substances which cause 

immunological contact urticaria without 

meeting the criteria for respiratory sensitizers shall be considered for classification 

as skin sensitizers. 

A.4.2.2.4.4.3 There is no recognized animal 

model available to identify substances which 

cause immunological contact urticaria. 

Therefore, classification will normally be 

based on human evidence, similar to that for 

skin sensitization. 

A.4.3 CLASSIFICATION CRITERIA FOR

MIXTURES

A.4.3.1 CLASSIFICATION OF MIXTURES WHEN

DATA ARE AVAILABLE FOR THE COMPLETE

MIXTURE

When reliable and good quality evidence, 

as described in the criteria for substances, 

493 

Occupational Safety and Health Admin., Labor § 1910.1200 

from human experience or appropriate studies in experimental animals, is available for 

the mixture, then the mixture shall be classified by weight of evidence evaluation of 

these data. Care must be exercised in evaluating data on mixtures that the dose used 

does not render the results inconclusive. 

A.4.3.2 CLASSIFICATION OF MIXTURES WHEN

DATA ARE NOT AVAILABLE FOR THE COMPLETE MIXTURE: BRIDGING PRINCIPLES

A.4.3.2.1 Where the mixture itself has not 

been tested to determine its sensitizing properties, but there are sufficient data on both 

the individual ingredients and similar tested 

mixtures to adequately characterize the hazards of the mixture, these data will be used 

in accordance with the following agreed 

bridging principles as found in paragraph 

A.0.5 of this Appendix: Dilution, Batching, 

Concentration of mixtures, Interpolation, 

Substantially similar mixtures, and 

Aerosols. 

A.4.3.3 CLASSIFICATION OF MIXTURES WHEN

DATA ARE AVAILABLE FOR ALL INGREDIENTS

OR ONLY FOR SOME INGREDIENTS OF THE

MIXTURE

The mixture shall be classified as a respiratory or skin sensitizer when at least one 

ingredient has been classified as a respiratory or skin sensitizer and is present at 

or above the appropriate cut-off value/concentration limit for the specific endpoint as 

shown in Table A.4.5. 

TABLE A.4.5—CUT-OFF VALUES/CONCENTRATION LIMITS OF INGREDIENTS OF A MIXTURE CLASSIFIED

AS EITHER RESPIRATORY SENSITIZERS OR SKIN SENSITIZERS THAT WOULD TRIGGER CLASSIFICATION OF THE MIXTURE

Ingredient classified as: 

Cut-off values/concentration limits triggering classification of a mixture as: 

Respiratory Sensitizer 

Category 1 

Skin Sensitizer 

Category 1 

Solid/liquid Gas All physical states 

Respiratory Sensitizer, Category 1 ................... ≥0.1% ≥0.1% 

Respiratory Sensitizer, Sub-category 1A .......... ≥0.1% ≥0.1% 

Respiratory Sensitizer, Sub-category 1B .......... ≥1.0% ≥0.2% 

Skin Sensitizer, Category 1 ............................... ........................................ ........................................ ≥0.1% 

Skin Sensitizer, Sub-category 1A ..................... ........................................ ........................................ ≥0.1% 

Skin Sensitizer, Sub-category 1B ..................... ........................................ ........................................ ≥1.0% 

A.5 GERM CELL MUTAGENICITY 

A.5.1 DEFINITIONS AND GENERAL

CONSIDERATIONS

A.5.1.1 A mutation is defined as a permanent change in the amount or structure of 

the genetic material in a cell. The term mutation applies both to heritable genetic 

changes that may be manifested at the 

phenotypic level and to the underlying DNA 

modifications when known (including, for example, specific base pair changes and chromosomal translocations). The term mutagenic and mutagen will be used for agents giving rise to an increased occurrence of 

mutations in populations of cells and/or organisms. 

A.5.1.2 The more general terms genotoxic 

and genotoxicity apply to agents or processes 

which alter the structure, information content, or segregation of DNA, including those 

which cause DNA damage by interfering with 

normal replication processes, or which in a 

non-physiological manner (temporarily) 

alter its replication. Genotoxicity test results are usually taken as indicators for mutagenic effects. 

A.5.1.3 This hazard class is primarily concerned with chemicals that may cause 

mutations in the germ cells of humans that 

can be transmitted to the progeny. However, 

mutagenicity/genotoxicity tests in vitro and 

in mammalian somatic cells in vivo are also 

considered in classifying substances and 

mixtures within this hazard class. 

A.5.2 CLASSIFICATION CRITERIA FOR

SUBSTANCES

A.5.2.1 The classification system provides 

for two different categories of germ cell 

mutagens to accommodate the weight of evidence available. The two-category system is 

described in the Figure A.5.1. 

FIGURE A.5.1—HAZARD CATEGORIES FOR GERM CELL MUTAGENS

CATEGORY 1: Substances known to induce heritable mutations or to be regarded as if they 

induce heritable mutations in the germ cells of humans. 

Category 1A: Substances known to induce heritable mutations in germ cells of humans. 

Positive evidence from human epidemiological studies. 

494 

§ 1910.1200 29 CFR Ch. XVII (7–1–13 Edition) 

5 It should be noted that the classification criteria for health hazards usually include a tiered 

scheme in which test data available on the complete mixture are considered as the first tier in 

the evaluation, followed by the applicable bridging principles, and lastly, cut-off values/concentration limits or additivity. However, this approach is not used for Germ Cell Mutagenicity. 

These criteria for Germ Cell Mutagenicity consider the cut-off values/concentration limits as 

the primary tier and allow the classification to 

be modified only on a case-by-case evaluation 

based on available test data for the mixture as 

a whole. 

FIGURE A.5.1—HAZARD CATEGORIES FOR GERM CELL MUTAGENS—Continued 

Category 1B: Substances which should be regarded as if they induce heritable mutations in 

the germ cells of humans. 

(a) Positive result(s) from in vivo heritable germ cell mutagenicity tests in mammals; 

or 

(b) Positive result(s) from in vivo somatic cell mutagenicity tests in mammals, in combination with some evidence that the substance has potential to cause mutations to 

germ cells. This supporting evidence may, for example, be derived from mutagenicity/genotoxicity tests in germ cells in vivo, or by demonstrating the ability of the 

substance or its metabolite(s) to interact with the genetic material of germ cells; or 

(c) Positive results from tests showing mutagenic effects in the germ cells of humans, 

without demonstration of transmission to progeny; for example, an increase in the 

frequency of aneuploidy in sperm cells of exposed people. 

CATEGORY 2: Substances which cause concern for humans owing to the possibility that they 

may induce heritable mutations in the germ cells of humans. 

Positive evidence obtained from experiments in mammals and/or in some cases from 

in vitro experiments, obtained from: 

(a) Somatic cell mutagenicity tests in vivo, in mammals; or 

(b) Other in vivo somatic cell genotoxicity tests which are supported by positive results from in vitro mutagenicity assays. 

Note: Substances which are positive in in vitro mammalian mutagenicity assays, and which also show chemical structure activity 

relationship to known germ cell mutagens, should be considered 

for classification as Category 2 mutagens. 

A.5.2.2 Specific considerations for classification of substances as germ cell mutagens: 

A.5.2.2.1 To arrive at a classification, test 

results are considered from experiments determining mutagenic and/or genotoxic effects in germ and/or somatic cells of exposed 

animals. Mutagenic and/or genotoxic effects 

determined in in vitro tests shall also be considered. 

A.5.2.2.2 The system is hazard based, 

classifying chemicals on the basis of their 

intrinsic ability to induce mutations in germ 

cells. The scheme is, therefore, not meant for 

the (quantitative) risk assessment of chemical substances. 

A.5.2.2.3 Classification for heritable effects in human germ cells is made on the 

basis of scientifically validated tests. Evaluation of the test results shall be done using 

expert judgment and all the available evidence shall be weighed for classification. 

A.5.2.2.4 The classification of substances 

shall be based on the total weight of evidence available, using expert judgment. In 

those instances where a single well-conducted test is used for classification, it shall 

provide clear and unambiguously positive results. The relevance of the route of exposure 

used in the study of the substance compared 

to the route of human exposure should also 

be taken into account. 

A.5.3 CLASSIFICATION CRITERIA FOR

MIXTURES 5

A.5.3.1 CLASSIFICATION OF MIXTURES WHEN

DATA ARE AVAILABLE FOR ALL INGREDIENTS

OR ONLY FOR SOME INGREDIENTS OF THE

MIXTURE

A.5.3.1.1 Classification of mixtures shall 

be based on the available test data for the individual ingredients of the mixture using 

cut-off values/concentration limits for the 

ingredients classified as germ cell mutagens. 

A.5.3.1.2 The mixture will be classified as 

a mutagen when at least one ingredient has 

been classified as a Category 1A, Category 1B 

or Category 2 mutagen and is present at or 

495 

Occupational Safety and Health Admin., Labor § 1910.1200 

above the appropriate cut-off value/concentration limit as shown in Table A.5.1 

below for Category 1 and 2 respectively. 

TABLE A.5.1—CUT-OFF VALUES/CONCENTRATION LIMITS OF INGREDIENTS OF A MIXTURE CLASSIFIED

AS GERM CELL MUTAGENS THAT WOULD TRIGGER CLASSIFICATION OF THE MIXTURE

Ingredient classified as: 

Cut-off/concentration limits triggering classification 

of a mixture as: 

Category 1 mutagen Category 2 mutagen 

Category 1A/B mutagen ................................................................................ ≥0.1% 

Category 2 mutagen ...................................................................................... ........................................ ≥1.0% 

Note: The cut-off values/concentration limits in the table above apply to solids and liquids (w/w units) as well as gases (v/v 

units). 

A.5.3.2 CLASSIFICATION OF MIXTURES WHEN

DATA ARE AVAILABLE FOR THE MIXTURE

ITSELF

The classification may be modified on a 

case-by-case basis based on the available test 

data for the mixture as a whole. In such 

cases, the test results for the mixture as a 

whole must be shown to be conclusive taking 

into account dose and other factors such as 

duration, observations and analysis (e.g. statistical analysis, test sensitivity) of germ 

cell mutagenicity test systems. 

A.5.3.3 CLASSIFICATION OF MIXTURES WHEN

DATA ARE NOT AVAILABLE FOR THE COMPLETE MIXTURE: BRIDGING PRINCIPLES

A.5.3.3.1 Where the mixture itself has not 

been tested to determine its germ cell mutagenicity hazard, but there are sufficient data 

on both the individual ingredients and similar tested mixtures to adequately characterize the hazards of the mixture, these data 

will be used in accordance with the following 

bridging principles as found in paragraph 

A.0.5 of this Appendix: Dilution, Batching, 

and Substantially similar mixtures. 

A.5.4 EXAMPLES OF SCIENTIFICALLY

VALIDATED TEST METHODS

A.5.4.1 Examples of in vivo heritable germ 

cell mutagenicity tests are: 

(a) Rodent dominant lethal mutation test 

(OECD 478) 

(b) Mouse heritable translocation assay 

(OECD 485) 

(c) Mouse specific locus test 

A.5.4.2 Examples of in vivo somatic cell mutagenicity tests are: 

(a) Mammalian bone marrow chromosome 

aberration test (OECD 475) 

(b) Mouse spot test (OECD 484) 

(c) Mammalian erythrocyte micronucleus 

test (OECD 474) 

A.5.4.3 Examples of mutagenicity/ 

genotoxicity tests in germ cells are: 

(a) Mutagenicity tests: 

(i) Mammalian spermatogonial chromosome aberration test (OECD 483) 

(ii) Spermatid micronucleus assay 

(b) Genotoxicity tests: 

(i) Sister chromatid exchange analysis in 

spermatogonia 

(ii) Unscheduled DNA synthesis test (UDS) 

in testicular cells 

A.5.4.4 Examples of genotoxicity tests in somatic cells are: 

(a) Liver Unscheduled DNA Synthesis 

(UDS) in vivo (OECD 486) 

(b) Mammalian bone marrow Sister Chromatid Exchanges (SCE) 

A.5.4.5 Examples of in vitro mutagenicity 

tests are: 

(a) In vitro mammalian chromosome aberration test (OECD 473) 

(b) In vitro mammalian cell gene mutation 

test (OECD 476) 

(c) Bacterial reverse mutation tests (OECD 

471) 

A.5.4.6 As new, scientifically validated tests 

arise, these may also be used in the total 

weight of evidence to be considered. 

A.6 CARCINOGENICITY 

A.6.1 DEFINITIONS

Carcinogen means a substance or a mixture 

of substances which induce cancer or increase its incidence. Substances and mixtures which have induced benign and malignant tumors in well-performed experimental 

studies on animals are considered also to be 

presumed or suspected human carcinogens 

unless there is strong evidence that the 

mechanism of tumor formation is not relevant for humans. 

Classification of a substance or mixture as 

posing a carcinogenic hazard is based on its 

inherent properties and does not provide information on the level of the human cancer 

risk which the use of the substance or mixture may represent. 

496 

§ 1910.1200 29 CFR Ch. XVII (7–1–13 Edition) 

6See Non-mandatory Appendix F Part A for 

further guidance regarding hazard classification 

for carcinogenicity. This appendix is consistent 

with the GHS adn is provided as guidance excerpted from the International Agency for Research on Cancer (IARC) ‘‘Monographs on the 

Evaluation of Carcinogenic Risks to Humans’’ 

(2006). 

A.6.2 CLASSIFICATION CRITERIA FOR

SUBSTANCES 6

A.6.2.1 For the purpose of classification for 

carcinogenicity, substances are allocated to 

one of two categories based on strength of 

evidence and additional weight of evidence 

considerations. In certain instances, routespecific classification may be warranted. 

FIGURE A.6.1—HAZARD CATEGORIES FOR CARCINOGENS

CATEGORY 1: Known or presumed human carcinogens. 

The classification of a substance as a Category 1 carcinogen is done on the basis of 

epidemiological and/or animal data. This classification is further distinguished on 

the basis of whether the evidence for classification is largely from human data 

(Category 1A) or from animal data (Category 1B): 

Category 1A: Known to have carcinogenic potential for humans. Classification in this category 

is largely based on human evidence. 

Category 1B: Presumed to have carcinogenic potential for humans. Classification in this category is largely based on animal evidence. 

The classification of a substance in Category 1A and 1B is based on strength of evidence together with weight of evidence considerations (See paragraph A.6.2.5). 

Such evidence may be derived from: 

—human studies that establish a causal relationship between human exposure to a substance and the development of cancer (known human carcinogen); or 

—animal experiments for which there is sufficient evidence to demonstrate 

animal carcinogenicity (presumed human carcinogen). 

In addition, on a case by case basis, scientific judgment may warrant a decision of 

presumed human carcinogenicity derived from studies showing limited evidence of 

carcinogenicity in humans together with limited evidence of carcinogenicity in experimental animals. 

CATEGORY 2: Suspected human carcinogens. 

The classification of a substance in Category 2 is done on the basis of evidence obtained from human and/or animal studies, but which is not sufficiently convincing to 

place the substance in Category 1A or B. This classification is based on strength 

of evidence together with weight of evidence considerations (See paragraph 

A.6.2.5). Such evidence may be from either limited evidence of carcinogenicity in 

human studies or from limited evidence of carcinogenicity in animal studies. 

Other considerations: Where the weight of evidence for the carcinogenicity of a substance 

does not meet the above criteria, any positive study conducted in accordance with established scientific principles, and which reports statistically significant findings regarding the 

carcinogenic potential of the substance, must be noted on the safety data sheet. 

A.6.2.2 Classification as a carcinogen is 

made on the basis of evidence from reliable 

and acceptable methods, and is intended to 

be used for substances which have an intrinsic property to produce such toxic effects. 

The evaluations are to be based on all existing data, peer-reviewed published studies and 

additional data accepted by regulatory agencies. 

A.6.2.3 Carcinogen classification is a onestep, criterion-based process that involves 

two interrelated determinations: evaluations 

of strength of evidence and consideration of 

all other relevant information to place substances with human cancer potential into 

hazard categories. 

A.6.2.4 Strength of evidence involves the 

enumeration of tumors in human and animal 

studies and determination of their level of 

statistical significance. Sufficient human 

evidence demonstrates causality between 

human exposure and the development of cancer, whereas sufficient evidence in animals 

shows a causal relationship between the 

agent and an increased incidence of tumors. 

Limited evidence in humans is demonstrated 

by a positive association between exposure 

and cancer, but a causal relationship cannot 

497 

Occupational Safety and Health Admin., Labor § 1910.1200 

7 It should be noted that the classification criteria for health hazards usually include a tiered 

scheme in which test data available on the complete mixture are considered as the first tier in 

the evaluation, followed by the applicable bridging principles, and lastly, cut-off values/concentration limit or additivity. However, this approach is not used for Carcinogenicity. These 

criteria for Carcinogenicity consider the cut-off 

values/concentration limits as the primary tier 

and allow the classification to be modified only 

on a case-by-case evaluation based on available 

test data for the mixture as a whole. 

be stated. Limited evidence in animals is 

provided when data suggest a carcinogenic 

effect, but are less than sufficient. (Guidance 

on consideration of important factors in the 

classification of carcinogenicity and a more 

detailed description of the terms ‘‘limited’’ 

and ‘‘sufficient’’ have been developed by the 

International Agency for Research on Cancer 

(IARC) and are provided in non-mandatory 

Appendix F). 

A.6.2.5 Weight of evidence: Beyond the determination of the strength of evidence for 

carcinogenicity, a number of other factors 

should be considered that influence the overall likelihood that an agent may pose a carcinogenic hazard in humans. The full list of 

factors that influence this determination is 

very lengthy, but some of the important 

ones are considered here. 

A.6.2.5.1 These factors can be viewed as either increasing or decreasing the level of 

concern for human carcinogenicity. The relative emphasis accorded to each factor depends upon the amount and coherence of evidence bearing on each. Generally there is a 

requirement for more complete information 

to decrease than to increase the level of concern. Additional considerations should be 

used in evaluating the tumor findings and 

the other factors in a case-by-case manner. 

A.6.2.5.2 Some important factors which 

may be taken into consideration, when assessing the overall level of concern are: 

(a) Tumor type and background incidence; 

(b) Multisite responses; 

(c) Progression of lesions to malignancy; 

(d) Reduced tumor latency; 

Additional factors which may increase or 

decrease the level of concern include: 

(e) Whether responses are in single or both 

sexes; 

(f) Whether responses are in a single species or several species; 

(g) Structural similarity or not to a substance(s) for which there is good evidence of 

carcinogenicity; 

(h) Routes of exposure; 

(i) Comparison of absorption, distribution, 

metabolism and excretion between test animals and humans; 

(j) The possibility of a confounding effect 

of excessive toxicity at test doses; and, 

(k) Mode of action and its relevance for humans, such as mutagenicity, cytotoxicity 

with growth stimulation, mitogenesis, 

immunosuppression. 

Mutagenicity: It is recognized that genetic 

events are central in the overall process of 

cancer development. Therefore evidence of 

mutagenic activity in vivo may indicate that 

a substance has a potential for carcinogenic 

effects. 

A.6.2.5.3 A substance that has not been 

tested for carcinogenicity may in certain instances be classified in Category 1A, Category 1B, or Category 2 based on tumor data 

from a structural analogue together with 

substantial support from consideration of 

other important factors such as formation of 

common significant metabolites, e.g., for 

benzidine congener dyes. 

A.6.2.5.4 The classification should also 

take into consideration whether or not the 

substance is absorbed by a given route(s); or 

whether there are only local tumors at the 

site of administration for the tested route(s), 

and adequate testing by other major route(s) 

show lack of carcinogenicity. 

A.6.2.5.5 It is important that whatever is 

known of the physico-chemical, 

toxicokinetic and toxicodynamic properties 

of the substances, as well as any available 

relevant information on chemical analogues, 

i.e., structure activity relationship, is taken 

into consideration when undertaking classification. 

A.6.3 CLASSIFICATION CRITERIA FOR

MIXTURES 7

A.6.3.1 The mixture shall be classified as a 

carcinogen when at least one ingredient has 

been classified as a Category 1 or Category 2 

carcinogen and is present at or above the appropriate cut-off value/concentration limit 

as shown in Table A.6.1. 

TABLE A.6.1—CUT-OFF VALUES/CONCENTRATION LIMITS OF INGREDIENTS OF A MIXTURE CLASSIFIED

AS CARCINOGEN THAT WOULD TRIGGER CLASSIFICATION OF THE MIXTURE

Ingredient classified as: Category 1 

carcinogen 

Category 2 

carcinogen 

Category 1 carcinogen .................................................................................. ≥0.1% 

498 

§ 1910.1200 29 CFR Ch. XVII (7–1–13 Edition) 

8See Non-mandatory Appendix F for further 

guidance regarding hazard classification for 

carcinogenicity and how to relate carcinogenicity classification information from IARC 

and NTP to GHS. 

TABLE A.6.1—CUT-OFF VALUES/CONCENTRATION LIMITS OF INGREDIENTS OF A MIXTURE CLASSIFIED

AS CARCINOGEN THAT WOULD TRIGGER CLASSIFICATION OF THE MIXTURE—Continued 

Ingredient classified as: Category 1 

carcinogen 

Category 2 

carcinogen 

Category 2 carcinogen .................................................................................. ................................ ≥0.1% (note 1). 

Note: If a Category 2 carcinogen ingredient is present in the mixture at a concentration between 0.1% and 1%, information is 

required on the SDS for a product. However, a label warning is optional. If a Category 2 carcinogen ingredient is present in the mixture at a concentration of ≥1%, both an SDS and a label is required and the information must be included on each. 

A.6.3.2 CLASSIFICATION OF MIXTURES WHEN

DATA ARE AVAILABLE FOR THE COMPLETE

MIXTURE

A mixture may be classified based on the 

available test data for the mixture as a 

whole. In such cases, the test results for the 

mixture as a whole must be shown to be conclusive taking into account dose and other 

factors such as duration, observations and 

analysis (e.g., statistical analysis, test sensitivity) of carcinogenicity test systems. 

A.6.3.3 CLASSIFICATION OF MIXTURES WHEN

DATA ARE NOT AVAILABLE FOR THE COMPLETE MIXTURE: BRIDGING PRINCIPLES

Where the mixture itself has not been tested to determine its carcinogenic hazard, but 

there are sufficient data on both the individual ingredients and similar tested mixtures to adequately characterize the hazards 

of the mixture, these data will be used in accordance with the following bridging principles as found in paragraph A.0.5 of this Appendix: Dilution; Batching; and Substantially similar mixtures. 

A.6.4 CLASSIFICATION OF CARCINOGENICITY 8

A.6.4.1 Chemical manufacturers, importers and employers evaluating chemicals may 

treat the following sources as establishing 

that a substance is a carcinogen or potential 

carcinogen for hazard communication purposes in lieu of applying the criteria described herein: 

A.6.4.1.1 National Toxicology Program 

(NTP), ‘‘Report on Carcinogens’’ (latest edition); 

A.6.4.1.2 International Agency for Research on Cancer (IARC) ‘‘Monographs on 

the Evaluation of Carcinogenic Risks to Humans’’ (latest editions) 

A.6.4.2 Where OSHA has included cancer 

as a health hazard to be considered by classifiers for a chemical covered by 29 CFR part 

1910, Subpart Z, Toxic and Hazardous Substances, chemical manufacturers, importers, 

and employers shall classify the chemical as 

a carcinogen. 

A.7 REPRODUCTIVE TOXICITY 

A.7.1 DEFINITIONS AND GENERAL

CONSIDERATIONS

A.7.1.1 Reproductive toxicity includes adverse effects on sexual function and fertility in 

adult males and females, as well as adverse 

effects on development of the offspring. Some 

reproductive toxic effects cannot be clearly 

assigned to either impairment of sexual 

function and fertility or to developmental 

toxicity. Nonetheless, chemicals with these 

effects shall be classified as reproductive 

toxicants. 

For classification purposes, the known induction of genetically based inheritable effects in the offspring is addressed in Germ cell 

mutagenicity (See A.5). 

A.7.1.2 Adverse effects on sexual function 

and fertility means any effect of chemicals 

that interferes with reproductive ability or 

sexual capacity. This includes, but is not 

limited to, alterations to the female and 

male reproductive system, adverse effects on 

onset of puberty, gamete production and 

transport, reproductive cycle normality, sexual behaviour, fertility, parturition, pregnancy outcomes, premature reproductive senescence, or modifications in other functions 

that are dependent on the integrity of the reproductive systems. 

A.7.1.3 Adverse effects on development of the 

offspring means any effect of chemicals 

which interferes with normal development of 

the conceptus either before or after birth, 

which is induced during pregnancy or results 

from parental exposure. These effects can be 

manifested at any point in the life span of 

the organism. The major manifestations of 

developmental toxicity include death of the 

developing organism, structural abnormality, altered growth and functional deficiency. 

A.7.1.4 Adverse effects on or via lactation 

are also included in reproductive toxicity, 

but for classification purposes, such effects 

are treated separately (See A.7.2.1). 

A.7.2 CLASSIFICATION CRITERIA FOR

SUBSTANCES

A.7.2.1 For the purpose of classification 

for reproductive toxicity, substances shall be 

classified in one of two categories in accordance with Figure A.7.1(a). Effects on sexual 

function and fertility, and on development, 

499 

Occupational Safety and Health Admin., Labor § 1910.1200 

shall be considered. In addition, effects on or 

via lactation shall be classified in a separate 

hazard category in accordance with Figure 

A.7.1(b). 

FIGURE A.7.1(a)—HAZARD CATEGORIES FOR REPRODUCTIVE TOXICANTS

CATEGORY 1: Known or presumed human reproductive toxicant. 

Substance shall be classified in Category 1 for reproductive toxicity when they are 

known to have produced an adverse effect on sexual function and fertility or on development in humans or when there is evidence from animal studies, possibly supplemented with other information, to provide a strong presumption that the substance has the capacity to interfere with reproduction in humans. The classification 

of a substance is further distinguished on the basis of whether the evidence for 

classification is primarily from human data (Category 1A) or from animal data (Category 1B). 

Category 1A: Known human reproductive toxicant. 

The classification of a substance in this category is largely based on evidence from 

humans. 

Category 1B: Presumed human reproductive toxicant. 

The classification of a substance in this category is largely based on evidence from 

experimental animals. Data from animal studies shall provide sufficient evidence of 

an adverse effect on sexual function and fertility or on development in the absence 

of other toxic effects, or if occurring together with other toxic effects the adverse effect on reproduction is considered not to be a secondary non-specific consequence 

of other toxic effects. However, when there is mechanistic information that raises 

doubt about the relevance of the effect for humans, classification in Category 2 

may be more appropriate. 

CATEGORY 2: Suspected human reproductive toxicant. 

Substances shall be classified in Category 2 for reproductive toxicity when there is 

some evidence from humans or experimental animals, possibly supplemented with 

other information, of an adverse effect on sexual function and fertility, or on development, in the absence of other toxic effects, or if occurring together with other 

toxic effects the adverse effect on reproduction is considered not to be a secondary non-specific consequence of the other toxic effects, and where the evidence is not sufficiently convincing to place the substance in Category 1. For instance, deficiencies in the study may make the quality of evidence less convincing, 

and in view of this, Category 2 would be the more appropriate classification. 

FIGURE A.7.1(b)—HAZARD CATEGORY FOR EFFECTS ON OR VIA LACTATION

EFFECTS ON OR VIA LACTATION 

Effects on or via lactation shall be classified in a separate single category. Chemicals that are 

absorbed by women and have been shown to interfere with lactation or that may be present 

(including metabolites) in breast milk in amounts sufficient to cause concern for the health 

of a breastfed child, shall be classified to indicate this property hazardous to breastfed babies. This classification shall be assigned on the basis of: 

(a) absorption, metabolism, distribution and excretion studies that indicate the likelihood the substance would be present in potentially toxic levels in breast milk; and/ 

or 

(b) results of one or two generation studies in animals which provide clear evidence 

of adverse effect in the offspring due to transfer in the milk or adverse effect on the 

quality of the milk; and/or 

(c) human evidence indicating a hazard to babies during the lactation period. 

A.7.2.2 BASIS OF CLASSIFICATION

A.7.2.2.1 Classification is made on the 

basis of the criteria, outlined above, an assessment of the total weight of evidence, and 

the use of expert judgment. Classification as 

a reproductive toxicant is intended to be 

used for substances which have an intrinsic, 

500 

§ 1910.1200 29 CFR Ch. XVII (7–1–13 Edition) 

specific property to produce an adverse effect on reproduction and substances should 

not be so classified if such an effect is produced solely as a non-specific secondary consequence of other toxic effects. 

A.7.2.2.2 In the evaluation of toxic effects 

on the developing offspring, it is important 

to consider the possible influence of maternal toxicity. 

A.7.2.2.3 For human evidence to provide 

the primary basis for a Category 1A classification there must be reliable evidence of an 

adverse effect on reproduction in humans. 

Evidence used for classification shall be from 

well conducted epidemiological studies, if 

available, which include the use of appropriate controls, balanced assessment, and 

due consideration of bias or confounding factors. Less rigorous data from studies in humans may be sufficient for a Category 1A 

classification if supplemented with adequate 

data from studies in experimental animals, 

but classification in Category 1B may also be 

considered. 

A.7.2.3 WEIGHT OF EVIDENCE

A.7.2.3.1 Classification as a reproductive 

toxicant is made on the basis of an assessment of the total weight of evidence using 

expert judgment. This means that all available information that bears on the determination of reproductive toxicity is considered together. Included is information such 

as epidemiological studies and case reports 

in humans and specific reproduction studies 

along with sub-chronic, chronic and special 

study results in animals that provide relevant information regarding toxicity to reproductive and related endocrine organs. 

Evaluation of substances chemically related 

to the material under study may also be included, particularly when information on the 

material is scarce. The weight given to the 

available evidence will be influenced by factors such as the quality of the studies, consistency of results, nature and severity of effects, level of statistical significance for 

intergroup differences, number of endpoints 

affected, relevance of route of administration to humans and freedom from bias. Both 

positive and negative results are considered 

together in a weight of evidence determination. However, a single, positive study performed according to good scientific principles and with statistically or biologically 

significant positive results may justify classification (See also A.7.2.2.3). 

A.7.2.3.2 Toxicokinetic studies in animals 

and humans, site of action and mechanism or 

mode of action study results may provide 

relevant information, which could reduce or 

increase concerns about the hazard to human 

health. If it is conclusively demonstrated 

that the clearly identified mechanism or 

mode of action has no relevance for humans 

or when the toxicokinetic differences are so 

marked that it is certain that the hazardous 

property will not be expressed in humans 

then a chemical which produces an adverse 

effect on reproduction in experimental animals should not be classified. 

A.7.2.3.3 In some reproductive toxicity 

studies in experimental animals the only effects recorded may be considered of low or 

minimal toxicological significance and classification may not necessarily be the outcome. These effects include, for example, 

small changes in semen parameters or in the 

incidence of spontaneous defects in the fetus, 

small changes in the proportions of common 

fetal variants such as are observed in skeletal examinations, or in fetal weights, or 

small differences in postnatal developmental 

assessments. 

A.7.2.3.4 Data from animal studies shall 

provide sufficient evidence of specific reproductive toxicity in the absence of other systemic toxic effects. However, if developmental toxicity occurs together with other 

toxic effects in the dam (mother), the potential influence of the generalized adverse effects should be assessed to the extent possible. The preferred approach is to consider 

adverse effects in the embryo/fetus first, and 

then evaluate maternal toxicity, along with 

any other factors which are likely to have 

influenced these effects, as part of the 

weight of evidence. In general, developmental effects that are observed at maternally toxic doses should not be automatically discounted. Discounting developmental 

effects that are observed at maternally toxic 

doses can only be done on a case-by-case 

basis when a causal relationship is established or refuted. 

A.7.2.3.5 If appropriate information is 

available it is important to try to determine 

whether developmental toxicity is due to a 

specific maternally mediated mechanism or 

to a non-specific secondary mechanism, like 

maternal stress and the disruption of homeostasis. Generally, the presence of maternal 

toxicity should not be used to negate findings of embryo/fetal effects, unless it can be 

clearly demonstrated that the effects are 

secondary non-specific effects. This is especially the case when the effects in the offspring are significant, e.g., irreversible effects such as structural malformations. In 

some situations it is reasonable to assume 

that reproductive toxicity is due to a secondary consequence of maternal toxicity and 

discount the effects, for example if the chemical is so toxic that dams fail to thrive and 

there is severe inanition; they are incapable 

of nursing pups; or they are prostrate or 

dying. 

A.7.2.4 MATERNAL TOXICITY

A.7.2.4.1 Development of the offspring 

throughout gestation and during the early 

postnatal stages can be influenced by toxic 

effects in the mother either through non-specific mechanisms related to stress and the 

501 

Occupational Safety and Health Admin., Labor § 1910.1200 

disruption of maternal homeostasis, or by 

specific maternally-mediated mechanisms. 

So, in the interpretation of the developmental outcome to decide classification for 

developmental effects it is important to consider the possible influence of maternal toxicity. This is a complex issue because of uncertainties surrounding the relationship between maternal toxicity and developmental 

outcome. Expert judgment and a weight of 

evidence approach, using all available studies, shall be used to determine the degree of 

influence to be attributed to maternal toxicity when interpreting the criteria for classification for developmental effects. The adverse effects in the embryo/fetus shall be 

first considered, and then maternal toxicity, 

along with any other factors which are likely to have influenced these effects, as weight 

of evidence, to help reach a conclusion about 

classification. 

A.7.2.4.2 Based on pragmatic observation, 

it is believed that maternal toxicity may, 

depending on severity, influence development via non-specific secondary mechanisms, producing effects such as depressed 

fetal weight, retarded ossification, and possibly resorptions and certain malformations 

in some strains of certain species. However, 

the limited numbers of studies which have 

investigated the relationship between developmental effects and general maternal toxicity have failed to demonstrate a consistent, reproducible relationship across species. Developmental effects which occur even 

in the presence of maternal toxicity are considered to be evidence of developmental toxicity, unless it can be unequivocally demonstrated on a case by case basis that the developmental effects are secondary to maternal toxicity. Moreover, classification shall 

be considered where there is a significant 

toxic effect in the offspring, e.g., irreversible 

effects such as structural malformations, 

embryo/fetal lethality, or significant postnatal functional deficiencies. 

A.7.2.4.3 Classification shall not automatically be discounted for chemicals that 

produce developmental toxicity only in association with maternal toxicity, even if a specific maternally-mediated mechanism has 

been demonstrated. In such a case, classification in Category 2 may be considered more 

appropriate than Category 1. However, when 

a chemical is so toxic that maternal death or 

severe inanition results, or the dams (mothers) are prostrate and incapable of nursing 

the pups, it is reasonable to assume that developmental toxicity is produced solely as a 

secondary consequence of maternal toxicity 

and discount the developmental effects. Classification is not necessarily the outcome in 

the case of minor developmental changes, 

e.g., a small reduction in fetal/pup body 

weight or retardation of ossification when 

seen in association with maternal toxicity. 

A.7.2.4.4 Some of the endpoints used to assess maternal toxicity are provided below. 

Data on these endpoints, if available, shall 

be evaluated in light of their statistical or 

biological significance and dose-response relationship. 

(a) Maternal mortality: An increased incidence of mortality among the treated dams 

over the controls shall be considered evidence of maternal toxicity if the increase occurs in a dose-related manner and can be attributed to the systemic toxicity of the test 

material. Maternal mortality greater than 

10% is considered excessive and the data for 

that dose level shall not normally be considered to need further evaluation. 

(b) Mating index (Number of animals with 

seminal plugs or sperm/Number of mated × 

100) 

(c) Fertility index (Number of animals 

with implants/Number of matings × 100) 

(d) Gestation length (If allowed to deliver) 

(e) Body weight and body weight change: 

Consideration of the maternal body weight 

change and/or adjusted (corrected) maternal 

body weight shall be included in the evaluation of maternal toxicity whenever such data 

are available. The calculation of an adjusted 

(corrected) mean maternal body weight 

change, which is the difference between the 

initial and terminal body weight minus the 

gravid uterine weight (or alternatively, the 

sum of the weights of the fetuses), may indicate whether the effect is maternal or intrauterine. In rabbits, the body weight gain 

may not be a useful indicator of maternal 

toxicity because of normal fluctuations in 

body weight during pregnancy. 

(f) Food and water consumption (if relevant): The observation of a significant decrease in the average food or water consumption in treated dams (mothers) compared to 

the control group may be useful in evaluating maternal toxicity, particularly when 

the test material is administered in the diet 

or drinking water. Changes in food or water 

consumption must be evaluated in conjunction with maternal body weights when determining if the effects noted are reflective of 

maternal toxicity or more simply, 

unpalatability of the test material in feed or 

water. 

(g) Clinical evaluations (including clinical 

signs, markers, and hematology and clinical 

chemistry studies): The observation of increased incidence of significant clinical signs 

of toxicity in treated dams (mothers) relative to the control group is useful in evaluating maternal toxicity. If this is to be used 

as the basis for the assessment of maternal 

toxicity, the types, incidence, degree and duration of clinical signs shall be reported in 

the study. Clinical signs of maternal intoxication include, but are not limited to: coma, 

prostration, hyperactivity, loss of righting 

reflex, ataxia, or labored breathing. 

502 

§ 1910.1200 29 CFR Ch. XVII (7–1–13 Edition) 

9 It should be noted that the classification criteria for health hazards usually include a tiered 

scheme in which test data available on the complete mixture are considered as the first tier in 

the evaluation, followed by the applicable bridging principles, and lastly, cut-off values/concentration limits or additivity. However, this approach is not used for Reproductive Toxicity. 

These criteria for Reproductive Toxicity consider the cut-off values/concentration limits as 

the primary tier and allow the classification to 

be modified only on a case-by-case evaluation 

(h) Post-mortem data: Increased incidence 

and/or severity of post-mortem findings may 

be indicative of maternal toxicity. This can 

include gross or microscopic pathological 

findings or organ weight data, including absolute organ weight, organ-to-body weight 

ratio, or organ-to-brain weight ratio. When 

supported by findings of adverse 

histopathological effects in the affected 

organ(s), the observation of a significant 

change in the average weight of suspected 

target organ(s) of treated dams (mothers), 

compared to those in the control group, may 

be considered evidence of maternal toxicity. 

A.7.2.5 ANIMAL AND EXPERIMENTAL DATA

A.7.2.5.1 A number of scientifically validated test methods are available, including 

methods for developmental toxicity testing 

(e.g., OECD Test Guideline 414, ICH Guideline S5A, 1993), methods for peri- and postnatal toxicity testing (e.g., ICH S5B, 1995), 

and methods for one or two-generation toxicity testing (e.g., OECD Test Guidelines 415, 

416) 

A.7.2.5.2 Results obtained from screening 

tests (e.g., OECD Guidelines 421—Reproduction/Developmental Toxicity Screening Test, 

and 422—Combined Repeated Dose Toxicity 

Study with Reproduction/Development Toxicity Screening Test) can also be used to justify classification, although the quality of 

this evidence is less reliable than that obtained through full studies. 

A.7.2.5.3 Adverse effects or changes, seen 

in short- or long-term repeated dose toxicity 

studies, which are judged likely to impair reproductive function and which occur in the 

absence of significant generalized toxicity, 

may be used as a basis for classification, e.g., 

histopathological changes in the gonads. 

A.7.2.5.4 Evidence from in vitro assays, or 

non-mammalian tests, and from analogous 

substances using structure-activity relationship (SAR), can contribute to the procedure 

for classification. In all cases of this nature, 

expert judgment must be used to assess the 

adequacy of the data. Inadequate data shall 

not be used as a primary support for classification. 

A.7.2.5.5 It is preferable that animal studies are conducted using appropriate routes of 

administration which relate to the potential 

route of human exposure. However, in practice, reproductive toxicity studies are commonly conducted using the oral route, and 

such studies will normally be suitable for 

evaluating the hazardous properties of the 

substance with respect to reproductive toxicity. However, if it can be conclusively demonstrated that the clearly identified mechanism or mode of action has no relevance for 

humans or when the toxicokinetic differences are so marked that it is certain that 

the hazardous property will not be expressed 

in humans then a substance which produces 

an adverse effect on reproduction in experimental animals should not be classified. 

A.7.2.5.6 Studies involving routes of administration such as intravenous or 

intraperitoneal injection, which may result 

in exposure of the reproductive organs to unrealistically high levels of the test substance, or elicit local damage to the reproductive organs, e.g., by irritation, must be 

interpreted with extreme caution and on 

their own are not normally the basis for 

classification. 

A.7.2.5.7 There is general agreement about 

the concept of a limit dose, above which the 

production of an adverse effect may be considered to be outside the criteria which lead 

to classification. Some test guidelines specify a limit dose, other test guidelines qualify 

the limit dose with a statement that higher 

doses may be necessary if anticipated human 

exposure is sufficiently high that an adequate margin of exposure would not be 

achieved. Also, due to species differences in 

toxicokinetics, establishing a specific limit 

dose may not be adequate for situations 

where humans are more sensitive than the 

animal model. 

A.7.2.5.8 In principle, adverse effects on 

reproduction seen only at very high dose levels in animal studies (for example doses that 

induce prostration, severe inappetence, excessive mortality) do not normally lead to 

classification, unless other information is 

available, for example, toxicokinetics information indicating that humans may be more 

susceptible than animals, to suggest that 

classification is appropriate. 

A.7.2.5.9 However, specification of the actual ‘‘limit dose’’ will depend upon the test 

method that has been employed to provide 

the test results. 

A.7.3 CLASSIFICATION CRITERIA FOR

MIXTURES 9

A.7.3.1 CLASSIFICATION OF MIXTURES WHEN

DATA ARE AVAILABLE FOR ALL INGREDIENTS

OR ONLY FOR SOME INGREDIENTS OF THE

MIXTURE

A.7.3.1.1 The mixture shall be classified as 

a reproductive toxicant when at least one ingredient has been classified as a Category 1 

503 

Occupational Safety and Health Admin., Labor § 1910.1200 

based on available test data for the mixture as 

a whole. 

or Category 2 reproductive toxicant and is 

present at or above the appropriate cut-off 

value/concentration limit specified in Table 

A.7.1 for Category 1 and 2, respectively. 

A.7.3.1.2 The mixture shall be classified 

for effects on or via lactation when at least 

one ingredient has been classified for effects 

on or via lactation and is present at or above 

the appropriate cut-off value/concentration 

limit specified in Table A.7.1 for the additional category for effects on or via lactation. 

TABLE A.7.1—CUT-OFF VALUES/CONCENTRATION LIMITS OF INGREDIENTS OF A MIXTURE CLASSIFIED

AS REPRODUCTIVE TOXICANTS OR FOR EFFECTS ON OR VIA LACTATION THAT TRIGGER CLASSIFICATION OF THE MIXTURE

Ingredients classified as: 

Cut-off values/concentration limits triggering classification of a mixture as: 

Category 1 reproductive toxicant Category 2 reproductive toxicant Additional category for 

effects on or via lactation 

Category 1 reproductive toxicant ................ ≥0.1% ..........................................

Category 2 reproductive toxicant ................ .......................................... ≥0.1% 

Additional category for effects on or via 

lactation .................................................... .......................................... .......................................... ≥0.1% 

A.7.3.2 CLASSIFICATION OF MIXTURES WHEN

DATA ARE AVAILABLE FOR THE COMPLETE

MIXTURE

Available test data for the mixture as a 

whole may be used for classification on a 

case-by-case basis. In such cases, the test results for the mixture as a whole must be 

shown to be conclusive taking into account 

dose and other factors such as duration, observations and analysis (e.g., statistical 

analysis, test sensitivity) of reproduction 

test systems. 

A.7.3.3 CLASSIFICATION OF MIXTURES WHEN

DATA ARE NOT AVAILABLE FOR THE COMPLETE MIXTURE: BRIDGING PRINCIPLES

A.7.3.3.1 Where the mixture itself has not 

been tested to determine its reproductive 

toxicity, but there are sufficient data on 

both the individual ingredients and similar 

tested mixtures to adequately characterize 

the hazards of the mixture, these data shall 

be used in accordance with the following 

bridging principles as found in paragraph 

A.0.5 of this Appendix: Dilution, Batching, 

and Substantially similar mixtures. 

A.8 SPECIFIC TARGET ORGAN TOXICITY 

SINGLE EXPOSURE 

A.8.1 DEFINITIONS AND GENERAL

CONSIDERATIONS

A.8.1.1 Specific target organ toxicity—single 

exposure, (STOT–SE) means specific, non-lethal target organ toxicity arising from a single exposure to a chemical. All significant 

health effects that can impair function, both 

reversible and irreversible, immediate and/or 

delayed and not specifically addressed in A.1 

to A.7 and A.10 of this Appendix are included. 

Specific target organ toxicity following repeated exposure is classified in accordance 

with SPECIFIC TARGET ORGAN TOXICITY— 

REPEATED EXPOSURE (A.9 of this Appendix) and is therefore not included here. 

A.8.1.2 Classification identifies the chemical as being a specific target organ toxicant 

and, as such, it presents a potential for adverse health effects in people who are exposed to it. 

A.8.1.3 The adverse health effects produced by a single exposure include consistent 

and identifiable toxic effects in humans; or, 

in experimental animals, toxicologically significant changes which have affected the 

function or morphology of a tissue/organ, or 

have produced serious changes to the biochemistry or hematology of the organism, 

and these changes are relevant for human 

health. Human data is the primary source of 

evidence for this hazard class. 

A.8.1.4 Assessment shall take into consideration not only significant changes in a single organ or biological system but also generalized changes of a less severe nature involving several organs. 

A.8.1.5 Specific target organ toxicity can 

occur by any route that is relevant for humans, i.e., principally oral, dermal or inhalation. 

A.8.1.6 The classification criteria for specific organ systemic toxicity single exposure 

are organized as criteria for substances Categories 1 and 2 (See A.8.2.1), criteria for substances Category 3 (See A.8.2.2) and criteria 

for mixtures (See A.8.3). See also Figure 

A.8.1. 

504 

§ 1910.1200 29 CFR Ch. XVII (7–1–13 Edition) 

A.8.2 CLASSIFICATION CRITERIA FOR

SUBSTANCES

A.8.2.1 SUBSTANCES OF CATEGORY 1 AND

CATEGORY 2 

A.8.2.1.1 Substances shall be classified for 

immediate or delayed effects separately, by 

the use of expert judgment on the basis of 

the weight of all evidence available, including the use of recommended guidance values 

(See A.8.2.1.9). Substances shall then be classified in Category 1 or 2, depending upon the 

nature and severity of the effect(s) observed, 

in accordance with Figure A.8.1. 

FIGURE A.8.1—HAZARD CATEGORIES FOR SPECIFIC TARGET ORGAN TOXICITY FOLLOWING SINGLE

EXPOSURE

CATEGORY 1: Substances that have produced significant toxicity in humans, or that, on the 

basis of evidence from studies in experimental animals can be presumed to have the potential to produce significant toxicity in humans following single exposure 

Substances are classified in Category 1 for STOT–SE on the basis of: 

(a) reliable and good quality evidence from human cases or epidemiological studies; or 

(b) observations from appropriate studies in experimental animals in which significant and/or 

severe toxic effects of relevance to human health were produced at generally low exposure 

concentrations. Guidance dose/concentration values are provided below (See A.8.2.1.9) to 

be used as part of weight-of-evidence evaluation. 

CATEGORY 2: Substances that, on the basis of evidence from studies in experimental animals, can be presumed to have the potential to be harmful to human health following single 

exposure 

Substances are classified in Category 2 for STOT–SE on the basis of observations from appropriate studies in experimental animals in which significant toxic effects, of relevance to 

human health, were produced at generally moderate exposure concentrations. Guidance 

dose/concentration values are provided below (See A.8.2.1.9) in order to help in classification. 

In exceptional cases, human evidence can also be used to place a substance in Category 2 

(See A.8.2.1.6). 

CATEGORY 3: Transient target organ effects 

There are target organ effects for which a substance does not meet the criteria to be classified in Categories 1 or 2 indicated above. These are effects which adversely alter human 

function for a short duration after exposure and from which humans may recover in a reasonable period without leaving significant alteration of structure or function. This category 

only includes narcotic effects and respiratory tract irritation. Substances are classified specifically for these effects as discussed in A.8.2.2. 

Note: The primary target organ/system shall be identified where possible, and where this is 

not possible, the substance shall be identified as a general toxicant. The data shall be evaluated and, where possible, shall not include secondary effects (e.g., a hepatotoxicant can 

produce secondary effects in the nervous or gastro-intestinal systems). 

A.8.2.1.2 The relevant route(s) of exposure 

by which the classified substance produces 

damage shall be identified. 

A.8.2.1.3 Classification is determined by 

expert judgment, on the basis of the weight 

of all evidence available including the guidance presented below. 

A.8.2.1.4 Weight of evidence of all available data, including human incidents, epidemiology, and studies conducted in experimental animals is used to substantiate specific target organ toxic effects that merit 

classification. 

A.8.2.1.5 The information required to 

evaluate specific target organ toxicity comes 

either from single exposure in humans (e.g., 

exposure at home, in the workplace or environmentally), or from studies conducted in 

experimental animals. The standard animal 

studies in rats or mice that provide this information are acute toxicity studies which 

can include clinical observations and detailed macroscopic and microscopic examination to enable the toxic effects on target 

tissues/organs to be identified. Results of 

acute toxicity studies conducted in other 

species may also provide relevant information. 

A.8.2.1.6 In exceptional cases, based on expert judgment, it may be appropriate to 

place certain substances with human evidence of target organ toxicity in Category 2: 

(a) when the weight of human evidence is not 

sufficiently convincing to warrant Category 

505 

Occupational Safety and Health Admin., Labor § 1910.1200 

1 classification, and/or (b) based on the nature and severity of effects. Dose/concentration levels in humans shall not be considered 

in the classification and any available evidence from animal studies shall be consistent with the Category 2 classification. In 

other words, if there are also animal data 

available on the substance that warrant Category 1 classification, the chemical shall be 

classified as Category 1. 

A.8.2.1.7 Effects considered to support 

classification for Category 1 and 2 

A.8.2.1.7.1 Classification is supported by 

evidence associating single exposure to the 

substance with a consistent and identifiable 

toxic effect. 

A.8.2.1.7.2 Evidence from human experience/incidents is usually restricted to reports of adverse health consequences, often 

with uncertainty about exposure conditions, 

and may not provide the scientific detail 

that can be obtained from well-conducted 

studies in experimental animals. 

A.8.2.1.7.3 Evidence from appropriate 

studies in experimental animals can furnish 

much more detail, in the form of clinical observations, and macroscopic and microscopic 

pathological examination and this can often 

reveal hazards that may not be life-threatening but could indicate functional impairment. Consequently all available evidence, 

and evidence relevance to human health, 

must be taken into consideration in the classification process. Relevant toxic effects in 

humans and/or animals include, but are not 

limited to: 

(a) Morbidity resulting from single exposure; 

(b) Significant functional changes, more 

than transient in nature, in the respiratory 

system, central or peripheral nervous systems, other organs or other organ systems, 

including signs of central nervous system depression and effects on special senses (e.g., 

sight, hearing and sense of smell); 

(c) Any consistent and significant adverse 

change in clinical biochemistry, hematology, 

or urinalysis parameters; 

(d) Significant organ damage that may be 

noted at necropsy and/or subsequently seen 

or confirmed at microscopic examination; 

(e) Multi-focal or diffuse necrosis, fibrosis 

or granuloma formation in vital organs with 

regenerative capacity; 

(f) Morphological changes that are potentially reversible but provide clear evidence 

of marked organ dysfunction; and, 

(g) Evidence of appreciable cell death (including cell degeneration and reduced cell 

number) in vital organs incapable of regeneration. 

A.8.2.1.8 Effects considered not to support 

classification for Category 1 and 2 

Effects may be seen in humans and/or animals that do not justify classification. Such 

effects include, but are not limited to: 

(a) Clinical observations or small changes 

in bodyweight gain, food consumption or 

water intake that may have some toxicological importance but that do not, by 

themselves, indicate ‘‘significant’’ toxicity; 

(b) Small changes in clinical biochemistry, 

hematology or urinalysis parameters and/or 

transient effects, when such changes or effects are of doubtful or of minimal toxicological importance; 

(c) Changes in organ weights with no evidence of organ dysfunction; 

(d) Adaptive responses that are not considered toxicologically relevant; and, 

(e) Substance-induced species-specific 

mechanisms of toxicity, i.e., demonstrated 

with reasonable certainty to be not relevant 

for human health, shall not justify classification. 

A.8.2.1.9 Guidance values to assist with 

classification based on the results obtained 

from studies conducted in experimental animals for Category 1 and 2 

A.8.2.1.9.1 In order to help reach a decision about whether a substance shall be classified or not, and to what degree it shall be 

classified (Category 1 vs. Category 2), dose/ 

concentration ‘‘guidance values’’ are provided for consideration of the dose/concentration which has been shown to produce 

significant health effects. The principal argument for proposing such guidance values is 

that all chemicals are potentially toxic and 

there has to be a reasonable dose/concentration above which a degree of toxic effect is 

acknowledged. 

A.8.2.1.9.2 Thus, in animal studies, when 

significant toxic effects are observed that indicate classification, consideration of the 

dose/concentration at which these effects 

were seen, in relation to the suggested guidance values, provides useful information to 

help assess the need to classify (since the 

toxic effects are a consequence of the hazardous property(ies) and also the dose/concentration). 

A.8.2.1.9.3 The guidance value (C) ranges 

for single-dose exposure which has produced 

a significant non-lethal toxic effect are those 

applicable to acute toxicity testing, as indicated in Table A.8.1. 

TABLE A.8.1—GUIDANCE VALUE RANGES FOR SINGLE-DOSE EXPOSURES

Route of exposure Units 

Guidance value ranges for: 

Category 1 Category 2 Category 3 

Oral (rat) ...................... mg/kg body weight ....... C ≤300 ......................... 2000 ≥C >300 .............. Guidance values do not 

apply. 

506 

§ 1910.1200 29 CFR Ch. XVII (7–1–13 Edition) 

TABLE A.8.1—GUIDANCE VALUE RANGES FOR SINGLE-DOSE EXPOSURES—Continued 

Route of exposure Units 

Guidance value ranges for: 

Category 1 Category 2 Category 3 

Dermal (rat or rabbit) ... mg/kg body weight ....... C ≤1,000 ...................... 2000 ≥C >1,000.

Inhalation (rat) gas ....... ppmV/4h ....................... C ≤2,500 ...................... 20,000 ≥C >2,500.

Inhalation (rat) vapor ... mg/1/4h ........................ C ≤10 ........................... 20 ≥C >10.

Inhalation (rat) dust/ 

mist/fume.

mg/l/4h ......................... C ≤1.0 .......................... 5.0 ≥C >1.0.

A.8.2.1.9.4 The guidance values and ranges 

mentioned in Table A.8.1 are intended only 

for guidance purposes, i.e., to be used as part 

of the weight of evidence approach, and to 

assist with decisions about classification. 

They are not intended as strict demarcation 

values. Guidance values are not provided for 

Category 3 since this classification is primarily based on human data; animal data 

may be included in the weight of evidence 

evaluation. 

A.8.2.1.9.5 Thus, it is feasible that a specific profile of toxicity occurs at a dose/concentration below the guidance value, e.g., 

<2000 mg/kg body weight by the oral route, 

however the nature of the effect may result 

in the decision not to classify. Conversely, a 

specific profile of toxicity may be seen in 

animal studies occurring at above a guidance 

value, e.g., ≥2000 mg/kg body weight by the 

oral route, and in addition there is supplementary information from other sources, 

e.g., other single dose studies, or human case 

experience, which supports a conclusion 

that, in view of the weight of evidence, classification is the prudent action to take. 

A.8.2.1.10 Other considerations 

A.8.2.1.10.1 When a substance is characterized only by use of animal data the classification process includes reference to dose/ 

concentration guidance values as one of the 

elements that contribute to the weight of 

evidence approach. 

A.8.2.1.10.2 When well-substantiated 

human data are available showing a specific 

target organ toxic effect that can be reliably 

attributed to single exposure to a substance, 

the substance shall be classified. Positive 

human data, regardless of probable dose, predominates over animal data. Thus, if a substance is unclassified because specific target 

organ toxicity observed was considered not 

relevant or significant to humans, if subsequent human incident data become available 

showing a specific target organ toxic effect, 

the substance shall be classified. 

A.8.2.1.10.3 A substance that has not been 

tested for specific target organ toxicity 

shall, where appropriate, be classified on the 

basis of data from a scientifically validated 

structure activity relationship and expert 

judgment-based extrapolation from a structural analogue that has previously been classified together with substantial support from 

consideration of other important factors 

such as formation of common significant metabolites. 

A.8.2.2 SUBSTANCES OF CATEGORY 3 

A.8.2.2.1 Criteria for respiratory tract irritation 

The criteria for classifying substances as 

Category 3 for respiratory tract irritation 

are: 

(a) Respiratory irritant effects (characterized by localized redness, edema, pruritis 

and/or pain) that impair function with symptoms such as cough, pain, choking, and 

breathing difficulties are included. It is recognized that this evaluation is based primarily on human data; 

(b) Subjective human observations supported by objective measurements of clear 

respiratory tract irritation (RTI) (e.g., 

electrophysiological responses, biomarkers 

of inflammation in nasal or bronchoalveolar 

lavage fluids); 

(c) The symptoms observed in humans 

shall also be typical of those that would be 

produced in the exposed population rather 

than being an isolated idiosyncratic reaction 

or response triggered only in individuals 

with hypersensitive airways. Ambiguous reports simply of ‘‘irritation’’ should be excluded as this term is commonly used to describe a wide range of sensations including 

those such as smell, unpleasant taste, a tickling sensation, and dryness, which are outside the scope of classification for respiratory tract irritation; 

(d) There are currently no scientifically 

validated animal tests that deal specifically 

with RTI; however, useful information may 

be obtained from the single and repeated inhalation toxicity tests. For example, animal 

studies may provide useful information in 

terms of clinical signs of toxicity (dyspnoea, 

rhinitis etc) and histopathology (e.g., hyperemia, edema, minimal inflammation, thickened mucous layer) which are reversible and 

may be reflective of the characteristic clinical symptoms described above. Such animal 

studies can be used as part of weight of evidence evaluation; and, 

(e) This special classification will occur 

only when more severe organ effects including the respiratory system are not observed 

507 

Occupational Safety and Health Admin., Labor § 1910.1200 

as those effects would require a higher classification. 

A.8.2.2.2 Criteria for narcotic effects 

The criteria for classifying substances in 

Category 3 for narcotic effects are: 

(a) Central nervous system depression including narcotic effects in humans such as 

drowsiness, narcosis, reduced alertness, loss 

of reflexes, lack of coordination, and vertigo 

are included. These effects can also be manifested as severe headache or nausea, and can 

lead to reduced judgment, dizziness, irritability, fatigue, impaired memory function, 

deficits in perception and coordination, reaction time, or sleepiness; and, 

(b) Narcotic effects observed in animal 

studies may include lethargy, lack of coordination righting reflex, narcosis, and ataxia. 

If these effects are not transient in nature, 

then they shall be considered for classification as Category 1 or 2. 

A.8.3 CLASSIFICATION CRITERIA FOR

MIXTURES

A.8.3.1 Mixtures are classified using the 

same criteria as for substances, or alternatively as described below. As with substances, mixtures may be classified for specific target organ toxicity following single 

exposure, repeated exposure, or both. 

A.8.3.2 CLASSIFICATION OF MIXTURES WHEN

DATA ARE AVAILABLE FOR THE COMPLETE

MIXTURE

When reliable and good quality evidence 

from human experience or appropriate studies in experimental animals, as described in 

the criteria for substances, is available for 

the mixture, then the mixture shall be classified by weight of evidence evaluation of 

this data. Care shall be exercised in evaluating data on mixtures, that the dose, duration, observation or analysis, do not render 

the results inconclusive. 

A.8.3.3 CLASSIFICATION OF MIXTURES WHEN

DATA ARE NOT AVAILABLE FOR THE COMPLETE MIXTURE: BRIDGING PRINCIPLES

A.8.3.3.1 Where the mixture itself has not 

been tested to determine its specific target 

organ toxicity, but there are sufficient data 

on both the individual ingredients and similar tested mixtures to adequately characterize the hazards of the mixture, these data 

shall be used in accordance with the following bridging principles as found in paragraph A.0.5 of this Appendix: Dilution, 

Batching, Concentration of mixtures, Interpolation within one toxicity category, Substantially similar mixtures, or Aerosols. 

A.8.3.4 CLASSIFICATION OF MIXTURES WHEN

DATA ARE AVAILABLE FOR ALL INGREDIENTS

OR ONLY FOR SOME INGREDIENTS OF THE

MIXTURE

A.8.3.4.1 Where there is no reliable evidence or test data for the specific mixture 

itself, and the bridging principles cannot be 

used to enable classification, then classification of the mixture is based on the classification of the ingredient substances. In this 

case, the mixture shall be classified as a specific target organ toxicant (specific organ 

specified), following single exposure, repeated exposure, or both when at least one 

ingredient has been classified as a Category 

1 or Category 2 specific target organ toxicant 

and is present at or above the appropriate 

cut-off value/concentration limit specified in 

Table A.8.2 for Categories 1 and 2, respectively. 

TABLE A.8.2—CUT-OFF VALUES/CONCENTRATION LIMITS OF INGREDIENTS OF A MIXTURE CLASSIFIED

AS A SPECIFIC TARGET ORGAN TOXICANT THAT WOULD TRIGGER CLASSIFICATION OF THE MIXTURE

AS CATEGORY 1 OR 2 

Ingredient classified as: 

Cut-off values/concentration 

limits triggering classification of a mixture as: 

Category 1 Category 2 

Category 1 Target organ toxicant ............................................................................................... ≥1.0% 

Category 2 Target organ toxicant ............................................................................................... ........................ ≥1.0% 

A.8.3.4.2 These cut-off values and consequent classifications shall be applied 

equally and appropriately to both single- and 

repeated-dose target organ toxicants. 

A.8.3.4.3 Mixtures shall be classified for 

either or both single and repeated dose toxicity independently. 

A.8.3.4.4 Care shall be exercised when 

toxicants affecting more than one organ system are combined that the potentiation or 

synergistic interactions are considered, because certain substances can cause target 

organ toxicity at <1% concentration when 

other ingredients in the mixture are known 

to potentiate its toxic effect. 

A.8.3.4.5 Care shall be exercised when extrapolating the toxicity of a mixture that 

contains Category 3 ingredient(s). A cut-off 

value/concentration limit of 20%, considered 

as an additive of all Category 3 ingredients 

for each hazard endpoint, is appropriate; 

however, this cut-off value/concentration 

508 

§ 1910.1200 29 CFR Ch. XVII (7–1–13 Edition) 

limit may be higher or lower depending on 

the Category 3 ingredient(s) involved and the 

fact that some effects such as respiratory 

tract irritation may not occur below a certain concentration while other effects such 

as narcotic effects may occur below this 20% 

value. Expert judgment shall be exercised. 

Respiratory tract irritation and narcotic effects are to be evaluated separately in accordance with the criteria given in A.8.2.2. 

When conducting classifications for these 

hazards, the contribution of each ingredient 

should be considered additive, unless there is 

evidence that the effects are not additive. 

A.9 SPECIFIC TARGET ORGAN TOXICITY 

REPEATED OR PROLONGED EXPOSURE 

A.9.1 DEFINITIONS AND GENERAL

CONSIDERATIONS

A.9.1.1 Specific target organ toxicity—repeated exposure (STOT–RE) means specific 

target organ toxicity arising from repeated 

exposure to a substance or mixture. All significant health effects that can impair function, both reversible and irreversible, immediate and/or delayed and not specifically addressed in A.1 to A.7 and A.10 of this Appendix are included. Specific target organ toxicity following a single-event exposure is 

classified in accordance with SPECIFIC TARGET ORGAN TOXICITY—SINGLE EXPOSURE 

(A.8 of this Appendix) and is therefore not included here. 

A.9.1.2 Classification identifies the substance or mixture as being a specific target 

organ toxicant and, as such, it may present 

a potential for adverse health effects in people who are exposed to it. 

A.9.1.3 These adverse health effects produced by repeated exposure include consistent and identifiable toxic effects in humans, or, in experimental animals, 

toxicologically significant changes which 

have affected the function or morphology of 

a tissue/organ, or have produced serious 

changes to the biochemistry or hematology 

of the organism and these changes are relevant for human health. Human data will be 

the primary source of evidence for this hazard class. 

A.9.1.4 Assessment shall take into consideration not only significant changes in a single organ or biological system but also generalized changes of a less severe nature involving several organs. 

A.9.1.5 Specific target organ toxicity can 

occur by any route that is relevant for humans, e.g., principally oral, dermal or inhalation. 

A.9.2 CLASSIFICATION CRITERIA FOR

SUBSTANCES

A.9.2.1 Substances shall be classified as 

STOT–RE by expert judgment on the basis of 

the weight of all evidence available, including the use of recommended guidance values 

which take into account the duration of exposure and the dose/concentration which produced the effect(s), (See A.9.2.9). Substances 

shall be placed in one of two categories, depending upon the nature and severity of the 

effect(s) observed, in accordance with Figure 

A.9.1. 

FIGURE A.9.1—HAZARD CATEGORIES FOR SPECIFIC TARGET ORGAN TOXICITY FOLLOWING REPEATED

EXPOSURE

CATEGORY 1: Substances that have produced significant toxicity in humans, or that, on the 

basis of evidence from studies in experimental animals can be presumed to have the potential to produce significant toxicity in humans following repeated or prolonged exposure 

Substances are classified in Category 1 for specific target organ toxicity (repeated 

exposure) on the basis of: 

(a) reliable and good quality evidence from human cases or epidemiological studies; 

or, 

(b) observations from appropriate studies in experimental animals in which significant 

and/or severe toxic effects, of relevance to human health, were produced at generally low exposure concentrations. Guidance dose/concentration values are provided below (See A.9.2.9) to be used as part of weight-of-evidence evaluation. 

CATEGORY 2: Substances that, on the basis of evidence from studies in experimental animals can be presumed to have the potential to be harmful to human health following repeated or prolonged exposure 

Substances are classified in Category 2 for specific target organ toxicity (repeated 

exposure) on the basis of observations from appropriate studies in experimental 

animals in which significant toxic effects, of relevance to human health, were produced at generally moderate exposure concentrations. Guidance dose/concentration values are provided below (See A.9.2.9) in order to help in classification. 

In exceptional cases human evidence can also be used to place a substance in Category 2 (See A.9.2.6). 

509 

Occupational Safety and Health Admin., Labor § 1910.1200 

FIGURE A.9.1—HAZARD CATEGORIES FOR SPECIFIC TARGET ORGAN TOXICITY FOLLOWING REPEATED

EXPOSURE—Continued 

Note: The primary target organ/system shall be identified where possible, or the substance 

shall be identified as a general toxicant. The data shall be carefully evaluated and, where 

possible, shall not include secondary effects (e.g., a hepatotoxicant can produce secondary 

effects in the nervous or gastro-intestinal systems). 

A.9.2.2 The relevant route of exposure by 

which the classified substance produces damage shall be identified. 

A.9.2.3 Classification is determined by expert judgment, on the basis of the weight of 

all evidence available including the guidance 

presented below. 

A.9.2.4 Weight of evidence of all data, including human incidents, epidemiology, and 

studies conducted in experimental animals, 

is used to substantiate specific target organ 

toxic effects that merit classification. 

A.9.2.5 The information required to evaluate specific target organ toxicity comes either from repeated exposure in humans, e.g., 

exposure at home, in the workplace or environmentally, or from studies conducted in 

experimental animals. The standard animal 

studies in rats or mice that provide this information are 28 day, 90 day or lifetime studies (up to 2 years) that include 

hematological, clinico-chemical and detailed 

macroscopic and microscopic examination to 

enable the toxic effects on target tissues/organs to be identified. Data from repeat dose 

studies performed in other species may also 

be used. Other long-term exposure studies, 

e.g., for carcinogenicity, neurotoxicity or reproductive toxicity, may also provide evidence of specific target organ toxicity that 

could be used in the assessment of classification. 

A.9.2.6 In exceptional cases, based on expert judgment, it may be appropriate to 

place certain substances with human evidence of specific target organ toxicity in 

Category 2: (a) when the weight of human 

evidence is not sufficiently convincing to 

warrant Category 1 classification, and/or (b) 

based on the nature and severity of effects. 

Dose/concentration levels in humans shall 

not be considered in the classification and 

any available evidence from animal studies 

shall be consistent with the Category 2 classification. In other words, if there are also 

animal data available on the substance that 

warrant Category 1 classification, the substance shall be classified as Category 1. 

A.9.2.7 EFFECTS CONSIDERED TO SUPPORT

CLASSIFICATION

A.9.2.7.1 Classification is supported by reliable evidence associating repeated exposure 

to the substance with a consistent and identifiable toxic effect. 

A.9.2.7.2 Evidence from human experience/ 

incidents is usually restricted to reports of 

adverse health consequences, often with uncertainty about exposure conditions, and 

may not provide the scientific detail that 

can be obtained from well-conducted studies 

in experimental animals. 

A.9.2.7.3 Evidence from appropriate studies in experimental animals can furnish 

much more detail, in the form of clinical observations, hematology, clinical chemistry, 

macroscopic and microscopic pathological 

examination and this can often reveal hazards that may not be life-threatening but 

could indicate functional impairment. Consequently all available evidence, and relevance to human health, must be taken into 

consideration in the classification process. 

Relevant toxic effects in humans and/or animals include, but are not limited to: 

(a) Morbidity or death resulting from repeated or long-term exposure. Morbidity or 

death may result from repeated exposure, 

even to relatively low doses/concentrations, 

due to bioaccumulation of the substance or 

its metabolites, or due to the overwhelming 

of the de-toxification process by repeated exposure; 

(b) Significant functional changes in the 

central or peripheral nervous systems or 

other organ systems, including signs of central nervous system depression and effects 

on special senses (e.g., sight, hearing and 

sense of smell); 

(c) Any consistent and significant adverse 

change in clinical biochemistry, hematology, 

or urinalysis parameters; 

(d) Significant organ damage that may be 

noted at necropsy and/or subsequently seen 

or confirmed at microscopic examination; 

(e) Multi-focal or diffuse necrosis, fibrosis 

or granuloma formation in vital organs with 

regenerative capacity; 

(f) Morphological changes that are potentially reversible but provide clear evidence 

of marked organ dysfunction (e.g., severe 

fatty change in the liver); and, 

(g) Evidence of appreciable cell death (including cell degeneration and reduced cell 

number) in vital organs incapable of regeneration. 

510 

§ 1910.1200 29 CFR Ch. XVII (7–1–13 Edition) 

A.9.2.8 EFFECTS CONSIDERED NOT TO

SUPPORT CLASSIFICATION

Effects may be seen in humans and/or animals that do not justify classification. Such 

effects include, but are not limited to: 

(a) Clinical observations or small changes 

in bodyweight gain, food consumption or 

water intake that may have some toxicological importance but that do not, by 

themselves, indicate ‘‘significant’’ toxicity; 

(b) Small changes in clinical biochemistry, 

hematology or urinalysis parameters and/or 

transient effects, when such changes or effects are of doubtful or of minimal toxicological importance; 

(c) Changes in organ weights with no evidence of organ dysfunction; 

(d) Adaptive responses that are not considered toxicologically relevant; 

(e) Substance-induced species-specific 

mechanisms of toxicity, i.e., demonstrated 

with reasonable certainty to be not relevant 

for human health, shall not justify classification. 

A.9.2.9 GUIDANCE VALUES TO ASSIST WITH

CLASSIFICATION BASED ON THE RESULTS OBTAINED FROM STUDIES CONDUCTED IN EXPERIMENTAL ANIMALS

A.9.2.9.1 In studies conducted in experimental animals, reliance on observation of 

effects alone, without reference to the duration of experimental exposure and dose/concentration, omits a fundamental concept of 

toxicology, i.e., all substances are potentially toxic, and what determines the toxicity is a function of the dose/concentration 

and the duration of exposure. In most studies 

conducted in experimental animals the test 

guidelines use an upper limit dose value. 

A.9.2.9.2 In order to help reach a decision 

about whether a substance shall be classified 

or not, and to what degree it shall be classified (Category 1 vs. Category 2), dose/concentration ‘‘guidance values’’ are provided in 

Table A.9.1 for consideration of the dose/concentration which has been shown to produce 

significant health effects. The principal argument for proposing such guidance values is 

that all chemicals are potentially toxic and 

there has to be a reasonable dose/concentration above which a degree of toxic effect is 

acknowledged. Also, repeated-dose studies 

conducted in experimental animals are designed to produce toxicity at the highest 

dose used in order to optimize the test objective and so most studies will reveal some 

toxic effect at least at this highest dose. 

What is therefore to be decided is not only 

what effects have been produced, but also at 

what dose/concentration they were produced 

and how relevant is that for humans. 

A.9.2.9.3 Thus, in animal studies, when 

significant toxic effects are observed that indicate classification, consideration of the duration of experimental exposure and the 

dose/concentration at which these effects 

were seen, in relation to the suggested guidance values, provides useful information to 

help assess the need to classify (since the 

toxic effects are a consequence of the hazardous property(ies) and also the duration of 

exposure and the dose/concentration). 

A.9.2.9.4 The decision to classify at all can 

be influenced by reference to the dose/concentration guidance values at or below which 

a significant toxic effect has been observed. 

A.9.2.9.5 The guidance values refer to effects seen in a standard 90-day toxicity study 

conducted in rats. They can be used as a 

basis to extrapolate equivalent guidance values for toxicity studies of greater or lesser 

duration, using dose/exposure time extrapolation similar to Haber’s rule for inhalation, 

which states essentially that the effective 

dose is directly proportional to the exposure 

concentration and the duration of exposure. 

The assessment should be done on a case-bycase basis; for example, for a 28-day study 

the guidance values below would be increased by a factor of three. 

A.9.2.9.6 Thus for Category 1 classification, significant toxic effects observed in a 

90-day repeated-dose study conducted in experimental animals and seen to occur at or 

below the (suggested) guidance values (C) as 

indicated in Table A.9.1 would justify classification: 

TABLE A.9.1—GUIDANCE VALUES TO ASSIST IN CATEGORY 1 CLASSIFICATION

[Applicable to a 90-day study] 

Route of exposure Units Guidance values 

(dose/concentration) 

Oral (rat) .................................................................. mg/kg body weight/day ........................................... C ≤10. 

Dermal (rat or rabbit) ............................................... mg/kg body weight/day ........................................... C ≤20. 

Inhalation (rat) gas ................................................... ppmV/6h/day ........................................................... C ≤50. 

Inhalation (rat) vapor ............................................... mg/liter/6h/day ......................................................... C ≤0.2. 

Inhalation (rat) dust/mist/fume ................................. mg/liter/6h/day ......................................................... C ≤0.02. 

A.9.2.9.7 For Category 2 classification, 

significant toxic effects observed in a 90-day 

repeated-dose study conducted in experimental animals and seen to occur within the 

511 

Occupational Safety and Health Admin., Labor § 1910.1200 

(suggested) guidance value ranges as indicated in Table A.9.2 would justify classification: 

TABLE A.9.2—GUIDANCE VALUES TO ASSIST IN CATEGORY 2 CLASSIFICATION

[Applicable to a 90-day study] 

Route of exposure Units Guidance values 

(dose/concentration) 

Oral (rat) .................................................................. mg/kg body weight/day ........................................... 10 <C ≤100. 

Dermal (rat or rabbit) ............................................... mg/kg body weight/day ........................................... 20 <C ≤200. 

Inhalation (rat) gas ................................................... ppmV/6h/day ........................................................... 50 <C ≤250. 

Inhalation (rat) vapor ............................................... mg/liter/6h/day ......................................................... 0.2 <C ≤1.0. 

Inhalation (rat) dust/mist/fume ................................. mg/liter/6h/day ......................................................... 0.02 <C ≤0.2. 

A.9.2.9.8 The guidance values and ranges 

mentioned in A.2.9.9.6 and A.2.9.9.7 are intended only for guidance purposes, i.e., to be 

used as part of the weight of evidence approach, and to assist with decisions about 

classification. They are not intended as 

strict demarcation values. 

A.9.2.9.9 Thus, it is possible that a specific 

profile of toxicity occurs in repeat-dose animal studies at a dose/concentration below 

the guidance value, e.g., <100 mg/kg body 

weight/day by the oral route, however the 

nature of the effect, e.g., nephrotoxicity seen 

only in male rats of a particular strain 

known to be susceptible to this effect, may 

result in the decision not to classify. Conversely, a specific profile of toxicity may be 

seen in animal studies occurring at above a 

guidance value, e.g., ≥100 mg/kg body weight/ 

day by the oral route, and in addition there 

is supplementary information from other 

sources, e.g., other long-term administration 

studies, or human case experience, which 

supports a conclusion that, in view of the 

weight of evidence, classification is prudent. 

A.9.2.10 OTHER CONSIDERATIONS

A.9.2.10.1 When a substance is characterized only by use of animal data the classification process includes reference to dose/ 

concentration guidance values as one of the 

elements that contribute to the weight of 

evidence approach. 

A.9.2.10.2 When well-substantiated human 

data are available showing a specific target 

organ toxic effect that can be reliably attributed to repeated or prolonged exposure to a 

substance, the substance shall be classified. 

Positive human data, regardless of probable 

dose, predominates over animal data. Thus, 

if a substance is unclassified because no specific target organ toxicity was seen at or 

below the dose/concentration guidance value 

for animal testing, if subsequent human incident data become available showing a specific target organ toxic effect, the substance 

shall be classified. 

A.9.2.10.3 A substance that has not been 

tested for specific target organ toxicity may 

in certain instances, where appropriate, be 

classified on the basis of data from a scientifically validated structure activity relationship and expert judgment-based extrapolation from a structural analogue that has 

previously been classified together with substantial support from consideration of other 

important factors such as formation of common significant metabolites. 

A.9.3 CLASSIFICATION CRITERIA FOR

MIXTURES

A.9.3.1 Mixtures are classified using the 

same criteria as for substances, or alternatively as described below. As with substances, mixtures may be classified for specific target organ toxicity following single 

exposure, repeated exposure, or both. 

A.9.3.2 CLASSIFICATION OF MIXTURES WHEN

DATA ARE AVAILABLE FOR THE COMPLETE

MIXTURE

When reliable and good quality evidence 

from human experience or appropriate studies in experimental animals, as described in 

the criteria for substances, is available for 

the mixture, then the mixture shall be classified by weight of evidence evaluation of 

these data. Care shall be exercised in evaluating data on mixtures, that the dose, duration, observation or analysis, do not render 

the results inconclusive. 

A.9.3.3 CLASSIFICATION OF MIXTURES WHEN

DATA ARE NOT AVAILABLE FOR THE COMPLETE MIXTURE: BRIDGING PRINCIPLES

A.9.3.3.1 Where the mixture itself has not 

been tested to determine its specific target 

organ toxicity, but there are sufficient data 

on both the individual ingredients and similar tested mixtures to adequately characterize the hazards of the mixture, these data 

shall be used in accordance with the following bridging principles as found in paragraph A.0.5 of this Appendix: Dilution; 

Batching; Concentration of mixtures; Interpolation within one toxicity category; Substantially similar mixtures; and Aerosols. 

512 

§ 1910.1200 29 CFR Ch. XVII (7–1–13 Edition) 

A.9.3.4 CLASSIFICATION OF MIXTURES WHEN

DATA ARE AVAILABLE FOR ALL INGREDIENTS

OR ONLY FOR SOME INGREDIENTS OF THE

MIXTURE

A.9.3.4.1 Where there is no reliable evidence or test data for the specific mixture 

itself, and the bridging principles cannot be 

used to enable classification, then classification of the mixture is based on the classification of the ingredient substances. In this 

case, the mixture shall be classified as a specific target organ toxicant (specific organ 

specified), following single exposure, repeated exposure, or both when at least one 

ingredient has been classified as a Category 

1 or Category 2 specific target organ toxicant 

and is present at or above the appropriate 

cut-off value/concentration limit specified in 

Table A.9.3 for Category 1 and 2 respectively. 

TABLE A.9.3—CUT-OFF VALUE/CONCENTRATION LIMITS OF INGREDIENTS OF A MIXTURE CLASSIFIED

AS A SPECIFIC TARGET ORGAN TOXICANT THAT WOULD TRIGGER CLASSIFICATION OF THE MIXTURE

AS CATEGORY 1 OR 2 

Ingredient classified as: 

Cut-off values/concentration 

limits triggering classification of 

a 

mixture as: 

Category 1 Category 2 

Category 1 Target organ toxicant ............................................................................................... ≥1.0% 

Category 2 Target organ toxicant ............................................................................................... ........................ ≥1.0% 

A.9.3.4.2 These cut-off values and consequent classifications shall be applied 

equally and appropriately to both single- and 

repeated-dose target organ toxicants. 

A.9.3.4.3 Mixtures shall be classified for 

either or both single- and repeated-dose toxicity independently. 

A.9.3.4.4 Care shall be exercised when 

toxicants affecting more than one organ system are combined that the potentiation or 

synergistic interactions are considered, because certain substances can cause specific 

target organ toxicity at <1% concentration 

when other ingredients in the mixture are 

known to potentiate its toxic effect. 

A.10 ASPIRATION HAZARD 

A.10.1 DEFINITIONS AND GENERAL AND

SPECIFIC CONSIDERATIONS

A.10.1.1 Aspiration means the entry of a 

liquid or solid chemical directly through the 

oral or nasal cavity, or indirectly from vomiting, into the trachea and lower respiratory 

system. 

A.10.1.2 Aspiration toxicity includes severe acute effects such as chemical pneumonia, varying degrees of pulmonary injury 

or death following aspiration. 

A.10.1.3 Aspiration is initiated at the moment of inspiration, in the time required to 

take one breath, as the causative material 

lodges at the crossroad of the upper respiratory and digestive tracts in the 

laryngopharyngeal region. 

A.10.1.4 Aspiration of a substance or mixture can occur as it is vomited following ingestion. This may have consequences for labeling, particularly where, due to acute toxicity, a recommendation may be considered 

to induce vomiting after ingestion. However, 

if the substance/mixture also presents an aspiration toxicity hazard, the recommendation to induce vomiting may need to be 

modified. 

A.10.1.5 SPECIFIC CONSIDERATIONS

A.10.1.5.1 The classification criteria refer 

to kinematic viscosity. The following provides the conversion between dynamic and 

kinematic viscosity: 

A.10.1.5.2 Although the definition of aspiration in A.10.1.1 includes the entry of solids 

into the respiratory system, classification 

according to (b) in table A.10.1 for Category 

1 is intended to apply to liquid substances 

and mixtures only. 

A.10.1.5.3 Classification of aerosol/mist 

products. 

Aerosol and mist products are usually dispensed in containers such as self-pressurized 


ER26MR12.130</MATH>
513 

Occupational Safety and Health Admin., Labor § 1910.1200 

containers, trigger and pump sprayers. Classification for these products shall be considered if their use may form a pool of product 

in the mouth, which then may be aspirated. 

If the mist or aerosol from a pressurized container is fine, a pool may not be formed. On 

the other hand, if a pressurized container 

dispenses product in a stream, a pool may be 

formed that may then be aspirated. Usually, 

the mist produced by trigger and pump 

sprayers is coarse and therefore, a pool may 

be formed that then may be aspirated. When 

the pump mechanism may be removed and 

contents are available to be swallowed then 

the classification of the products should be 

considered. 

A.10.2 CLASSIFICATION CRITERIA FOR

SUBSTANCES

TABLE A.10.1—CRITERIA FOR ASPIRATION TOXICITY

Category Criteria 

Category 1: Chemicals known to cause human aspiration toxicity hazards or to be regarded as if they cause human aspiration toxicity hazard.

A substance shall be classified in Category 1: 

(a) If reliable and good quality human evidence indicates 

that it causes aspiration toxicity (See note); or 

(b) If it is a hydrocarbon and has a kinematic viscosity 

≤20.5 mm2/s, measured at 40 °C. 

Note: Examples of substances included in Category 1 are certain hydrocarbons, turpentine and pine oil. 

A.10.3 CLASSIFICATION CRITERIA FOR

MIXTURES

A.10.3.1 CLASSIFICATION WHEN DATA ARE

AVAILABLE FOR THE COMPLETE MIXTURE

A mixture shall be classified in Category 1 

based on reliable and good quality human 

evidence. 

A.10.3.2 CLASSIFICATION OF MIXTURES WHEN

DATA ARE NOT AVAILABLE FOR THE COMPLETE MIXTURE: BRIDGING PRINCIPLES

A.10.3.2.1 Where the mixture itself has not 

been tested to determine its aspiration toxicity, but there are sufficient data on both 

the individual ingredients and similar tested 

mixtures to adequately characterize the hazard of the mixture, these data shall be used 

in accordance with the following bridging 

principles as found in paragraph A.0.5 of this 

Appendix: Dilution; Batching; Concentration 

of mixtures; Interpolation within one toxicity category; and Substantially similar 

mixtures. For application of the dilution 

bridging principle, the concentration of aspiration toxicants shall not be less than 10%. 

A.10.3.3 CLASSIFICATION OF MIXTURES WHEN

DATA ARE AVAILABLE FOR ALL INGREDIENTS

OR ONLY FOR SOME INGREDIENTS OF THE

MIXTURE

A.10.3.3.1 A mixture which contains ≥10% 

of an ingredient or ingredients classified in 

Category 1, and has a kinematic viscosity 

≤20.5 mm2/s, measured at 40 °C, shall be classified in Category 1. 

A.10.3.3.2 In the case of a mixture which 

separates into two or more distinct layers, 

one of which contains ≥10% of an ingredient 

or ingredients classified in Category 1 and 

has a kinematic viscosity ≤20.5 mm2/s, measured at 40 °C, then the entire mixture shall 

be classified in Category 1. 

APPENDIX B TO §1910.1200—PHYSICAL CRITERIA

(MANDATORY) 

B.1 EXPLOSIVES 

B.1.1 DEFINITIONS AND GENERAL

CONSIDERATIONS

B.1.1.1 An explosive chemical is a solid or 

liquid chemical which is in itself capable by 

chemical reaction of producing gas at such a 

temperature and pressure and at such a 

speed as to cause damage to the surroundings. Pyrotechnic chemicals are included even when they do not evolve gases. 

A pyrotechnic chemical is a chemical designed to produce an effect by heat, light, 

sound, gas or smoke or a combination of 

these as the result of non-detonative selfsustaining exothermic chemical reactions. 

An explosive item is an item containing one 

or more explosive chemicals. 

A pyrotechnic item is an item containing 

one or more pyrotechnic chemicals. 

An unstable explosive is an explosive which 

is thermally unstable and/or too sensitive for 

normal handling, transport, or use. 

An intentional explosive is a chemical or 

item which is manufactured with a view to 

produce a practical explosive or pyrotechnic 

effect. 

B.1.1.2 The class of explosives comprises: 

(a) Explosive chemicals; 

(b) Explosive items, except devices containing explosive chemicals in such quantity 

or of such a character that their inadvertent 

or accidental ignition or initiation shall not 

cause any effect external to the device either 

by projection, fire, smoke, heat or loud 

noise; and 

(c) Chemicals and items not included under 

(a) and (b) above which are manufactured 

with the view to producing a practical explosive or pyrotechnic effect. 

514 

§ 1910.1200 29 CFR Ch. XVII (7–1–13 Edition) 

B.1.2 CLASSIFICATION CRITERIA

Chemicals and items of this class shall be 

classified as unstable explosives or shall be 

assigned to one of the following six divisions 

depending on the type of hazard they 

present: 

(a) Division 1.1—Chemicals and items 

which have a mass explosion hazard (a mass 

explosion is one which affects almost the entire quantity present virtually instantaneously); 

(b) Division 1.2—Chemicals and items 

which have a projection hazard but not a 

mass explosion hazard; 

(c) Division 1.3—Chemicals and items 

which have a fire hazard and either a minor 

blast hazard or a minor projection hazard or 

both, but not a mass explosion hazard: 

(i) Combustion of which gives rise to considerable radiant heat; or 

(ii) Which burn one after another, producing minor blast or projection effects or 

both; 

(d) Division 1.4—Chemicals and items 

which present no significant hazard: chemicals and items which present only a small 

hazard in the event of ignition or initiation. 

The effects are largely confined to the package and no projection of fragments of appreciable size or range is to be expected. An external fire shall not cause virtually instantaneous explosion of almost the entire contents of the package; 

(e) Division 1.5—Very insensitive chemicals which have a mass explosion hazard: 

chemicals which have a mass explosion hazard but are so insensitive that there is very 

little probability of initiation or of transition from burning to detonation under normal conditions; 

(f) Division 1.6—Extremely insensitive 

items which do not have a mass explosion 

hazard: items which contain only extremely 

insensitive detonating chemicals and which 

demonstrate a negligible probability of accidental initiation or propagation. 

B.1.3 ADDITIONAL CLASSIFICATION

CONSIDERATIONS

B.1.3.1 Explosives shall be classified as unstable explosives or shall be assigned to one 

of the six divisions identified in B.1.2 in accordance with the three step procedure in 

Part I of the UN ST/SG/AC.10 (incorporated 

by reference; See §1910.6). The first step is to 

ascertain whether the substance or mixture 

has explosive effects (Test Series 1). The second step is the acceptance procedure (Test 

Series 2 to 4) and the third step is the assignment to a hazard division (Test Series 5 to 7). 

The assessment whether a candidate for 

‘‘ammonium nitrate emulsion or suspension 

or gel, intermediate for blasting explosives 

(ANE)’’ is insensitive enough for inclusion as 

an oxidizing liquid (See B.13) or an oxidizing 

solid (See B.14) is determined by Test Series 

8 tests. 

NOTE: Classification of solid chemicals 

shall be based on tests performed on the 

chemical as presented. If, for example, for 

the purposes of supply or transport, the same 

chemical is to be presented in a physical 

form different from that which was tested 

and which is considered likely to materially 

alter its performance in a classification test, 

classification must be based on testing of the 

chemical in the new form. 

B.1.3.2 Explosive properties are associated 

with the presence of certain chemical groups 

in a molecule which can react to produce 

very rapid increases in temperature or pressure. The screening procedure in B.1.3.1 is 

aimed at identifying the presence of such reactive groups and the potential for rapid energy release. If the screening procedure identifies the chemical as a potential explosive, 

the acceptance procedure (See section 10.3 of 

the UN ST/SG/AC.10 (incorporated by reference; See §1910.6)) is necessary for classification. 

NOTE: Neither a Series 1 type (a) propagation of detonation test nor a Series 2 type (a) 

test of sensitivity to detonative shock is necessary if the exothermic decomposition energy of organic materials is less than 800 J/ 

g. 

B.1.3.3 If a mixture contains any known 

explosives, the acceptance procedure is necessary for classification. 

B.1.3.4 A chemical is not classified as explosive if: 

(a) There are no chemical groups associated with explosive properties present in the 

molecule. Examples of groups which may indicate explosive properties are given in 

Table A6.1 in Appendix 6 of the UN ST/SG/ 

AC.10 (incorporated by reference; See 

§1910.6); or 

(b) The substance contains chemical 

groups associated with explosive properties 

which include oxygen and the calculated oxygen balance is less than ¥200. 

The oxygen balance is calculated for the 

chemical reaction: 

CXHyOz + [x + (y/4) ¥ (z/2)] O2 → x. CO2 + (y/ 

2) H2O 

using the formula: 

oxygen balance = ¥1600 [2x +(y/2) ¥z]/molecular weight; 

or 

(c) The organic substance or a homogenous 

mixture of organic substances contains 

chemical groups associated with explosive 

properties but the exothermic decomposition 

energy is less than 500 J/g and the onset of 

exothermic decomposition is below 500 °C 

(932 °F). The exothermic decomposition energy may be determined using a suitable 

calorimetric technique; or 

515 

Occupational Safety and Health Admin., Labor § 1910.1200 

(d) For mixtures of inorganic oxidizing 

substances with organic material(s), the concentration of the inorganic oxidizing substance is: 

(i) Less than 15%, by mass, if the oxidizing 

substance is assigned to Category 1 or 2; 

(ii) Less than 30%, by mass, if the oxidizing 

substance is assigned to Category 3. 

B.2 FLAMMABLE GASES 

B.2.1 DEFINITION

Flammable gas means a gas having a flammable range with air at 20 °C (68 °F) and a 

standard pressure of 101.3 kPa (14.7 psi). 

B.2.2 CLASSIFICATION CRITERIA

A flammable gas shall be classified in one 

of the two categories for this class in accordance with Table B.2.1: 

TABLE B.2.1—CRITERIA FOR FLAMMABLE GASES

Category Criteria 

1 ................................. Gases, which at 20 °C (68 °F) and a standard pressure of 101.3 kPa (14.7 psi): 

(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. 

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. 

NOTE: Aerosols should not be classified as 

flammable gases. See B.3. 

B.2.3 ADDITIONAL CLASSIFICATION

CONSIDERATIONS

Flammability shall be determined by tests 

or by calculation in accordance with ISO 

10156 (incorporated by reference; See §1910.6). 

Where insufficient data are available to use 

this method, equivalent validated methods 

may be used. 

B.3 FLAMMABLE AEROSOLS 

B.3.1 DEFINITION

Aerosol means any non-refillable receptacle 

containing a gas compressed, liquefied or 

dissolved under pressure, and fitted with a 

release device allowing the contents to be 

ejected as particles in suspension in a gas, or 

as a foam, paste, powder, liquid or gas. 

B.3.2 CLASSIFICATION CRITERIA

B.3.2.1 Aerosols shall be considered for 

classification as flammable if they contain 

any component which is classified as flammable in accordance with this Appendix, i.e.: 

Flammable liquids (See B.6); 

Flammable gases (See B.2); 

Flammable solids (See B.7). 

NOTE 1: Flammable components do not include pyrophoric, self-heating or water-reactive chemicals. 

NOTE 2: Flammable aerosols do not fall additionally within the scope of flammable 

gases, flammable liquids, or flammable solids. 

B.3.2.2 A flammable aerosol shall be classified in one of the two categories for this 

class in accordance with Table B.3.1. 

TABLE B.3.1—CRITERIA FOR FLAMMABLE AEROSOLS

Category Criteria 

1 ................................. Contains ≥ 85% flammable components and the chemical heat of combustion is ≥ 30 kJ/g; or 

(a) For spray aerosols, in the ignition distance test, ignition occurs at a distance ≥ 75 cm (29.5 in), or 

(b) For foam aerosols, in the aerosol foam flammability test 

(i) The flame height is ≥ 20 cm (7.87 in) and the flame duration ≥ 2 s; or 

(ii) The flame height is ≥ 4 cm (1.57 in) and the flame duration ≥ 7 s 

2 ................................. Contains > 1% flammable components, or the heat of combustion is ≥ 20 kJ/g; and 

(a) for spray aerosols, in the ignition distance test, ignition occurs at a distance ≥ 15 cm (5.9 in), or 

in the enclosed space ignition test, the 

(i) Time equivalent is ≤ 300 s/m3; or 

(ii) Deflagration density is ≤ 300 g/m3

(b) For foam aerosols, in the aerosol foam flammability test, the flame height is ≥ 4 cm and the flame 

duration is ≥ 2 s 

and it does not meet the criteria for Category 1 

NOTE: Aerosols not submitted to the flammability classification procedures in this Appendix shall be classified as extremely 

flammable (Category 1). 

516 

§ 1910.1200 29 CFR Ch. XVII (7–1–13 Edition) 

B.3.3 ADDITIONAL CLASSIFICATION

CONSIDERATIONS

B.3.3.1 To classify a flammable aerosol, 

data on its flammable components, on its 

chemical heat of combustion and, if applicable, the results of the aerosol foam flammability test (for foam aerosols) and of the ignition distance test and enclosed space test 

(for spray aerosols) are necessary. 

B.3.3.2 The chemical heat of combustion 

(DHc), in kilojoules per gram (kJ/g), is the 

product of the theoretical heat of combustion (DHcomb), and a combustion efficiency, 

usually less than 1.0 (a typical combustion 

efficiency is 0.95 or 95%). 

For a composite aerosol formulation, the 

chemical heat of combustion is the summation of the weighted heats of combustion for 

the individual components, as follows: 

Where: 

DHc = chemical heat of combustion (kJ/g); 

wi% = mass fraction of component i in the 

product; 

DHc(i) = specific heat of combustion (kJ/g) of 

component i in the product; 

The chemical heats of combustion shall be 

found in literature, calculated or determined 

by tests (See ASTM D240–02, ISO 13943, Sections 86.1 to 86.3, and NFPA 30B (incorporated by reference; See §1910.6)). 

B.3.3.3 The Ignition Distance Test, Enclosed Space Ignition Test and Aerosol Foam 

Flammability Test shall be performed in accordance with sub-sections 31.4, 31.5 and 31.6 

of the of the UN ST/SG/AC.10 (incorporated 

by reference; See §1910.6). 

B.4 OXIDIZING GASES 

B.4.1 DEFINITION

Oxidizing gas means any gas which may, 

generally by providing oxygen, cause or contribute to the combustion of other material 

more than air does. 

NOTE: ‘‘Gases which cause or contribute to 

the combustion of other material more than 

air does’’ means pure gases or gas mixtures 

with an oxidizing power greater than 23.5% 

(as determined by a method specified in ISO 

10156 or 10156–2 (incorporated by reference, 

See §1910.6) or an equivalent testing method.) 

B.4.2 CLASSIFICATION CRITERIA

An oxidizing gas shall be classified in a single category for this class in accordance with 

Table B.4.1: 

TABLE B.4.1—CRITERIA FOR OXIDIZING GASES

Category Criteria 

1 ................................. Any gas which may, generally by providing oxygen, cause or contribute to the combustion of other material more than air does. 

B.4.3 ADDITIONAL CLASSIFICATION

CONSIDERATIONS

Classification shall be in accordance with 

tests or calculation methods as described in 

ISO 10156 (incorporated by reference; See 

§1910.6) and ISO 10156–2 (incorporated by reference; See §1910.6). 

B.5 GASES UNDER PRESSURE 

B.5.1 DEFINITION

Gases under pressure are gases which are 

contained in a receptacle at a pressure of 200 

kPa (29 psi) (gauge) or more, or which are 

liquefied or liquefied and refrigerated. 

They comprise compressed gases, liquefied 

gases, dissolved gases and refrigerated liquefied gases. 

B.5.2 CLASSIFICATION CRITERIA

Gases under pressure shall be classified in 

one of four groups in accordance with Table 

B.5.1: 


ER26MR12.067</GPH>
517 

Occupational Safety and Health Admin., Labor § 1910.1200 

TABLE B.5.1—CRITERIA FOR GASES UNDER PRESSURE

Group Criteria 

Compressed gas ................... A gas which when under pressure is entirely gaseous at ¥50 °C (¥8 °F), including all gases 

with a critical temperature1 ≤¥50 °C (¥58 °F). 

Liquefied gas ......................... A gas which when under pressure is partially liquid at temperatures above ¥50 °C (¥58 °F). A 

distinction is made between: 

(a) High pressure liquefied gas: A gas with a critical temperature 1 between ¥50 °C (¥58 

°F) and +65 °C (149 °F); and 

(b) Low pressure liquefied gas: A gas with a critical temperature 1 above +65 °C (149 °F). 

Refrigerated liquefied gas ..... A gas which is made partially liquid because of its low temperature. 

Dissolved gas ........................ A gas which when under pressure is dissolved in a liquid phase solvent. 

1The critical temperature is the temperature above which a pure gas cannot be liquefied, regardless of the degree of 

compression. 

B.6 FLAMMABLE LIQUIDS 

B.6.1 DEFINITION

Flammable liquid means a liquid having a 

flash point of not more than 93 °C (199.4 °F). 

Flash point means the minimum temperature at which a liquid gives off vapor in sufficient concentration to form an ignitable 

mixture with air near the surface of the liquid, as determined by a method identified in 

Section B.6.3. 

B.6.2 CLASSIFICATION CRITERIA

A flammable liquid shall be classified in 

one of four categories in accordance with 

Table B.6.1: 

TABLE B.6.1—CRITERIA FOR FLAMMABLE LIQUIDS

Category Criteria 

1 ....................................... Flash point <23 °C (73.4 °F) and initial boiling point ≤35 °C (95 °F). 

2 ....................................... Flash point <23 °C (73.4 °F) and initial boiling point >35 °C (95 °F). 

3 ....................................... Flash point ≥23 °C (73.4 °F) and ≤60 °C (140 °F). 

4 ....................................... Flash point >60 °C (140 °F) and ≤93 °C (199.4 °F). 

B.6.3 ADDITIONAL CLASSIFICATION

CONSIDERATIONS

The flash point shall be determined in accordance with ASTM D56–05, ASTM D3278, 

ASTM D3828, ASTM D93–08 (incorporated by 

reference; See §1910.6), or any other method 

specified in GHS Revision 3, Chapter 2.6. 

The initial boiling point shall be determined in accordance with ASTM D86–07a or 

ASTM D1078 (incorporated by reference; See 

§1910.6). 

B.7 FLAMMABLE SOLIDS 

B.7.1 DEFINITIONS

Flammable solid means a solid which is a 

readily combustible solid, or which may 

cause or contribute to fire through friction. 

Readily combustible solids are powdered, 

granular, or pasty chemicals which are dangerous if they can be easily ignited by brief 

contact with an ignition source, such as a 

burning match, and if the flame spreads rapidly. 

B.7.2 CLASSIFICATION CRITERIA

B.7.2.1 Powdered, granular or pasty 

chemicals shall be classified as flammable 

solids when the time of burning of one or 

more of the test runs, performed in accordance with the test method described in the 

UN ST/SG/AC.10 (incorporated by reference; 

See §1910.6), Part III, sub-section 33.2.1, is 

less than 45 s or the rate of burning is more 

than 2.2 mm/s (0.0866 in/s). 

B.7.2.2 Powders of metals or metal alloys 

shall be classified as flammable solids when 

they can be ignited and the reaction spreads 

over the whole length of the sample in 10 

min or less. 

B.7.2.3 Solids which may cause fire 

through friction shall be classified in this 

class by analogy with existing entries (e.g., 

matches) until definitive criteria are established. 

B.7.2.4 A flammable solid shall be classified in one of the two categories for this 

class using Method N.1 as described in Part 

III, sub-section 33.2.1 of the UN ST/SG/AC.10 

(incorporated by reference; See §1910.6), in 

accordance with Table B.7.1: 

TABLE B.7.1—CRITERIA FOR FLAMMABLE SOLIDS

Category Criteria 

1 ................................................................................................... Burning rate test: 

518 

§ 1910.1200 29 CFR Ch. XVII (7–1–13 Edition) 

TABLE B.7.1—CRITERIA FOR FLAMMABLE SOLIDS—Continued 

Category Criteria 

Chemicals other than metal powders: 

(a) Wetted zone does not stop fire; and 

(b) Burning time <45 s or burning rate >2.2 mm/s. 

Metal powders: Burning time ≤5 min. 

2 ................................................................................................... Burning rate test: 

Chemicals other than metal powders: 

(a) Wetted zone stops the fire for at least 4 min; and 

(b) Burning time <45 s or burning rate >2.2 mm/s. 

Metal powders: Burning time >5 min and ≤10 min. 

NOTE: Classification of solid chemicals 

shall be based on tests performed on the 

chemical as presented. If, for example, for 

the purposes of supply or transport, the same 

chemical is to be presented in a physical 

form different from that which was tested 

and which is considered likely to materially 

alter its performance in a classification test, 

classification must be based on testing of the 

chemical in the new form. 

B.8 SELF-REACTIVE CHEMICALS 

B.8.1 DEFINITIONS

Self-reactive chemicals are thermally unstable liquid or solid chemicals liable to undergo a strongly exothermic decomposition 

even without participation of oxygen (air). 

This definition excludes chemicals classified 

under this section as explosives, organic peroxides, oxidizing liquids or oxidizing solids. 

A self-reactive chemical is regarded as possessing explosive properties when in laboratory testing the formulation is liable to detonate, to deflagrate rapidly or to show a violent effect when heated under confinement. 

B.8.2 CLASSIFICATION CRITERIA

B.8.2.1 A self-reactive chemical shall be 

considered for classification in this class unless: 

(a) It is classified as an explosive according 

to B.1 of this appendix; 

(b) It is classified as an oxidizing liquid or 

an oxidizing solid according to B.13 or B.14 of 

this appendix, except that a mixture of oxidizing substances which contains 5% or more 

of combustible organic substances shall be 

classified as a self-reactive chemical according to the procedure defined in B.8.2.2; 

(c) It is classified as an organic peroxide 

according to B.15 of this appendix; 

(d) Its heat of decomposition is less than 

300 J/g; or 

(e) Its self-accelerating decomposition 

temperature (SADT) is greater than 75 °C 

(167 °F) for a 50 kg (110 lb) package. 

B.8.2.2 Mixtures of oxidizing substances, 

meeting the criteria for classification as oxidizing liquids or oxidizing solids, which contain 5% or more of combustible organic substances and which do not meet the criteria 

mentioned in B.8.2.1 (a), (c), (d) or (e), shall 

be subjected to the self-reactive chemicals 

classification procedure in B.8.2.3. Such a 

mixture showing the properties of a self-reactive chemical type B to F shall be classified as a self-reactive chemical. 

B.8.2.3 Self-reactive chemicals shall be 

classified in one of the seven categories of 

‘‘types A to G’’ for this class, according to 

the following principles: 

(a) Any self-reactive chemical which can 

detonate or deflagrate rapidly, as packaged, 

will be defined as self-reactive chemical 

TYPE A; 

(b) Any self-reactive chemical possessing 

explosive properties and which, as packaged, 

neither detonates nor deflagrates rapidly, 

but is liable to undergo a thermal explosion 

in that package will be defined as self-reactive chemical TYPE B; 

(c) Any self-reactive chemical possessing 

explosive properties when the chemical as 

packaged cannot detonate or deflagrate rapidly or undergo a thermal explosion will be 

defined as self-reactive chemical TYPE C; 

(d) Any self-reactive chemical which in 

laboratory testing meets the criteria in 

(d)(i), (ii), or (iii) will be defined as self-reactive chemical TYPE D: 

(i) Detonates partially, does not deflagrate 

rapidly and shows no violent effect when 

heated under confinement; or 

(ii) Does not detonate at all, deflagrates 

slowly and shows no violent effect when 

heated under confinement; or 

(iii) Does not detonate or deflagrate at all 

and shows a medium effect when heated 

under confinement; 

(e) Any self-reactive chemical which, in 

laboratory testing, neither detonates nor 

deflagrates at all and shows low or no effect 

when heated under confinement will be defined as self-reactive chemical TYPE E; 

(f) Any self-reactive chemical 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 will be defined as self-reactive 

chemical TYPE F; 

(g) Any self-reactive chemical which, in 

laboratory testing, neither detonates in the 

519 

Occupational Safety and Health Admin., Labor § 1910.1200 

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 (140 °F) to 

75 °C (167 °F) for a 50 kg (110 lb) package), 

and, for liquid mixtures, a diluent having a 

boiling point greater than or equal to 150 °C 

(302 °F) is used for desensitization will be defined as self-reactive chemical TYPE G. If 

the mixture is not thermally stable or a diluent having a boiling point less than 150 °C 

(302 °F) is used for desensitization, the mixture shall be defined as self-reactive chemical TYPE F. 

B.8.3 ADDITIONAL CLASSIFICATION

CONSIDERATIONS

B.8.3.1 For purposes of classification, the 

properties of self-reactive chemicals shall be 

determined in accordance with test series A 

to H as described in Part II of the UN ST/SG/ 

AC.10 (incorporated by reference; See 

§1910.6). 

B.8.3.2 Self-accelerating decomposition 

temperature (SADT) shall be determined in 

accordance with the UN ST/SG/AC.10, Part 

II, section 28 (incorporated by reference; See 

§1910.6). 

B.8.3.3 The classification procedures for 

self-reactive substances and mixtures need 

not be applied if: 

(a) There are no chemical groups present in 

the molecule associated with explosive or 

self-reactive properties; examples of such 

groups are given in Tables A6.1 and A6.2 in 

the Appendix 6 of the UN ST/SG/AC.10 (incorporated by reference; See §1910.6); or 

(b) For a single organic substance or a homogeneous mixture of organic substances, 

the estimated SADT is greater than 75 °C 

(167 °F) or the exothermic decomposition energy is less than 300 J/g. The onset temperature and decomposition energy may be estimated using a suitable calorimetric technique (See 20.3.3.3 in Part II of the UN ST/SG/ 

AC.10 (incorporated by reference; See 

§1910.6)). 

B.9 PYROPHORIC LIQUIDS 

B.9.1 DEFINITION

Pyrophoric liquid means a liquid which, 

even in small quantities, is liable to ignite 

within five minutes after coming into contact with air. 

B.9.2 CLASSIFICATION CRITERIA

A pyrophoric liquid shall be classified in a 

single category for this class using test N.3 

in Part III, sub-section 33.3.1.5 of the UN ST/ 

SG/AC.10 (incorporated by reference; See 

§1910.6), in accordance with Table B.9.1: 

TABLE B.9.1—CRITERIA FOR PYROPHORIC LIQUIDS

Category Criteria 

1 ................................. The liquid ignites within 5 min when added to an inert carrier and exposed to air, or it ignites or chars a 

filter paper on contact with air within 5 min. 

B.9.3 ADDITIONAL CLASSIFICATION

CONSIDERATIONS

The classification procedure for pyrophoric 

liquids need not be applied when experience 

in production or handling shows that the 

chemical does not ignite spontaneously on 

coming into contact with air at normal temperatures (i.e., the substance is known to be 

stable at room temperature for prolonged periods of time (days)). 

B.10 PYROPHORIC SOLIDS 

B.10.1 DEFINITION

Pyrophoric solid means a solid which, even 

in small quantities, is liable to ignite within 

five minutes after coming into contact with 

air. 

B.10.2 CLASSIFICATION CRITERIA

A pyrophoric solid shall be classified in a 

single category for this class using test N.2 

in Part III, sub-section 33.3.1.4 of the UN ST/ 

SG/AC.10 (incorporated by reference; See 

§1910.6), in accordance with Table B.10.1: 

TABLE B.10.1—CRITERIA FOR PYROPHORIC SOLIDS

Category Criteria 

1 ............................................. The solid ignites within 5 min of coming into contact with air. 

NOTE: Classification of solid chemicals 

shall be based on tests performed on the 

chemical as presented. If, for example, for 

the purposes of supply or transport, the same 

chemical is to be presented in a physical 

form different from that which was tested 

520 

§ 1910.1200 29 CFR Ch. XVII (7–1–13 Edition) 

and which is considered likely to materially 

alter its performance in a classification test, 

classification must be based on testing of the 

chemical in the new form. 

B.10.3 ADDITIONAL CLASSIFICATION

CONSIDERATIONS

The classification procedure for pyrophoric 

solids need not be applied when experience in 

production or handling shows that the chemical does not ignite spontaneously on coming 

into contact with air at normal temperatures (i.e., the chemical is known to be stable at room temperature for prolonged periods of time (days)). 

B.11 SELF-HEATING CHEMICALS 

B.11.1 DEFINITION

A self-heating chemical is a solid or liquid 

chemical, other than a pyrophoric liquid or 

solid, which, by reaction with air and without energy supply, is liable to self-heat; this 

chemical differs from a pyrophoric liquid or 

solid in that it will ignite only when in large 

amounts (kilograms) and after long periods 

of time (hours or days). 

NOTE: Self-heating of a substance or mixture is a process where the gradual reaction 

of that substance or mixture with oxygen (in 

air) generates heat. If the rate of heat production exceeds the rate of heat loss, then 

the temperature of the substance or mixture 

will rise which, after an induction time, may 

lead to self-ignition and combustion. 

B.11.2 CLASSIFICATION CRITERIA

B.11.2.1 A self-heating chemical shall be 

classified in one of the two categories for 

this class if, in tests performed in accordance 

with test method N.4 in Part III, sub-section 

33.3.1.6 of the UN ST/SG/AC.10 (incorporated 

by reference; See §1910.6), the result meets 

the criteria shown in Table B.11.1. 

TABLE B.11.1—CRITERIA FOR SELF-HEATING CHEMICALS

Category Criteria 

1 ................................. A positive result is obtained in a test using a 25 mm sample cube at 140 °C (284 °F). 

2 ................................. A negative result is obtained in a test using a 25 mm cube sample at 140 °C (284 °F), a positive result 

is obtained in a test using a 100 mm sample cube at 140 °C (284 °F), and: 

(a) The unit volume of the chemical is more than 3 m3; or 

(b) A positive result is obtained in a test using a 100 mm cube sample at 120 °C (248 °F) and the 

unit volume of the chemical is more than 450 liters; or 

(c) A positive result is obtained in a test using a 100 mm cube sample at 100 °C (212 °F). 

B.11.2.2 Chemicals with a temperature of 

spontaneous combustion higher than 50 °C 

(122 °F) for a volume of 27 m3 shall not be 

classified as self-heating chemicals. 

B.11.2.3 Chemicals with a spontaneous ignition temperature higher than 50 °C (122 °F) 

for a volume of 450 liters shall not be classified in Category 1 of this class. 

B.11.3 ADDITIONAL CLASSIFICATION

CONSIDERATIONS

B.11.3.1 The classification procedure for 

self-heating chemicals need not be applied if 

the results of a screening test can be adequately correlated with the classification 

test and an appropriate safety margin is applied. 

B.11.3.2 Examples of screening tests are: 

(a) The Grewer Oven test (VDI guideline 

2263, part 1, 1990, Test methods for the Determination of the Safety Characteristics of 

Dusts) with an onset temperature 80°K above 

the reference temperature for a volume of 1 

l; 

(b) The Bulk Powder Screening Test (Gibson, N. Harper, D. J. Rogers, R. Evaluation 

of the fire and explosion risks in drying powders, Plant Operations Progress, 4 (3), 181– 

189, 1985) with an onset temperature 60°K 

above the reference temperature for a volume of 1 l. 

B.12 CHEMICALS WHICH, IN CONTACT 

WITH WATER, EMIT FLAMMABLE GASES 

B.12.1 DEFINITION

Chemicals which, in contact with water, emit 

flammable gases are solid or liquid chemicals 

which, by interaction with water, are liable 

to become spontaneously flammable or to 

give off flammable gases in dangerous quantities. 

B.12.2 CLASSIFICATION CRITERIA

B.12.2.1 A chemical which, in contact with 

water, emits flammable gases shall be classified in one of the three categories for this 

class, using test N.5 in Part III, sub-section 

33.4.1.4 of the UN ST/SG/AC.10 (incorporated 

by reference; See §1910.6), in accordance with 

Table B.12.1: 

521 

Occupational Safety and Health Admin., Labor § 1910.1200 

TABLE B.12.1—CRITERIA FOR CHEMICALS WHICH, IN CONTACT WITH WATER, EMIT FLAMMABLE

GASES

Category Criteria 

1 ................................. Any chemical which reacts vigorously with water at ambient temperatures and demonstrates generally a 

tendency for the gas produced to ignite spontaneously, or which reacts readily with water at ambient 

temperatures such that the rate of evolution of flammable gas is equal to or greater than 10 liters per 

kilogram of chemical over any one minute. 

2 ................................. Any chemical which reacts readily with water at ambient temperatures such that the maximum rate of 

evolution of flammable gas is equal to or greater than 20 liters per kilogram of chemical per hour, and 

which does not meet the criteria for Category 1. 

3 ................................. Any chemical which reacts slowly with water at ambient temperatures such that the maximum rate of 

evolution of flammable gas is equal to or greater than 1 liter per kilogram of chemical per hour, and 

which does not meet the criteria for Categories 1 and 2. 

NOTE: Classification of solid chemicals 

shall be based on tests performed on the 

chemical as presented. If, for example, for 

the purposes of supply or transport, the same 

chemical is to be presented in a physical 

form different from that which was tested 

and which is considered likely to materially 

alter its performance in a classification test, 

classification must be based on testing of the 

chemical in the new form. 

B.12.2.2 A chemical is classified as a 

chemical which, in contact with water emits 

flammable gases if spontaneous ignition 

takes place in any step of the test procedure. 

B.12.3 ADDITIONAL CLASSIFICATION

CONSIDERATIONS

The classification procedure for this class 

need not be applied if: 

(a) The chemical structure of the chemical 

does not contain metals or metalloids; 

(b) Experience in production or handling 

shows that the chemical does not react with 

water, (e.g., the chemical is manufactured 

with water or washed with water); or 

(c) The chemical is known to be soluble in 

water to form a stable mixture. 

B.13 OXIDIZING LIQUIDS 

B.13.1 DEFINITION

Oxidizing liquid means a liquid which, while 

in itself not necessarily combustible, may, 

generally by yielding oxygen, cause, or contribute to, the combustion of other material. 

B.13.2 CLASSIFICATION CRITERIA

An oxidizing liquid shall be classified in 

one of the three categories for this class 

using test O.2 in Part III, sub-section 34.4.2 of 

the UN ST/SG/AC.10 (incorporated by reference; See §1910.6), in accordance with 

Table B.13.1: 

TABLE B.13.1—CRITERIA FOR OXIDIZING LIQUIDS

Category Criteria 

1 ................................. Any chemical which, in the 1:1 mixture, by mass, of chemical and cellulose tested, spontaneously ignites; or the mean pressure rise time of a 1:1 mixture, by mass, of chemical and cellulose is less than 

that of a 1:1 mixture, by mass, of 50% perchloric acid and cellulose; 

2 ................................. Any chemical which, in the 1:1 mixture, by mass, of chemical and cellulose tested, exhibits a mean 

pressure rise time less than or equal to the mean pressure rise time of a 1:1 mixture, by mass, of 

40% aqueous sodium chlorate solution and cellulose; and the criteria for Category 1 are not met; 

3 ................................. Any chemical which, in the 1:1 mixture, by mass, of chemical and cellulose tested, exhibits a mean 

pressure rise time less than or equal to the mean pressure rise time of a 1:1 mixture, by mass, of 

65% aqueous nitric acid and cellulose; and the criteria for Categories 1 and 2 are not met. 

B.13.3 ADDITIONAL CLASSIFICATION

CONSIDERATIONS

B.13.3.1 For organic chemicals, the classification procedure for this class shall not be 

applied if: 

(a) The chemical does not contain oxygen, 

fluorine or chlorine; or 

(b) The chemical contains oxygen, fluorine 

or chlorine and these elements are chemically bonded only to carbon or hydrogen. 

B.13.3.2 For inorganic chemicals, the classification procedure for this class shall not 

be applied if the chemical does not contain 

oxygen or halogen atoms. 

B.13.3.3 In the event of divergence between test results and known experience in 

the handling and use of chemicals which 

shows them to be oxidizing, judgments based 

on known experience shall take precedence 

over test results. 

B.13.3.4 In cases where chemicals generate 

a pressure rise (too high or too low), caused 

by chemical reactions not characterizing the 

oxidizing properties of the chemical, the test 

described in Part III, sub-section 34.4.2 of the 

522 

§ 1910.1200 29 CFR Ch. XVII (7–1–13 Edition) 

UN ST/SG/AC.10 (incorporated by reference; 

See §1910.6) shall be repeated with an inert 

substance (e.g., diatomite (kieselguhr)) in 

place of the cellulose in order to clarify the 

nature of the reaction. 

B.14 OXIDIZING SOLIDS 

B.14.1 DEFINITION

Oxidizing solid means a solid which, while 

in itself is not necessarily combustible, may, 

generally by yielding oxygen, cause, or contribute to, the combustion of other material. 

B.14.2 CLASSIFICATION CRITERIA

An oxidizing solid shall be classified in one 

of the three categories for this class using 

test O.1 in Part III, sub-section 34.4.1 of the 

UN ST/SG/AC.10 (incorporated by reference; 

See §1910.6), in accordance with Table B.14.1: 

TABLE B.14.1—CRITERIA FOR OXIDIZING SOLIDS

Category Criteria 

1 ................................. Any chemical which, in the 4:1 or 1:1 sample-to-cellulose ratio (by mass) tested, exhibits a mean burning time less than the mean burning time of a 3:2 mixture, by mass, of potassium bromate and cellulose. 

2 ................................. Any chemical which, in the 4:1 or 1:1 sample-to-cellulose ratio (by mass) tested, exhibits a mean burning time equal to or less than the mean burning time of a 2:3 mixture (by mass) of potassium bromate and cellulose and the criteria for Category 1 are not met. 

3 ................................. Any chemical which, in the 4:1 or 1:1 sample-to-cellulose ratio (by mass) tested, exhibits a mean burning time equal to or less than the mean burning time of a 3:7 mixture (by mass) of potassium bromate and cellulose and the criteria for Categories 1 and 2 are not met. 

NOTE 1: Some oxidizing solids may present 

explosion hazards under certain conditions 

(e.g., when stored in large quantities). For 

example, some types of ammonium nitrate 

may give rise to an explosion hazard under 

extreme conditions and the ‘‘Resistance to 

detonation test’’ (IMO: Code of Safe Practice 

for Solid Bulk Cargoes, 2005, Annex 3, Test 5) 

may be used to assess this hazard. When information indicates that an oxidizing solid 

may present an explosion hazard, it shall be 

indicated on the Safety Data Sheet. 

NOTE 2: Classification of solid chemicals 

shall be based on tests performed on the 

chemical as presented. If, for example, for 

the purposes of supply or transport, the same 

chemical is to be presented in a physical 

form different from that which was tested 

and which is considered likely to materially 

alter its performance in a classification test, 

classification must be based on testing of the 

chemical in the new form. 

B.14.3 ADDITIONAL CLASSIFICATION

CONSIDERATIONS

B.14.3.1 For organic chemicals, the classification procedure for this class shall not be 

applied if: 

(a) The chemical does not contain oxygen, 

fluorine or chlorine; or 

(b) The chemical contains oxygen, fluorine 

or chlorine and these elements are chemically bonded only to carbon or hydrogen. 

B.14.3.2 For inorganic chemicals, the classification procedure for this class shall not 

be applied if the chemical does not contain 

oxygen or halogen atoms. 

B.14.3.3 In the event of divergence between test results and known experience in 

the handling and use of chemicals which 

shows them to be oxidizing, judgements 

based on known experience shall take precedence over test results. 

B.15 ORGANIC PEROXIDES 

B.15.1 DEFINITION

B.15.1.1 Organic peroxide means a liquid or 

solid organic chemical which contains the 

bivalent –0–0– structure and as such is considered a derivative of hydrogen peroxide, 

where one or both of the hydrogen atoms 

have been replaced by organic radicals. The 

term organic peroxide includes organic peroxide mixtures containing at least one organic peroxide. Organic peroxides are thermally unstable chemicals, which may undergo exothermic self-accelerating decomposition. In addition, they may have one or more 

of the following properties: 

(a) Be liable to explosive decomposition; 

(b) Burn rapidly; 

(c) Be sensitive to impact or friction; 

(d) React dangerously with other substances. 

B.15.1.2 An organic peroxide is regarded as 

possessing explosive properties when in laboratory testing the formulation is liable to 

detonate, to deflagrate rapidly or to show a 

violent effect when heated under confinement. 

B.15.2 CLASSIFICATION CRITERIA

B.15.2.1 Any organic peroxide shall be 

considered for classification in this class, unless it contains: 

(a) Not more than 1.0% available oxygen 

from the organic peroxides when containing 

not more than 1.0% hydrogen peroxide; or 

523 

Occupational Safety and Health Admin., Labor § 1910.1200 

(b) Not more than 0.5% available oxygen 

from the organic peroxides when containing 

more than 1.0% but not more than 7.0% hydrogen peroxide. 

NOTE: The available oxygen content (%) of 

an organic peroxide mixture is given by the 

formula: 

Where: 

ni = number of peroxygen groups per molecule of organic peroxide i; 

ci = concentration (mass %) of organic peroxide i; 

mi = molecular mass of organic peroxide i. 

B.15.2.2 Organic peroxides shall be classified in one of the seven categories of ‘‘Types 

A to G’’ for this class, according to the following principles: 

(a) Any organic peroxide which, as packaged, can detonate or deflagrate rapidly 

shall be defined as organic peroxide TYPE A; 

(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 shall be defined as organic peroxide 

TYPE B; 

(c) Any organic peroxide possessing explosive properties when the chemical as packaged cannot detonate or deflagrate rapidly 

or undergo a thermal explosion shall be defined as organic peroxide TYPE C; 

(d) Any organic peroxide which in laboratory testing meets the criteria in (d)(i), (ii), 

or (iii) shall be defined as organic peroxide 

TYPE D: 

(i) Detonates partially, does not deflagrate 

rapidly and shows no violent effect when 

heated under confinement; or 

(ii) Does not detonate at all, deflagrates 

slowly and shows no violent effect when 

heated under confinement; or 

(iii) 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 shall be defined as organic peroxide TYPE E; 

(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 shall be defined as organic peroxide TYPE F; 

(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 (140 °F) or 

higher for a 50 kg (110 lb) package), and, for 

liquid mixtures, a diluent having a boiling 

point of not less than 150 °C (302 °F) is used 

for desensitization, shall be defined as organic peroxide TYPE G. If the organic peroxide is not thermally stable or a diluent 

having a boiling point less than 150 °C (302 

°F) is used for desensitization, it shall be defined as organic peroxide TYPE F. 

B.15.3 ADDITIONAL CLASSIFICATION

CONSIDERATIONS

B.15.3.1 For purposes of classification, the 

properties of organic peroxides shall be determined in accordance with test series A to 

H as described in Part II of the UN ST/SG/ 

AC.10 (incorporated by reference; See 

§1910.6). 

B.15.3.2 Self-accelerating decomposition 

temperature (SADT) shall be determined in 

accordance with the UN ST/SG/AC.10 (incorporated by reference; See §1910.6), Part II, 

section 28. 

B.15.3.3 Mixtures of organic peroxides 

may be classified as the same type of organic 

peroxide as that of the most dangerous ingredient. However, as two stable ingredients 

can form a thermally less stable mixture, 

the SADT of the mixture shall be determined. 

B.16 CORROSIVE TO METALS 

B.16.1 DEFINITION

A chemical which is corrosive to metals means 

a chemical which by chemical action will 

materially damage, or even destroy, metals. 

B.16.2 CLASSIFICATION CRITERIA

A chemical which is corrosive to metals 

shall be classified in a single category for 

this class, using the test in Part III, sub-section 37.4 of the UN ST/SG/AC.10 (incorporated by reference; See §1910.6), in accordance with Table B.16.1: 


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TABLE B.16.1—CRITERIA FOR CHEMICALS CORROSIVE TO METAL

Category Criteria 

1 ................................. Corrosion rate on either steel or aluminium surfaces exceeding 6.25 mm per year at a test temperature 

of 55 °C (131 °F) when tested on both materials. 

NOTE: Where an initial test on either steel 

or aluminium indicates the chemical being 

tested is corrosive, the follow-up test on the 

other metal is not necessary. 

B.16.3 ADDITIONAL CLASSIFICATION

CONSIDERATIONS

The specimen to be used for the test shall 

be made of the following materials: 

(a) For the purposes of testing steel, steel 

types S235JR+CR (1.0037 resp.St 37–2), 

S275J2G3+CR (1.0144 resp.St 44–3), ISO 3574, 

Unified Numbering System (UNS) G 10200, or 

SAE 1020; 

(b) For the purposes of testing aluminium: 

Non-clad types 7075–T6 or AZ5GU–T6. 

APPENDIX C TO §1910.1200—ALLOCATION OF

LABEL ELEMENTS (MANDATORY) 

C.1 The label for each hazardous chemical 

shall include the product identifier used on 

the safety data sheet. 

C.1.1 The labels on shipped containers 

shall also include the name, address, and 

telephone number of the chemical manufacturer, importer, or responsible party. 

C.2 The label for each hazardous chemical 

that is classified shall include the signal 

word, hazard statement(s), pictogram(s), and 

precautionary statement(s) specified in C.4 

for each hazard class and associated hazard 

category, except as provided for in C.2.1 

through C.2.4. 

C.2.1 PRECEDENCE OF HAZARD INFORMATION

C.2.1.1 If the signal word ‘‘Danger’’ is included, the signal word ‘‘Warning’’ shall not 

appear; 

C.2.1.2 If the skull and crossbones pictogram is included, the exclamation mark pictogram shall not appear where it is used for 

acute toxicity; 

C.2.1.3 If the corrosive pictogram is included, the exclamation mark pictogram 

shall not appear where it is used for skin or 

eye irritation; 

C.2.1.4 If the health hazard pictogram is 

included for respiratory sensitization, the 

exclamation mark pictogram shall not appear where it is used for skin sensitization or 

for skin or eye irritation. 

C.2.2 HAZARD STATEMENT TEXT

C.2.2.1 The text of all applicable hazard 

statements shall appear on the label, except 

as otherwise specified. The information in 

italics shall be included as part of the hazard 

statement as provided. For example: ‘‘causes 

damage to organs (state all organs affected) 

through prolonged or repeated exposure 

(state route of exposure if no other routes of exposure cause the hazard)’’. Hazard statements 

may be combined where appropriate to reduce the information on the label and improve readability, as long as all of the hazards are conveyed as required. 

C.2.2.2 If the chemical manufacturer, importer, or responsible party can demonstrate 

that all or part of the hazard statement is 

inappropriate to a specific substance or mixture, the corresponding statement may be 

omitted from the label. 

C.2.3 PICTOGRAMS

C.2.3.1 Pictograms shall be in the shape of 

a square set at a point and shall include a 

black hazard symbol on a white background 

with a red frame sufficiently wide to be 

clearly visible. A square red frame set at a 

point without a hazard symbol is not a pictogram and is not permitted on the label. 

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C.2.4 PRECAUTIONARY STATEMENT TEXT

C.2.4.1 There are four types of precautionary statements presented, ‘‘prevention,’’ ‘‘response,’’ ‘‘storage,’’ and ‘‘disposal.’’ The core part of the precautionary 

statement is presented in bold print. This is 

the text, except as otherwise specified, that 

shall appear on the label. Where additional 

information is required, it is indicated in 

plain text. 

C.2.4.2 When a backslash or diagonal 

mark (/) appears in the precautionary statement text, it indicates that a choice has to 

be made between the separated phrases. In 

such cases, the chemical manufacturer, importer, or responsible party can choose the 

most appropriate phrase(s). For example, 

‘‘Wear protective gloves/protective clothing/ 

eye protection/face protection’’ could read 

‘‘wear eye protection’’. 

C.2.4.3 When three full stops (* * *) appear 

in the precautionary statement text, they 

indicate that all applicable conditions are 

not listed. For example, in ‘‘Use explosionproof electrical/ventilating/lighting/* * */ 

equipment’’, the use of ‘‘* * *’’ indicates that 

other equipment may need to be specified. In 

such cases, the chemical manufacturer, importer, or responsible party can choose the 

other conditions to be specified. 

C.2.4.4 When text in italics is used in a precautionary statement, this indicates specific 

conditions applying to the use or allocation 

of the precautionary statement. For example, ‘‘Use explosion-proof electrical/ventilating/lighting/* * */equipment’’ is only required for flammable solids ‘‘if dust clouds 

can occur’’. Text in italics is intended to be 

an explanatory, conditional note and is not 

intended to appear on the label. 

C.2.4.5 Where square brackets ([ ]) appear 

around text in a precautionary statement, 

this indicates that the text in square brackets is not appropriate in every case and 

should be used only in certain circumstances. In these cases, conditions for 

use explaining when the text should be used 

are provided. For example, one precautionary statement states: ‘‘[In case of inadequate ventilation] wear respiratory protection.’’ This statement is given with the 

condition for use ‘‘– text in square brackets 

may be used if additional information is provided with the chemical at the point of use 

that explains what type of ventilation would 

be adequate for safe use’’. This means that, 

if additional information is provided with 

the chemical explaining what type of ventilation would be adequate for safe use, the 

text in square brackets should be used and 

the statement would read: ‘‘In case of inadequate ventilation wear respiratory protection.’’ However, if the chemical is supplied 

without such ventilation information, the 

text in square brackets should not be used, 

and the precautionary statement should 

read: ‘‘Wear respiratory protection.’’ 

C.2.4.6 Precautionary statements may be 

combined or consolidated to save label space 

and improve readability. For example, ‘‘Keep 

away from heat, sparks and open flame,’’ 

‘‘Store in a well-ventilated place’’ and ‘‘Keep 

cool’’ can be combined to read ‘‘Keep away 

from heat, sparks and open flame and store 

in a cool, well-ventilated place.’’ 

C.2.4.7 In most cases, the precautionary 

statements are independent (e.g., the phrases 

for explosive hazards do not modify those related to certain health hazards, and products 

that are classified for both hazard classes 

shall bear appropriate precautionary statements for both). Where a chemical is classified for a number of hazards, and the precautionary statements are similar, the most 

stringent shall be included on the label (this 

will be applicable mainly to preventive 

measures). An order of precedence may be 


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imposed by the chemical manufacturer, importer or responsible party in situations 

where phrases concern ‘‘Response.’’ Rapid 

action may be crucial. For example, if a 

chemical is carcinogenic and acutely toxic, 

rapid action may be crucial, and first aid 

measures for acute toxicity will take precedence over those for long-term effects. In addition, medical attention to delayed health 

effects may be required in cases of incidental 

exposure, even if not associated with immediate symptoms of intoxication. 

C.2.4.8 If the chemical manufacturer, importer, or responsible party can demonstrate 

that a precautionary statement is inappropriate to a specific substance or mixture, the 

precautionary statement may be omitted 

from the label. 

C.3 SUPPLEMENTARY HAZARD INFORMATION

C.3.1 To ensure that non-standardized information does not lead to unnecessarily 

wide variation or undermine the required information, supplementary information on 

the label is limited to when it provides further detail and does not contradict or cast 

doubt on the validity of the standardized 

hazard information. 

C.3.2 Where the chemical manufacturer, 

importer, or distributor chooses to add supplementary information on the label, the 

placement of supplemental information shall 

not impede identification of information required by this section. 

C.3.3 Where an ingredient with unknown 

acute toxicity is used in a mixture at a concentration ≥1%, and the mixture is not classified based on testing of the mixture as a 

whole, a statement that X% of the mixture 

consists of ingredient(s) of unknown acute 

toxicity is required on the label. 

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APPENDIX D TO §1910.1200—SAFETY DATA

SHEETS (MANDATORY) 

A safety data sheet (SDS) shall include the 

information specified in Table D.1 under the 

section number and heading indicated for 

sections 1–11 and 16. If no relevant information is found for any given subheading within a section, the SDS shall clearly indicate 


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that no applicable information is available. 

Sections 12–15 may be included in the SDS, 

but are not mandatory. 

TABLE D.1—MINIMUM INFORMATION FOR AN SDS 

Heading Subheading 

1. Identification ............................................ (a) Product identifier used on the label; 

(b) Other means of identification; 

(c) Recommended use of the chemical and restrictions on use; 

(d) Name, address, and telephone number of the chemical manufacturer, importer, 

or other responsible party; 

(e) Emergency phone number. 

2. Hazard(s) identification ........................... (a) Classification of the chemical in accordance with paragraph (d) of § 1910.1200; 

(b) Signal word, hazard statement(s), symbol(s) and precautionary statement(s) in 

accordance with paragraph (f) of § 1910.1200. (Hazard symbols may be provided 

as graphical reproductions in black and white or the name of the symbol, e.g., 

flame, skull and crossbones); 

(c) Describe any hazards not otherwise classified that have been identified during 

the classification process; 

(d) Where an ingredient with unknown acute toxicity is used in a mixture at a concentration ≥1% and the mixture is not classified based on testing of the mixture 

as a whole, a statement that X% of the mixture consists of ingredient(s) of unknown acute toxicity is required. 

3. Composition/information on ingredients Except as provided for in paragraph (i) of § 1910.1200 on trade secrets: 

For Substances 

(a) Chemical name; 

(b) Common name and synonyms; 

(c) CAS number and other unique identifiers; 

(d) Impurities and stabilizing additives which are themselves classified and which 

contribute to the classification of the substance. 

For Mixtures 

In addition to the information required for substances: 

(a) The chemical name and concentration (exact percentage) or concentration 

ranges of all ingredients which are classified as health hazards in accordance 

with paragraph (d) of § 1910.1200 and 

(1) Are present above their cut-off/concentration limits; or 

(2) Present a health risk below the cut-off/concentration limits. 

(b) The concentration (exact percentage) shall be specified unless a trade secret 

claim is made in accordance with paragraph (i) of § 1910.1200, when there is 

batch-to-batch variability in the production of a mixture, or for a group of substantially similar mixtures (See A.0.5.1.2) with similar chemical composition. In 

these cases, concentration ranges may be used. 

For All Chemicals Where a Trade Secret is Claimed 

Where a trade secret is claimed in accordance with paragraph (i) of § 1910.1200, a 

statement that the specific chemical identity and/or exact percentage (concentration) of composition has been withheld as a trade secret is required. 

4. First-aid measures .................................. (a) Description of necessary measures, subdivided according to the different routes 

of exposure, i.e., inhalation, skin and eye contact, and ingestion; 

(b) Most important symptoms/effects, acute and delayed. 

(c) Indication of immediate medical attention and special treatment needed, if necessary. 

5. Fire-fighting measures ............................ (a) Suitable (and unsuitable) extinguishing media. 

(b) Specific hazards arising from the chemical (e.g., nature of any hazardous combustion products). 

(c) Special protective equipment and precautions for fire-fighters. 

6. Accidental release measures .................. (a) Personal precautions, protective equipment, and emergency procedures. 

(b) Methods and materials for containment and cleaning up. 

7. Handling and storage .............................. (a) Precautions for safe handling. 

(b) Conditions for safe storage, including any incompatibilities. 

8. Exposure controls/personal protection ... (a) OSHA permissible exposure limit (PEL), American Conference of Governmental 

Industrial Hygienists (ACGIH) Threshold Limit Value (TLV), and any other exposure limit used or recommended by the chemical manufacturer, importer, or employer preparing the safety data sheet, where available. 

(b) Appropriate engineering controls. 

(c) Individual protection measures, such as personal protective equipment. 

9. Physical and chemical properties ........... (a) Appearance (physical state, color, etc.); 

(b) Odor; 

(c) Odor threshold; 

(d) pH; 

(e) Melting point/freezing point; 

(f) Initial boiling point and boiling range; 

(g) Flash point; 

(h) Evaporation rate; 

(i) Flammability (solid, gas); 

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TABLE D.1—MINIMUM INFORMATION FOR AN SDS—Continued 

Heading Subheading 

(j) Upper/lower flammability or explosive limits; 

(k) Vapor pressure; 

(l) Vapor density; 

(m) Relative density; 

(n) Solubility(ies); 

(o) Partition coefficient: n-octanol/water; 

(p) Auto-ignition temperature; 

(q) Decomposition temperature; 

(r) Viscosity. 

10. Stability and reactivity ........................... (a) Reactivity; 

(b) Chemical stability; 

(c) Possibility of hazardous reactions; 

(d) Conditions to avoid (e.g., static discharge, shock, or vibration); 

(e) Incompatible materials; 

(f) Hazardous decomposition products. 

11. Toxicological information ...................... Description of the various toxicological (health) effects and the available data used 

to identify those effects, including: 

(a) Information on the likely routes of exposure (inhalation, ingestion, skin and eye 

contact); 

(b) Symptoms related to the physical, chemical and toxicological characteristics; 

(c) Delayed and immediate effects and also chronic effects from short- and longterm exposure; 

(d) Numerical measures of toxicity (such as acute toxicity estimates). 

(e) Whether the hazardous chemical is listed in the National Toxicology Program 

(NTP) Report on Carcinogens (latest edition) or has been found to be a potential 

carcinogen in the International Agency for Research on Cancer (IARC) Monographs (latest edition), or by OSHA. 

12. Ecological information (Non-mandatory) (a) Ecotoxicity (aquatic and terrestrial, where available); 

(b) Persistence and degradability; 

(c) Bioaccumulative potential; 

(d) Mobility in soil; 

(e) Other adverse effects (such as hazardous to the ozone layer). 

13. Disposal considerations (Non-mandatory).Description of waste residues and information on their safe handling and methods 

of disposal, including the disposal of any contaminated packaging. 

14. Transport information (Non-mandatory) (a) UN number; 

(b) UN proper shipping name; 

(c) Transport hazard class(es); 

(d) Packing group, if applicable; 

(e) Environmental hazards (e.g., Marine pollutant (Yes/No)); 

(f) Transport in bulk (according to Annex II of MARPOL 73/78 and the IBC Code); 

(g) Special precautions which a user needs to be aware of, or needs to comply 

with, in connection with transport or conveyance either within or outside their 

premises. 

15. Regulatory information (Non-mandatory).Safety, health and environmental regulations specific for the product in question. 

16. Other information, including date of 

preparation or last revision.

The date of preparation of the SDS or the last change to it. 

APPENDIX E TO §1910.1200—DEFINITION OF

‘‘TRADE SECRET’’ (MANDATORY) 

The following is a reprint of the Restatement of Torts section 757, comment b (1939): 

b. Definition of trade secret. A trade secret 

may consist of any formula, pattern, device 

or compilation of information which is used 

in one’s business, and which gives him an opportunity to obtain an advantage over competitors who do not know or use it. It may be 

a formula for a chemical compound, a process of manufacturing, treating or preserving 

materials, a pattern for a machine or other 

device, or a list of customers. It differs from 

other secret information in a business (see 

s759 of the Restatement of Torts which is not 

included in this Appendix) in that it is not 

simply information as to single or ephemeral 

events in the conduct of the business, as, for 

example, the amount or other terms of a secret bid for a contract or the salary of certain employees, or the security investments 

made or contemplated, or the date fixed for 

the announcement of a new policy or for 

bringing out a new model or the like. A trade 

secret is a process or device for continuous 

use in the operations of the business. Generally it relates to the production of goods, 

as, for example, a machine or formula for the 

production of an article. It may, however, relate to the sale of goods or to other operations in the business, such as a code for determining discounts, rebates or other concessions in a price list or catalogue, or a list of 

specialized customers, or a method of bookkeeping or other office management. 

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1 The text of Appendix F, Part A, on the IARC 

Monographs, is paraphrased from the 2006 Preamble to the ‘‘Monographs on the Evaluation of 

Carcinogenic Risks to Humans’’; the Classifier is 

referred to the full IARC Preamble for the complete text. The text is not part of the agreed 

GHS text on the harmonized system developed 

by the OECD Task Force-HCL. 

Secrecy. The subject matter of a trade secret must be secret. Matters of public knowledge or of general knowledge in an industry 

cannot be appropriated by one as his secret. 

Matters which are completely disclosed by 

the goods which one markets cannot be his 

secret. Substantially, a trade secret is 

known only in the particular business in 

which it is used. It is not requisite that only 

the proprietor of the business know it. He 

may, without losing his protection, communicate it to employees involved in its use. He 

may likewise communicate it to others 

pledged to secrecy. Others may also know of 

it independently, as, for example, when they 

have discovered the process or formula by 

independent invention and are keeping it secret. Nevertheless, a substantial element of 

secrecy must exist, so that, except by the 

use of improper means, there would be difficulty in acquiring the information. An 

exact definition of a trade secret is not possible. Some factors to be considered in determining whether given information is one’s 

trade secret are: (1) The extent to which the 

information is known outside of his business; 

(2) the extent to which it is known by employees and others involved in his business; 

(3) the extent of measures taken by him to 

guard the secrecy of the information; (4) the 

value of the information to him and his competitors; (5) the amount of effort or money 

expended by him in developing the information; (6) the ease or difficulty with which the 

information could be properly acquired or 

duplicated by others. 

Novelty and prior art. A trade secret may be 

a device or process which is patentable; but 

it need not be that. It may be a device or 

process which is clearly anticipated in the 

prior art or one which is merely a mechanical improvement that a good mechanic can 

make. Novelty and invention are not requisite for a trade secret as they are for patentability. These requirements are essential 

to patentability because a patent protects 

against unlicensed use of the patented device 

or process even by one who discovers it properly through independent research. The patent monopoly is a reward to the inventor. 

But such is not the case with a trade secret. 

Its protection is not based on a policy of rewarding or otherwise encouraging the development of secret processes or devices. The 

protection is merely against breach of faith 

and reprehensible means of learning another’s secret. For this limited protection it 

is not appropriate to require also the kind of 

novelty and invention which is a requisite of 

patentability. The nature of the secret is, 

however, an important factor in determining 

the kind of relief that is appropriate against 

one who is subject to liability under the rule 

stated in this Section. Thus, if the secret 

consists of a device or process which is a 

novel invention, one who acquires the secret 

wrongfully is ordinarily enjoined from further use of it and is required to account for 

the profits derived from his past use. If, on 

the other hand, the secret consists of mechanical improvements that a good mechanic can make without resort to the secret, the wrongdoer’s liability may be limited to damages, and an injunction against 

future use of the improvements made with 

the aid of the secret may be inappropriate. 

APPENDIX F TO §1910.1200—GUIDANCE FOR

HAZARD CLASSIFICATIONS RE: CARCINOGENICITY (NON-MANDATORY) 

The mandatory criteria for classification 

of a chemical for carcinogenicity under HCS 

(§1910.1200) are found in Appendix A.6 to this 

section. This non-mandatory Appendix provides additional guidance on hazard classification for carcinogenicity. Part A of Appendix F includes background guidance provided by GHS based on the Preamble of the 

International Agency for Research on Cancer 

(IARC) ‘‘Monographs on the Evaluation of 

Carcinogenic Risks to Humans’’ (2006). Part 

B provides IARC classification information. 

Part C provides background guidance from 

the National Toxicology Program (NTP) 

‘‘Report on Carcinogens’’ (RoC), and Part D 

is a table that compares GHS carcinogen 

hazard categories to carcinogen classifications under IARC and NTP, allowing classifiers to be able to use information from 

IARC and NTP RoC carcinogen classifications to complete their classifications under 

the GHS, and thus the HCS. 

PART A: BACKGROUND GUIDANCE 1

As noted in Footnote 6 of Appendix A.6. to 

this section, the GHS includes as guidance 

for classifiers information taken from the 

Preamble of the International Agency for 

Research on Cancer (IARC) ‘‘Monographs on 

the Evaluation of Carcinogenic Risks to Humans’’ (2006), providing guidance on the evaluation of the strength and evidence of carcinogenic risks to humans. This guidance 

also discusses some additional considerations in classification and an approach to 

analysis, rather than hard-and-fast rules. 

Part A is consistent with Appendix A.6, and 

should help in evaluating information to determine carcinogenicity. 

Carcinogenicity in humans: 

The evidence relevant to carcinogenicity 

from studies in humans is classified into one 

of the following categories: 

588 

§ 1910.1200 29 CFR Ch. XVII (7–1–13 Edition) 

(a) Sufficient evidence of carcinogenicity: 

A causal relationship has been established 

between exposure to the agent and human 

cancer. That is, a positive relationship has 

been observed between the exposure and cancer in studies in which chance, bias and confounding could be ruled out with reasonable 

confidence. 

(b) Limited evidence of carcinogenicity: A 

positive association has been observed between exposure to the agent and cancer for 

which a causal interpretation is considered 

by the Working Group to be credible, but 

chance, bias or confounding could not be 

ruled out with reasonable confidence. 

In some instances, the above categories 

may be used to classify the degree of evidence related to carcinogenicity in specific 

organs or tissues. 

Carcinogenicity in experimental animals: 

The evidence relevant to carcinogenicity 

in experimental animals is classified into 

one of the following categories: 

(a) Sufficient evidence of carcinogenicity: 

A causal relationship has been established 

between the agent and an increased incidence of malignant neoplasms or of an appropriate combination of benign and malignant 

neoplasms in two or more species of animals 

or two or more independent studies in one 

species carried out at different times or in 

different laboratories or under different protocols. An increased incidence of tumors in 

both sexes of a single species in a well-conducted study, ideally conducted under Good 

Laboratory Practices, can also provide sufficient evidence. 

Exceptionally, a single study in one species 

and sex might be considered to provide sufficient evidence of carcinogenicity when malignant neoplasms occur to an unusual degree with regard to incidence, site, type of 

tumor or age at onset, or when there are 

strong findings of tumors at multiple sites. 

(b) Limited evidence of carcinogenicity: 

The data suggest a carcinogenic effect but 

are limited for making a definitive evaluation because, e.g. the evidence of carcinogenicity is restricted to a single experiment; 

there are unresolved questions regarding the 

adequacy of the design, conduct or interpretation of the studies; the agent increases the 

incidence only of benign neoplasms or lesions of uncertain neoplastic potential; or 

the evidence of carcinogenicity is restricted 

to studies that demonstrate only promoting 

activity in a narrow range of tissues or organs. 

Guidance on How To Consider Important Factors in Classification of Carcinogenicity (See 

Reference Section) 

The weight of evidence analysis called for 

in GHS and the HCS (§1910.1200) is an integrative approach that considers important 

factors in determining carcinogenic potential along with the strength of evidence analysis. The IPCS ‘‘Conceptual Framework for 

Evaluating a Mode of Action for Chemical Carcinogenesis’’ (2001), International Life 

Sciences Institute (ILSI) ‘‘Framework for 

Human Relevance Analysis of Information on 

Carcinogenic Modes of Action’’ (Meek, et al., 

2003; Cohen et al., 2003, 2004), and Preamble to 

the IARC Monographs (2006; Section B.6. 

(Scientific Review and Evaluation; Evaluation and Rationale)) provide a basis for systematic assessments that may be performed 

in a consistent fashion. The IPCS also convened a panel in 2004 to further develop and 

clarify the human relevance framework. 

However, the above documents are not intended to dictate answers, nor provide lists 

of criteria to be checked off. 

Mode of Action 

Various documents on carcinogen assessment all note that mode of action in and of 

itself, or consideration of comparative metabolism, should be evaluated on a case-bycase basis and are part of an analytic evaluative approach. One must look closely at any 

mode of action in animal experiments, taking into consideration comparative 

toxicokinetics/toxicodynamics between the 

animal test species and humans to determine 

the relevance of the results to humans. This 

may lead to the possibility of discounting 

very specific effects of certain types of substances. Life stage-dependent effects on cellular differentiation may also lead to qualitative differences between animals and humans. Only if a mode of action of tumor development is conclusively determined not to 

be operative in humans may the carcinogenic evidence for that tumor be discounted. 

However, a weight of evidence evaluation for 

a substance calls for any other tumorigenic 

activity to be evaluated, as well. 

Responses in Multiple Animal Experiments 

Positive responses in several species add to 

the weight of evidence that a substance is a 

carcinogen. Taking into account all of the 

factors listed in A.6.2.5.2 and more, such 

chemicals with positive outcomes in two or 

more species would be provisionally considered to be classified in GHS Category 1B 

until human relevance of animal results are 

assessed in their entirety. It should be noted, 

however, that positive results for one species 

in at least two independent studies, or a single positive study showing unusually strong 

evidence of malignancy may also lead to 

Category 1B. 

Responses Are in One Sex or Both Sexes 

Any case of gender-specific tumors should 

be evaluated in light of the total 

tumorigenic response to the substance observed at other sites (multi-site responses or 

incidence above background) in determining 

the carcinogenic potential of the substance. 

589 

Occupational Safety and Health Admin., Labor § 1910.1200 

2While most international agencies do not 

consider kidney tumors coincident with α2uglobulin nephropathy to be a predictor of risk in 

humans, this view is not universally held. (See: 

Doi et al., 2007). 3 Preamble of the International Agency for Research on Cancer (IARC) ‘‘Monographs on the 

Evaluation of Carcinogenic Risks to Humans’’ 

(2006). 

If tumors are seen only in one sex of an 

animal species, the mode of action should be 

carefully evaluated to see if the response is 

consistent with the postulated mode of action. Effects seen only in one sex in a test 

species may be less convincing than effects 

seen in both sexes, unless there is a clear 

patho-physiological difference consistent 

with the mode of action to explain the single 

sex response. 

Confounding Effects of Excessive Toxicity or 

Localized Effects 

Tumors occurring only at excessive doses 

associated with severe toxicity generally 

have doubtful potential for carcinogenicity 

in humans. In addition, tumors occurring 

only at sites of contact and/or only at excessive doses need to be carefully evaluated for 

human relevance for carcinogenic hazard. 

For example, forestomach tumors, following 

administration by gavage of an irritating or 

corrosive, non-mutagenic chemical, may be 

of questionable relevance. However, such determinations must be evaluated carefully in 

justifying the carcinogenic potential for humans; any occurrence of other tumors at distant sites must also be considered. 

Tumor Type, Reduced Tumor Latency 

Unusual tumor types or tumors occurring 

with reduced latency may add to the weight 

of evidence for the carcinogenic potential of 

a substance, even if the tumors are not statistically significant. 

Toxicokinetic behavior is normally assumed to be similar in animals and humans, 

at least from a qualitative perspective. On 

the other hand, certain tumor types in animals may be associated with toxicokinetics 

or toxicodynamics that are unique to the 

animal species tested and may not be predictive of carcinogenicity in humans. Very 

few such examples have been agreed internationally. However, one example is the lack 

of human relevance of kidney tumors in 

male rats associated with compounds causing a2u-globulin nephropathy (IARC, Scientific Publication N° 147 2). Even when a 

particular tumor type may be discounted, 

expert judgment must be used in assessing 

the total tumor profile in any animal experiment. 

PART B: INTERNATIONAL AGENCY FOR

RESEARCH ON CANCER (IARC) 3

IARC Carcinogen Classification Categories: 

Group 1: The agent is carcinogenic to humans 

This category is used when there is sufficient evidence of carcinogenicity in humans. 

Exceptionally, an agent may be placed in 

this category when evidence of carcinogenicity in humans is less than sufficient but 

there is sufficient evidence of carcinogenicity 

in experimental animals and strong evidence 

in exposed humans that the agent acts 

through a relevant mechanism of carcinogenicity. 

Group 2: 

This category includes agents for which, at 

one extreme, the degree of evidence of carcinogenicity in humans is almost sufficient, 

as well as those for which, at the other extreme, there are no human data but for 

which there is evidence of carcinogenicity in 

experimental animals. Agents are assigned 

to either Group 2A (probably carcinogenic to 

humans) or Group 2B (possibly carcinogenic to 

humans) on the basis of epidemiological and 

experimental evidence of carcinogenicity 

and mechanistic and other relevant data. 

The terms probably carcinogenic and possibly 

carcinogenic have no quantitative significance and are used simply as descriptors of 

different levels of evidence of human carcinogenicity, with probably carcinogenic signifying a higher level of evidence than possibly carcinogenic. 

Group 2A: The agent is probably carcinogenic to human. 

This category is used when there is limited 

evidence of carcinogenicity in humans and sufficient evidence of carcinogenicity in experimental animals. In some cases, an agent may 

be classified in this category when there is 

inadequate evidence of carcinogenicity in humans and sufficient evidence of carcinogenicity 

in experimental animals and strong evidence 

that the carcinogenesis is mediated by a 

mechanism that also operates in humans. 

Exceptionally, an agent may be classified in 

this category solely on the basis of limited 

evidence of carcinogenicity in humans. An 

agent may be assigned to this category if it 

clearly belongs, based on mechanistic considerations, to a class of agents for which 

one or more members have been classified in 

Group 1 or Group 2A. 

Group 2B: The agent is possibly carcinogenic 

to humans. 

This category is used for agents for which 

there is limited evidence of carcinogenicity in 

humans and less than sufficient evidence of 

carcinogenicity in experimental animals. It 

may also be used when there is inadequate 

evidence of carcinogenicity in humans but 

there is sufficient evidence of carcinogenicity 

in experimental animals. In some instances, 

590 

§ 1910.1200 29 CFR Ch. XVII (7–1–13 Edition) 

4See: http://ntp.niehs.nih.gov/go/15209. 5 This evidence can include traditional cancer 

epidemiology studies, data from clinical studies, 

and/or data derived from the study of tissues or 

cells from humans exposed to the substance in 

question that can be useful for evaluating 

whether a relevant cancer mechanism is operating in people. 

an agent for which there is inadequate evidence of carcinogenicity in humans and less 

than sufficient evidence of carcinogenicity in 

experimental animals together with supporting evidence from mechanistic and other 

relevant data may be placed in this group. 

An agent may be classified in this category 

solely on the basis of strong evidence from 

mechanistic and other relevant data. 

PART C: NATIONAL TOXICOLOGY PROGRAM

(NTP), ‘‘REPORT ON CARCINOGENS’’, BACKGROUND GUIDANCE

NTP Listing Criteria 4: 

The criteria for listing an agent, substance, mixture, or exposure circumstance in 

the Report on Carcinogens (RoC) are as follows: 

Known To Be A Human Carcinogen: There 

is sufficient evidence of carcinogenicity from 

studies in humans 5 that indicates a causal 

relationship between exposure to the agent, 

substance, or mixture, and human cancer. 

Reasonably Anticipated To Be A Human 

Carcinogen: There is limited evidence of carcinogenicity from studies in humans that indicates that a causal interpretation is credible, but that alternative explanations, such 

as chance, bias, or confounding factors, could 

not adequately be excluded, 

or 

there is sufficient evidence of carcinogenicity from studies in experimental animals that indicates there is an increased incidence of malignant and/or a combination of 

malignant and benign tumors in multiple 

species or at multiple tissue sites, or by multiple routes of exposure, or to an unusual degree with regard to incidence, site, or type of 

tumor, or age at onset, 

or 

there is less than sufficient evidence of carcinogenicity in humans or laboratory animals; however, the agent, substance, or mixture belongs to a well-defined, structurallyrelated class of substances whose members 

are listed in a previous Report on Carcinogens as either known to be a human carcinogen or reasonably anticipated to be a 

human carcinogen, or there is convincing 

relevant information that the agent acts 

through mechanisms indicating it would 

likely cause cancer in humans. 

Conclusions regarding carcinogenicity in 

humans or experimental animals are based 

on scientific judgment, with consideration 

given to all relevant information. Relevant 

information includes, but is not limited to, 

dose response, route of exposure, chemical 

structure, metabolism, pharmacokinetics, 

sensitive sub-populations, genetic effects, or 

other data relating to mechanism of action 

or factors that may be unique to a given substance. For example, there may be substances for which there is evidence of carcinogenicity in laboratory animals, but 

there are compelling data indicating that 

the agent acts through mechanisms that do 

not operate in humans and would therefore 

not reasonably be anticipated to cause cancer in humans. 

PART D: TABLE RELATING APPROXIMATE

EQUIVALENCES AMONG IARC, NTP ROC, AND

GHS CARCINOGENICITY CLASSIFICATIONS

The following table may be used to perform hazard classifications for carcinogenicity under the HCS (§1910.1200). It relates the approximated GHS hazard categories for carcinogenicity to the classifications provided by IARC and NTP, as described in Parts B and C of this Appendix. 

APPROXIMATE EQUIVALENCES AMONG CARCINOGEN CLASSIFICATION SCHEMES

IARC GHS NTP RoC 

Group 1 .................................... Category 1A ............................ Known. 

Group 2A .................................. Category 1B ............................ Reasonably Anticipated (See Note 1). 

Group 2B .................................. Category 2 ............................... Reasonably Anticipated (See Note 1). 

Note 1: 

1. Limited evidence of carcinogenicity from 

studies in humans (corresponding to IARC 2A/ 

GHS 1B); 

2. Sufficient evidence of carcinogenicity from 

studies in experimental animals (again, essentially corresponding to IARC 2A/GHS 1B); 

3. Less than sufficient evidence of carcinogenicity in humans or laboratory animals; however: 

a. The agent, substance, or mixture belongs to 

a well-defined, structurally-related class of substances whose members are listed in a previous 

RoC as either ‘‘Known’’ or ‘‘Reasonably Anticipated’’ to be a human carcinogen, or 

591 

Occupational Safety and Health Admin., Labor § 1910.1450 

b. There is convincing relevant information 

that the agent acts through mechanisms indicating it would likely cause cancer in humans. 

*REFERENCES

Cohen, S.M., J. Klaunig, M.E. Meek, R.N. 

Hill, T. Pastoor, L. Lehman-McKeeman, 

J. Bucher, D.G. Longfellow, J. Seed, V. 

Dellarco, P. Fenner-Crisp, and D. Patton. 

2004. Evaluating the human relevance of 

chemically induced animal tumors. 

Toxicol. Sci. 78(2):181–186. 

Cohen, S.M., M.E. Meek, J.E. Klaunig, D.E. 

Patton, P.A. Fenner-Crisp. 2003. The 

human relevance of information on carcinogenic modes of action: Overview. 

Crit. Rev. Toxicol. 33(6):581–9. 

Meek, M.E., J.R. Bucher, S.M. Cohen, V. 

Dellarco, R.N. Hill, L. LehmanMcKeeman, D.G. Longfellow, T. Pastoor, 

J. Seed, D.E. Patton. 2003. A framework 

for human relevance analysis of information on carcinogenic modes of action. 

Crit. Rev. Toxicol. 33(6):591–653. 

Sonich-Mullin, C., R. Fielder, J. Wiltse, K. 

Baetcke, J. Dempsey, P. Fenner-Crisp, D. 

Grant, M. Hartley, A. Knapp, D. Kroese, 

I. Mangelsdorf, E. Meek, J.M. Rice, and 

M. Younes. 2001. The conceptual framework for evaluating a mode of action for 

chemical carcinogenesis. Reg. Toxicol. 

Pharm. 34:146–152. 

International Programme on Chemical Safety Harmonization Group. 2004. Report of 

the First Meeting of the Cancer Working 

Group. World Health Organization. Report IPCS/HSC–CWG–1/04. Geneva. 

International Agency for Research on Cancer. IARC Monographs on the Evaluation 

of Carcinogenic Risks to Human. Preambles to Volumes. World Health Organization. Lyon, France. 

Cohen, S.M., P.A. Fenner-Crisp, and D.E. 

Patton. 2003. Special Issue: Cancer Modes 

of Action and Human Relevance. Critical 

Reviews in Toxicology, R.O. McClellan, 

ed., Volume 33/Issue 6. CRC Press. 

Capen, C.C., E. Dybing, and J.D. Wilbourn. 

1999. Species differences in thyroid, kidney and urinary bladder carcinogenesis. 

International Agency for Research on 

Cancer, Scientific Publication N° 147. 

Doi, A.M., G. Hill, J. Seely, J.R. Hailey, G. 

Kissling, and J.R. Buchera. 2007. a2uGlobulin nephropathy and renal tumors 

in National Toxicology Program studies. 

Toxicol. Pathol. 35:533–540. 

[59 FR 6170, Feb. 9, 1994, as amended at 59 FR 

17479, Apr. 13, 1994; 59 FR 65948, Dec. 22, 1994; 

61 FR 9245, Mar. 7. 1996; 77 FR 17785, Mar. 26, 

2012; 78 FR 9313, Feb. 8, 2013] 

§ 1910.1201 Retention of DOT markings, placards and labels. 

(a) Any employer who receives a 

package of hazardous material which is 

required to be marked, labeled or placarded in accordance with the U. S. Department of Transportation’s Hazardous Materials Regulations (49 CFR 

Parts 171 through 180) shall retain 

those markings, labels and placards on 

the package until the packaging is sufficiently cleaned of residue and purged 

of vapors to remove any potential hazards. 

(b) Any employer who receives a 

freight container, rail freight car, 

motor vehicle, or transport vehicle 

that is required to be marked or placarded in accordance with the Hazardous Materials Regulations shall retain those markings and placards on 

the freight container, rail freight car, 

motor vehicle or transport vehicle 

until the hazardous materials which require the marking or placarding are 

sufficiently removed to prevent any potential hazards. 

(c) Markings, placards and labels 

shall be maintained in a manner that 

ensures that they are readily visible. 

(d) For non-bulk packages which will 

not be reshipped, the provisions of this 

section are met if a label or other acceptable marking is affixed in accordance with the Hazard Communication 

Standard (29 CFR 1910.1200). 

(e) For the purposes of this section, 

the term ‘‘hazardous material’’ and 

any other terms not defined in this section have the same definition as in the 

Hazardous Materials Regulations (49 

CFR Parts 171 through 180). 

[59 FR 36700, July 19, 1994] 

§ 1910.1450 Occupational exposure to 

hazardous chemicals in laboratories. 

(a) Scope and application. (1) This section shall apply to all employers engaged in the laboratory use of hazardous chemicals as defined below. 

(2) Where this section applies, it shall 

supersede, for laboratories, the requirements of all other OSHA health standards in 29 CFR part 1910, subpart Z, except as follows: