Scope of 13 Carcinogens

The 13 carcinogens covered are 4‑Nitrobiphenyl; alpha‑Naphthylamine; methyl chloromethyl ether; 3,3'‑Dichlorobenzidine (and its salts); bis‑Chloromethyl ether; beta‑Naphthylamine; Benzidine; 4‑Aminodiphenyl; Ethyleneimine; beta‑Propiolactone; 2‑Acetylaminofluorene; 4‑Dimethylaminoazobenzene; and N‑Nitrosodimethylamine. For the exact list and CAS numbers, see 1910.1003(a)(1).

A mixture is exempt from this section when it contains less than 0.1% by weight or volume of certain highly hazardous carcinogens and less than 1.0% by weight or volume of other listed carcinogens, as specified. Specifically, mixtures with under 0.1% of 4‑Nitrobiphenyl; methyl chloromethyl ether; bis‑chloromethyl ether; beta‑Naphthylamine; benzidine; or 4‑Aminodiphenyl are exempt, and mixtures with under 1.0% of alpha‑Naphthylamine; 3,3'‑Dichlorobenzidine (and its salts); Ethyleneimine; beta‑Propiolactone; 2‑Acetylaminofluorene; 4‑Dimethylaminoazobenzene; or N‑Nitrosodimethylamine are exempt. See 1910.1003(a)(2) and its subparagraphs 1910.1003(a)(2)(i) and 1910.1003(a)(2)(ii).

The standard generally does not apply to transshipment in sealed containers, except employers must still meet the labeling requirements specified in paragraphs (e)(2), (e)(3), and (e)(4). See 1910.1003(a).

An isolated system is a fully enclosed structure (other than the vessel of containment) that is impervious to the passage of the carcinogen and would prevent the chemical from entering other work areas if leakage or spillage occurred; employees working with an isolated system must wash their hands and arms when they finish the assigned task and before doing other activities. See the definitions and the requirement in 1910.1003(b) and 1910.1003(c)(1).

A closed system is an operation where containment prevents release of the carcinogen into regulated or nonregulated areas; when carcinogens are stored in sealed containers or contained in a closed system, access must be restricted to authorized employees only. See the definitions in 1910.1003(b) and the closed system operation rule in 1910.1003(c)(2)(i).

An open‑vessel system is an operation in an open vessel that is not in an isolated system, a laboratory‑type hood, or another system providing equivalent protection; open‑vessel system operations are prohibited by the standard. See the definition in 1910.1003(b) and the prohibition in 1910.1003(c)(3).

A laboratory‑type hood is a device enclosed on three sides and top/bottom and must draw air inward at an average linear face velocity of 150 feet per minute with a minimum of 125 feet per minute; it must also be designed so the operation does not require insertion of any body part other than hands and arms. See the definition in 1910.1003(b).

An absolute filter is one capable of retaining 99.97% of a monodisperse aerosol of 0.3 µm particles; this definition is relevant when specifying filtration or respiratory protection and other engineering controls for contaminated air. See the definition in 1910.1003(b).

An employer must establish a regulated area wherever one of the 13 carcinogens is manufactured, processed, used, repackaged, released, handled, or stored. See the general requirement in 1910.1003(c).

Employees who are exposed to 4‑Nitrobiphenyl; alpha‑Naphthylamine; 3,3'‑Dichlorobenzidine (and its salts); beta‑Naphthylamine; benzidine; 4‑Aminodiphenyl; 2‑Acetylaminofluorene; 4‑Dimethylaminoazobenzene; and N‑Nitrosodimethylamine must wash their hands, forearms, face, and neck upon each exit from the regulated area, near the exit point, and before doing other activities. See 1910.1003(c)(2)(ii).

When transferring from a closed system, charging/discharging, or otherwise opening a closed system (including operations in laboratory‑type hoods), access must be restricted to authorized employees only, and continuous local exhaust ventilation must be provided so air moves from ordinary work areas toward the operation; exhaust must not be discharged to regulated, nonregulated, or external areas unless decontaminated, and sufficient clean makeup air must be supplied. See 1910.1003(c)(4)(i) and 1910.1003(c)(4)(ii).

Employees must be provided with and required to wear clean, full‑body protective clothing (such as smocks, coveralls, or long‑sleeved shirt and pants), shoe covers, and gloves before entering the regulated area for transfer operations; prior to each exit they must remove and leave protective clothing and equipment at the exit point and place used clothing/equipment in impervious containers for decontamination or disposal (with contents identified per paragraph (e)). See 1910.1003(c)(4)(iii) and 1910.1003(c)(4)(v).

For handling operations involving 4‑Nitrobiphenyl; alpha‑Naphthylamine; 3,3'‑Dichlorobenzidine (and its salts); beta‑Naphthylamine; benzidine; 4‑Aminodiphenyl; 2‑Acetylaminofluorene; 4‑Dimethylaminoazobenzene; and N‑Nitrosodimethylamine, employers must provide and ensure employees wear a NIOSH‑certified air‑purifying half‑mask respirator with particulate filters. For handling methyl chloromethyl ether; bis‑Chloromethyl ether; Ethyleneimine; and beta‑Propiolactone, employers must provide and ensure employees wear either a self‑contained breathing apparatus with a full facepiece and pressure‑demand (or other positive‑pressure) mode, or a supplied‑air respirator with full facepiece operated in pressure‑demand (or other positive‑pressure) mode in combination with an auxiliary positive‑pressure self‑contained breathing apparatus. See 1910.1003(c)(4)(iv).

Yes. Employers may substitute respirators that provide employees higher levels of protection than those specified in the standard. See 1910.1003(c)(4)(v).

No. Drinking fountains are prohibited inside regulated areas. See 1910.1003(c)(4)(vi).

Employees exposed to 4‑Nitrobiphenyl; alpha‑Naphthylamine; 3,3'‑Dichlorobenzidine (and its salts); beta‑Naphthylamine; benzidine; 4‑Aminodiphenyl; 2‑Acetylaminofluorene; 4‑Dimethylaminoazobenzene; and N‑Nitrosodimethylamine must be required to shower after their final exit of the day. See 1910.1003(c)(4)(vii).

Authorized employees performing cleanup of leaks, spills, maintenance, or repairs on contaminated systems must be provided with and required to wear clean, impervious garments (including gloves and boots) and a continuous‑air supplied hood in accordance with [1910.134]; they must be decontaminated before removing the protective garments and hood and must shower after removing them. See 1910.1003(c)(5)(i), 1910.1003(c)(5)(ii), 1910.1003(c)(5)(iii), and the respiratory program requirements in 1910.134.

Yes. Employers must implement a respiratory protection program that covers each employee required to use a respirator under this section, following the requirements in [1910.134] (with specific exceptions listed in 1910.1003). See 1910.1003(d)(1) and 1910.134.

In an emergency, the employer must evacuate the potentially affected area promptly, eliminate hazardous conditions and decontaminate the area before resuming normal operations, and institute special medical surveillance by a physician within 24 hours for employees present in the potentially affected area at the time of the emergency. See 1910.1003(d)(2) and the detailed subparagraphs 1910.1003(d)(2)(i)–(iv).

Emergency deluge showers and eyewash fountains with running potable water must be located near, within sight of, and on the same level as locations where direct exposure to Ethyleneimine or beta‑Propiolactone would be most likely due to equipment failure or improper work practice. See 1910.1003(d)(2)(v).

Inside regulated areas the storage or consumption of food and beverages, storage or application of cosmetics, smoking, storage or use of tobacco or chewing products, and the chewing of such products are prohibited. See 1910.1003(d)(3)(i).

No. Exhaust air from the continuous local exhaust ventilation used during transfer or opening operations must not be discharged into regulated areas, nonregulated areas, or the external environment unless it has been decontaminated; clean makeup air must also be supplied to maintain proper ventilation. See 1910.1003(c)(4)(ii).

Employers must require employees to remove and leave protective clothing and equipment at the point of exit and, at the last exit of the day, place used clothing and equipment in impervious containers at the exit for decontamination or disposal; the contents of those impervious containers must be identified as required under paragraph (e) of the section. See 1910.1003(c)(4)(v).

Authorized employees cleaning up leaks, spills, or doing maintenance that could result in direct contact must wear a continuous‑air supplied hood, and that hood must be provided in accordance with [1910.134] (the Respiratory Protection standard). See 1910.1003(c)(5)(i) and 1910.134.

Employees are required to wash hands, forearms, face, and neck on each exit from the regulated area, close to the point of exit; employees exposed to the listed group of more hazardous carcinogens (such as 4‑Nitrobiphenyl, alpha‑Naphthylamine, benzidine, etc.) must also be required to shower after their last exit of the day. See 1910.1003(c)(4)(vii).

Employers must provide washing facilities whenever this section requires employees to wash, and those facilities must meet the requirements in 1910.141(d)(1) and (d)(2)(ii)–(vii).

• Provide sinks and fixtures sized and located per 1910.141(d)(1).
• Follow the specific washing-facility details in 1910.141(d)(2)(ii)–(vii).

Practical tips: make sure sinks are cleanable, supplied with potable water, and located so employees can wash before leaving the regulated area.

Shower facilities are required whenever this section requires employees to shower, and they must be provided in accordance with 1910.141(d)(3).

• Ensure showers are accessible, usable, and maintained as described in 1910.141(d)(3).
• Consider privacy, hot water availability, and drainage when locating shower facilities.

Employers must provide clean change rooms for employees who wear protective clothing and equipment, and those change rooms must meet the requirements of 1910.141(e).

• Provide enough lockers or storage for the number of employees who must change clothes.
• Keep change rooms clean and separate from contaminated areas as required by 1910.141(e).

Toilets in regulated areas must be placed in a separate room, as required by 1910.1003(d)(3)(v).

• This separate room prevents cross-contamination between toilet facilities and work areas.
• Ensure the toilet room is maintained, ventilated, and cleaned to prevent spread of contaminants.

Regulated areas (except outdoor systems) must be maintained under negative pressure relative to nonregulated areas, with equal clean makeup air replacing removed air; local exhaust ventilation can be used to meet this requirement as stated in 1910.1003(d)(4)(i).

• Negative pressure prevents contaminated air from escaping the regulated area.
• If you use local exhaust, provide clean makeup air in equal volume to maintain balance.
• Test and monitor airflow regularly to confirm negative pressure is maintained.

Employers must move any equipment, materials, or other items into or out of a regulated area in a way that does not cause contamination of nonregulated areas or the external environment, per 1910.1003(d)(4)(ii).

Practical controls include:

• Using sealed containers or double-bagging for contaminated items.
• Passing items through an airlock or decontamination booth.
• Cleaning and decontaminating items before removal, per written decontamination procedures.

Decontamination procedures must be established and implemented to remove the carcinogens addressed by this section from surfaces of materials, equipment, and the decontamination facility itself, as required by 1910.1003(d)(4)(iii).

Good practice for those procedures:

• Describe cleaning agents and methods (wet wiping, HEPA vacuuming, approved solvents).
• Define sequence (from least to most contaminated zones) and frequency of cleaning.
• Specify who performs decontamination, required PPE, waste handling, and verification (e.g., visual inspection or wipe sampling).
• Keep written, train employees on the procedure, and review/update it when processes change.

Dry sweeping and dry mopping are prohibited for the listed carcinogens: 4-Nitrobiphenyl; alpha-Naphthylamine; 3,3′-Dichlorobenzidine (and its salts); beta-Naphthylamine; Benzidine; 4-Aminodiphenyl; 2-Acetylaminofluorene; 4-Dimethylaminoazo-benzene; and N-Nitrosodimethylamine, per 1910.1003(d)(4)(iv).

Recommended alternatives:

• Use HEPA-filtered vacuums for dust and residues.
• Use wet-wiping or wet-mopping methods with appropriate cleaning agents.
• Collect and dispose of waste as hazardous material, following your written procedures and 1910.1200 labeling and SDS requirements.

Yes. Chemical manufacturers, importers, distributors and employers must comply with all requirements of the Hazard Communication Standard for each carcinogen listed in 1910.1003(e)(1)(iv).

• Include these carcinogens in your hazard classification, labeling, safety data sheets (SDS), and training program under 1910.1200.
• Ensure SDSs are available to employees and downstream users.

Employers must address at least the specific hazards listed in 1910.1003(e)(1)(iv) when classifying these carcinogens, and include them in the hazard communication program so employees have access to container labels, safety data sheets, and training, as required by 1910.1003(e)(1)(ii)–(iii).

• Make sure training covers the specific health effects (e.g., cancer, skin irritation, liver effects) listed for each substance.
• Keep labels and SDSs up-to-date and available where employees can read them.

The standard lists these carcinogens in 1910.1003(e)(1)(iv):

• 4-Nitrobiphenyl
• alpha-Naphthylamine
• Methyl chloromethyl ether
• 3,3′-Dichlorobenzidine (and its salts)
• bis-Chloromethyl ether
• beta-Naphthylamine
• Benzidine
• 4-Aminodiphenyl
• Ethyleneimine
• beta-Propiolactone
• 2-Acetylaminofluorene
• 4-Dimethylaminoazo-benzene
• N-Nitrosodimethylamine

Each entry in the list also notes associated health effects (for example, skin irritation, mutagenicity, liver effects) as detailed in the paragraphs of 1910.1003(e)(1)(iv).

Employers must post entrances to regulated areas with signs that read: "DANGER (CHEMICAL IDENTIFICATION) MAY CAUSE CANCER AUTHORIZED PERSONNEL ONLY," and for operations covered by paragraph (c)(5) use the legend required in 1910.1003(e)(2)(i)–(ii).

• If specific protective equipment is required, the sign in 1910.1003(e)(2) also includes the extended legend: "DANGER (CHEMICAL IDENTIFICATION) MAY CAUSE CANCER WEAR AIR-SUPPLIED HOODS, IMPERVIOUS SUITS, AND PROTECTIVE EQUIPMENT IN THIS AREA AUTHORIZED PERSONNEL ONLY."

Prior to June 1, 2016, employers were allowed to use older legends such as "CANCER-SUSPECT AGENT AUTHORIZED PERSONNEL ONLY" or an alternate extended legend in place of the current text, as described in 1910.1003(e)(2)(iii)–(iv).

• Those alternate legends were explicitly grandfathered only prior to June 1, 2016.
• To comply now, use the current required legends in 1910.1003(e)(2).

Employers must post appropriate signs and instructions at the entrance to, and exit from, regulated areas that inform employees of the procedures they must follow when entering and leaving, as required by 1910.1003(e)(2)(v).

Examples of required instructions:

• Donning and doffing procedures for protective clothing and respirators.
• Decontamination steps and waste handling instructions.
• Emergency exit and spill-response steps.

No statement that contradicts or detracts from the effect of any required warning, information, or instruction may appear on or near required signs, labels, or instructions, in accordance with 1910.1003(e)(3).

• Avoid adding any promotional, reassuring, or confusing text near required warnings that could reduce their impact or clarity.

Employees must receive a training and indoctrination program covering specified topics (such as the nature of carcinogenic hazards, operations that could cause exposure, medical surveillance, decontamination, emergency procedures, recognition of release conditions, and first aid) before being authorized to enter a regulated area, and this training must be reviewed at their first training and annually thereafter as required by 1910.1003(e)(4)(i) and (i)(I).

• Include hands-on familiarization with decontamination and emergency procedures required under 1910.1003(e)(4)(ii).

OSHA requires employers to prescribe, post, familiarize employees with, and rehearse specific emergency procedures related to operations covered by this section, as stated in 1910.1003(e)(4)(ii).

• Post clear, step-by-step emergency instructions at workstations and regulated-area exits.
• Rehearse emergency drills so employees know their roles and response steps.

Yes. All materials relating to the training and indoctrination program must be provided upon request to authorized representatives of the Assistant Secretary and the Director, as required by 1910.1003(e)(4)(iii).

• Keep training records and curricula organized and ready to share during inspections or upon official request.

Employers must provide a medical surveillance program at no cost that includes a preassignment physical examination before assignment and periodic physical examinations at least annually for authorized employees, as required by 1910.1003(g)(1)(i)–(ii).

• Examinations must consider conditions of increased risk (for example pregnancy, immunosuppression, or cigarette smoking) per 1910.1003(g)(1)(iii).
• Ensure exams are performed by a physician and that employees understand the purpose of medical surveillance.

Employers must maintain complete and accurate records of all required medical examinations for the duration of the employee's employment, and provide those records upon request to employees, designated representatives, the Assistant Secretary, and the Director in accordance with 1910.1003(g)(2)(i)–(ii).

• Records access must follow 1910.1020 procedures for employee exposure and medical records.
• Any examining physician must also provide the employer a statement of the employee's suitability for the specific exposure per 1910.1003(g)(2)(iii).

Employers must ensure movement of items from a regulated area to the outside does not cause contamination of nonregulated areas or the environment by following methods required in 1910.1003(d)(4)(ii).

Practical controls include:

• Decontaminating and sealing items inside the regulated area before removal.
• Using dedicated transition zones or containment carts to prevent spreading contamination.
• Following written decontamination and waste-handling procedures in 1910.1003(d)(4)(iii).

Signs for operations covered in paragraph (c)(5) must comply with the posting requirements in 1910.1003(e)(2)(ii) and use the appropriate legend for those operations. You can find the details of paragraph (c)(5) at 1910.1003(c)(5).

• Paragraph (c)(5) identifies specific operations that the standard covers; review it to determine if your operation triggers the special signage and controls referenced in 1910.1003(e)(2).