OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov.

February 17, 1982

                 Regional Administrator

                 Acting ARA for Technical Support

THRU:             JOHN B. MILES, JR.
                 Director Office of Field Coordination

FROM:             PATRICK R. TYSON
                 Federal Compliance and State Programs

SUBJECT:          Showering Requirements of the Acrylonitrile Standard,
                 29 CFR 1910.1045

This is in response to your memorandum dated January 14, 1982 (copy enclosed for reference).

When liquid acrylonitrile is handled in other than totally closed systems, and employees working with or around the liquid must wear impermeable protective clothing or other equipment because eye or skin contact may occur, then clearly, in accordance with 29 CFR 1910.1045(m)(2), the employees must shower at the end of the work shift. It is sound practice to establish a blanket, unconditional requirement for employees to shower in the described circumstances, because there is no practical way of knowing for sure that any given employee did not actually come into contact with the liquid at some time or other during the work shift.

Some employers, however, require employees working solely around totally closed system for handling acrylonitrile to wear impermeable protective clothing, on the off-chance that a break in the system might result in a "massive release" of acrylonitrile. We do not interpret 29 CFR 1910.1045(m)(2) to require these employees to shower at the end of the work shift if no break in the closed system occurred. Here there would be no sound basis for requiring the employees to shower at the end of the work shift since, if there were no break in the closed system, the employees obviously would not have been exposed to liquid acrylonitrile, and showering would be unnecessary. Moreover, it appears highly unlikely that a break in the system could occur without supervisory employees being aware of it. We do interpret 29 CFR 1910.1045(m)(2) to require that these employees shower at the end of the work shift, however, should a break in the closed system occur.

In order to expedite this information, we will address you inquiry about "massive release" in a separate memorandum.


January 14, 1982

                  Director Office of Field Coordination

FROM:              ALAN C. MCMILLAN
                  Regional Administrator

THRU:              ALVAH O. CONLEY
                  Acting ARA for Technical Support

SUBJECT:           Request for Clarification of Reply to Rohm and Haas
                  Company from the Director of Health Standards
                  Programs (1979) Pertinent to the Requirements of
                  the Acrylonitrile Standard 1910.1045

The Cincinnati Area Office issued a citation to the Monsanto Port Plastics Plant for failure to enforce showering by its exposed employees as required in standard 1910.1045(j)(1), (m)(2), and as discussed in the preamble to the standard (FR 45805). This plant secured a copy of a letter (enclosed) to Rohm and Haas Company by the Director of Health Standards Programs (1979) which, in part, discussed showering requirements. Both companies have interpreted the letter content as stating that showering is not a mandatory requirement in the acrylonitrile standard. The Monsanto Port Plastics Plant has filed a Statement of Intent to contest the citation issued by the Cincinnati Area Office.

It is requested that this office be provided with a prompt reply which clearly states the mandatory showering requirements of the acrylonitrile standard - 1910.1045(j)(1), (m)(2), and the preamble (FR 45805). A 30-day extension has been secured by the OSHA Solicitor to delay filing the contest and is pending on the reply from the National Office.

As an additional item, please note Item 2. of the letter which requests a definition for "unexpected massive release" pertinent to the situation described on Page 3.

Any questions you may have regarding this memorandum may be directed to Al Conley (312-353-2220) of my staff.


December 2, 1981

                  Field Coordinator

THRU:              ALAN C. MCMILLAN
                  Acting Regional Administrator
                  MICHAEL G. CONNORS
                  ARA Technical Support

                  Area Director

SUBJECT:           Clarification of the Acrylonitrile Standard

1. Showering Requirement

Attached is a letter from Grover Wrenn to Rohm and Haas Company stating:

"Showering at the end of the workshift which is required when the protective clothing or equipment is known, suspected or believed to have contacted liquid acrylonitrile."

This statement is in direct conflict with the standard, the preamble, and our information booklets.


"Where eye or skin contact with liquid AN may occur, the employer shall provide at no cost to the employee, and assure that employees wear, impermeable protective clothing...."


"The employer shall assure that employees wearing protective clothing or equipment for protection from skin contact with liquid AN shall shower at the end of the work shift."

Preamble 43 FR 45805

"The final standard contains a requirement for employees who have had or are suspected of having had skin contact with liquid AN to shower immediately after the contact is discovered. In addition, employees required to wear protective clothing to prevent skin contact with liquid AN are required to shower at the end of the shift."

Acrylonitrile Standard: Management's Role OSHA 3060, p. 13

"And you must make sure that employees wearing the protective clothing and equipment shower at the end of the work shift."

Acrylonitrile: Worker Health Alert OSHA 3059, p. 12

"Even if you don't think you have spilled acrylonitrile on your skin, you must shower at the end of your work shift to prevent skin irritation, contamination of your street clothes and accidental exposure of your family or friends."

We feel that Wrenn's letter is in error, and Rohm and Haas should be so advised. Monsanto's Port Plastics Plant has also relied upon this letter and has not made showering mandatory. They were cited for this condition and have contested.

2. Definition of an "unexpected massive release."

An "emergency" as defined in the standard means:

"any occurrence such as, but not limited to, equipment failure, rupture of containers, or failure of control equipment which results in an unexpected massive release of AN."

The preamble states:

"The term "emergency", as used in the proposal, covered any release of AN above the ceiling limit. The breadth of this definition would have required the employer to implement the emergency procedures and notify the OSHA area office whenever the ceiling was exceeded. As was noted by several commentators, such a requirement would apply to many situations which could not truly be deemed as "emergencies" (Exs. 92: 149). In addition, we recognize that this would tend to lessen the employee's awareness of true emergency conditions if and when they did occur. "Emergency" has been redefined, as in the vinyl chloride standard, to refer to a "massive release" of AN. The employer is best able to determine if an emergency exists in his facilities. His central obligation under the standard, which is to limit employees' exposures to AN is, therefore, supplemented by the requirement to take further action when emergency situations arise." (43 FR 45795)

The definition of "emergency" in the vinyl chloride (VC) standard is similar to that of the AN standard. The VC preamble states:

"the definition of emergency has been recast in terms of an unexpected massive release. The main objection to the section on emergency situations in the proposal was that, as the term was defined, many ordinary leaks or operations resulting in a small release of vinyl chloride would be considered emergencies. This was not the intent of the proposal." (39 FR 3589)

An actual incident illustrates the problem. On 2/12/81, an AN batch experienced control problems. The batch contents were vented into the vent system, rupturing the knock out point pot rupture disc and spilling onto the roof. Ventilation fans pulled AN vapors into the building, contaminating several production areas and the control room. AN concentrations in the control room were as follows:

       4:55 a.m.   50 ppm
       6:02 a.m.   35 ppm
       7:09 a.m.    9 ppm

All nonessential personnel were evacuated, and others wore half-face respirators.

Around 2:00 p.m., a damaged SAN bottom valve was forced open using N2 pressure. Mechanics observing this operation from the second floor experienced eye irritation due to high AN levels.

We feel that this situation constitutes an "emergency" as defined in the standard. However, the company did not consider it an emergency and did not report it. Guidelines should be developed on what constitutes an "unexpected massive release."

March 23, 1979

Dr. Isadore Rosenthal
Rohm and Haas Company
Box 584
Bristol, Pennsylvania 19007

Dear Dr. Rosenthal:

This is in response to Dr. Renshaw's letter of November 6, 1978 to Ms. Kleiner and in reference to Dr. Hanna's letter of January 4, 1979 to you. I greatly regret the delay in reply.

The first question set forth in Dr. Renshaw's letter pertains to the alarm system required under paragraph 1910.1045 (i)(e) of the acrylonitrile standard. This paragraph requires a general alarm to be installed to alert employees when exposures exceed the ceiling limit. As mentioned in the preamble (45803), the release of acrylonitrile above the ceiling limit is not always "an emergency"; however, the standard does require the installation of an alarm system, to be activated by the release of acrylonitrile above the ceiling limit.

The second question is related to the establishment of a specific method for fit testing of respirators. The standard does not a specific methodology for quantitative fit testing and left the selection of the test method to employers. For your information and convenience, I am enclosing a list of references which may prove valuable for your purpose. This list is included in Los Alamos report #LA- 6084-MS, available from National Technical Information Service, U.S. Department of Commerce, 5285 Port Regal Road, Springfield, Virginia 22151.

The third question is associated with mandatory showering. This mandatory showering consists of two provisions:

Immediate showering which is required when direct skin or eye contact occurs of when nonimpermeable clothing become wetted with acrylonitrile (paragraphs (j)(2)(iii) and (m)(3)).

Showering at the end of the work shift which is required when the protective clothing or equipment is known, suspected or believed to have contacted liquid acrylonitrile. In such occurrences, decontamination of the protective clothing or equipment is required to precede this mandatory showering (paragraph (m)(2)).

If we can be of further assistance, please feel free to contact us.


Grover C. Wrenn
Health Standards Program