School of Medicine Nephropathology Laboratory: Formaldehyde/Xylene Safety


School of Medicine Nephropathology Laboratory: Formaldehyde/Xylene Safety


I. Principle

Formaldehyde and xylene vapor concentration must be maintained below the following maxima, expressed as parts per million, in all area of the Anatomic Pathology Department where formaldehyde or xylene are used.

Formaldehyde and xylene vapor concentrations must be monitored in all areas where these reagents are used. Initial monitoring involves identifying all employees who may be exposed at or above the action level or at or above the short-term exposure limit (STEL) and accurately determining the exposure of each employee identified. After the initial formaldehyde monitoring procedure, further periodic formaldehyde monitoring is mandated if results of the initial monitoring equals or exceeds 0.5 ppm (8-hour time-weighted exposure, the "action level") or 0.2 ppm (STEL). Initial monitoring must be repeated any time there is a change in production, equipment, process, personnel, or control measures which may result in new or additional exposure to formaldehyde for any employee involved in the activity.

The laboratory may discontinue periodic formaldehyde monitoring if:

  1. results from two (2) consecutive sampling periods taken at least seven (7) days apart show that employee exposure is below the action level limit and the short-term exposure limit; and
  2. no change has occurred in production, equipment, process, or personnel or control measures that may result in new or additional exposure to formaldehyde; and
  3. there have been no reports of conditions that may be associated with formaldehyde exposure.

If any personnel report signs or symptoms of respiratory or dermal conditions associated with formaldehyde exposure, the laboratory must promptly monitor the affected person's exposure.

Xylene must be monitored initially, but there is no requirement for periodic monitoring of xylene.

II. Action Limits

Action Limits for Exposure to Formaldehyde and Xylene
  8-hour Time-Weighted Exposure Limit Action Level (8-hour Time-Weighted Exposure) 15-Minute Short-Term Average Exposure Limit (STEL)
Formaldehyde 0.75 ppm 0.5 ppm 2.0 ppm
Xylene 100 ppm   150 ppm

III. Records

Records of formalin/xylene monitoring have indicated that employees were not exposed to concentrations greater than the detection limit. On 02/27/2020, all employee's 15-minute and 8-hour formaldehyde readings were below the OSHA STEL recommendation (chart above). However, the 15-minute formaldehyde readings for all employees were over the NIOSH Recommended Expsosure Limit (REL) of 0.1 ppm. All results for xylene monitoring were below OSHA standards and NIOSH guidelines. Due to the formaldehyde results that were above the NIOSH REL, it was recommended that employees be monitored periodically. UNC Environment, Health & Safety (EHS) recommends that xylene monitoring only continues for new employees since the results are historically below the limits. All records are found in the Safety manual in room 408/412. Any records of corrective action when exposure limits are exceeded must be retained in the Safety Manual. 

IV. Proper Handling

The proper PPE must be worn when handling formaldehyde (formalin) and xylene. This includes lab coat, gloves (8-mil or two 4-mil gloves), eye protection, and closed-toed shoes. Proper handling includes only working with these chemicals in a certified chemical fume hood with sash at or lower than recommended height. If in small quantities, such as patient vials, chemicals can be handled over an operational fume adsorber. When containers of said chemicals are moved, they must be closed/enclosed.

V. History

Created: 7/25/12 LHR

Replaces: N/A


  • 5/28/20 KDB
  • LEC 2/11/20
  • 7/2/18 LHR
  • 6/29/16


Article ID: 134319
Sun 7/11/21 10:28 AM
Wed 2/1/23 12:37 PM
Effective Date
If the date on which this document became/becomes enforceable differs from the Origination or Last Revision, this attribute reflects the date on which it is/was enforcable.
05/28/2020 12:00 AM
Issuing Officer
Name of the document Issuing Officer. This is the individual whose organizational authority covers the policy scope and who is primarily responsible for the policy.
Issuing Officer Title
Title of the person who is primarily responsible for issuing this policy.
Medical Laboratory Supervisor
Last Review
Date on which the most recent document review was completed.
02/01/2023 12:00 AM
Last Revised
Date on which the most recent changes to this document were approved.
05/28/2020 12:00 AM
Next Review
Date on which the next document review is due.
02/01/2024 12:00 AM
Date on which the original version of this document was first made official.
07/25/2012 12:00 AM
Responsible Unit
School, Department, or other organizational unit issuing this document.
School of Medicine - Nephropathology Laboratory