Laboratory of Pathology - Staff

Formaldehyde and Xylene Monitoring and Facts

Environmental Monitoring for Formaldehyde and/or Xylene

The Laboratory of Pathology actively participates in the NIH Formaldehyde and NIH Xylene Monitoring Programs.

• LP laboratories are monitored for Formaldehyde at least annually, and repeated any time there is a change in production, equipment, process, personnel or control measures which may result in new or additional formaldehyde exposure.
  
  

  • Formaldehyde and xylene vapor concentrations must be monitored in all areas where these reagents are used:  e.g. surgical pathology gross dissection room, frozen section area, histology laboratory, autopsy room, etc. Xylene vapor concentration monitoring in histology laboratories should include manual and automated coverslipping areas, as these locations are often not ventilated. Initial monitoring involves identifying all employees who may be exposed at or above the action level or at or above the STEL and accurately determining the exposure of each employee identified. Further formaldehyde monitoring is mandated at least every six months if results of the initial monitoring equal or exceed 0.5 ppm (8 hr time-weighted exposure, the “action level”) or at least once per year if the results exceed the short term exposure limit (STEL) 2.0 ppm. The laboratory may discontinue periodic formaldehyde monitoring if results from two consecutive sampling periods taken at least seven days apart show that employee exposure is below the action level and the short-term exposure limit, and 1) no change has occurred in production, equipment, process or personnel or control measures that may result in new or additional exposure to formaldehyde, and 2) there have been no reports of conditions that may be associated with formaldehyde exposure.

  • Formaldehyde 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. 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. Repeat monitoring should be considered when there is a change in production, equipment, process, personnel, or control measures likely to increase exposure levels.

Please contact the Division of Occupational Health & Safety Office of Research Services to request Formaldehyde and/or Xylene monitoring.

Records of all testing must be reviewed with all staff in the laboratory, and a copy turned in to the Clinical Manager.

FORMALDEHYDE Facts (Adopted from OSHA standard 29 CFR 1910.1048)

Introduction

To protect workers exposed to formaldehyde, the Occupational Safety and Health Administration (OSHA) standard (29 CFR 1910.1048) applies to formaldehyde gas, its solutions, and a variety of materials such as trioxane, paraformaldehyde, and resin formulations, and solids and mixtures containing formaldehyde that serve as sources of the substance. In addition to setting permissible exposure levels, exposure monitoring and training, the standard requires medical surveillance and medical removal, recordkeeping, regulated areas, hazard communication, emergency procedures, primary reliance on engineering and work practices to control exposure, and maintenance and selection of personal protective equipment.

The permissible exposure limit (PEL) for formaldehyde in all workplaces (including general industry, construction, and maritime, but not in agriculture) covered by the OSHA Act is 0.75 ppm measured as an 8-hour time weighted average (TWA). The standard includes a 2 ppm short-term exposure limit (STEL) (i.e., maximum exposure allowed during a 15-minute period). The "action level" is 0.5 ppm measured over 8 hours.

The standard requires that the employer conduct initial monitoring to identify all employees who are exposed to formaldehyde at or above the action level or STEL and to accurately determine the exposure of each employee so identified.

If the exposure level is maintained below the STEL and the action level, employers may discontinue exposure monitoring, until such there is a change which could affect exposure levels. The employer must also monitor employee exposure promptly, upon receiving reports of formaldehyde-related signs and symptoms.

Substance

Formaldehyde (Methanol; 37% aqueous solution (usually containing 10 to 15% methanol) is called formalin; solid polymer is called paraformaldehyde)

CAS 50-00-0

Formula

HCHO

Physical Properties

• Clear, colorless liquid
• Formaldehyde:  Boiling point -19 °C, melting point -92 °C
• Formalin:  Boiling point 96 °C, melting point -15 °C
• Miscible with water
• Odor:  Pungent odor detectable at 1 ppm
• Vapor Density:  ~1 (air = 1.0)
• Vapor Pressure:  Formaldehyde: 10 mmHg at -88 °C
• Formalin:  23 to 26 mmHg at 25 °C
• Flash Point:  50 °C for formalin containing 15% methanol
• Autoignition Temperature:  424 °C for formalin containing 15% methanol

Toxicity Data

Lethal Dose oral (rat) - 500 mg/kg

Lethal Dose skin (rabbit) - 270 mg/kg

Lethal Concentration inhale (rat) - 203 mg/m (2 hours)

Major Hazards

Probable human carcinogen (OSHA "select carcinogen"); moderate acute toxicity; skin sensitizer.

Toxicity

Formaldehyde is moderately toxic by skin contact and inhalation. Exposure to formaldehyde gas can cause irritation of the eyes and respiratory tract, coughing, dry throat, tightening of the chest, headache, a sensation of pressure in the head, and palpitations of the heart. Exposure to 0.1 to 5 ppm causes irritation of the eyes, nose, and throat; above 10 ppm severe lacrimation occurs, burning in the nose and throat is experienced, and breathing becomes difficult. Acute exposure to concentrations above 25 ppm can cause serious injury, including fatal pulmonary edema. Formaldehyde has low acute toxicity via the oral route. Ingestion can cause irritation of the mouth, throat, and stomach, nausea, vomiting, convulsions, and coma. An oral dose of 30 to 100 mL of 37% formalin can be fatal in humans. Formalin solutions can cause severe eye burns and loss of vision. Eye contact may lead to delayed effects that are not appreciably eased by eye washing.

Formaldehyde is regulated by OSHA as a carcinogen (Standard 1910.1048) and is listed in IARC Group 2A ("probable human carcinogen"). This substance is classified as a "select carcinogen" under the criteria of the OSHA Laboratory Standard. Prolonged or repeated exposure to formaldehyde can cause dermatitis and sensitization of the skin and respiratory tract. Following skin contact, a symptom-free period may occur in sensitized individuals. Subsequent exposures can then lead to itching, redness, and the formation of blisters.

Flammability and Explosibility

Formaldehyde gas is extremely flammable; formalin solution is a combustible liquid (NFPA rating = 2 for 37% formaldehyde (15% methanol), NFPA rating = 4 for 37% formaldehyde (methanol free)). Toxic vapors may be given off in a fire. Carbon dioxide or dry chemical extinguishers should be used to fight formaldehyde fires.

Reactivity and Incompatibility

Formaldehyde may react violently with strong oxidizing agents, ammonia and strong alkalis, isocyanates, peracids, anhydrides, and inorganic acids. Formaldehyde reacts with HCl to form the potent carcinogen, bis-chloromethyl ether.

Storage and Handling

Because of its carcinogenicity and flammability, formaldehyde should be handled using the "basic prudent practices", supplemented by the additional precautions for work with compounds of high chronic toxicity and extremely flammable substances. In particular, work with formaldehyde should be conducted in a fume hood to prevent exposure by inhalation, and splash goggles and impermeable gloves should be worn at all times to prevent eye and skin contact. Formaldehyde should be used only in areas free of ignition sources. Containers of formaldehyde should be stored in secondary containers in areas separate from oxidizers and bases.

Accidents or Possible Exposures

In the event of skin contact, immediately wash with soap and water and remove contaminated clothing. In case of eye contact, promptly wash with copious amounts of water for 15 min (lifting upper and lower lids occasionally) and obtain medical attention from Occupational Medical Services located in 10/6C306; 496-4411. If formaldehyde is ingested, obtain medical attention immediately. If large amounts of this compound are inhaled, move the person to fresh air and seek medical attention at once.

In the event of a spill, remove all ignition sources, soak up the formaldehyde with a spill pillow or absorbent material, place in an appropriate container, and dispose of properly. Respiratory protection may be necessary in the event of a large spill or release in a confined area. In this situation, close all windows and leave the lab immediately (always make sure the lab door is closed behind you to prevent the vapors from moving into the hallway). Call 911 and alert operator of the spill. Do not re-enter the room until appropriate authorities determine the area is safe.

Disposal

Excess formaldehyde and waste material containing this substance should be placed in an appropriate container, clearly labeled, and handled according to your institution's waste disposal guidelines. For further information, contact the Environmental Protection Branch (EPB) at 496-7990 and for pick-up call 496-4710.

XYLENE Facts (Adopted from NIH DOHS Xylene Surveillance Program)

INTRODUCTION

A xylene surveillance program has been established at the National Institutes of Health (NIH) to: 

1)      Identify and quantify exposure levels of workers in the Clinical Center potentially  exposed to xylene

2)      To  provide  information  on  the  effectiveness  of  the  controls  being  used  to  minimize  exposures.  

Surveys  provide  documentation  of  surveillance  activities  to  both  the  Joint  Commission  on  Accreditation  of Healthcare  Organizations  (JCAHO)  and  the  College  of  American  Pathologists  (CAP).  The program is maintained by the Technical Assistance Branch (TAB) of the Division of Occupational  Health  and  Safety  (DOHS).    Medical  surveillance  of  NIH  employees  is  provided  by  the  Occupational  Medical  Service  (OMS).    Personnel  in  the  Clinical  Center  are  covered  by  this  protocol.    All  other  NIH  laboratories  where  potential  xylene  exposure  results  from  the  handling and  use  of  xylene  are  covered  by  the  Occupational  Safety  and  Health  Administration  (OSHA) Laboratory Standard, 29 CFR 1910.1450.

Xylene (o-, m-, and p-isomers), C 8H10[CAS 1330-20-7] is a colorless liquid with an aromatic hydrocarbon odor (odor threshold ranging from ~1 - 40 ppm) and is a dangerous fire hazard (class 1C flammable liquid) from heat, flame and powerful oxidizers.  Xylene is insoluble in water but it is soluble in alcohol, ether and organic solvents.  In histology and pathology areas xylene is used in cover slipping and mounting of slides.

Synonyms include: dimethylbenzene, methyl toluene and xylol.

Xylene vapor causes irritation to the eyes, mucous membranes and skin.  At high concentrations it has caused narcosis.  Exposure to xylene liquid on the skin causes erythema, dryness and defatting.  

OCCUPATIONAL EXPOSURE CRITERIA

For evaluating employee exposures to xylene, the NIH uses exposure criteria established by both the Occupational Safety and Health Administration (OSHA) and the American Conference of

Governmental Industrial Hygienists (ACGIH).  OSHA has set a permissible exposure limit (PEL) of 100 ppm as an 8 hour time-weighted-average (TWA) for xylene.  The Threshold Limit Value (TLV), an 8 hour TWA workday exposure level from ACGIH, is also 100 ppm. The Short Term Exposure Level (STEL), an ACGIH exposure level that should not be exceeded during any 15 minute time period of the workday, is 150 ppm. OSHA indicates that xylene has an odor threshold of ~ 1 ppm.

PERSONAL PROTECTIVE EQUIPMENT

In  those  locations  or  during  those  procedures  where  it  is  determined  by  monitoring  that  xylene  vapors  exceed  the  OSHA  PEL,  appropriate  engineering  controls  will  be  instituted  to  lower  xylene  exposures.    Until  the  engineering  controls  are  instituted,  workers  will  wear  half-face  respirators,   fitted   with   organic   vapor   cartridges,   and   participate   in   the   NIH   Respiratory   Protection Program administrated by the TAB.    Because  xylene  has  the  potential  to  cause  skin  and  eye  irritation,  additional  personal  protective  equipment,  such  as  splash-proof  goggles,  nitrile  gloves and  lab  coats,  or  aprons  should  also  be  made available to workers who use xylene.