5.1.7 FreonŽ

Freon includes a number of gaseous, colorless chlorofluorocarbons. Those must commonly used in hospitals are Freon 12 (dichlorodifluoromethane) Freon 11 (fluorotrichloromethane) and Freon 22 (chlorodifluoromethane).

5.1.7.1 Hazard location

Workers may encounter Freon hazards in the pathology laboratory, with it is used to prepare frozen tissue sections, in aerosol cans, where it is used as a propellant, in central supply departments, where it is used in combination with ethylene oxide for sterilization, and in refrigerant gas. Freon can freeze the skin and also cause defatting.

5.1.7.2 Potential Health Effects

Exposure to Freon may cause eye and skin irritation or sensitization. High concentrations of Freon cause severe depression of the central nervous system, weakness, dizziness, convulsions, and cardiac arrhythmia, irregular heart beat, ACGIH 1986. In one study of pathology residents in a Boston hospital, all residents in their second and third years experienced palpitations that appeared to be associated with the addition of the surgical pathology rotation to their schedules. On this rotation, the only procedure that could have possibly caused palpitations was the preparation of frozen sections in which a Freon-22-based aerosol was used to decrease work time. Freon exposures of 300 ppm were measured over a 2-min period for workers engaged in tissue preparation. Four residents experienced palpitations severe enough to prompt electrocardiograms (Speizer et al. 1975). A number of deaths (7 in 1967, 31 in 1968, and 27 in 1969) have been reported among persons "sniffing" Freons intentionally (Reinhardt et al. 1971).

5.1.7.3 Standards and Recommendations

The OSHA PEL for Freon 11 is 1000 ppm (5600 mg/m³) as an 8-hr TWA; the OSHA PEL for Freon 12 is 1,000 ppm as an 8-hr TWA. The ACGIH TLVs for Freon 11 and Freon 12 are identical to the respective OSHA PEL’s. There is no OSHA PEL for Freon 22, but the ACGIH TLV for Freon 22 is 1,000 ppm as an 8-hr TWA. There are no NIOSH REL’s for the Freon compounds.

5.1.7.4 Environmental Monitoring

Freon concentrations can be estimated using direct-reading colorimetric detector tubes or determined by charcoal-tube adsorption and gas chromatography analysis.

5.1.7.5 Exposure Control Methods

5.1.7.5.1 Engineering controls

Local exhaust ventilation hoods should be installed to carry Freon vapors away from laboratory workers. Ventilation controls that protect workers adequately from ethylene oxide during sterilizing procedures will also protect them from Freon.

5.1.7.5.2 protective equipment

Goggles, aprons, and protective gloves should be provided to workers exposed to large amounts of Freon such as those encountered in the repair of refrigerant systems. Because Freon does not have adequate warning properties, only approved atmosphere-supplying respirators should be used.

5.1.7.5.2 Work practices

Hand contact should be minimized because of the possibility of sensitization. Workers should be warned against touching their eyes with contaminated hands or gloves for the same reason.

5.1.7.6 Medical Monitoring

A cardiovascular history should be obtained from each worker exposed to Freon because exposure may pose a greater risk to those with cardiovascular problems. Eyes, skin, cardiac symptoms, and electrocardiograms should be monitored periodically for exposed workers.

5.1.8 Mercury

Elemental mercury is a metallic element that is liquid at room temperature.

5.1.8.1 Hazard Location

Mercury is used in many types of hospital equipment and can be found in thermometers, Coulter counters, Van Slyke apparatus, Miller-Abbot and Cantor tubes, and sphygmomanometers (Notani-Sharma 1980). Mercury is also used in dental amalgams. Exposure to mercury in the hospital is usually the result of an accidental spill. The two procedures during which such exposures usually occur are (1) repair of broken sphygmomanometers in central supply or maintenance, and (2) sterilization and centrifugation of thermometers in central supply (Notani-Sharma 1980).

5.1.8.2 Potential Health Effects

Although inhalation is the major route of entry for mercury, the element can also be absorbed through the skin.

Exposure to short-term high levels of mercury can produce severe respiratory irritation, digestive disturbances, and marked renal damage (NIOSH 1973a).

Long-term exposure to low levels of mercury results in the classic mad hatter syndrome, named for the makers of felt hats who used mercury in processing. This syndrome is characterized by emotional instability and irritability, tremors, inflammation of the gums, gingivitis, excessive salivation, anorexia, and weight loss. Mercury has also been reported as a cause of sensitization dermatitis (NIOSH 1973a).

5.1.8.3 Standards and Recommendations

The current OSHA PEL for mercury is 0.1 mg/m³ as a ceiling value (29 CFR 1910.1000, Table Z2). The NIOSH REL is 0.05 mg/m³ as an 8-hr TWA (NIOSH 1973a). 5.1.8.4 Environmental Monitoring

Mercury vapors can be measured with a direct-reading colorimetric dosimeter, diffusion tubes, or mercury vapor analyzer, mercury sniffer, or with charcoal tubes impregnated with iodine. Particulate contamination can be collection on a filter for subsequent analysis.

If mercury spills are not promptly cleaned up, mercury may accumulate in the carpeting, on floors, and on other surfaces such as porous laboratory sinks and counters. In most cases, workers in these situations were unaware that mercury vaporizes easily at room temperatures.

In one investigation (Harrington 1974), several workers in a quality-control laboratory noticed their jewelry becoming silvered with no apparent cause. A source of mercury vapor was found when droplets of mercury were observed in the sink, on a bench, on the floor, and in the clothing of the lab assistants. The floor was removed, and pools of mercury were discovered. In another laboratory, nearly 7 lb. of mercury was discovered beneath the floor (Harrington 1974). A study of 298 dentists reported that 30% of those with urine mercury levels above 20 micrograms/g had polyneuropathies, nervous system symptoms (Shapiro et al. 1982). Other surveys have found high background levels of mercury in the air of about 10% of the dental offices and elevated mercury levels in the urine and hair of workers in these offices (Shapiro et al. 1982).

5.1.8.5 Exposure Control Methods

5.1.8.5.1 Engineering controls

Emergency engineering procedures for handling mercury contamination should include procedures for cleanup as well as for respirator selection. Exhaust systems should be designed and maintained to prevent the accumulation or recirculation of mercury vapor into the workroom.

5.1.8.5.2 Protective equipment

Disposable protective equipment such as shoe covers, protective gloves, special mercury vapor respirators, and gowns and hoods should be used while cleaning up mercury spills.

5.1.8.5.3 Work practices

Spills should be cleaned up promptly with special mercury vacuum cleaners, disposable protective equipment, and a water-soluble mercury decontaminant. Mercury wastes must be disposed of according to US Environmental Protection Agency regulations (40 CFR 261.24).

All spill areas should be clearly posted until adequate cleanup has been accomplished. If the spill is extensive, patients and personnel other than the cleanup crew should be removed from the area.

5.1.8.6 Medical Monitoring

Pre-exposure data should be recorded for the respiratory tract, nervous system, kidneys, and skin of any worker who may be exposed to mercury. Urine mercury levels should be monitored periodically in workers who are routinely or accidentally exposed to this element. Although there is no critical level of mercury in urine that indicates mercury poisoning, observers have suggested that 0.1 to 0.5 mg of mercury/liter of urine has clinical significance (NIOSH 1973a).

5.1.9 Methyl Methacrylate

5.1.9.1 Hazard Location

Methyl methacrylate is an acrylic cement-like substance commonly used in operation rooms to secure surgical prostheses to bone, e.g. in total hip replacements. This compound is also used in dental prostheses (NIOSH 1977e). The two components, a liquid and a powder, are mixed immediately before use.

In a study of operating room exposures, concentrations of methyl methacrylate reached 280 ppm immediately after the components were mixed, but fell below 50 ppm within 2 min and to 2 ppm after 6 min (ACGIH 1986). The mixing process usually takes no more than 2 min.

5.1.9.2 Potential Health Effects

5.1.9.2.1 Acute effects

Methyl methacrylate has been reported to have an odor threshold about 0.08 ppm (Amoore and Hautala 1983). At concentrations in excess of 400 ppm, methyl methacrylate affects the central nervous system (ACGIH 1986). Methyl methacrylate is an eye, skin, and mucous membrane irritant in concentrations at or above 170 to 250 ppm. Patients exposed to this compound have suffered acute episodes of hypotension, low blood pressure, and cardiac arrest (Hyderally and Miller 1976).

5.1.9.2.2 Chronic effects

Methyl methacrylate has been reported to produce degenerative liver changes in experimental animals (NIOSH 1977e). This chemical has also been reported to be mutagenic, but has not been found to be carcinogenic in rats or mice. Methyl methacrylate has also been reported to be teratogenic (Singh et al. 1972).

5.1.9.3 Standards and Recommendations

The OSHA PEL, as well as the ACGIH TLV, for methyl methacrylate is 100 ppm (410 mg/m³) as an 8-hr TWA (29 CFR 19190.1000, Table Z1; ACGIH 1987). NIOSH has not recommended a standard for methyl methacrylate.

5.1.9.4 Environmental Monitoring

Methyl methacrylate is monitored in the environment by sampling with an adsorption tube and analyzing with gas chromatography (NIOSH 1980a).

5.1.9.5 Exposure Control Methods

5.1.9.5.1 engineering controls

A local exhaust hood should be used to conduct exhaust fumes from the area in which methyl methacrylate is mixed. A tent hood may be used unless mixing can be done in a separately ventilated area. Portable hoods are available for operating room use.

5.1.9.5.2 Protective equipment

Workers who handle methyl methacrylate should wear personal protective equipment and clothing. This may include gloves, goggles, face shields, and respirators, as appropriate. Portable hoods are available for operating room use.

5.1.9.5.3 Work practices

Workers should be instructed to avoid touching contaminated hands or gloves to their eyes or mouths.

5.1.9.6 Medical Monitoring

Pre-exposure data should be recorded for the skin and respiratory systems of workers who may be exposed to methyl methacrylate. Periodic monitoring thereafter should emphasize the skin and respiratory systems.

5.1.10 Peracetic Acid PAA

5.1.10.1 Hazard Location

Peracetic acid, peroxyacetic acid, is used in hospitals to sterilize the surfaces of medical instruments and may be found in laboratories, central supply, and patient care units.

5.1.10.2 Potential Health Effects

Peracetic acid, peroxyacetic acid, is a strong skin, eye, and mucous membrane irritant in both humans and animals. Continued skin exposure may cause liver, kidney, and heart problems. Peracetic acid has been observed to promote wart-like tumors, skin papillomas, in rats (NIOSH 1985). As a result, direct skin contact and exposure to vapors should be restricted.

5.1.10.3 Standards and Recommendations

Currently no standards exist for regulating exposures to peracetic acid, and no recommendations have been made by others such as NIOSH, ACGIH, or ANSI.

5.1.10.4. Exposure Control Methods

Use of an isolation chamber should eliminate major exposure to peracetic acid vapors in hospitals. This chamber should be checked frequently for defects. Peracetic acid should never be used outside this chamber.

5.1.11 Solvents

5.1.11.1 Hazard Location

The generic term solvent refers to a large number of chemicals used in medical laboratories. Some are used widely as cleaning agents in housekeeping and maintenance, and some are present in inks and in cleaning agents in print shops.

5.1.11.2 Potential Health Effects

Most solvents can be absorbed through the skin or by inhalation and ingestion.

5.1.11.2.1 Acute effects

Many solvents act as central nervous system depressants, causing headaches, dizziness, weakness, nausea, and other symptoms, NIOSH 1986c. Solvents may also irritate eyes, skin, and the upper respiratory tract. Prolonged contact may result in defatting and dehydration of the skin.

5.1.11.2.2 Chronic effects

Long-term exposure to some solvents has been associated with cancer, adverse reproductive effects, cardiovascular problems, and damage to the liver, kidneys, central nervous system, and hematopoietic system (see Table 5-2)(NIOSH 1974, 1975a, 1977a).

5.1.11.3 Standards and Recommendations

The hospital safety officer should develop an inventory of solvents in use and consult 29 CFR 1910.1000 for the pertinent OSHA PEL. The safety officer should also consult the NIOSH criteria documents. Current Intelligence Bulletins, and other documents on solvents, which are listed by compound in NIOSH Recommendations for Occupational Safety and Health Standards (CDC 1986).

5.1.11.4 Environmental Monitoring

NIOSH investigations have found high concentrations of solvents, either as TWA’s or as peaks during certain processes in medical laboratories (NIOSH 1981f). The effects reported by workers are frequently those of a combination of solvents, each one of which is present at a concentration below the established standard. No regulation exists to cover the additive or synergistic effects of similar chemicals.

Solvents can be collected on adsorbent charcoal for later analysis, or they can be directly measured with colorimetric detector tubes or passive dosimeters. For a more detailed description of sampling procedures for solvents, refer to the Technical Industrial Processes Sourcebook (Wood 1984) and Air Sampling Instruments for Evaluation of Atmospheric Contaminants (ACGIH 1983).

5.1.11.5 Exposure Control Methods

5.1.11.5.1 Substitution

A less hazardous solvent can frequently be substituted for one of those discussed.

5.1.11.5.2 Engineering Controls

Local exhaust ventilation and enclosure of solvent vapor sources are the preferred methods for controlling exposures to solvents in laboratories. When selecting engineering and other controls, consideration must be given to not only the toxicity of the solvent, but to its flammability and explosion potential as well.

5.1.11.5.3 protective equipment

Protective gloves help prevent absorption of solvents through the skin. Respirators, rubber aprons, goggles, and boots may be required during certain procedures or during cleanup of spills.

5.1.11.5.4 Work practices

Workers should be thoroughly trained to recognize the symptoms of solvent exposure, to avoid eating in potentially contaminated areas, to work only under exhaust hoods when handling solvents and to follow those work practices recommended for specific solvents.

5.1.11.6 Medical Monitoring

Pre-exposure information should be recorded for worker who will be exposed to solvents and should include baseline and current date on the skin, kidney, liver, and nervous and hematopoietic systems NIOSH 1986b. Kidney and liver function tests and a complete blood count should be performed.

5.1.12 Waste Anesthetic Gases

The principal source of waste anesthetic gas in the hospital is leakage from anesthetic equipment. Nitrous oxide, enflurane, halothane, and isoflurane are currently the most widely used inhalation anesthetic agents in the US (NIOSH 1977c; Whitcher 1987b). Methoxyflurane, once in general use, is now used primarily in veterinary procedures (Whitcher 1987b).

5.1.12.1 Hazard Location

In 1977, NIOSH estimated that some 50,000 operating-room personnel excluding surgeons, were exposed each year to waste anesthetic gases (NIOSH 1977c). Exposures occur in operating rooms; labor delivery, and recovery rooms; dental operatories; emergency rooms; outpatient clinics; and miscellaneous locations.

Leakage from anesthetic equipment is in most cases associated with the work practices and habits of the anesthesiologists and nurse anesthetists. Incorrect installation and maintenance of scavenging systems is also a major factor.

Exposures may occur in the following ways:

• Gas may escape during hook-up and check-out of the system.

• Excess gas may seep over the lip of the patient’s mask.

• The patient may exhale gas into the room.

• Leaks may occur in the anesthetic breathing system.

• Scavenging systems may be misused or not used at all.

The degree of exposure in the operating room depends on the mount of leakage, the adequacy of the ventilation system, and the type of operation being done. Gas leakage occurs primarily when face masks are used for short procedures and a problem exists with the anesthetist’s technique or with the patient’s facial anatomy (e.g. when the patient has no teeth).

A related problem is the exposure of recovery room personnel to waste gases in the exhaled breath of post-operative patients. Nitrous oxide, halothane, and methoxyflurane have all been found in the exhaled breath of both patients and operating room staff for periods ranging from hours to several days after the administration of the anesthetic (NIOSH 1977c). This phenomenon may pose a significant health hazard to staff in crowded recovery rooms with a high patient turnover rate.

5.1.12.2 Potential Health Effects

5.1.12.2.1 Acute effects

Workers exposed to excessive amounts of anesthetic gases begin to feel like anesthetized patients, experiencing drowsiness, irritability, depression, headache, nausea, fatigue, and problems of judgment and coordination (NIOSH 1977c). These behavioral effects are of particular concern because both the success of the surgery and health of the operating room staff may be compromised.

5.1.12.2.2 Chronic effects

Epidemiologic studies have found increased incidences of embryo toxicity, liver and kidney disease, and cancer among groups of female personnel working in the operating room, Cohen et al 1975. Some observers have suggested a relationship between exposure to waste anesthetic gases and reports of increased cancer rates and adverse effects on reproduction among exposed workers (NIOSH 1977c).

5.1.12.2.3 Reproductive effects

A 1975 survey (Cohen et al.1975) indicated an increased risk of spontaneous abortion among female anesthesiologists, nurse-anesthetists, and other staff personnel who worked in operating rooms during their first trimester of pregnancy and the year preceding. An increased risk of congenital abnormalities also existed among the live-born babies of exposed female participants in the survey. Studies have also shown a higher incidence of miscarriage in the wives of male operating-room personnel (Cohen et al. 1975).

5.1.12.3 Standards and Recommendations

NIOSH has recommended exposure limits for the following anesthetic gases (NIOSH 1977c).

Chloroform	2 ppm (9.76 mg/m3) ceiling (1 hr)
Trichloroethylene*	2 ppm (10.75 mg/m3) ceiling (1 hr)
Halothane	2 ppm (16.15 mg/m3) ceiling (1 hr)
Methoxyflurane	2 ppm (13.5 mg/m3) ceiling (1 hr)
Enflurane	2 ppm (15.1 mg/m3) ceiling (1 hr)
Fluroxene	2 ppm (10.31 mg/m3) ceiling (1 hr)
Nitrous oxide	25 ppm (30 mg/m3) as a TWA over period of use
*NIOSH recommends that trichloroethylene be regarded as a potential occupational carcinogen, (NIOSH 1978b).

When nitrous oxide is used in combination with the halogenated agents described above, control of nitrous oxide to 25 ppm during the administration period will result in concentrations of the halogenated agents of about 0.5 ppm.

5.1.12.4 Environmental monitoring

The vapors of anesthetic agents such as enflurane, halothane and isoflurane can be monitored with charcoal tubes. Nitrous oxide can be monitored with a direct-reading infrared analyzer or by passive dosimeters.

Records of all collected air samples should be kept, and results should be noted in the medical records of the corresponding workers. Detailed descriptions of sampling procedures for nitrous oxide are available from several sources (Eger 1985; Saidman and Smith 1984; Wood 1984; Whitcher 1987a).

5.1.12.5 Exposure Control Methods

The following documents detail the components of a control program for waste anesthetic gases; Development and Evaluation of Methods for the Elimination of Waste Anesthetic Gases and Vapors in Hospitals (NIOSH 1975b), Criteria for a Recommended Standard: Occupational Exposure to Waste Anesthetic Gases and Vapors (NIOSH 1977c), Controlling Waste Anesthetic Gases (AHA 1980), ANSI Standard for Anesthetic Equipment: Scavenging Systems for Excess Anesthetic Gases (ANSI 1982), Nitrous Oxide (N₂O) (Eger 1985), Occupational Exposure to Inhalation Anesthetics: An Update (Whitcher 1987a), and Monitoring Exposure to Inhalation Anesthetics (Saidman and Smith 1984).

5.1.12.5.1 Engineering controls

A scavenging system is the basic engineering control for waste anesthetic gases. Such systems collect waste gas and ventilate it from the operating room. Although some scavenging systems are elaborate and costly, adequate systems can be inexpensive and can dramatically reduce contamination of the operating room environment. A scavenging system should be selected, installed, used, and maintained according to the references listed above in 5.1.12.5.

The equipment must be regularly monitored for leakage, improper design, or tubing defects. In some cases, poor wall connections and compression fittings or other defective equipment may be the sources of leakage.

The 1977 NIOSH document entitled Criteria for a Recommended Standard: Occupational Exposure to Waste Anesthetic Gases and Vapors (NIOSH 1977c) contains information on control procedures and work practices that have been demonstrated to reduce anesthetic gas concentrations to the NIOSH recommended exposure limits. A more thorough discussion of ventilation systems for anesthetic gases and their disposal can be found in the NFPA Health Care Facilities Handbook (NFPA 1984), which contains the complete text of NFPA 99 (Standard for Health Care Facilities). Stoner et al. (1982) provide a general description of the control of anesthetic gases, including discussions of physiological effects, anesthetic methods, and monitoring techniques.

The International Labour Office proposes three steps to control exposure to waste anesthetic gases (Parmeggiani 1983): (1) installing a proper nonrecirculating air conditioning system with a minimum of 20 room air exchanges per hour; (2) installing a scavenging system for collecting waste gases at the anesthetic breathing level, and (3) using low-flow rates of anesthetic gases.

5.1.12.5.2 Personal protective equipment

Personal protective equipment is not needed or recommended if an adequate control program is in place. However, monitoring should be done, and personal protective equipment should be available for use in case of an emergency.

5.1.12.5.3 Work practices

Operating-room workers can protect themselves from excess exposure by properly connecting the scavenging equipment, turning the gas off when the breathing system is disconnected from the patient, and ensuring that all patients have properly fitting masks.

5.1.12.5.4 Training programs

Workers involved with waste anesthetic gases should be trained to recognize, understand, monitor, and reduce the health and safety risks of exposure to these substances.

5.1.12.6 Medical Monitoring

Workers exposed to anesthetic gases should have complete medical histories on file. These should include family, genetic, and occupational histories and the outcomes of all pregnancies of female workers or of the wives of male workers. Baseline data should be obtained on the hepatic, renal, and hematopoietic systems. Exposed workers should be monitored periodically for liver and kidney function.