Epidemiologic Notes and Reports Occupational Exposures to Formaldehyde in Dialysis Units

A company in Illinois that operates three dialysis centers became concerned about the occupational exposure of its employees to formaldehyde. Formaldehyde is used as a chemical germicide to control bacterial contamination in water distribution systems and in the dialysis fluid pathways of artificial kidney machines. In addition, formaldehyde is used to disinfect hollowfiber dialyzers (artificial kidneys) that are reprocessed and reused only by the same patient. The company requested an investigation by the National Institute for Occupational Safety and Health (NIOSH) to determine the extent of employee exposure to formaldehyde.

Investigators from NIOSH conducted an initial environmental survey of the facilities in April 1982 and a follow-up environmental survey in June 1982. In the areas used to reprocess dialyzers, they collected air samples to analyze for formaldehyde in the personal breathing zones of workers. The results showed that workers at two of the three facilities involved were exposed to formaldehyde concentrations of 0.50 and 0.57 parts per million (ppm), respectively, as a time-weighted average (TWA) (1). The current Occupational Safety and Health Administration standard establishes a permissible exposure of 3 ppm, 8-hour TWA; NIOSH recommends minimizing workplace exposure levels and limiting exposure to the lowest feasible level (2,3).

Based on NIOSH recommendations, the company modified the system used to deliver formaldehyde by incorporating an automatic metering system so that the operation did not have to be performed manually. In addition, the company changed work practices to include capping storage containers, running water continuously during the disinfection operation, and educating employees about the adverse health effects of formaldehyde. In a follow-up environmental survey, conducted in December 1982 after these changes were instituted, NIOSH found that TWA concentrations of formaldehyde at all three facilities had fallen below the limit of detection (5 ug/sample, about 0.34 ppm based on a 12-liter air sample).

NIOSH has also documented significant occupational exposures to formaldehyde in recent studies at several other dialysis units (4-7). Studies at hospitals in San Francisco and Honolulu showed airborne concentrations of formaldehyde as high as 0.9 ppm and 1.3 ppm, respectively. Employees in the dialysis units of both hospitals were experiencing cough, headache, and eye, nose, and throat irritation. These symptoms are consistent with the effects of exposure to formaldehyde vapor. In Denver, Colorado, another evaluation at a dialysis unit showed levels of formaldehyde ranging as high as 1.6 ppm (6). The two highest levels were found in the room where dialyzers were being reprocessed and disinfected with formaldehyde. At this evaluation, work practice was changed so that water was run continuously into the sink whenever the formaldehyde in a hemodialyzer was drained into that sink. This served to flush formaldehyde down the drain and lowered its airborne levels. Reported by Hazard Evaluations and Technical Assistance Br, Div of Surveillance, Hazard Evaluations, and Field Studies, National Institute for Occupational Safety and Health, CDC.

Editorial Note

Editorial Note: Nearly 80,000 patients in the United States undergo maintenance dialysis at approximately 1,400 facilities licensed by the Health Care Financing Administration. About 80% of these dialysis centers use formaldehyde to disinfect hemodialysis systems that include treated water distribution systems, dialysis fluid proportioning systems, and artificial kidney machines. In 1983, over 50% of these dialysis centers reused the disposal hollowfiber dialyzers, and approximately 90% used formaldehyde to disinfect hemodialyzers during the reprocessing procedure (8). Consequently, the potential for environmental exposure of dialysis-center employees and dialysis patients to formaldehyde is relatively high.

Formaldehyde has a sharp odor that is noticeable at very low levels (less than 1 ppm). At formaldehyde concentrations ranging from 0.1 to 5 ppm, the first signs or symptoms of exposure are burning of the eyes, tearing (lacrimation), and general irritation to the upper respiratory passages (9). Higher exposures (10-20 ppm) may produce coughing, tightness in the chest, a sense of pressure in the head, and cardiac palpitation (10,11). In one report, inhalation provocation tests showed that hypersensitivity to the formaldehyde used to disinfect artificial kidney machines was responsible for attacks of wheezing accompanied by productive cough in two of 28 members of the nursing staff in a hemodialysis unit. Three other members of the same staff who were continuously exposed to this substance occupationally had developed similar recurrent but less frequent episodes since joining the unit (12). Dermatitis has also been reported among workers exposed to formaldehyde or to resins that contain formaldehyde (13).

To minimize exposure to formaldehyde in dialysis units, CDC recommends the following:

1. Employees working in dialysis units should be fully informed about the adverse health effects of formaldehyde and should wear proper protective equipment whenever handling concentrated formaldehyde or preparing dilute formaldehyde solutions. (Protective equipment should include rubber gloves, protective aprons, and eye and face protection.)

2. Hoses connecting free-standing modular components of hemodialysis systems to drain lines should be air tight to prevent formaldehyde vapors from escaping into treatment rooms.

3. Employees should spend as little time as possible in areas where hemodialyzers are reprocessed. Water should be kept running continuously in the sinks when the hemodialyzers are being reprocessed to help reduce exposure to formaldehyde. Based on recent animal studies, which show that formaldehyde

induces a rare form of nasal cancer (14-16), as well as epidemiologic investigations that indicate excess cancer rates in formaldehyde-exposed workers, CDC recommends that formaldehyde in the workplace be handled as an occupational carcinogen. As a prudent public health measure, engineering controls and stringent work practices should be employed to reduce occupational exposure to the lowest possible limit.

References

1. National Institute for Occupational Safety and Health. Health hazard evaluation report no. HETA 82-205-1314. Cincinnati, Ohio: National Institute for Occupational Safety and Health, 1983.

2. Occupational Safety and Health Administration. OSHA safety and health standards. Washington, D.C.: Occupational Safety and Health Administration, 1980 (revised). (29 CFR 1910.1000).

3. CDC. NIOSH recommendations for occupational safety and health standards. MMWR 1985;34(1 suppl):17S.

4. National Institute for Occupational Safety and Health. Health hazard evaluation report no. HETA 82-303-1271. Cincinnati, Ohio: National Institute for Occupational Safety and Health, 1983.

5. National Institute for Occupational Safety and Health. Health hazard evaluation report no. HETA 81-211-984. Cincinnati, Ohio: National Institute for Occupational Safety and Health, 1982.

6. National Institute for Occupational Safety and Health. Health hazard evaluation report no. HETA 82-084-1147. Cincinnati, Ohio: National Institute for Occupational Safety and Health, 1982.

7. National Institute for Occupational Safety and Health. Walk-through survey report of the dialysis unit, Christ Hospital, Cincinnati, Ohio. Report no.\125.18. Cincinnati, Ohio: National Institute for Occupational Safety and Health, 1982.

8. Bland L, Alter M, Favero M, Carson L, Cusik L. Hemodialyzer reuse: practices in the United States and implication for infection control. Trans Am Soc Artificial Intern Organs 1985;31:556-8.

9. National Institute for Occupational Safety and Health. Formaldehyde: evidence of carcinogenicity. Cincinnati, Ohio: National Institute for Occupational Safety and Health, April 15, 1981. NIOSH Current Intelligence Bulletin 34 DHEW publication no. (NIOSH) 81-111.

10. Loomis TA. Formaldehyde toxicity. Arch Pathol Lab Med 1975;103:321-4.

11. Kerfoot EJ, Mooney TF. Formaldehyde and paraformaldehyde study in funeral homes. Am Indust Hyg Assoc J 1975;36:533-7.

12. Hendrick DJ, Lane DJ. Occupational formalin asthma. Br J Indust Med 1977;34:11-8.

13. Proctor NH, Hughes JP. Chemical hazards of the workplace. Philadelphia: JB Lippencott, 1978.

14. Chemical Industry Institute of Toxicology. Statement concerning research findings, Docket No. 11109. Research Triangle Park, North Carolina: Chemical Industry Institute of Toxicology. October 8, 1979.

15. Albert RE, Sellakumar AR, Laskin S, Kuschner M, Nelson M, Snyder CA. Nasal cancer in the rat induced by gaseous formaldehyde and hydrogen chloride. J Natl Cancer Inst 1982;68:597-603.

16. Swenberg JA, Kerns WD, Mitchell RI, Gralla EJ, Pavkov KL. Induction oF squamous cell carcinomas of the rat nasal cavity by inhalation exposure to formaldehyde vapor. Cancer Res 1980;40: 3398-402.

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