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Workplace Exposures to Corrosion-Inhibiting Chemicals
from a Steam Humidification System -- Ohio, 1988
On December 5, 1988, at 11:45 a.m., boiler steam was released
to humidify an electrical components manufacturing plant in Ohio.
At noon, employees returning from lunch noticed an odor described
as musty, pungent, "ammonia-like," or "radiator-like," and the
work area was evacuated. During the next several hours, 77 (64%)
of the 121 employees working in the plant became ill; symptoms
included rapid onset of headache; nausea; vomiting; dizziness;
and eye, nose, and throat irritation. Forty employees were
evaluated by the company nurse; 11 of these received further
examination at local hospitals but were subsequently released.
The steam humidification was turned off in most work areas by
1:15 p.m.
On December 8, boiler steam was reintroduced into the work
area, producing the same odor and resulting in evacuation of
affected areas; no illnesses were reported. Company management
and the local union jointly requested an investigation of the
problem by CDC's National Institute for Occupational Safety and
Health (NIOSH). Investigators determined that during the third
week of September, two corrosion-inhibiting chemicals,
diethylaminoethanol (DEAE) and cyclohexylamine (CHA), had been
added to the boiler water at four times normal strength, as
recommended by the supplier; the boiler was left idle, and the
concentration of DEAE and CHA was not diluted before the boiler
was used on December 5.
Persons working in the humidified area on December 5 were at
increased risk for becoming ill (illness defined as the presence
of at least two of the above symptoms), compared with employees
in other areas of the plant that were not humidified by steam
(relative risk: 4.3; 95% confidence interval=2.1-9.1). On
December 9, after workers had left for the day, steam was
released into the work area, and samples of air and boiler water
were collected for analysis (1). DEAE and CHA were not detected
in either air or water.
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: When present in boiler water, DEAE and CHA can
become airborne in boiler steam, which can result in inhalational
and/or dermal uptake by exposed persons. Higher acute exposures
through this mechanism are more likely if these chemicals are
added to a steam-generating system in a single large quantity
rather than continuously in small amounts.
Most boilers require daily addition of fresh water to
compensate for losses from escaping steam and drained condensate.
Although the amount of water added to this boiler between the
outbreak and the time when samples were obtained is not known,
dilution of the treated boiler water during the intervening 4
days may account for the failure to detect DEAE or CHA.
DEAE and CHA are both strong mucosal irritants. In one report,
a laboratory worker who was inadvertently exposed for less than
30 seconds to DEAE at an estimated concentration of 100 ppm (480
mg/m3) developed nausea and vomiting within 5 minutes (2). No
data are available on human health risks associated with
long-term, low-level airborne exposure to these amines.* The
Occupational Safety and Health Administration (OSHA) permissible
exposure limits (PELs) for DEAE and CHA are, respectively, 50
mg/m3 (10 ppm) and 40 mg/m3 (10 ppm) (4) and are established at
levels intended to prevent mucosal irritation symptoms. NIOSH has
no recommended exposure limit for either substance.
NIOSH has previously investigated three clusters of illnesses
related to exposure to boiler steam that contained DEAE or
related corrosion-inhibiting chemicals. In 1981, 24 employees in
the office area of a production building developed skin rashes;
many of the employees also reported dry throats, headaches, and
chest tightness (5). Investigators concluded that the dermatitis
resulted from exposure to a condensation or reaction product of
DEAE that had been added to the air-handling system. In 1982,
employees in a museum where DEAE had been added to a
humidification system reported eye irritation and dermatitis (6).
Air sampling detected DEAE concentrations of only 0.05 mg/m3 and
0.04 mg/m3, and direct contact with released DEAE that had
subsequently condensed on surfaces was proposed as an exposure
pathway (6). In 1988, hospital staff nurses reported symptoms of
eye and upper respiratory tract irritation after the introduction
of CHA and morpholine (a similar nitrogen-containing corrosion
inhibitor) into boiler water used to humidify a nursery and
neonatal intensive care unit (NIOSH, unpublished data).
The OSHA PELs for DEAE and CHA were promulgated for the
protection of industrial workers and are not intended to protect
members of the general public, which may include children, the
elderly, those in ill health, and others who may be particularly
sensitive to the effects of these substances. As a result of the
investigation in this report, NIOSH recommended that the
electronics manufacturer discontinue use of amine-based
corrosion-inhibiting chemicals in boiler steam that is
intentionally released to humidify occupied buildings. At least
one major supplier of corrosion-inhibiting chemicals has
recognized this potential health hazard associated with DEAE and,
in 1983, advised its customers against such use (Union Carbide
Corporation, unpublished data, 1985).
References
NIOSH. NIOSH manual for analytical methods. 3rd ed.
Cincinnati: US Department of Health and Human Services, Public
Health Service, CDC, 1984; DHHS publication no. (NIOSH)84-100.
Cornish HH. Oral and inhalation toxicity of
2-diethylaminoethanol. Am Ind Hyg Assoc J 1965;26:479-84.
Meiners AF, Gadberry H, Carson BL, Owens HP, Lapp TW. Volatile
corrosion inhibitors and boiler water additives: potential of
nitrosamine formation. Washington, DC: US Environmental
Protection Agency, 1980; EPA report no. 560/11-80-023.
Office of the Federal Register. Code of federal regulations:
occupational safety and health standards. Subpart Z: Air
contaminants--permissible exposure limits. Table Z-1-A.
Washington, DC: Office of the Federal Register, National Archives
and Records Administration, 1989. (29 CFR ***1910.1000).
McManus K, Baker D, NIOSH. Health hazard evaluation report no.
HETA 81-247-958. Cincinnati: US Department of Health and Human
Services, Public Health Service, CDC, 1981.
Fannick N, Lipscomb J, McManus K, NIOSH. Health hazard
evaluation report no. HETA 83-020-1351. Cincinnati: US Department
of Health and Human Services, Public Health Service, CDC, 1983.
Under certain conditions, it is theoretically possible that
DEAE (or related compounds) in boiler water may be converted to
nitrosamines, which are suspected human carcinogens. No
experimental evidence exists to indicate whether this occurs,
particularly in boiler systems of the type discussed here (3).
Disclaimer
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