Re: Ammonia and Bleach

From: donald j haarmann (donald-haarmann_at_worldnet.att.net)
Date: 12/30/04 

Date: Thu, 30 Dec 2004 00:09:06 GMT

"Aplin17" <aplin17@cs.com> wrote in message news:20041229182122.10314.00001778@mb-m25.news.cs.com...

> What chemical reactions happen when you mix ammonia and bleach and why is it
> dangerous?

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Chemical and Engineering News Janurary 2, 1989

Nonconfrontational facts about household chemicals. Mentioned here earlier was
"the vast amount of chlorine given off by reaction of Clorox (about a 51% solution of
sodium hypochlorite) with products like Vanish, detergents, and ammonia" (C&EN,
Sept. 19, 1988, page 56). These words being slightly off the mark, an anonymous
correspondent wishes "to point out a few facts in a nonconfrontational manner."

He or she writes that a pH dependent equilibrium exists among hypochlorite,
hypochlorous acid, and chlorine. "Above pH 7.5, hypochlorite ion predominates. Some-
where around pH 5 it becomes possible for free chlorine to exist in solution. The rub is
that chlorine is much less soluble than either HOCI or OCI, and at about pH 2 or 3 it
comes boiling out. This is why you don't mix chlorine bleach with acids. A
garden-variety toilet bowl cleaner is usually a moderately strong acid such as
phosphoric acid or sodium bisulfate, which easily delivers a pH around 2. It's amazing
how much chlorine you can get out of a pint of bleach. That's why products like Clorox
bleach and Vanish toilet bowl cleaner carry ... warning notices on their labels. Isn't it
amazing how few people bother to read?"

Ammonia is a different case, the correspondent goes on. "Mix an ammonia solution
with hypochlorite and you get chloramines-NH2Cl, NHCl2, and NCl3. The chloramines
are alkaline but less soluble than ammonia, so they bubble out. They are also
poisonous. That's what happens when you mix hypochlorite bleach with household
ammonia.

"So what happens when you mix bleach with detergents? Clean clothes."

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MMWR September 13, 1991 / 40(36); 619-621,627-629

Epidemiologic Notes and Reports Chlorine Gas Toxicity from Mixture of Bleach with Other
Cleaning Products – California

>From October 1987 through November 1989, five episodes of chlorine gas exposure with
toxicity to at least 14 persons occurred at two state hospitals in California. Each hospital
provides inpatient treatment to approximately 1000 forensic psychiatric patients. As part of
their rehabilitation programs, selected patients perform cleaning duties under the
supervision of janitors or nursing staff. Each incident occurred during the performance of
these duties and involved the mixture of bleach (sodium hypochlorite) and a phosphoric
acid cleaner by inpatients. This mixture produced chlorine gas and other chemical
byproducts (Figure 1a and 1b), and resulted in temporary illness in exposed persons.
Hospital A

Episode 1. On October 18, 1987, a patient poured an undetermined amount of a 4%
phosphoric acid cleaner into a bucket containing diluted bleach. A chemical reaction
occurred immediately, releasing an irritating gas. The patient was assisted from the room,
and the cleaning solution was diluted with water and poured down a drain. Windows were
opened to ventilate the area, and the ward was evacuated. The patient complained of
anxiety, chest tightness, difficulty breathing, and heartburn; physical examination revealed
scattered bibasilar pulmonary rhonchi. He was treated with supplementary oxygen, and
most symptoms subsided after 1 hour.

Episode 2. On December 19, 1987, a patient mopped a bathroom floor with a 4%
phosphoric acid solution, then rinsed the floor with water. Immediately after he applied a
bleach and water solution to the floor, a noxious gas with a strong odor was emitted. The
mixture was poured down a drain, and the floor was again rinsed with water; however,
because the room's exhaust fan was inoperative and windows had been sealed shut, the
gas dispersed throughout the ward and caused symptoms in other patients. The ward was
evacuated; patients and staff returned after 1-1/2 hours when the odor had dissipated.
Within an hour of their return, additional patients and staff complained of symptoms
including nausea, eye irritation, tearing, sore throat, headache, cough, and chest
tightness; one patient had an acute exacerbation of asthma. The ward was reevacuated
until the following day. The local fire department assisted with ventilation.

Episode 3. On December 25, 1987, a patient mixed approximately 1/2 L of bleach and 1 L
of a 4% phosphoric acid cleaner in a bucket, creating a noxious gas. The patient rapidly
developed eye irritation followed by fatigue; four employees developed symptoms that
included a lightheaded dizziness, nausea, eye and nose irritation, headache, and chest
tightness. The ward was evacuated until chemical residues on the bathroom floors had
been rinsed and air exchange had been completed using the existing exhaust fan system.
For some persons, symptoms persisted for several hours. More than an hour after the
episode, two employees entered an enclosed nursing office 50 feet from the gas release
site; despite the absence of a detectable chlorine odor, both promptly experienced
recurrent symptoms.

Following these three incidents, patients and employees were interviewed to establish
policies to prevent recurrences. Each incident involved the same phosphoric acid
formulation. The three patients had been supervised by different staff; they denied mixing
the chemicals intentionally to create a disturbance, denied knowing each other, and
denied knowledge of previous episodes. Each incident occurred on a weekend or holiday,
when janitors were off duty and the patients were cleaning bathroom floors while being
supervised by ward nursing staff without constant observation.

Beginning December 29, controls were instituted on the storage and use of the phosphoric
acid cleaner at hospital A. The cleaner was dispensed by housekeeping supervisors to
janitors, who kept it locked in storage areas accessible to employees only.

Episode 4. Despite more stringent controls over the use of cleaning products, a fourth
episode occurred. On November 3, 1989, a patient supervised by a new employee was
allowed in a locked storage area and poured an undetermined amount of 4% phosphoric
acid cleaner into a bucket containing bleach and water, immediately producing a cloud of
noxious vapor.

The employee assisted the patient from the area, then returned to the area and poured
the contents of the bucket down a sink. The employee, who was exposed to the vapors for
less than 1 minute, reported immediate throat and nasal burning that persisted for more
than 24 hours, as well as transient dizziness and nausea. Supplemental oxygen was
administered at a local acute-care hospital emergency room for 3 hours. The employee
completely recovered within 36 hours following exposure. The patient had no symptoms.
Following this incident, acidic cleaning products at hospital A were locked in the offices of
housekeeping supervisors; access was available only to janitors and was denied to both
nursing staff and patients. In addition, the hospital has prohibited the mixing of cleaning
products. No further incidents have occurred. Hospital B

On December 7, 1988, a patient assisting in janitorial duties mixed bleach with phosphoric
acid cleaner. Immediately a noxious gas with a strong odor was detected and prompted
the evacuation of two wards for 1-1/2 hours. Fire department personnel using self-
contained breathing equipment disposed of the chemicals and ventilated the area. The
patient experienced vomiting, cough, and inspiratory discomfort; elevated blood pressure
and fever were noted when the patient was treated in the emergency room. Five
employees who helped evacuate the ward complained of symptoms including eye irritation
and shortness of breath. Employees and patients returned approximately 1-1/2 hours after
the area was ventilated. After this incident, hospital B instituted warning labels on all
chemical cleaning products and posted precautionary (i.e., "do not mix") signs on janitorial
closets. Bleach and acidic cleaning products were restricted to use by staff. No further
incidents involving phosphoric acid products have occurred at this hospital. Product Label
Investigation and Modifications

The label of the phosphoric acid cleaner involved in all five incidents did not list the active
ingredient nor warn of the potential for toxic reactions when phosphoric acid was mixed
with other chemicals. The material safety data *** (MSDS) did not describe potentially
toxic chemical reactions or incompatibilities. The labels and MSDSs of two other products
containing phosphoric acid in use at hospital A, including one with a 30% acid
concentration, also lacked information on reactions and incompatibilities with hypochlorite.
After notification by hospital A in December 1987 about episodes 1-3, a new label was
supplied by the chemical manufacturer in early 1988 for use by institutional customers
wishing to transfer the product into smaller storage containers. The new label included the
statement: "Do not mix with other chemicals (such as bleach or ammonia)." In 1989, the
product's label was revised to add a similar statement. The MSDS was revised in May
1991; it now mentions incompatibility with ammonia or bleach but still does not state what
will result from those mixtures.

The product is marketed directly by the manufacturer to institutions in Arizona, California,
Montana, Oregon, and Washington. It is not sold in stores to the general public and
therefore is not considered a consumer product by the U.S. Consumer Product Safety
Commission (CPSC) and is exempt from labeling requirements of the federal Hazardous
Substances Act. However, according to the California Department of Industrial Relations,
Division of Occupational Safety and Health (Cal-OSHA), as a California workplace product
it is subject to the state's hazard communication standards, which require the label to list
the phosphoric acid and appropriate hazard warnings and the MSDS to include reactivity
and incompatibilities; the wording to describe the chemical interactions is not specified by
law (R.E. Erickson, Cal-OSHA, personal communication, 1991). Reported by: RP Hattis,
MD, California Dept of Mental Health; JR Greer, MD, S Dietrich, DO, S Olafsson, MD,
Dept of Preventive Medicine, Loma Linda Univ, Loma Linda; KR McAndrew, Long Beach
Memorial Hospital, California. Health Studies Br, Div of Environmental Hazards and
Health Effects, National Center for Environmental Health and Injury Control, CDC.
Editorial Note

Editorial Note: The chemicals involved in the first three incidents were a standard
household bleach (5.25% sodium hypochlorite solution [NaOCl]) and a 4% phosphoric
acid (H3PO4) cleaning agent. When sodium hypochlorite and an acid are mixed, chlorine
gas and water are released (Figure 1a). Chlorine gas reacts with the water to form
hydrochloric and hypochlorous acids (Figure 1b). Chlorine gas may cause a variety of
symptoms as a function of the severity of exposure (1-3). Hydrochloric acid also causes
inflammation that may, along with nascent oxygen release, be one of the mechanisms of
tissue damage by chlorine (4).

Mild mucous membrane irritation may occur in some persons after several hours at levels
as low as the threshold limit value (TLV) of 1 ppm (1,3); this TLV may warrant
reassessment (1). A level of at least 3 ppm may cause extreme irritation of the eyes and
respiratory tract, but a detectable odor is usually not present below 3.5 ppm (2).
Symptoms following exposure to chlorine have included irritation of the eyes, nose, and
throat; dizziness; cough; and chest pain or constriction. Severe exposure may cause
pulmonary edema, bronchiolar and alveolar damage, and pneumomediastinum (1,2,4-6).
When bleach is mixed with ammonia-containing compounds, monochloramine (NH2Cl)
(Figure 1c) and dichloramine (NHCl2) (Figure 1d) are formed, which may produce tearing,
respiratory tract irritation, and nausea. These compounds decompose in water to
hypochlorous acid and free ammonia gas (6-8); the former combines with moisture
forming hydrochloric acid and toxic nascent oxygen (8); the latter is a respiratory and
mucous membrane irritant and can cause pulmonary edema and pneumonia (6,7).

Only four case reports have been published of chlorine toxicity from mixing bleach with
acid cleaning agents, including one describing near-fatal pulmonary edema, two of
pneumomediastinum, and one of mild illness in which other family members also became
symptomatic. None of these reports involved phosphoric acid; in three, inadequate
ventilation probably contributed to the toxic effects (4-6). However, the American
Association of Poison Control Centers data collection system listed 409 cases of chlorine
exposure in 1990 from acid mixtures with hypochlorite that were reported from 72
participating centers serving 77% of the U.S. population. Of these cases, 395 (97%) were
unintentional exposures and 356 (87%) occurred among persons aged >17 years; 128
required treatment in health-care facilities. Of 340 exposures for which outcome was
known, 292 were considered to have caused minor and 30 moderate illness (9). Cases
recorded by poison-control centers probably underrepresent substantially the episodes
actually occurring; for example, no poison-control center was consulted about the five
incidents in this report.

A directive for CPSC compliance staff for monitoring the chemical product industry
requires labels on consumer products containing 5% or more hypochlorite to include
warnings against mixing with acids and other household chemicals and for labels of
products containing 3% or more ammonia to warn against mixing with chlorine-type
bleaches or other household chemicals (10). There is no required warning for phosphoric
acid, nor does the CPSC routinely inspect any chemical consumer products. Products
sold only for institutional or other workplace use are not monitored by CPSC, and the
responsible occupational health and safety agencies (the federal Occupational Safety and
Health Administration or a state agency) rely on manufacturers/importers and employers
to be informed of potential health hazards of workplace chemicals and to inform
customers and employees by MSDSs (11,12). Agencies monitor workplace chemical
labeling and MSDSs by periodic inspections, with feedback to companies with deficiencies
(13). The probability that any given chemical product will be reviewed by this process is
low. No complete compilation has been made of the millions of consumer and industrial
chemical product formulations, labels, and MSDSs in the United States. There is no
federal requirement that wording on labels and MSDSs be cleared by a regulatory agency
as a precondition for sale or distribution of chemical products.

Three approaches can be implemented to prevent potential toxic exposures in institutional
and other industrial settings from mixtures of bleach with other cleaning agents:

1. Housekeeping policies should be established in institutions to educate new or untrained
employees and patients or inmates who assist in cleaning about the potential danger of
chemical mixtures and to provide constant supervision for persons whose judgement may
be impaired. When this is not possible, use of such chemicals should be restricted to fully
trained and experienced employees.

2. When chlorine gas is unintentionally released, areas in which the gas could circulate
should be evacuated until sufficient air exchanges have occurred to ensure that the gas
has been eliminated. The absence of odor is not a reliable indicator of safety. Pending the
complete evacuation of gas, employees involved in cleanup or onsite investigation of such
incidents should wear protective respiratory equipment, and none should enter without a
companion (14).

3. OSHA and state agencies designated by federally approved state occupational safety
and health plans should contact all known manufacturers and importers of cleaning
products that contain hypochlorite, acids, or ammonia and are used in institutions and
other workplaces to clarify and reinforce proper labeling and MSDS requirements and to
encourage education of their customers about nonmixing.

References
1. Arena JM. Poisoning--toxicology, symptoms, treatment. 5th ed. Springfield, Illinois:
Charles C. Thomas, 1986:298-300,316- 8,692.
2. Sax NI, Lewis RJ. Dangerous properties of industrial materials. 7th ed. Vol 2. New York:
Van Nostrand Reinhold, 1989:768.
3. Ellenhorn MJ, Barceloux DG. Medical toxicology: diagnosis and treatment of human
poisonings. New York: Elseviere, 1988:878,891,903.
4. Jones FL. Chlorine poisoning from mixing household cleaners [Letter]. JAMA
1972;222:1312.
5. Gapany-Gapanavicius M, Yellin A, Almog S, Tirosh M. Pneumomediastinum--a
complication of chlorine exposure from mixing household cleaning agents. JAMA
1982;248:349-50.
6. Faigel HC. Hazards to health: mixtures of household cleaning agents. N Engl J Med
1964;271:618.
7. Gosselin RE. Clinical toxicology of commercial products. 5th ed. Baltimore: Williams
and Wilkins, 1984:111-204.
8. Gapany-Gapanavicius M, Molho M, Tirosh M. Chloramine-induced pneumonitis from
mixing household cleaning agents. Br Med J 1982;285:1086.
9. Litovitz TL, Bailey KM, Mitz BF, et al. 1990 Annual report of the American Association of
Poison Control Centers national data collection system. Am J Emerg Med 1991;9:461-
509.
10. Office of the Federal Register. Code of federal regulations: hazardous substances
labeling guide. Washington, DC: Office of the Federal Register, National Archives and
Records Administration, 1984. (16 CFR 1500.121).
11. Occupational Safety and Health Administration. Preamble to final rule on hazard
communication. Federal Register 1983:48:53337.
12. Occupational Safety and Health Administration. Hazard communication. Federal
Register 1987;52:31852-86.
13. Occupational Safety and Health Administration, Office of Health Compliance
Assistance. Inspection procedures for the hazard communication standard. Washington,
DC: Occupational Safety and Health Administration, 1990. [Instruction CPL 2- 2.38C].
NIOSH. Occupational exposure to chlorine: criteria for a recommended standard.
Cincinnati, Ohio: US Department of Health, Education, and Welfare, Public Health
Service, 1976. 

-- 
donald j haarmann
---------------------------
The Chymists are a strange Class of Mortals, impelled
by an incomprehensible Impulse to take their Pleasure
amid Smoke and Vapour, Fume and Flame, Poison
and Poverty — Yet  among all these Evils, I seem
to live so sweetly that may I die if I would change
places with the Persian King!
Johann Beccher
Physica Subterranea, 1703
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