CAUTION: Unless otherwise noted, the quantitative information on these fact
sheets are from "EPA Health Effects Notebook for Hazardous Air
Pollutants-Draft", EPA-452/D-95-00, PB95-503579, December 1994." Please conduct
a current literature search and check the appropriate current online
database for the most recent quantitative information.
Acute (short-term) exposure to high levels (>30 ppm) of chlorine in
humans results in chest pain, vomiting, toxic pneumonitis, pulmonaryedema, and death. At lower level, (<3 ppm), chlorine is a potent
irritantto the eyes, the upper respiratory tract, and lungs.
Limited information is available on the chronic effects of chlorine in
humans. Reports from the older literature stated that chronic exposure to
concentrations of chlorine of around 5 ppm caused respiratory complaints,
corrosion of the teeth, inflammation of the mucous membranes of the nose, and
increased susceptibility to tuburculosis.
The Reference Concentration (RfC) and the Reference Dose (RfD) for
chlorine are under review by the U.S. Environmental Protection Agency (EPA).
No information is available on the developmental or reproductive effects
of chlorine in humans or animals via inhalation exposure. A study reported no
adverse effects on growth, lifespan, or fertility in rats exposed to 100 ppm
chlorine in their drinking water for their entire lifespan, over seven
generations.
No information is available on the carcinogenic effects of chlorine in
humans from inhalation exposure, and chlorine has not been found to be
carcinogenic in oral animal studies. EPA has not classified chlorine for
carcinogenicity.
Please Note: The main source of information for this fact sheet is EPA's
Drinking Water Criteria Document for Chlorine, Hypochlorous Acid and
Hypochlorite Ion. Other secondary sources include the Hazardous Substances
Data Bank (HSDB), a database of summaries of peer-reviewed literature, and the
Registry of Toxic Effects of Chemical Substances (RTECS), a database of toxic
effects that are not peer reviewed.
Environmental/Occupational Exposure
Workers may be exposed to chlorine in industries where it is produced or
used, particularly in the food and paper industries. In addition, persons
breathing air around these industries may be exposed to chlorine. (1)
Exposure to chlorine may also occur through drinking water and swimming
pool water, where it is used as a disinfectant. (2)
Accidental releases are another potential source of chlorine exposure. (3)
Assessing Personal Exposure
No data were located regarding detection of personal exposure to chlorine.
Health Hazard Information
Acute Effects:
Chlorine is a potent irritant in humans to the eyes, the upper respiratory
tract, and the lungs. Several studies have reported the following effects:
0.014 to 0.054 ppm: tickling of the nose; 0.04 to 0.097 ppm: tickling of the
throat; 0.06 to 0.3 ppm; itching of the nose and cough, stinging, or dryness
of the nose and throat; 0.35 to 0.72 ppm: burning of the conjunctiva and pain
after 15 minutes; above 1.0 ppm: discomfort ranging from ocular and
respiratory irritation to coughing, shortness of breath, and headaches. (4)
Higher levels of chlorine have resulted in the following effects in
humans: 1 to 3 ppm: mild mucous membrane irritation; 30 ppm: chest pain,
vomiting, dypsnea, cough; 46 to 60 ppm: toxic pneumonitis and pulmonary edema;
430 ppm: lethal after 30 minutes; 1,000 ppm: fatal within a few minutes. (3)
Chlorine is extremely irritating to the skin and can cause severe burns.
(3)
Acute animal tests, such as the LC50 test in rats and mice,
have shown chlorine to have high acute toxicity. (5)
EPA'sOffice of Air Quality Planning and Standards, for a hazard ranking
under Section 112(g) of the Clean Air Act Amendments, considers chlorine to be
a "high concern" pollutant based on severe acute toxicity. (6)
Chronic Effects(Noncancer):
Several studies in the older literature reported that chronic exposure to
chlorine concentrations of around 5 ppm caused respiratory complaints,
corrosion of the teeth, inflammation of the mucous membranes of the nose, and
increased susceptibility to tuberculosis in workers. (7)
Animal studies have reported decreased body weight gain, eye and nose
irritation, and effects on the respiratory tract, liver, and kidney from
chronic inhalation exposure to chlorine. (4)
Other studies have indicated that exposure to chlorine, via inhalation,
may alter disease resistance in animals, with higher incidences of emphysema,
pneumonia, and tuberculosis reported. (4)
The RfC and the RfD for chlorine are under review by EPA. (8)
Reproductive/Developmental Effects:
No information is available on the developmental or reproductive effects
of chlorine in humans or animals via inhalation exposure.
No adverse effects on growth, lifespan, or fertility were reported in rats
exposed to 100 ppm chlorine in their drinking water for their entire lifespan,
over seven generations. (4)
Since chlorine is highly reactive, uptake at sites such as the ovaries and
testes which are remote from the respiratory tract, is anticipated to be
minimal. (2)
No information is available on the carcinogenic effects of chlorine in
humans from inhalation exposure.
Several human studies have investigated the relationship between exposure
to chlorinated drinking water and cancer. These studies were not designed to
assess whether chlorine itself causes cancer, but whether trihalomethanes or
other organic compounds occurring in drinking water as a result of
chlorination are associated with an increased risk of cancer. These studies
show an association between bladder and rectal cancer and chlorination
byproducts in drinking water. (5)
Chlorine has not been found to be carcinogenic in animals; no tumors were
noted in a study where rats were exposed to 100 ppm chlorine in their drinking
water over their lifespan, for 7 generations (see Reproductive/Developmental
Effects section). (4)
Another study evaluated the potential carcinogenicity of chlorinated
drinking water in rats and mice and found no statistically significant
increase in tumors that could be related to the chlorinated water. (2)
EPA has not classified chlorine for carcinogenicity. (8)
Physical Properties
Chlorine is a greenish-yellow gas that is slightly soluble in water. (7)
Chlorine has a suffocating odor; the odor threshold is 0.31 ppm. (9)
The chemical formula for chlorine is Cl2, and its molecular
weight is 70.90 g/mol. (4)
Uses
Chlorine is used for water disinfection and for treatment of sewage
effluent. It is also used to disinfect equipment and utensils in beverage and
food processing plants, and as an intermediate in the manufacture of a number
of organic products such as antifreeze, rubber, cleaning agents, and
pharmaceuticals. (2,4)
Conversion Factors: To convert from ppm to mg/m3:
mg/m3 = (ppm) × (molecular weight of the compound)/(24.45). For
chlorine: 1 ppm = 2.9 mg/m3.Health Data from Inhalation
Exposure
Concentration (mg/m3)
Health numbersa
Regulatory, advisory numbersb
Reference
1,000,000.0
-- -- -- -- 100,000.0
-- -- -- -- 10,000.0
-- -- -- -- 1,000.0
-- -- -- -- 100.0
LC50 (rats) (849 mg/m3)
LC50 (mice) (397 mg/m3)
5
5
-- -- -- -- 10.0
-- -- -- -- 1.0
OSHA PEL and ACGIH TLV (3 mg/m3)
OSHA PEL, ACGIH TLV, and NIOSH REL (1.5 mg/m3)
4
4
ACGIH
TLV--American Conference of Governmental and Industrial Hygienists' threshold
limit value expressed as a time-weighted average; the concentration of a
substance to which most workers can be exposed without adverse effects.
LC50 (Lethal Concentration50)--A calculated
concentration of a chemical in air to which exposure for a specific length of
time is expected to cause death in 50% of a defined experimental animal
population. NIOSH REL--National Institute of Occupational Safety and
Health's recommended exposure limit; NIOSH-recommended exposure limit for an 8-
or 10-h time-weighted-average exposure and/or ceiling. OSHA
PEL--Occupational Safety and Health Administration's permissible exposure limit
expressed as a time-weighted average; the concentration of a substance to which
most workers can be exposed without adverse effects averaged over a normal 8-h
workday or a 40-h workweek.
a Health numbers are toxicological numbers from animal testing or
risk assessment values developed by EPA. b Regulatory numbers are
values that have been incorporated in Government regulations, while advisory
numbers are nonregulatory values provided by the Government or other groups as
advice.
References
U.S. Environmental Protection Agency. Drinking Water Criteria Document
for Chlorine, Hypochlorous Acid and Hypochlorite Ion. (External Review
Draft.) Environmental Criteria and Assessment Office, Office of Health and
Environmental Assessment, Cincinnati, OH. 1992.
U.S. Environmental Protection Agency. Integrated Risk Information
System (IRIS) on Chlorine. Environmental Criteria and Assessment Office,
Office of Health and Environmental Assessment, Office of Research and
Development, Cincinnati, OH. 1993.
U.S. Department of Health and Human Services. Hazardous Substances Data
Bank (HSDB, online database). National Toxicology Information Program,
National Library of Medicine, Bethesda, MD. 1993.
E.J. Calabrese and E.M. Kenyon. Air Toxics and Risk Assessment.
Lewis Publishers, Chelsea, MI. 1991.
R.D. Morris, A. Audet, I.F. Angelillo, T. C. Chalmers, and F. Mosteller.
Chlorination, Chlorination by-products, and cancer: A meta-analysis.
American Journal of Public Health, 82(7):955-977. 1992.
U.S. Environmental Protection Agency. Ambient Water Quality Criteria
for Chlorine. EPA 440/5-84-030. Office of Water Regulations and
Standards, Washington, DC. 1985.
American Council of Government of Industrial Hygienists (ACGIH).
Documentation of the Threshold Limit Values. Fourth Edition.
Cincinnati, OH. 1986.
U.S. Department of Health and Human Services. Registry of Toxic Effects of
Chemical Substances (RTECS, online database). National Toxicology Information
Program, National Library of Medicine, Bethesda, MD. 1993.
J.E. Amoore and E. Hautala. Odor as an aid to chemical safety: Odor
thresholds compared with threshold limit values and volatilities for 214
industrial chemicals in air and water dilution. Journal of Applied
Toxicology, 3(6):272-290. 1983.
