Chlorine

CAS RN: 7782-50-5

Toxicity Summary

IDENTIFICATION AND USE: Chlorine is a greenish yellow gas, and becomes a clear to amber liquid under pressure and has a pungent suffocating odor. The major uses of chlorine are in the manufacture of chlorinated organic chemicals and inorganic chemicals. It is used as a bleaching agent in the manufacture of pulp and paper; in bleaching textiles, in the manufacture of pesticides, herbicides, refrigerants, propellants, household and commercial bleaches, detergents for automatic dish washers, antifreeze, antiknock compounds, plastics, synthetic rubbers, adhesives, pharmaceuticals, drinking and swimming water purification, sanitation of industrial and sewage wastes and in the degassing of aluminum metal. HUMAN EXPOSURE AND TOXICITY: Chlorine has a suffocating pungent odor and the gas irritates the eyes and causes tears. Exposure to chlorine gas can be from oral, inhalation and dermal and eye routes. Chlorine gas can lead to ocular irritation and burns. Skin exposure can cause irritation, pain, erythema, blister and burns. Liquid chlorine on contact can burn the skin and eyes. Initially the irritation of the eyes, nose and throat, followed by coughing and wheezing, dyspnea, sputum production and chest pain. Larger exposures may lead to hyperchloremic acidosis, anoxia and may lead to cardiac or respiratory arrest. Chemical pneumonitis may follow. The effects of chronic exposure to chlorine among workers at a pulp mill have shown persistent respiratory symptoms. Bronchial obstruction and bronchial hyper-responsiveness were noted. There have also been occasional reports of asthma precipitated by exposure to chlorinated water. In a series of in vitro experiments on a human lymphocyte culture system reported that chlorine concn 2-20 times those normally found in drinking water induced chromatid and chromosome breaks, translocations, dicentric chromosomes, and gaps. ANIMAL STUDIES: Exposure of rats to 3 or 9 ppm chlorine for 6 hr/day, 5 days/week for 6 weeks was associated with decreased body weight, increased hematocrit and white cell count (in females exposed to 9 ppm only), and increases in clinical chemistry measures suggestive of altered renal function. There was gross evidence of an inflammatory reaction in the upper and lower respiratory tract among animals exposed to a 9 ppm concentration of chlorine; animals exposed to 3 ppm exhibited these effects to a lesser degree. Water containing 0, 70, 140, or 275 ppm chlorine was provided to groups of 70 rats or mice of each sex for up to 2 years. Although the marginal increase in leukemia incidence in the mid- and high-dose female rats suggested a possible association with the administration of chlorinated water, the incidence of leukemia was not clearly dose related. There was no indication of reduced latency of leukemia, and the incidence of leukemia in concurrent controls was less than the mean for historical controls; furthermore, there was no supporting evidence of an effect in male rats. Thus, the marginal increase in leukemia incidence in female rats was considered equivocal evidence of carcinogenic activity. There were no neoplasms or nonneoplastic lesions in male rats or in male or female mice that were clearly associated with the consumption of chlorinated water. In vivo induction of micronuclei (MN) was studied in polychromatic erythrocytes (PCEs) derived from bone marrow of chlorinated drinking water (CDW)-treated Wistar rats. The results demonstrated significant increases of micronucleated PCEs in the bone marrow of rats fed with relatively low CDW doses (33.3mL/kg body weight per day). ECOTOXICITY STUDIES: Estuarine water was chlorinated to 10 mg/L, aged 10-35 days and then used as growth medium for three phytoplankton species, Thalassiosira pseudonana, Dunaliella species, Isochrysis galbana. Total residual chlorine compounds were undetectable in the chlorinated water; two species did not grow even after the water had been aged 35 days. A more resistant species grew in chlorinated water aged 23 or 35 days but did not grow in water aged 10 days. All three species grew well in the same water that had not been chlorinated.
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