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Chlorine [Cl, 17]
of asthma in swimmers. Additionally, eye and skin irritation in swimmers has been
hypothesized to originate from Cl exposure.
Chlorine is the main monovalent anion of extracellular fluids; with Na or K, it
forms salts, and with hydrogen it forms HCl. Chlorine ions constitute about 65% of
the total anions of the blood plasma and other extracellular fluids within the mammalian body. Chlorine ions are also known to be present in the red blood cells.
Chlorine is essential for the regulation of osmotic pressure and acid–base balance
and plays a specific role in the transportation of oxygen and carbon dioxide in the
blood. It is necessary for the absorption of proteins and metallic minerals, as well
as vitamin B 12 .
Chlorine is stored, to a limited extent, in the skin, subcutaneous tissues, and skeleton; it constitutes two-thirds of the negatively charged ions in the blood. It is readily
absorbed and excreted according to the body requirements. Gastric secretion is composed of chlorides in the form of HCl and salts. Chlorine is readily absorbed during
digestion. Its rate of excretion through sweat, urine, and intestinal expulsion is high.
Chlorine provides the acid medium for the activation of the gastric enzymes and
digestion in the stomach. HCl made in the stomach has two main purposes: to help
destroy germs that arrived with the food and to help pepsin, an enzyme, break down
the proteins of foodstuffs, ensuring that essential nutrients are made available to the
body.
In the immune system, which is charged with fighting off the daily invasion of
germs, Cl is very useful. When infections take place, hypochlorite, a Cl-containing
compound, which is known as disinfectant, forms in white blood cells. Hypochlorite
itself attacks the germs, or helps to activate other agents that do this work.
The requirement for Cl has not been ascertained, but if NaCl is taken liberally, it
ensures the adequate intake of chloride as well. Thus, most of the chloride taken is
from the common salt used during food processing and preparation. Sodium chloride (table salt) is the most common Cl compound associated with foods. Chlorine,
in the form of NaCl, is used in many processed foods to prevent the growth of microorganisms, reduce the perception of dryness and enhance the flavor of the product.
The minimum requirement for Cl by adults is about 700 mg per day. Tolerable daily
intake for Cl is estimated for 150 μg/kg bw (WHO 2011a).
Common salt helps the body to normally meet the requirements of Na and Cl.
The body’s supplies of Cl are rapidly depleted during hot weather, when excessive
perspiration reduces the fluid content of the body. Stored chlorides may become
dangerously low in periods of severe vomiting and diarrhea, and in diseases that produce severe alkalosis, an accumulation of base or loss of acid in the body. Excessive
chloride levels, on the other hand, can result in water retention and in elevated
blood pressure, as well as increased risk of developing cancer. Also, excess chloride
becomes free-radical initiator, resulting in the damage of the arterial walls, leading
to arteriosclerosis.
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