Environmental Engineering Reference
In-Depth Information
Cerebrovascular disease (stroke) — an occlusion or rupture of an artery to
the brain.
•
Arteriosclerosis — a thickening or hardening of the walls of the arteries, as
in old age. Atheroselerosis is the most common form; fatty substances (con-
taining cholesterol) deposited on the inner lining restrict the flow of blood
in the arteries, causing coronary thrombosis (an occlusion of arteries sup-
plying heart muscle). Hypertension (high blood pressure) and hypertensive
heart disease. Rheumatic fever and rheumatic heart disease.
•
The risk factors associated with cardiovascular diseases include cigarette
smoking, poor nutrition, socioeconomic status, age, sedentary way of life, family
history, severe stress, personality type, and high blood pressure. Cardiovascular
diseases have also been linked to high amounts of total fats, saturated fats,
cholesterol, and sodium in the diet. Persons with cardiovascular diseases are
more sensitive to carbon monoxide in low concentrations. Obesity and excessive
alcohol intake are associated with hypertension.
The Council on Environmental Quality
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confirmed reports showing that the
death rates from cardiovascular diseases tend to decrease as the hardness of
drinking water increases, but the factor is not considered to be hardness per
se. The direct relationship between cardiovascular death rates and the degree of
softness or acidity of water, according to Schroeder, points to cadmium as the
suspect.
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Large concentrations of cadmium may also be related to hypertension
in addition to kidney damage, chronic bronchitis, and emphysema. Cadmium
builds up in the human body. Low levels of magnesium in soft drinking water
are also linked to sudden cardiac death. The indications are that the effects of soft
water on cardiovascular diseases may be relatively small. Nevertheless, the water
association deserves close attention since cardiovascular disease deaths account
for about one-third of all deaths in the United States.
There is also evidence associating the ingestion of sodium with heart disease
as well as with kidney disease and cirrhosis of the liver. Soft waters and reused
waters generally contain higher concentrations of sodium than hard waters. Inci-
dentally, diet drinks generally contain more sodium than regular soft drinks, as do
sodium-containing dried milk preparations and cream substitutes. Home drink-
ing water supplies softened by the ion exchange process (most home softeners)
contain too much sodium for persons on sodium-restricted diets.
∗
This can be
avoided by having the cold-water line bypass the softener and using only the cold
water for drinking and cooking. Other sources of sodium in drinking water are
road salt contamination of surface and groundwater supplies; the sodium hydrox-
ide, sodium carbonate, and sodium hypochlorite used in water treatment; sodium
in distilled and bottled water; carbonated water in soft drinks; lime - soda ash
and zeolite softened municipal water supplies; and natural minerals in sources of
drinking water. The total body burden including that from food and drink must
∗
Each grain per gallon (17.1 mg/1) of hardness removed will add 8 mg/1 sodium to the treated water.