Environmental Engineering Reference
In-Depth Information
supplies.
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Oral hygiene, including at least daily teeth brushing, consumption of
fewer sweets, followed by a water rinse or drink, is also basic to caries reduction.
Studies have found that consumption of fluoridated water does not lead to
adverse health effects. A federal study involving almost 1 million persons in 46
American cities showed virtually no difference in death rates, including from
cancer, between 24 cities using fluoridated water and 22 without fluoridated
water.
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The long-term consumption of water high in fluoride (8 - 20 mg/1) is reported
to cause bone changes. On the one hand, an intake of 20 mg fluoride per day for
20 or more years may cause crippling fluorosis, and death can come from a single
dose of 2,250 to 4,500 mg. On the other hand, optimal concentrations of fluoride
in drinking water and food appear to be beneficial in preventing osteoporosis.
Sporotrichosis
Conifer seedlings packed in sphagnum moss can cause papules or skin ulcers
and inflammation on the hands and arms, which can then spread to other parts
of the body. This disease is caused by a fungus,
Sporothrix schenckii
, found in
moss, hay, soil, and decaying vegetation. Protective clothing, including gloves
and long-sleeved shirts, should be worn when handling sphagnum moss or
seedlings.
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Nutritional Deficiency and Related Diseases
Severe examples of diseases caused by deficiencies in the diet are not common
in the United States and other developed countries; however, they do occur.
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These deficiencies are found much more often in less developed countries of
the world. There are, however, many people whose diet is slightly deficient in
one or more nutrients but who show no clinically detectable symptoms for many
years. Most malnutrition takes the form of protein deficiency. Diarrheal diseases
and resulting malabsorption may compound nutritional deficiencies; hence, basic
environmental sanitation, including safe water, availability and use of latrines,
clean food handling, hand washing, personal hygiene, and refrigeration of food,
are essential elements of a comprehensive nutrition program. Deficiency of a
nutrient does not by itself necessarily cause disease. Predisposing host and envi-
ronmental factors as noted are also involved, and this must not be overlooked in
the development of a control program.
Recommended daily dietary allowances for the maintenance of good nutrition,
to be consumed in a variety of foods to provide other less defined required
nutrients, are shown in Table 3.4.
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Of the more than 60 mineral elements found
in living things, nine are considered essential to human life. These are iron,
iodine, fluoride, copper, manganese, zinc, selenium, chromium, and cobalt. The
role of other minerals is not well established.
There has been a great deal of interest in the adoption of a balanced, healthy
diet to help minimize deaths due to heart disease and cancer, which, together
