340 ENVIRONMENTAL HEALTH
an overfl owing cesspool or septic tank system, or its improper
treatment and disposal into a stream or lake, immediately sets
the stage for possible disease transmission. The means may be a
child’s ball, the house fl y, or ingestion of contaminated water or
food. Sanitary safeguards, including adequate water treatment,
must therefore be always maintained if the water- and fi lthborne
diseases are to be held in check.
It may appear inconceivable, but there are still many urban
areas, as well as suburban areas, in the United States and abroad
where the discharge of raw or inadequately treated sewage to
roadside ditches and streams is commonplace. Although the
disease hazard is ever present, the public pressure for sewage
treatment and water pollution abatement stems more from aes-
thetic, recreational, and related economic considerations rather
than from actual disease hazard and transmission. As a matter
of fact, a critical reappraisal may be in order to review current
expenditures and perhaps achieve a better balance in the allo-
cation of public funds for the public good.
Whereas a safe and adequate water supply is taken for
granted by most people in the United States, for about 2 bil-
lion people, about two thirds of the world’s population, this is
still a dream. The availability of any reasonably clean water in
less developed areas of the world just to wash and bathe would
go a long way toward the reduction of such scourges as sca-
bies and other skin diseases, yaws and trachoma, and the high
infant mortality. The lack of a safe water makes commonplace
high incidences of shigellosis, amebiasis, schistosomiasis,
leptospirosis, infectious hepatitis, typhoid, and paratyphoid.^10
Between 1923 and 1937 there were an average of 43
milkborne outbreaks with 1724 cases and 47 deaths reported
each year in the United States. Between 1938 and 1956 an
average of 24 milkborne outbreaks per year with 980 cases
and 5 deaths were reported to the U.S. Public Health Service.
Between 1957 and 1960 the outbreaks averaged 9 and the
cases 151 per year. There were no deaths reported since 1949.
The success achieved in the control of milkborne illnesses
can be attributed to the practical elimination of the sale of
raw milk, greatly improved equipment and to effective con-
trol over the pasteurization of milk and milk products.
Whereas milkborne diseases have been brought under con-
trol, foodborne illnesses remain unnecessarily high. Between
1938 and 1956 there were reported 4647 outbreaks, 179,773
cases and 439 deaths. In 1967, there were still 273 outbreaks
reported with 22,171 cases and 15 deaths. The major bacteria
related to foodborne illnesses in recent years (1967–68) are
Salmonella, C. perfringens, and Staphylococcus. Banquets
accounted for over half of the illnesses reported with schools
and restaurants making up most of the rest. The largest
number of outbreaks occurred in the home.^11
In addition to waterborne and foodborne diseases, con-
sideration should be given to the environmental related respi-
ratory diseases, the insectborne diseases and zoonoses, and
the many miscellaneous diseases. These too must be con-
trolled to the extent possible where indicated. The common
cold, encephalitides, malaria, rabies, and disabilities related
to air pollution are examples.
More effect must be directed to the total environmental
pressures and insults to which the body is subjected. Thecumulative body burden of all deleterious substances gaining
access to the body through the air, food, drink, and skin must
be examined both individually and in combination. The syner-
gistic effects and neutralizing effects must be learned in order
that proper preventive measures may be applied. It has been
diffi cult to determine the effects of the presence or absence of
certain trace elements in air, water, and food on human health.
Some elements such as fl uorine for the control of tooth decay,
iodine to control goiter, and iron to control iron-defi ciency
anemia have been recognized as being benefi cial in proper
amounts. But the action of trace amounts ingested individu-
ally and in combination of lead, cadmium zinc, hexavalent
chromium, nickel, mercury, manganese, and other chemicals
are often insidious. The effects are extended in time to the
point where direct relationship with morbidity and mortality is
diffi cult to prove in view of the many possible intervening and
confusing factors. Some may even prove to be benefi cial.MercuryA brief discussion of one of these metals, namely mercury, is
of interest. The poisoning associated with (a) the consump-
tion of mercury contaminated fi sh in Japan between 1953
and 1964; (b) bread made from mercury-contaminated wheat
seed in West Pakistan in 1961, in Central Iraq in 1960 and
1965, and in Panorama, Guatemala in 1963 and 1964; (c) pork
from hogs fed methylmercury treated seed in Alamogordo,
New Mexico; and (d) methylmercury treated seed eaten by
birds in Sweden, directed worldwide attention to this prob-
lem. The discovery of moderate amounts of mercury in tuna
and most fresh water fi sh, and relatively large amounts in
swordfi sh, by many investigators in 1969 and 1970 tended to
further dramatize the problem. 12, 13,^14
The organic methylmercury forms of mercury are highly
toxic. Depending on the concentration and intake, it can
cause unusual weakness, fatigue and apathy followed by
neurological disorders. Numbness around the mouth, loss of
side vision, poor coordination in speech and gait, tremors
of hands, irritability and depression are additional symptoms
leading possibly to blindness, paralysis, and death. The mer-
cury also attacks vital organs such as the liver and kidney. It
concentrates in the fetus and can cause birth defects.
Mercury has an estimated biological half-life of 70 to
74 days in man, depending on such factors as age, size, and
metabolism, and is excreted mostly in the feces at the rate of
about one percent per day. Mercury persists in large fi sh such
as pike one to two years.
Mercury is ubiquitous in the environment. The sources are
both natural and manmade. Natural sources are leachings and
volatilization from mercury containing geological formations.
Manmade sources are waste discharges from chloralkali and
pulp manufacturing plants, mining, chemical manufacture and
formulation, the manufacture of mercury seals and controls,
treated seeds, combustion of fossil fuels, fallout, and surface
runoff. The mercury ends up in lakes, streams and tidal waters,
and in the bottom mud and sludge deposits.
Microorganisms and macroorganisms in water and
bottom deposits can transform metallic mercury, inorganicC005_009_r03.indd 340C005_009_r03.indd 340 11/18/2005 10:24:46 AM11/18/2005 10:24:46 AM