Encyclopedia of Health and Medicine

30 Preventive Medicine
health organizations form the Healthy People
Consortium.
HEALTHY PEOPLE 2010 LEADING HEALTH INDICATORS
access to health care
environmental quality
IMMUNIZATION
injury and VIOLENCE
mental health
overweight and OBESITY
physical activity
responsible sexual behavior
SUBSTANCE ABUSE
TOBACCO use
See also HEALTH RISK FACTORS; LIFESTYLE AND
HEALTH.
heavy-metal poisoning Toxicity due to metals
such as lead, mercury, copper, and iron can have
serious and even lethal health consequences,
especially among children. Heavy metals occur
naturally in the environment. They are present in
soil and in plants that grow underground, and in
water. Heavy metals are also the by-products of
manufacturing processes. They can quickly accumulate
to hazardous levels when they leach into
drinking water supplies or enter the food chain
when farmers irrigate crops using contaminated
water. Some metal pollutants are also present in
the air. Numerous environmental laws enacted
over the past 30 years have significantly reduced
the presence of heavy metals as pollutants; and
various standards, such as those for drinking
water, require monitoring of metal and mineral
levels. The US Environmental Protection Agency
(EPA) monitors and enforces these laws.
Lead Federal regulations have banned lead in
paints, inks, and gasoline for several decades.
Nonetheless lead poisoning continues to be a
problem, particularly among children, who are
vulnerable to damage at much lower levels of
ingestion. Houses built before 1977 may still have
leaded paint on the walls and especially wood
trim, which young children may peel off and eat.
Lead also can enter water supplies when the pipes
that carry it are made of lead. As the pipes deteriorate
they release lead into the water they carry.
Though many larger municipalities have replaced
old lead pipes, many smaller ones have not. The
smaller body size of children makes them especially
vulnerable to toxic accumulations of lead.
When the body stops receiving fresh supplies of
lead, it can slowly process the lead that has accumulated,
and eventually most body systems return
to normal.
Mercury The natural forms of mercury are liquid
or gas. It forms different chemicals when it
combines with other substances. Manufacturing
processes combine mercury with oxygen or chlorine
to form inorganic combinations, called salts,
used in industrial applications such as caustic soda
and batteries. Dentists use inorganic mercury
compounds in fillings for TEETH. In nature mercury
combines with carbon (methylmercury), usually
in water, to form organic compounds. These
organic mercury compounds accumulate in fish
and shellfish.
The liquid nature of mercury has given
rise to perceptions that it has mystical
or supernatural abilities. Some spiritual
and ritualistic practices use mercury,
also called quicksilver or azogue, in
baths, burned in candles, and sprinkled
on surfaces. Like any other form of
mercury, however, quicksilver is toxic.
Many people who handle, breathe, or
ingest quicksilver suffer mercury poisoning.
Excessive amounts of mercury in the body can
result in permanent damage to the BRAIN and kidneys.
Studies link two forms of mercury—mercury
chloride and methylmercury—with an increased
risk for developing CANCER. Many people are concerned
about the health risks possibly associated
with mercury dental fillings (also called dental
amalgam). The American Dental Association and
the US Food and Drug Administration (FDA),
among other health agencies, have issued position
statements supporting the continued use of mercury
fillings because there are no conclusive studies
that correlate its use to mercury poisoning.
However, most dentists offer alternative materials
for people who are concerned about mercury
fillings.
By far the most significant source of mercury
among Americans is seafood. In 2004 the FDA
issued a health advisory regarding mercury levels
in four kinds of fish: swordfish, king mackerel,
shark, and tilefish. These fish are at the top of the
food chain; they live for many years, subsisting on