Dames & Moore, 1999 - USDA Forest Service

Constituent
Lead
Manganese
Molybdenum
Acute Toxicity Summary
Acute inorganic lead intoxication in humans is
characterized by encephalopathy, abdominal pain,
hemolysis, liver damage, renal tubular necrosis, seizures,
coma, and respiratory arrest.
Toxicity following acute ingestion of inorganic manganese
salts is unlikely since they are poorly absorbed from the
gastrointestinal tract. If dust or fume is inhaled in
sufficient quantity, may produce "metal fume fever".
Toxic effects include damage to liver, kidneys, and
sometimes adrenals and spleen. Subchronic exposure can
produce decreased growth rate, male infertility, weight
loss, and abnormalities of bone or joint in forelegs of
animals. Some molybdenum salts are irritating to eyes and
mucous membranes. With oral exposures, fatty
degeneration of liver and kidney occur in animals.
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TABLE 7.1-44 (CONTINUED)
TOXICITY PROFILES FOR INDICATOR HAZARDOUS SUBSTANCES
Chronic Toxicity Summary
Chronic low levels of exposure to lead can
affect the hematopoietic system, the nervous
system, and the cardiovascular system. Lead
inhibits several key enzymes involved in
heme biosyntheses. One characteristic effect
of chronic lead intoxication is anemia, by
reduction of both hemoglobin production and
shortened erythrocyte survival. In humans,
lead exposure has resulted in nervous system
injury including reduced hand-eye
coordination, reaction time, visual motor
performance, and nerve conduction velocity.
Developing children appear especially
sensitive to lead-induced nervous system
injury. Lead can also affect the immune
system and produce gingival lead lines.
Epidemiological studies have indicated that
chronic lead exposure may be associated
with increased blood pressure in humans.
Exposure to lead is associated with sterility.
abortion, neonatal mortality, and morbidity.
Organolead compounds are neurotoxic.
Systemic toxicity is most common following
chronic inhalation or ingestion. Two clinical
patterns are common: one involving the
degeneration of the CNS resulting in
manganese psychosis; and the other
involving acute pneumonitis.
Joint deformities occur with prolonged
exposure. Toxicity depends on many dietary
factors that affect trace metals. In most
species, toxicity includes loss of appetite,
reduced growth, anemia, hair loss, loss of
hair color, bone defects. Molybdenum has
been implicated in human gout and bone-
crippling disease, but its involvement has not
been proven.
Cancer Potential
Lead salts have shown some
evidence of carcinogenicity in
animals at very high exposure
levels.
Existing studies are inadequate to
assess the carcinogenicity of
manganese.
Cancer potential is not indicated.
Other
i
Children are especially sensitive to
low-level exposures to lead.
Manganese is an element considered
essential to human health. High levels
may interfere with iron absorption.
Divalent mangangese (2+) is about 2
to 3 times more toxic than is
manganese(3+).
Molybdenum is an essential nutrient in
humans. Species vary in sensitivity.
Ruminants are especially sensitive to
molybdenum toxicity. Molybdenum
salts differ in toxicity. Copper
prevents accumulation of molybdenum
in liver. Molybdenum may interact
with other metals, and may increase
fluoride retention.