Acute and chronic mercury poisoning affects the
kidneys, central nervous system, and the gastrointestinal tract. The
three telltale symptoms of mercury poisoning are impaired articulation,
irregularity of muscular action, and constricted visual fields. Mercury
poisoning through chronic exposure to metallic and inorganic forms of
mercury generally produces nervousness, lassitude, tremor, and mucous
membrane irritation. Inorganic mercury poisoning is associated primarily
with peripheral effects, including gastroenteritis and tubular
nephritis, whereas organic compounds predominantly affect the central
nervous system (CNS) and effects may be severe and irreversible.2
Chronic
inorganic mercury poisoning is an occupational disease of smelters,
mercury miners, gilders, and factory workers. Inhalation of mercury
vapors may lead to pneumonitis, cough, fever, and other pulmonary
symptoms. The most reliable way to measure exposure to inorganic mercury
is to measure urinary mercury levels. Correlation between urine levels
and symptoms is poor, however.
The most common nonindustrial
source of mercury poisoning is the consumption of methyl
mercury-contaminated fish. Organic mercury poisoning is best detected in
whole blood, as this form of mercury is located mainly in the RBCs.
Organic mercury poisoning may develop quickly and is usually a more
serious disease. Studies conducted by the CDC3 found that
approximately 6% of childbearing-age women had levels at or above a
reference dose, an estimated level assumed to be without appreciable
harm (>5.8 µg/L). Women who are pregnant or who intend to become
pregnant should follow federal and state advisories on consumption of
fish.
Additional general population exposure to mercury is from
coal-fired power plants where an estimated 75 tons of mercury are
emitted into the atmosphere each year.4
BEI® are
reference values intended as guidelines for evaluation of occupational
exposure. BEI® represent biological levels of chemicals that correspond
to workers with inhalation exposure equivalent to the threshold limit
value (TLV®) of the chemicals. TLV®s refer to the airborne
concentrations of substances and represent conditions under which it is
believed that nearly all workers may be repeatedly exposed, day after
day, without adverse health effects.5