revised final - Agency for Toxic Substances and Disease Registry ...

MERCURY 222
2. HEALTH EFFECTS
Phenylmercuric acetate is another form of organic mercury to which the general public may be exposed.
Although phenylmercury compounds are considered organomercurials, they are absorbed less efficiently
by the gastrointestinal tract than is methylmercury. Once inside the body, phenylmercury is rapidly
metabolized to Hg ++ , and its effects are, therefore, similar to those of mercuric salts.
Dimethylmercury is an extremely toxic form of organic mercury, and very small exposures can cause se
vere and irreversible delayed neurotoxicity, including death. Dimethylmercury is thought to be
metabolized to methylmercury prior to crossing the blood-brain barrier. Dimethylmercury is used in the
calibration of laboratory equipment, as a reagent, and in the manufacture of other chemicals. Unlike other
forms of mercury, dimethylmercury is quickly absorbed through intact skin, and it will penetrate latex or
polyvinyl gloves. It is highly volatile, will readily evaporate, and can be inhaled. Based on its vapor
pressure of 58.8 mm at 23.7 EC, Toribara et al. (1997) estimated that a cubic meter of saturated air could
hold more than 600 g of dimethylmercury. A recent case history of a chemist who died from an accidental
spill of dimethylmercury is prompting calls for its removal as an analytical standard as a safety precaution
to prevent further accidents.
Upon significant inhalation exposure to metallic mercury vapors, some people (primarily children) may
exhibit a syndrome known as acrodynia, or pink disease. Acrodynia is often characterized by severe leg
cramps; irritability; and erythema and subsequent peeling of the hands, nose, and soles of the feet. Itching,
swelling, fever, tachycardia, elevated blood pressure, excessive salivation or perspiration, morbilliform
rashes, fretfulness, sleeplessness, and/or weakness may also be present. It was formerly thought that this
syndrome occurred exclusively in children, but recent reported cases in teenagers and adults have shown
that these groups are also susceptible.
Occupational mercury exposures generally occur when workers inhale metallic mercury vapors. Some
dermal absorption may occur from skin contact with contaminated air, but the rate is low (less than 3% of
the inhaled dose). Dialkyl mercury compounds, which are not normally found in hazardous waste sites,
are rapidly and extensively absorbed from both dermal and inhalation routes of exposure.
Mercury is a naturally occurring element in the earth’s crust. It is considered to have been a component of
the lithosphere since the planet was formed approximately 4.5 billion years ago. However, levels of
mercury at or near the earth’s surface (environmental background levels) are increasing as mercury
continues to be released from the earth’s crust by both natural (weathering, volcanoes) and human (mining,