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

MERCURY 169
2.3.1.3 Dermal Exposure
2. HEALTH EFFECTS
Metallic and Inorganic Mercury. Hursh et al. (1989) conclude that dermal absorption of mercury vapor
poses a very minor occupational hazard compared to inhalation exposure. They measured dermal absorption
of radiolabeled metallic mercury vapor in five human volunteers, using arm skin as representing the whole
body skin. About half of the mercury taken up was shed by desquamation of epidermal cells during the
following several weeks. The remainder was slowly and diffusely released into the general circulation in
contrast to the rapid release and more focal release from the lungs. When absorption for the total skin area
(as represented by the forearm skin) was compared with the inhalation route for the same ambient
concentration, the dermal route absorbed was estimated at 2.6% of the amount absorbed by the lung.
There was no information found on the dermal absorption of liquid metallic mercury, but unless the skin
surface was damaged or the contaminated surface was occluded, it would not be expected to be high (i.e., in
light of the very low absorption rate from the gastrointestinal tract). On the other hand, sloughing from the
gastrointestinal tract may account for the low rate of absorption.
Indirect evidence of dermal absorption is provided by clinical case studies in which mercury intoxication
was reported in individuals following dermal application of ointments that contained inorganic mercury
salts (Bourgeois et al. 1986; DeBont et al. 1986).
Absorption of mercurous salts in animals can occur through the skin (Schamberg et al. 1918); however, no
quantitative data are available. The rate of absorption for mercuric chloride was not evaluated in any study.
However, skin biopsies taken from 2 to 96 hours after application of a 0.1% solution of mercuric chloride
showed electron-dense deposits, tentatively identified as mercury, in the cells in the dermis, indicating that
mercuric chloride could penetrate the outer layer of the skin (Silberberg et al. 1969).
Organic Mercury. No information was identified for absorption of methylmercury via dermal absorption.
There is extremely important hazard assessment information on the dermal absorption of dialkylmercurials.
A case history indicates nearly complete absorption of dimethylmercury through the skin resulting in a
highly toxic exposure pathway. The exposure occurred to a 48-year-old female chemistry professor who
was admitted to the hospital 5 months (154 days) after she inadvertently spilled several drops (estimated at
0.4–0.5 mL) of dimethylmercury from the tip of her pipette onto the back of her disposable latex gloves