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

MERCURY 340
2. HEALTH EFFECTS
Information concerning metallic mercury exists primarily for the inhalation route of exposure in humans
and animals (see Figure 2-8). Human data exist for all categories of effect following inhalation exposure
to metallic mercury vapor. The results from inhalation studies in animals have been reported for all end
points except immunological and genotoxic effects, and cancer. With the exception of case studies on
contact dermatitis and neurological effects after acute and occupational dermal exposure to metallic
mercury in humans, no studies were located for either the oral or dermal routes of exposure for either
humans or animals.
Existing information on inorganic mercury salts is shown in Figure 2-9. No studies were found on the
health effects from inhaled mercury salts in humans or animals. A number of case histories for acute or
chronic oral exposure to mercury salts provide information on systemic and neurological effects and death.
Some case histories and occupational studies provide information on dermal exposures to mercury salts at
acute, intermediate, and chronic exposures leading to death, immunologic, neurologic, and systemic
effects. No animal inhalation studies for inorganic mercury salts were identified, and only one acute study
provides limited information on death from dermal exposure. A number of animal studies that have
investigated the effects from oral exposure to mercury salts provide good information on systemic effects;
limited information on cancer, neurologic, immunologic, and genotoxic effects; and no information on
reproductive or developmental effects.
Information on methylmercuric and phenylmercuric mercury is presented in Figures 2-10 and 2-11. These
two forms of organic mercury were chosen to represent the group of organic mercurials because they have
been detected at Superfund sites, and because methylmercury is the predominant form of organic mercury
in the environment. There is a paucity of information on phenylmercury. Only a few case histories are
available for effects following inhalation exposure (death, acute or chronic systemic effects, and
neurologic effects), and the information from these reports is very limited. Only one case history for acute
systemic effects following dermal exposure to phenylmercury was identified. One chronic oral study in
rats and a cancer study in rats and mice provide the only animal data for phenylmercury. In contrast, there
are a number of human studies on systemic, neurologic, and developmental effects resulting from an oral
exposure to methylmercury. No human toxicity data were identified for immunologic, reproductive, or
genotoxic effect, nor for carcinogenicity. The human data for methylmercury are accompanied by a
relatively large number of animal studies representing all three exposure durations and providing some,
although often limited, information for all health effects categories. As with phenylmercury, there are only
a few case histories for inhalation and dermal exposures, with limited information on neurologic and