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

MERCURY
1. PUBLIC HEALTH STATEMENT
level exposure of laboratory animals to inorganic mercury has been shown to affect the developing
fetus and may cause termination of the pregnancy.
Animals exposed orally to long-term, high levels of methylmercury or phenylmercury in
laboratory studies experienced damage to the kidneys, stomach, and large intestine; changes in
blood pressure and heart rate; adverse effects on the developing fetus, sperm, and male
reproductive organs; and increases in the number of spontaneous abortions and stillbirths.
Adverse effects on the nervous system of animals occur at lower doses than do harmful effects to
most other systems of the body. This difference indicates that the nervous system is more
sensitive to methylmercury toxicity than are other organs in the body. Animal studies also provide
evidence of damage to the nervous system from exposure to methylmercury during development,
and evidence suggests that the effects worsen with age, even after the exposure stops.
Some rat and mice strains that are susceptible to autoimmune responses develop kidney damage as
a result of an immune response when exposed to relatively low levels of mercury vapor or mercury
chloride.
Animals given inorganic mercury salts by mouth for most of their lifetime had increases in some
kinds of tumors at the highest dose tested. Rats and mice that received organic mercury (methyl­
mercury or phenylmercury) in their drinking water or feed for most of their lives had an increased
incidence of cancer of the kidney, but this affected only the males that received the highest amount
of mercury given (not the females). Since the high doses caused severe damage to the kidneys
prior to the cancer, these animal studies provide only limited information about whether mercury
causes cancer in humans. As a result, the Department of Health and Human Services (DHHS) and
the International Agency for Research on Cancer (IARC) have not classified mercury as to its
human carcinogenicity. The Environmental Protection Agency has determined that mercury
chloride and methylmercury are possible human carcinogens. Chapter 2 contains more
information on the health effects of mercury in humans and animals.
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