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

MERCURY 335
2. HEALTH EFFECTS
protected against by pretreatment with zinc (Zalups and Cherian 1992). Data in rats suggest that zinc can
induce metallothionein in the renal cortex and cause mercury accumulation in the kidneys to shift from the
outer medulla to the cortex, where a greater percentage is bound to the induced metallothionein. However,
despite its potential use for interfering with the mercury-induced renal effects, zinc also prolongs retention
in the body.
2.11 ADEQUACY OF THE DATABASE
Section 104(i)(5) of CERCLA, as amended, directs the Administrator of ATSDR (in consultation with the
Administrator of EPA and agencies and programs of the Public Health Service) to assess whether adequate
information on the health effects of mercury is available. Where adequate information is not available,
ATSDR, in conjunction with the National Toxicology Program (NTP), is required to assure the initiation
of a program of research designed to determine the health effects (and techniques for developing methods
to determine such health effects) of mercury.
The following categories of possible data needs have been identified by a joint team of scientists from
ATSDR, NTP, and EPA. They are defined as substance-specific informational needs that if met would
reduce the uncertainties of human health assessment. This definition should not be interpreted to mean
that all data needs discussed in this section must be filled. In the future, the identified data needs will be
evaluated and prioritized, and a substance-specific research agenda will be proposed.
2.11.1 Existing Information on Health Effects of Mercury
The existing data on health effects of inhalation, oral, and dermal exposure of humans and animals to
inorganic and organic mercury are summarized in Figures 2-8 to 2-11. The purpose of these figures is to
illustrate the existing information concerning the health effects of inorganic and organic mercury. Each
dot in the figures indicates that one or more studies provide information associated with that particular
effect. The dot does not imply anything about the quality of the study or studies. Gaps in this figure
should not be interpreted as "data needs." A data need, as defined in ATSDR's Decision Guide for
Identifying Substance-Specific Data Needs Related to Toxicological Profiles (ATSDR 1989), is substancespecific
information necessary to conduct comprehensive public health assessments. Generally, ATSDR
defines a data gap more broadly as any substance-specific information missing from the scientific
literature.