physiologically based pharmacokinetic model-
During fiscal year 2000, ATSDR and EPA
ing, a state-of-the-art technique, to estimate oral
finalized information to support development of
intakes of methylene chloride-contaminated
a TSCA test rule for eight substances that
environmental media that would not produce
ATSDR previously had identified as having
human immunotoxicity. This research is being
research needs. A test rule is the legally enforce-
conducted because ATSDR has identified
able document that describes (1) EPA's author-
ingestion of contaminated media as the most
ity to require testing, (2) the specific testing
common exposure route for methylene chloride
required, (3) why it is required, and (4) who
at hazardous waste sites.
should conduct the testing. The proposed test
rule will address substance-specific research
Substances with Some Research Needs
needs identified in ATSDR's priority data needs
Being Addressed by
documents. In a recent meeting between offi-
Private-SectorVoluntarism
cials of EPA and ATSDR, EPA identified the
Methylene chloride
ATSDR test rule as its top priority for fiscal
year 2001. Publication of the proposed test rule
Polychlorinated biphenyls
is expected in the spring of 2001.
Tetrachloroethylene
Trichloroethylene
Private Sector Voluntarism
ATSDR encourages industry to voluntarily
Vinyl chloride
conduct needed research into the toxicity of
Trichloroethylene
priority chemicals. During fiscal year 2000,
ATSDR had Memoranda of Understanding in
During fiscal year 2000, ATSDR signed a third
place with three private-sector organizations--
agreement with HSIA that covers a develop-
General Electric Company (GE), Halogenated
mental toxicity study on trichloroethylene, a
Solvents Industry Alliance, Incorporated
substance found in at least 932 NPL sites. This
(HSIA), and the American Chemistry Council
study addresses an important research need for
(ACC), formerly called the Chemical Manufac-
trichloroethylene, that is, to determine whether
turers Association,--to address about 10
the development of the young is affected by
research needs for 5 substances.
breathing this chemical. HSIA has completed
the study, and it is currently undergoing outside
peer review.
Methylene Chloride
During fiscal year 2000, ATSDR reviewed and
Vinyl Chloride
accepted the conclusions of an HSIA study
covering the immunotoxicity of methylene
During fiscal year 1996, ATSDR entered into an
chloride, a substance found in at least 842 NPL
agreement with the American Chemistry
sites. The data from the study indicated that
Council covering a study on reproductive and
inhalation exposure to methylene chloride at a
developmental toxicity for vinyl chloride, a
concentration of 5,187 parts per million did not
substance found in at least 544 NPL sites. Vinyl
result in any sign of immunotoxicity. This study
chloride ranks fourth on the agency's Priority
addresses an important research need for
List of Hazardous Substances. This study
methylene chloride, that is, to determine
addresses two important research needs for
whether the immune system is a susceptible
vinyl chloride, that is, to determine whether the
target organ for this chemical via inhalation
reproductive system and the development of the
exposure. As a next step, HSIA plans to use
young are targets of this chemical via inhalation
34 chapter 2
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