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Tetraethyl lead
CASRN 78-00-2
Contents
0109
Tetraethyl lead; CASRN 78-00-2
Health assessment information on a chemical substance is included in IRIS only
after a comprehensive review of chronic toxicity data by U.S. EPA health
scientists from several Program Offices and the Office of Research and
Development. The summaries presented in Sections I and II represent a
consensus reached in the review process. Background information and
explanations of the methods used to derive the values given in IRIS are
provided in the Background Documents.
STATUS OF DATA FOR Tetraethyl lead
File On-Line 01/31/1987
Category (section) Status Last Revised
----------------------------------------- -------- ------------
Oral RfD Assessment (I.A.) on-line 03/01/1988
Inhalation RfC Assessment (I.B.) no data
Carcinogenicity Assessment (II.) no data
_I. CHRONIC HEALTH HAZARD ASSESSMENTS FOR NONCARCINOGENIC EFFECTS
__I.A. REFERENCE DOSE FOR CHRONIC ORAL EXPOSURE (RfD)
Substance Name -- Tetraethyl lead
CASRN -- 78-00-2
Last Revised -- 03/01/1988
The oral Reference Dose (RfD) is based on the assumption that thresholds exist
for certain toxic effects such as cellular necrosis. It is expressed in units
of mg/kg-day. In general, the RfD is an estimate (with uncertainty spanning
perhaps an order of magnitude) of a daily exposure to the human population
(including sensitive subgroups) that is likely to be without an appreciable
risk of deleterious effects during a lifetime. Please refer to the Background
Document for an elaboration of these concepts. RfDs can also be derived for
the noncarcinogenic health effects of substances that are also carcinogens.
Therefore, it is essential to refer to other sources of information concerning
the carcinogenicity of this substance. If the U.S. EPA has evaluated this
substance for potential human carcinogenicity, a summary of that evaluation
will be contained in Section II of this file.
___I.A.1. ORAL RfD SUMMARY
Critical Effect Experimental Doses* UF MF RfD
-------------------- ----------------------- ----- --- ---------
Histopathology of NOAEL: none 10,000 1 1E-7
liver and thymus mg/kg/day
LOAEL: 1.7 ug/kg/day
Rat Subchronic converted to
Study 0.0012 mg/kg/day
Schepers, 1964
*Conversion Factors: 5 days/7 days; thus, 1.7 ug/kg/day x 5 days/7 days =
1.2 ug/kg/day
___I.A.2. PRINCIPAL AND SUPPORTING STUDIES (ORAL RfD)
Schepers, G.W. 1964. Tetraethyl and tetramethyl lead. Arch. Environ.
Health. 8: 277-295.
In a 20-week study, Schepers (1964) administered tetraethyl lead in peanut oil
by gavage to groups of 12 CD rats (6/sex) at 1.7 and 170 ug/kg/bw 5 days/week.
Gross observations revealed swollen livers and fatty plaques in the thymus at
both dose groups. Histologic preparations revealed hepatocyte vacuolization,
cytoplasmic degeneration and neuronal damage among low-dose rats. Rats
exposed to the higher dose developed similar, but more severe,
histopathologies. Based on these findings, a LOAEL of 1.2 ug/kg/day (1.7
ug/kg/day x 5 days/7 days) was determined.
A subchronic inhalation study by Davis et al. (1963) in rats and dogs supports
these findings. However, the equivalent oral doses derived from this study
are SUBSTantially higher than the LOAEL derived from the Schepers (1964)
study. Therefore, a human RfD of 0.0001 ug/kg/day was derived based on the
LOAEL of 1.2 ug/kg/day from Schepers (1964) and on a standard scaling factor
of 10,000.
___I.A.3. UNCERTAINTY AND MODIFYING FACTORS (ORAL RfD)
UF -- The uncertainty factor of 10,000 represents 10 to extrapolate from
animal to human, 10 to convert subchronic to chronic exposure, and 10 to
protect for sensitive humans, and an additional factor of 10 to convert a
LOAEL to a NOAEL.
MF -- None
___I.A.4. ADDITIONAL COMMENTS (ORAL RfD)
The data base contained limited long-term oral studies, as well as limited
subchronic inhalation and oral data. Reproductive, carcinogenicity, and
teratogenicity data are available, but are inconclusive. Limited
epidemiologic data are also available.
___I.A.5. CONFIDENCE IN THE ORAL RfD
Study -- Medium
Data Base -- Medium
RfD -- Medium
The chosen study is given medium to low confidence because, although only a
few animals/sex/dose were tested, a good histopathologic exam was conducted
and a dose-severity was observed. The data base was considered to have medium
to low confidence because some supporting information was available.
Confidence in the RfD can also be considered medium to low.
___I.A.6. EPA DOCUMENTATION AND REVIEW OF THE ORAL RfD
Source Document -- This assessment is not presented in any existing U.S. EPA
document.
Other EPA Documentation -- None
Agency Work Group Review -- 08/05/1985
Verification Date -- 08/05/1985
___I.A.7. EPA CONTACTS (ORAL RfD)
Please contact the Risk Information Hotline for all questions concerning this
assessment or IRIS, in general, at (513)569-7254 (phone), (513)569-7159 (FAX)
or RIH.IRIS@EPAMAIL.EPA.GOV (internet address).
__I.B. REFERENCE CONCENTRATION FOR CHRONIC INHALATION EXPOSURE (RfC)
Substance Name -- Tetraethyl lead
CASRN -- 78-00-2
Not available at this time.
_II. CARCINOGENICITY ASSESSMENT FOR LIFETIME EXPOSURE
Substance Name -- Tetraethyl lead
CASRN -- 78-00-2
This substance/agent has not undergone a complete evaluation and determination
under US EPA's IRIS program for evidence of human carcinogenic potential.
_VI. BIBLIOGRAPHY
Substance Name -- Tetraethyl lead
CASRN -- 78-00-2
Last Revised -- 01/01/1990
__VI.A. ORAL RfD REFERENCES
Davis, R.K., A.W. Horton, E.E. Larson and K.L. Stemmer. 1963. Inhalation of
tetramethyllead and tetraethyllead. Arch. Environ. Health. 6: 473-479.
Schepers, G.W. 1964. Tetraethyl and tetramethyl lead. Arch. Environ.
Health. 8: 277-295.
__VI.B. INHALATION RfC REFERENCES
None
__VI.C. CARCINOGENICITY ASSESSMENT REFERENCES
None
_VII. REVISION HISTORY
Substance Name -- Tetraethyl lead
CASRN -- 78-00-2
-------- -------- --------------------------------------------------------
Date Section Description
-------- -------- --------------------------------------------------------
04/10/1987 I.A.1. RfD exponent corrected
01/01/1990 VI. Bibliography on-line
01/01/1992 I.A.7. Primary contact changed
01/01/1992 IV. Regulatory actions updated
VIII. SYNONYMS
Substance Name -- Tetraethyl lead
CASRN -- 78-00-2
Last Revised -- 01/31/1987
78-00-2
Lead, Tetraethyl-
NCI-C54988
Plumbane, Tetraethyl-
TEL
Tetraethyl Lead
Tetraethylplumbane
Last updated: 5 May 1998
URL: http://www.epa.gov/iris/SUBST/0109.HTM
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