Environmental Profiles of Chemical Flame-Retardant Alternatives for

Basis for Conclusion:
The only study evaluating the potential immunotoxicity of TDCPP (Luster et al., 1981) predates
the guideline for immunotoxicity (note that the OPPTS guideline cites other works by this
author). There is some uncertainty as the test material, reported as Fyrol FR2, but mis-identified
by the authors as tris(2,3-dichloropropyl) phosphate. The study methods differed from the
guideline in the short exposure period (4 rather than 28 days), parenteral administration (rather
than oral or inhalation route), measurement of serum immunoglobulins in non-immunized rather
than immunized mice, and the omission of some tests (enumeration of immunological cell
subpopulations, test for NK-cell activity). The results do not provide dose–response information
as to immunotoxicity of TDCPP following subchronic exposure by oral or inhalation routes of
exposure.
Immunotoxicity (OPPTS Harmonized Guideline 870.7800)
Critical study
Type: Immunotoxicity, subcutaneous, acute
Species, strain, sex, number: Mouse, B6C3F 1, 6-8 females/dose
Doses: 0, 0.25, 2.5, or 25 mg/kg/day (Total cumulative doses of 0, 1, 10, or 100 mg/kg)
Identity: Stauffer Fyrol FR-2, lot 4670-3-23. This is the same lot as TDCPP tested in the 2-year
oral assay by Freudenthal and Henrich (2000)
Purity: Stauffer, purity >95%
Vehicle: Corn oil
Route: Subcutaneous injection
Exposure duration, frequency: 4 days, once daily
Method: Observations included body weight, hematology, clinical chemistry (5 parameters)
terminal necropsy, organ weights (liver, spleen and thymus), histopathology of spleen, thymus,
and eight other organs, plaque-forming assay response to sheep red blood cells, and serum
immunoglobulin quantification (non-immunized mice only). Non-guideline tests included
proliferative capacity of granulocyte-macrophage progenitor cells (bone marrow), in vitro
lymphoproliferative (LP) responses to mitogens, delayed hypersensitivity response to keyhole
limpet hemocyanin. Extensive statistical analysis.
Results: Twenty percent of high-dose mice exhibited lymphoid depletion of the thymus.
Statistically significant decreases in vitro lipopolysaccharide (B-cell antigen) at 2.5 mg/kg/day
and concanavalin A (T-cell antigen) at 25 mg/kg/day.
Reference: Luster et al., 1981
GENOTOXICITY
Conclusion: The available genotoxicity data were judged adequate to meet the endpoint.
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