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Immunotoxicity

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Description of key information

The NOEL for immunotoxicity was 1% (approx 700 mg/kg bw) in a study conducted by Hinton et al,(1987).

Key value for chemical safety assessment

Effect on immunotoxicity: via oral route

Endpoint conclusion
Dose descriptor:
NOAEL
700 mg/kg bw/day

Additional information

Five groups of 10 male and 10 female SP rats were fed diets containing 0, 0.25, 0.5, 0.75 and 1% of triphenylphosphate in the diet for 120 days (Hinton, 1987). The animals were observed for clinical symptoms. Body weights and food consumption were recorded weekly. Blood samples were analysed for total protein and by electrophoresis of plasma proteins. Immunotoxicity was assessed by measurements of the weights of lymphoid organs, immuno-histochemical evaluation of spleen, thymus, lymph nodes and the humorall response to antigens. At the 1% dose level reduced growth rate was detected. There were no significant differences between immunized and non-immunized animals. The weights of lymphoid organs (spleen, thymus) varied in a non-dose-dependent way. No significant changes were fund in these organs and lymph nodes by histopathological examination and no significant alterations of serum protein were detected. Electrophoresis revealed increased levels of alpha- and beta globulin in male/female rats but effects were similar at all dose levels, relative to the control group. Only non-dose-dependent varation was found in the humoral immune response to sheep red blood cells in female rats. In this non-validated assay no effects were observed in a range of parameters of immune function in rats receiving oral doses up to 700 mg/kg bw/day (1%). The NOEL for immunotoxicity was 1% of TPP in the diet and 0.75% (517 mg/kg bw/day) for general toxicity due to a slight reduction of body weight gain at the highest dose level.

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