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EC number: 231-669-9
CAS number: 7681-53-0
The potential toxicity of sodium hypophosphite following repeated administration was investigated according to OECD guideline 422 and EPA guideline OPPTS 870.3650. Sodium hypophosphite is of low toxicity by repeated administration:The NOAEL was established to 1080 mg/kg/day.
studies are reported for this endpoint:
objective of the first study was to determine dose-levels of Sodium
hypophosphite to be administered in a combined repeated-dose toxicity
study with the reproduction/ developmental toxicity screening test.
second study, which was
chosen as the key study, is
the combined repeated dose toxicity study with
reproduction/developmental toxicity screening test.
This study was performed according to OECD guideline 422 and was
conducted in compliance with the principles of Good Laboratory
the main study, three groups of 10 males and 10 females were
administered Sodium hypophosphite once daily by gavage for 2 weeks
before mating, during mating (up to 3 weeks), and, for the females,
through gestation until day 5post-partum. The dose-levels
selected on the basis of a 2- week range finding toxicity study were
101, 309 and 1080 mg/kg/day. A
vehicle control group received purified water.
signs and mortality were checked daily and detailed clinical
observations were performed weekly. Body weight and food consumption
were recorded weekly until mating and then at designated intervals
throughout gestation and lactation. A Functional Observation Battery
including touch response, forelimb grip strength, pupillary reflex,
visual stimulus response, auditary startle reflex, tail pinch response,
righting reflex, landing foot splay, rectal temperature and motor
activity was performed at the end of the study. Blood and urine samples
were taken for analysis of haematology, clinical chemistry and
urinalysis at the end of the study.
were sacrificed after completion of the mating period and females on day
6 post-partum. Afterwards the designated organs were weighed and
gross pathology as well as histopathology were performed.
were no treatment-related unscheduled deaths during the study and no
relevant clinical signs were observed. There were no treatment-related
effects on body weight, body weight gain or food consumption at any
dose-level. The functional observation battery assessment and hematology
and blood biochemistry revealed no treatment-related effects but males
from all groups had protein in the urine at a non-dose-related incidence.
There were no treatment-related
macroscopic findings and the only effect on organ weights was a lower
thymus weight in females treated at 309 or 1080 mg/kg/day which, in the
absence of histopathological changes was considered to be of low
toxicological significance. Microscopic examination revealed minimal
increased epithelial thickness of the forestomach, in males treated at
309 mg/kg/day and in both sexes treated at 1080 mg/kg/day.
change was considered to be related to treatment with the test item.
However, due to the minimal degree of severity of this change compared
with the administered dose-level (more than 1000 mg/kg/day), this effect
was considered to be non-adverse and in the absence of a similar
structure in the stomach from human beings, this change was not
considered relevant for human health.
these experimental conditions the No Observed Adverse Effect Level
(NOAEL) was 1080 mg/kg/day.
to the criteria laid down in EU regulation (EC) n° 1272/2008 (CLP) and
the EU directive 67/548/EEC, sodium hypophosphite is not classified for
repeated dose toxicity by oral route.
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