Tris(2-ethylhexyl) phosphate

Endpoint summary

Description of key information

Conclusion:

The test item turned out to be of low toxicity after repeated applications to mice and rats.

Slight, isolated and not consistent deviations were observed on hematology and blood chemistry (males only) in a sub-acute toxicity study in rats similar to OECD TG 407 (including a recovery group).

These effects should not be regarded as toxicologically significant, due to the fact that they were only in some cases statistically significant (due to high variability of the respective parameter) and were observed just in one without confirmation by the other sex.

Additionally, no effects on organs were observed [including hematopoietic organs (bone marrow, spleen, lymph node, thymus and heart)] in the same study as well as in sub chronic and comprehensive chronic studies in rats and mice at similar and higher doses.

The only effects observed in sub-chronic and chronic studies were local inflammation in the gastric mucosa in mice (considered not to be relevant for systemic toxicity) and slight-moderate depression in body weight gain in rats and mice.

Based on the sub-chronic and chronic studies in rats a NOAEL of 1000 mg/kg bw/day was selected as starting point for the repeated dose systemic toxicity.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: No OECD study or GLP defined.

Principles of method if other than guideline:

other: oral repeated dose toxicity study in rats.

GLP compliance:

not specified

Limit test:

no

Species:

rat

Strain:

other: F344/N

Sex:

male/female

Route of administration:

oral: gavage

Vehicle:

other: corn oil

Analytical verification of doses or concentrations:

yes

Duration of treatment / exposure:

13 weeks

Frequency of treatment:

5 d/w

Remarks:

Doses / Concentrations:
0, 250, 500, 1000, 2000 or 4000 mg/kg bw
Basis:
other: gavage

No. of animals per sex per dose:

10

Control animals:

other: yes (corn oil)

Details on study design:

Post-exposure period: no

Clinical signs:

effects observed, treatment-related

Mortality:

mortality observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not specified

Water consumption and compound intake (if drinking water study):

not specified

Ophthalmological findings:

not specified

Haematological findings:

not specified

Clinical biochemistry findings:

not specified

Urinalysis findings:

not specified

Behaviour (functional findings):

no effects observed

Organ weight findings including organ / body weight ratios:

not specified

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

not specified

Histopathological findings: neoplastic:

no effects observed

Details on results:

Diminuated bw. of female rats beginning at the dose of 2000 mg/kg bw and in male rats beginning at the dose of 4000 mg/kg bw (5%); no substance-related histopathological findings.

Dose descriptor:

NOEL

Effect level:

ca. 1 000 mg/kg bw/day (nominal)

Sex:

female

Basis for effect level:

other: diminuated bw of female rats beginning at the dose of 2000 mg/kg bw .

Dose descriptor:

NOEL

Effect level:

ca. 2 000 mg/kg bw/day (nominal)

Sex:

male

Basis for effect level:

other: diminuated bw of male rats beginning at the dose of 4000 mg/kg bw .

Critical effects observed:

not specified

Survival and mean body weights of rats in the 13 weeks gavage studies:

		Mean Body Weights (grams)
Dose (mg/kg bw)	Survival*	Initial	Final	Change	Final Weight relative to Vehicle Controls *** (percent)
Male
0	**9/10	105	285	+ 180	--
250	10/10	106	292	+ 186	+ 2.5
500	10/10	107	304	+ 197	+ 6.7
1000	**8/10	106	302	+ 196	+ 6.0
2000	**7/10	108	300	+ 192	+ 5.3
4000	**9/10	105	270	+ 165	- 5.3
Female
0	10/10	101	179	+ 78	--
250	10/10	100	178	+ 78	- 0.6
500	10/10	102	176	+ 74	- 1.7
1000	10/10	100	177	+ 77	- 1.1
2000	**9/10	100	161	+ 61	-10.1
4000	**9/10	101	170	+ 69	- 5.0

* Number surviving/number per group

** Deaths were a result of gavage error

*** Final weight relative to vehicle controls= Fianal weight (Dosed group)* Final weight (Vehicle control) x 100

Final Weight (Vehicle Control)

Executive summary:

In a 13 week oral repeated dose study male and female four-week-old F344/N rats were administered by gavage with the test substance (5 days per week). The study was conducted to evaluate the cumulative toxicity of the test substance and to determine the doses to be used in the 2 -year studies. Groups of rats of each sex were administered 0, 250, 500, 1000, 2000 or 4000 mg/kg bw. test substance, 5 days per week for 13 weeks by gavage. The animals were checked twice daily for signs of moribundity and mortality; moribund animals were killed. Animal weights were recorded weekly. At the end of the 13 -week studies, survivors were killed. Necropsies were performed on all animals, except those excessively autolyzed or cannibalized. No hematology or clinical biochemistry was performed. The following tissues were examined microscopically in vehicle controls, highest dose group, and all animals that died during the study: gross lesions and tissue masses, mandibular lymph node, salivary gland, sternebrae, including marrow, thyroid, parathyroids, small intestine, colon, liver, prostate/testes or ovaries/uterus, lungs and mainstem bronchi, mammary gland, skin, heart, esophagus, stomach, brain, thymus, trachea, pancreas, spleen, kidneys, adrenal glands, urinary bladder, pituitary, spinal cord if neurological signs were present, eyes if grossly abnormal. No compound related deaths, slight-moderate depression of weight gain at 2000 or 4000 mg/kg in female rats and at 4000 mg/kg bw. in male rats could be seen. No histopathologic effects could be observed. The NOEL in female rats was 1000 mg/kg bw. and 2000 mg/kg bw. in male animals .

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 000 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Quality of whole database:

The database for acute oral toxicity meets the information requirements under REACH Annex VIII to X, with reliable studies used for the endpoint.

Additional information

The test substance was studied for oral toxicity in a 28-day repeated dose toxicity test similar to OECD TG 407 (including a recovery group) in male and female Crj:CD (SD) rats, at doses of 0, 30, 100, 300 and 1000 mg/kg/day, administered in sesame oil via gavage.

Summarized following effects were observed: In female rats of the 300 and 1000 mg/kg/day dose groups the prothrombine time was shortened, while in male rats of the 1000 mg/kg group the activated partial thromboplastin time was prolonged. These changes were no longer reported after a 14 day recovery period. Since the observations give no consistent picture and are not confirmed by the respective other sex and no effects on organs were observed in that study and other repeated dose toxicity studies (including chronic studies in rats and mice) this observation is not regarded as biologically relevant and adverse.

 

The serum cholinesterase activity was reduced significantly in male rats of the 300 mg/kg/day group. Also in the 1000 mg/kg bw/day group the serum cholinesterase activity was reduced, but not significantly (high standard deviation in all groups). A decrease of cholinesterase was also recorded at the end of the 14 days recovery period in the 1000 mg/kg bw/day male dose groups (CIPC, 1995). Since the variability of the parameter is high, this slight deviation is observed only in one sex (males) and no neurotoxic effects were observed in an acute toxicity study in hen and no deviation in erythrocyte cholinesterase activity was measured in a 28 days cat study (for further details see also chapter ´Neurotoxicity´), the isolated observation of a reduction in serum cholinesterase is not regarded as an adverse effect.

 

 

In a 13 week oral repeated dose study male and female four-week-old F344/N rats were administered by gavage with the test substance (5 days per week). The study was conducted to evaluate the cumulative toxicity of the test substance and to determine the doses to be used in the 2 -year studies. Groups of rats of each sex were administered 0, 250, 500, 1000, 2000 or 4000 mg/kg bw. test substance, 5 days per week for 13 weeks by gavage. The animals were checked twice daily for signs of moribundity and mortality; moribund animals were killed. Animal weights were recorded weekly. At the end of the 13 -week studies, survivors were killed. Necropsies were performed on all animals, except those excessively autolyzed or cannibalized. No hematology or clinical biochemistry was performed.

The following tissues were examined microscopically in vehicle controls, highest dose group, and all animals that died during the study: gross lesions and tissue masses, mandibular lymph node, salivary gland, sternebrae, including marrow, thyroid, parathyroids, small intestine, colon, liver, prostate/testes or ovaries/uterus, lungs and mainstem bronchi, mammary gland, skin, heart, esophagus, stomach, brain, thymus, trachea, pancreas, spleen, kidneys, adrenal glands, urinary bladder, pituitary, spinal cord if neurological signs were present, eyes if grossly abnormal.

No compound related deaths, slight-moderate depression of weight gain at 2000 or 4000 mg/kg in female rats and at 4000 mg/kg bw. in male rats could be seen. No histopathologic effects could be observed.

The NOEL in female rats was 1000 mg/kg bw. and 2000 mg/kg bw. in male animals (NTP, 1984).

 

In a Two-Year study in male and female rats the animals were treated orally by gavage 5 days per week for 103 weeks. The doses of test substance administered were 1000 or 2000 mg/kg in female rats and 2000 or 4000 mg/kg in male rats. Survival rates and mean body weight gains of dosed female rats were comparable to those of their respective vehicle controls. Microscopic evaluation was performed on the same organs as in the sub-chronic study discussed above. Survival rates of dosed male rats were comparable to that of the vehicle controls; but body weight gains were depressed at higher doses. The NOEL in female rats was 2000 mg/kg bw. and <2000 mg/kg bw in male rats (NTP, 1984).

 

In a 13 week oral repeated dose study male and female four-week-old B6C3F1 mice were administered by gavage with the test substance (5 days per week). The study was conducted to evaluate the cumulative toxicity of the test substance and to determine the doses to be used in the 2 -year studies. Groups of 10 mice of each sex were administered 0, 500, 1000, 2000, 4000 or 8000 mg/kg bw. test substance, 5 days per week for 13 weeks by gavage. The animals were checked twice daily for signs of moribundity and mortality; moribund animals were killed. Animal weights were recorded weekly. At the end of the 13 -week studies, survivors were killed. Necropsies were performed on all animals, except those excessively autolyzed or cannibalized.

The following tissues were examined microscopically in vehicle controls, highest dose group, and all animals that died during the study: gross lesions and tissue masses, mandibular lymph node, salivary gland, sternebrae, including marrow, thyroid, parathyroids, small intestine, colon, liver, prostate/testes or ovaries/uterus, lungs and mainstem bronchi, mammary gland, skin, heart, esophagus, stomach, brain, thymus, trachea, pancreas, spleen, kidneys, adrenal glands, urinary bladder, pituitary, spinal cord if neurological signs were present, eyes if grossly abnormal, gallbladder. No hematology or clinical biochemistry was performed.

No compound related deaths could be seen. Slight-moderate depression of weight gain at 4000 mg/kg (4.5%) in female mice and at 8000 mg/kg bw (7.1%) in male mice could be observed. Inflammatory lesions in the gastric mucosa were observed in all dose groups, with increased severity in the higher dose groups. Ulceration was observed in the forestomach of 1/10 males at 2000 mg/kg/day, 1/10 females at 4000 mg/kg/day and 1/10 males and 3/10 females at 8000 mg/kg/day.

The LOEL was 500 mg/kg bw based on the local inflammation in the gastric mucosa (NTP, 1984).

 

In a Two-Year study in male and female B6C3F1 mice the animals were treated orally by gavage 5 days per week for 103 weeks. The doses of test substance administered were 500 or 1000 mg/kg. In male mice the survival was statistically significantly diminuated in the lower dose group (500 mg/kg). In the high dose group also deaths were observed, but not statistically significant compared to the control group. The NOEL therefore was <500 mg/kg bw for male mice and 1000 mg/kg bw for female mice (NTP, 1984).

 

In an old and limited documented repeated dermal application study in rabbits the test substance was applied to the closely clipped, intact skin of the upper back of each of six male rabbits, at a daily dose of 0.1 ml. Applications were made on a five-day per week basis; four of the animals received a total of ten applications and the remaining two received 20 applications. The animals were observed for toxic effects and signs of dermal irritation daily. Initial, weekly, and terminal body weights were recorded. Two rabbits were sacrificed three days following the tenth application; two were sacrificed 17 days after the tenth application, and the remaining two on the third day after the 20th application. The animals appeared normal and gained weight; no alterations were observed at necropsy. In the skin moderate erythema following the first application, following subsequent applications was observed. The erythema did not increase in intensity, but a gradual increase in the size of the affected zone was observed. After the fifths application desquamination, hemorrhagic areas and thickening of the skin was seen. Microscopic examination revealed hyperkeratosis and parakeratosis. A Good recovery was evident in animals in which applications were stopped 17 days prior to sacrifice (MacFarland, 1966).

 

In an old and limited documented 3 month repeated inhalation study in guinea pigs performed in the same laboratory two different concentrations of test substance aerosol were used in three chambers ( 1.6 and 9.6 mg/m³); the third served as control. The animals were exposed for six hours a day, five days per week, to a total of 60 exposures. Two deaths were recorded, one in the control and one in the low level test substance group; both deaths occurred during the ninth week of exposure. The only gross sign observed was piloerection, seen in both control and treated groups throughout the 12 -week period. Body weights decreased in all three groups during the first week of exposure but steadily increased in the succeeding weeks. The mean kidney weight to body weight ratio for both test substance groups was significantly lower than that of the control group. No significant differences were found in the red blood cell and plasma cholinesterase activities between the control group and either of the treated groups. Gross pathological examination of the two guinea pigs which died during the ninth week of exposure showed extensive consolidation of lung tissue. When the surviving animals were sacrificed at the end of the 12 week´s exposure, midly congested lungs were noted in a quarter of the guinea pigs in the control group, but no abnormalities were found in the test substance treated animals. Microscopic examination of the tissue revealed only inconsistent and apparently reversible changes in the renal parenchyma of the high level test substance groups. Histopathological alterations in the lung and liver were confined to those due to coincidental disease. Sections of the spinal cord and sciatic nerve stained to demonstrate the myelin sheaths showed no pathologic alteration (MacFarland, 1966).

 

In an old and limited documented 3 month repeated inhalation study in mongrel dogs performed in the same laboratory three different concentrations of test substance aerosol were used in three chambers (10.8; 26.4 or 85 mg/m³); the fourth served as control. The animals were exposed for six hours a day, five days per week, to a total of 60 exposures.

No deaths occurred in the dog study. A dose-response relationship was evident in the results obtained from dogs in the conditioned avoidance response technique. Normal increases in body weights were recorded in the dogs. The appearance of the organs in dogs at sacrifice was essentially normal. Mild chronic inflammatory changes were noted in the pulmonary parenchyma of the test substance-exposed dogs (MacFarland, 1966).

 

In an old and limited documented 3 month repeated inhalation study in rhesus monkeys performed in the same laboratory three different concentrations of test substance aerosol were used in three chambers (10.8; 26.4 or 85 mg/m³); the fourth served as control. The animals were exposed for six hours a day, five days per week, to a total of 60 exposures. No deaths occurred in the monkey groups during the study; also no effects were detected in the evaluation of trained behavior in the performance of monkeys in the visual discrimination test. No significant alterations in hematological and biochemical parameters were detected. Normal body weights were recorded. Appearance of the organs in dogs and monkeys at sacrifice was essentially normal. No histological abnormalities were detected in the tissues from the monkeys (MacFarland, 1966).

 

Adult male and female Fischer rats were exposed to TEHP, Tris(2-ethylhexyl) phosphate (300, 1000 and 3000 mg/kg body weight [BW]/day) or DEHPA, di(2-ethylhexyl) phosphoric acid (20, 60 and 180 mg/kg BW/day) by gavage for 28 consecutive days, to assess and compare their toxicities. Rat bodyweight gains and relative organ weights were determined, a hematology and clinical chemistry analysis were determined, urinary TEHP and DEHPA excretion were measured and agross and histopathology examination performed.

Although impaired weight gains and hydrolysis of TEHP to DEHPA were observed exclusively in male rats, similar alterations of liver enzymatic activities, serum clinical chemistry, hematology and histopathology were often observed in both males and females. Similarities between the effects of TEHP and DEHPA were also noted. Given that the effects of TEHP on rat weight gains, organ weights and histology, hematology and clinical chemistry were mostly limited to the 3000-mg TEHP/kg BW/day treatment group, the no-observed adverse-effect level for TEHP was estimated at 1000 mg TEHP/kg BW/day. 

Justification for classification or non-classification

The substance does not meet the classification criteria for repeated dose toxicity in accordance with Regulation (EC) 1272/2008 (CLP).