Trisodium trimetaphosphate

Repeated dose toxicity: dermal

Administrative data

Endpoint:

sub-chronic toxicity: dermal

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

a short-term toxicity study does not need to be conducted because a reliable sub-chronic (90 days) or chronic toxicity study is available, conducted with an appropriate species, dosage, solvent and route of administration

Cross-reference

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Endpoint:

chronic toxicity: oral

Remarks:

combined repeated dose and carcinogenicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 453 (Combined Chronic Toxicity / Carcinogenicity Studies)

Deviations:

yes

Remarks:

please see 'any other information on materials and methods'

Principles of method if other than guideline:

2 year chronic feeding study in rats.

GLP compliance:

no

Remarks:

study predates GLP

Limit test:

no

Species:

rat

Strain:

other: Rochester Strain (Ex-Wistar 1923)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: no data
- Age at study initiation: 21 days, post-weaning
- Weight at study initiation: 85-88g for the males, 81-82g for the females
- Fasting period before study: no data
- Housing: The rats were housed 5 to a cage in galvanized iron cages with screen doors; a metal pan containing wood shavings served as a cage floor.
- Diet (e.g. ad libitum): Purina Fox Chow Meal, ad libitum
- Water (e.g. ad libitum): Rochester tap water supply, ad libitum
- Acclimation period: no data


ENVIRONMENTAL CONDITIONS
no data

IN-LIFE DATES: From: day 0 of study To: week 104

Route of administration:

oral: feed

Vehicle:

unchanged (no vehicle)

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS: no data

DIET PREPARATION
- Rate of preparation of diet (frequency): weekly, freshly
- Mixing appropriate amounts with (Type of food): Purina Fox Chow Meal
- Storage temperature of food: no data
- other: the trimetaphosphate was mixed with a mechanical mixer into the basal ration of Purina Fox Chow Meal and stored in galvanized iron pails with covers.

Analytical verification of doses or concentrations:

no

Details on analytical verification of doses or concentrations:

not applicable

Duration of treatment / exposure:

104 weeks

Frequency of treatment:

daily, ad libitum

Remarks:

Doses / Concentrations:
0.0% (controls), 0.1%, 1.0%, & 10.0%
Basis:
nominal in diet

No. of animals per sex per dose:

50/sex/group

Control animals:

yes, plain diet

Details on study design:

- Dose selection rationale:
Pilot studies.
The acute toxicity of the test material when given intra-peritoneally was estimated in young, adult, female albino rats. The LD50 was calculated to be 3650 ± 620 mg/kg.

In a pilot feeding study of one month's duration, three groups of 5 male rats were fed: 0.2%, 2.0% and 10.0% sodium trimetaphosphate. The rats were serially sacrificed on the 3rd, 7th, 15th and 28th days. The 10.0% group showed retardation in growth, slight increase in kidney weight, [two of three rats] exhibitied phosphate nephritis of kidney tubules by day 15, but by day 28 none of the 5 rats examined showed phosphate nephritis. None of the rats died.

Pilot study: Two dogs were dosed with trimetaphosphate as follows: 0.1g/kg/day for one month and 1.0g/kg/day rising incrementally to 4.0g/kg/day for one month. Insignificant weight changes occurred in the 0.1g/kg/day animal, the dog given a final dose of 4.0g/kg/day lost bodyweight from 12.7 kg to 11.3 kg. Urine samples showed no abnormalities for sugar or protein content, blood samples yielded normal hematological values, organ weights at the time of sacrifice were within the normal range, the heart of the dog given the greater dose was at the upper limit of the normal range of heart weights. Thorough histological studies showed no changes in the tissues of the dog given 0.1g/kg/day. Only the kidneys in the dog dose at 4.0g/kg/day showed any change, they exhibited phosphate-nephritis-like damage.

- Rationale for animal assignment (if not random): anaimals were grouped according to approximate weights and sex. There is no data for the choice of animals used, however, rats are described in the OECD guideline.

- Rationale for selecting satellite groups: no data

- Post-exposure recovery period in satellite groups: not applicable

- Section schedule rationale (if not random): no data

Positive control:

no positive control

Observations and examinations performed and frequency:

DETAILED CLINICAL OBSERVATIONS: No data

BODY WEIGHT: Yes
- Time schedule for examinations: yes (weekly for the first twelve weeks, biweekly thereafter )

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
yes - After one month of the dietary regimen, 5 male rats from the control and from the 10.0% groups were tested. After 4 months on the diet each animal was provided with a set amount of basal or treated diet for the daily recording of food consumption for the 1 month measurement. For the 4 month measurement, control animals were provided with the amount of diet consumed by the treated animal on the preceding day. Body weights were also monitored during this measurement period.

HAEMATOLOGY: Yes
Number of animals: 5 animals/sex/group
Time points: Study initiation and on study days 34-41, 65-71, 93, 125, 142, 181, 229, 310, 379, 457, 560, 664, 707 and 730.
Parameters: Haematocrit, haemoglobin concentration, erythrocyte count, erythrocyte characteristics, total and differential leukocyte count, plasma cell.
Parameters not evaluated: platelet count, prothrombin time, mean activated partial thromboplastin time, mean corpuscular volume, mean corpuscular haemoglobin and haemoglobin concentration.
Anaesthetic used for blood collection: No data
Animals fasted: No data

URINALYSIS: Yes
Number of animals: 5 animals/sex/group
Time points: Pre-test and After approximately 4, 8, 12, 16, 20 and 23 months on study.
Parameters: protein, glucose.
Parameters not evaluated: Appearance, volume, osmolality, specific gravity, pH, blood.
Metabolism cages used for collection of urine: No data
Animals fasted: No data

Sacrifice and pathology:

ORGAN WEIGHTS:
All surviving animals at terminal sacrifice. The numbers of animals/group examined for organ weights from the control males and females were 16 and 19 animals/ group, respectively. The numbers of animals/group examined from the low, mid and high dose males were 15, 18 and 20 animals/group, respectively. The numbers of animals/group from the low, mid and high dose females were 21, 17 and 6 animals/group, respectively.
Organs: Liver, kidneys, testes, spleen, brain, stomach, lungs, heart
Organs not evaluated: adrenals, epididymides, uterus, ovaries, thyroid.

GROSS PATHOLOGY:
Macroscopic examination of organs looking for treatment-related lesions.

HISTOPATHOLOGY:
Animals at terminal sacrifice were examined for histopathology. Ten animals per sex per group were examined, except for the high dose females. Only 6 high dose females survived to termination.
Organs: Brain, small and large intestines, stomach, liver, kidneys, adrenals, spleen, heart, trachea, lungs, gonads, urinary bladder, bone marrow, skeletal muscle and any abnormal tissue.
Other: skeletal muscle, bone.

Organs not evaluated: pituitary, thyroid, parathyroid, thymus, oesophagus, salivary glands, pancreas, adrenals, uterus, female mammary gland, prostate, lymph node, peripheral nerve, bone marrow, skin, eyes, aorta, cervix, coagulating gland, epididymides, Haderian gland, lacrimal gland, sseminal vesicles, trachea

Other examinations:

Bone analysis: 10 animals from all male groups and 9, 8, 10 and 6 females from the control, low, mid and high dose groups, respectively: length and weight of the femurs, composition of bone (% water, dry weight, ash weight, % organic material, % calcium, % phosphorus, calcium:phosphate ratio). Mortality was monitored throughout the study.

Statistics:

no data

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):

no effects observed

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Clinical biochemistry findings:

not examined

Urinalysis findings:

no effects observed

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

no effects observed

Details on results:

MORTALITY
Mortality was due primarily to respiratory infections and pericarditis-peritonitis. Some animals, mainly control rats, died due to excessive heat due to a thermostat failure.
There was no increase in mortality with increasing dose of test material. Median life span was similar to controls for all groups except the high dose females. The high dose females showed a reduced life span, 489 days compared to 685 in the control females. There is a high percentage of deaths due to other causes (not specified) in the high dose female group.

CLININCAL SIGNS
Some animals fed the high dose diet had moderate to severe diarhea. Aside from a softness of the feces (a possible mild cathartic action) in the groups given the 10% diet, the rats were healthy and maintainted good condition throughout the study.

BODY WEIGHT AND WEIGHT GAIN
Growth retardation was observed in rats of both sexes at the high dose (10.0% in diet) during the study. At the mid-dose level (1.0% in diet), males exhibited growth retardation during the first 12 months, then the growth rate was compensated and body weights were similar to controls at 24 months. Females administered the mid-dose level did not show growth retardation. There were no effects on growth at the low dose in either sex (0.1% in diet).

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study)
After one month, control and high dose males consumed similar amount of diet. After 4 months, control and high dose animals of both sexes exhibited similar food consumption in the pair-fed measurement.

HAEMATOLOGY
Repeated blood samples gave normal hematological values. All values in the treated groups were within the normal ranges, except for lower red blood cell counts and hematocrit levels in the high dose female group.

URINALYSIS
No effects on glucose or protein in urine at any dose level at any evaluation time.

ORGAN WEIGHTS
The fresh organ weights are comparable from group to group with the exception of smaller livers in the male rats given the 10% diet. The high average lung weight in the male 0.1% group can be traced to a single anomolous rat. When organ weights are expressed on the basis of body weights the small size of the carcass is reflected in the larger ratios for several organs. The larger stomach, brain, testes weights can be attributed to reasonably normal weight organs in smaller carcasses.
The organ weights gave no evidence of any specific toxic effect of TMP when given in the diets over a period of 2 years.

GROSS PATHOLOGY
Gross necropsy examination found no treatment-related lesions associated with test material dose administration.

HISTOPATHOLOGY: NON-NEOPLASTIC
The kidneys displayed concretions across all dose groups, including control, low and mid dose females and high dose males and females. These calcifications are thought to be due to nematode infections and not related to treatment.

HISTOPATHOLOGY: NEOPLASTIC (if applicable)
The incidence of tumours among survivors at terminal sacrifice did not show any significant increase in any particular tumour type related to treatment. All other lesions were typical of old and ill rats.
Deaths related to tumors did not show a relationship to treatment. Up to 3 rats (/50) per group during the 2 year period
Monthly counts of tumours were provided. No specific treatment-related trend in time-to-tumour development was observed.

BONE ANALYSIS:
The 10.0% dose animals of both sexes exhibited higher calcium and phosphorus percentages in ash and lower water content compared to controls.
Femur length was slightly reduced among high dose males and to a lesser extent among high dose females. Since both the femur weights and body weights were both reduced, the femur weight:body weight ratios were not reduced and even increased for the high dose females because the body weights were reduced more than the femur weight. The reduction in femur weight indicated that a true growth retardation occurred.

OTHER: In high dose animals of both sexes exhibited higher calcium and phosphorus percentages in ash and lower water content compared to controls. This hypercalcification can be considered treatment-related.

Dose descriptor:

NOAEL

Effect level:

ca. 500 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

female

Basis for effect level:

other: Normal growth seen in rats on a diet containing 1% of the test material

Dose descriptor:

NOAEL

Effect level:

ca. 500 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male

Basis for effect level:

other: see 'Remark'

Critical effects observed:

not specified

NOAEL calculated in accordance with Appendix F, guidelines for the preparation of toxicological working papers for the joint FAO/WHO expert committee on food additives, December 2000.

Conclusions:

Reduced median life span and reduced red blood cell count and hematocrit were noted in high dose females. Histopathological evaluation indicated kidney concretions which were considered to be due to infections and aging. Kidney calcification in the high dose group may have been related to treatment. There was no apparent increase in tumour incidence to suggest a carcinogenic effect, though the number of survivors at termination was generally low due to infections or other causes in all dose groups. The high dose (10% in the diet) is excessive and exceeds the current guidance for a limit dose of no more than 5% in the diet. The high dose exceeded the maximum tolerated dose as evidenced by the reduced median life span among females.

Results and discussion

Target system / organ toxicity

Critical effects observed:

not specified