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Administrative data

Description of key information

Repeated dose toxicity: oral;
Four studies are available for this endpoint:
- A key study (Hodge HC 1960) performed in rats demonstrates that there is not specific target organ toxicity when administered ad libitum in the diets of male and female rats for a period of 2 years. The data for this key study are sufficient to infer that that test material should not be classified for STOT-RE under the EU CLP Regulation. A toxicologist expert assessment of the key study is provided to support this conclusion.
- There are also three supporting studies which support the findings of the key study for 90 day and 28 day testing periods. Above the thresholds for classification no target organ toxicity was noted at gross necroscopy.
Based on exposure considerations (to be presented in the CSR), and the toxicokinetic and physicochemical properties of the test substance it was considered to be scientifically justifiable to waive in vivo testing for inhalation and dermal repeat dose administration.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records
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:
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 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.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed
Dose descriptor:
NOAEL
500 mg/kg bw/day
Study duration:
chronic
Species:
rat
Quality of whole database:
The dataset has been reviewed by an external assessor (M Weiner, TOXpertise, LLC) and it is concluded that the data is adequate and reliable for use as a key study under REACH. Please see expert report attached in endpoint under 'background information'.

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

ADAPTATIONS TO THE STANDARD REGIMEN:

SUB-CHRONIC REPEATED-DOSE TOXICITY (SECTION 8.6.2):

According to Annex IX, section 8.6.2, column 2 of Regulation No. 1907/2006 (REACH), a sub-chronic (90 day) study does not need to be conducted if: a reliable chronic toxicity study is available. A two year oral feed study is provided and therefore the sub-chronic (90 day) study is not required for this substance.

INHALATION TOXICITY:

According to the ECHA's Guidance on information requirements and chemical safety assessment Chapter R.7c: Endpoint specific guidance:

For inhaled substances the processes of deposition of the substance on the surface of the respiratory tract and the actual absorption have to be differentiated. Both processes are influenced by the physico-chemical characteristics of a chemical. The granulometry of trisodium trimetaphosphate indicates that the substance is inhalable and therefore the risks of inhalation need to be addressed in consideration of specific target organ toxicity via repeat exposure (STOT-RE).

Inhalable dusts, including the test material, may be absorbed directly from the respiratory tract or, through the action of clearance mechanisms the material can be cleared from the respiratory tract by the muco-cillary escalator and then swallowed, adding to systemic toxicity via the oral route. It has already been concluded that STOT-RE via the oral route is of low potential systemic toxicity (EU CLP), therefore we can disregard any potential risk from inhaled dust that is cleared from the airways and subsequently swallowed.

With regards to the potential of STOT-RE via absorption through the epithelial lining of the respiratory tract and the potential damaging effects which the test material may have on the organs of the respiratory system:

- Systemic absorption; water-soluble dusts (such as trisodium trimetaphosphate) would readily diffuse/ dissolve into the mucus lining of the respiratory tract, however, trisodium trimetaphosphate is not a lipophilic substance and therefore does not have the potential to be absorbed directly across the respiratory tract epithelium. Another consideration of systemic absorption are the aqueous pores lining the respiratory tract, however, despite being hydrophilic the size of trisodium trimetaphosphate (>200 mol. wt) makes this absorption via aqueous pores unlikely. Given this evidence it can be suggested that the respiratory tract will impede systemic absorption of trisodium trimetaphosphate.

Finally, it is worth highlighting that the effect on the lungs themselves is likely to be minimal based on the following considerations:

- The limit test conducted for acute inhalation toxicity (Griffiths D, 2012) did not result in toxicity, at gross necroscopy none of the animals tested revealed any lesions or abnormality of the lung tissue.

- As discussed above, trisodium trimetaphosphate is readily absorbed by the mucosal lining for clearance by the mucocilliary escalator.

- The assessment of eye irritation concluded that trisodium trimetaphosphate did not have a significant effect on the delicate tissue of the eye, therefore it is reasonable to assume that exposure to lung tissue would be similarly unaffected.

Taken together this evidence suggests that further in vivo testing for repeated dose toxicity; short-term, sub-chronic and chronic, will not be necessary, especially as orally administered test material was concluded not to be classified (EU CLP).

DERMAL TOXICITY:

According to Annex VIII, Section 8.6.1, Column 2 and Annex IX, Section 8.6.2, Column 2 of Regulation (EC) No. 1907/2006 (REACH) testing by the dermal route is appropriate if 1) inhalation of the substance is unlikely, 2) skin contact in production and/or use is likely and 3) physiochemical and toxicological properties suggest potential for a significant rate of absorption through the skin and 4) one of the following conditions is met:

• Toxicity is observed in the acute dermal toxicity test at lower doses than in the oral toxicity test,

Or

• Systemic effects or other evidence of absorption is observed in skin and/or eye irritation studies,

Or

• In vitro tests indicate significant dermal absorption,

Or

• Significant dermal toxicity or dermal penetration is recognised for structurally-related substances.

 

The dermal route of exposure is possible for trisodium trimetaphosphate (based on patterns of use), however due to the physical nature and known toxicological properties trisodium trimetaphosphate is not anticipated to pose a hazard via the dermal route for the following reasons:

As trisodium trimetaphosphate is an inorganic ionic solid, with a molecular weight of >200 and is unlikely to be lipophilic, the dermal route is not considered to be a significant route of exposure as the substance is not expected to penetrate the epidermis in any significant quantities and therefore systemic toxicity is unlikely.

 

The conclusion that trisodium trimetaphosphate is of low systemic toxicity is supported by a lack of systemic effects or other evidence of absorption in the skin or eye irritation studies conducted and a lack of systemic toxicity when administered via the oral route for up to 2 years.

Based on the rationale above and taking into consideration that oral exposure represents a worst-case scenario for systemic uptake. No further testing for repeated dose toxicity via the dermal route is considered to be scientifically justified.


Justification for classification or non-classification

Calcification of the kidneys was noted in animals treated with trisodium trimetaphosphate. However, this is not an effect that is sufficient to result in a classification for STOT-RE (kidney) given that rats are susceptible to kidney problems and no assessment of the historical incidence in the strain investigated was made. In addition, the NOAEL calculated from this study would not be sufficient for classification as per the guidance values derived using Haber's rule for a 2 -year study in accordance with the Guidance on the Application of the CLP Criteria.

The data used have been determined to be acceptable for assessment and no further animal testing is justified. Trisodium trimetaphosphate is not considered to be classified for STOT-RE, in accordance with Regulation (EC) No 1272/2008 (EU CLP).

Conversion from % in diet to mg/kg bw was calculated in accordance with Appendix F of the guidelines for the preparation of toxicological working papers for the joint FAO/WHO expert committee on food additives, December 2000.