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Toxicological information

Repeated dose toxicity: oral

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Administrative data

sub-chronic toxicity: oral
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Older proprietary study, conducted by a reputable laboratory according to scientifically accepted methods, similar to current guidelines.

Data source

Reference Type:
study report
Report Date:

Materials and methods

Test guideline
equivalent or similar to
OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity in Rodents)
Principles of method if other than guideline:
The methods are comparable to OECD 408.
GLP compliance:
: study predates GLP
Limit test:

Test material

Details on test material:
The test substance was trimethylolpropane, TMP 99, obtained from Perstorp on 20th December 1968. The identity of the test substance was confirmed by infared spectroscopy. A read-across is proposed from this substance based on structural similarities.

Test animals

Details on test animals and environmental conditions:
The animals were male and female weanling Wistar-derived albino rats from the test facility colony. They were assigned to treatment groups by body weight.
Food and water were provided ad libitum. The rats were housed in groups of 5 in screen bottom cages, in a room kept at a constant temperature of approximately 24°C.

Administration / exposure

Route of administration:
oral: feed
unchanged (no vehicle)
Details on oral exposure:
Groups of rats were fed the stock diet (see additional information on materials and methods) with TMP added at levels of 0, 0.03, 0.1, 0.3 and 1.0%. The test compound was thoroughly mixed into the diet using a mechanical blender. The diets were freshly prepared once a fortnight and were stored at room temperature.
Analytical verification of doses or concentrations:
Duration of treatment / exposure:
90 days
Frequency of treatment:
Daily - ad libitum in diet
Doses / concentrations
Doses / Concentrations:
0, 0.03, 0.1, 0.3 and 1.0%
nominal in diet
No. of animals per sex per dose:
Ten rats/sex/dose
Control animals:
yes, plain diet
Details on study design:
Rats were assigned to groups by body weight, and housed in groups of 5. There were 10 rats/sex/dose. Test diets were available ad libitum.
Positive control:
A positive control was not examined.


Observations and examinations performed and frequency:
Rats were observed for mortality, general condition and behaviour.
Individual body weights were recorded weekly. The food intake (and food efficiency) of each group was determined during the first 4 weeks, and during weeks 11 and 12.
Haematology parameters determined at weeks 4 and 12 were: haemaglobin content, packed cell volume, red blood cell count, total and differential white blood cell count.
Clinical chemistry parameters determined at study termination were: serum glutamic-pyruvic transaminase (SGPT), serum glutamic-oxaloacetic transaminase (SGOT), serum alkaline phosphatase (SAP), total serum protein, albumin and albumin-globulin ratio.
Urinalysis was conducted upon pooled urine samples of 10 males and 10 females of each group in week 13: appearance, pH, glucose, albumin, occult blood and ketones.
Sacrifice and pathology:
In week 14 all rats were killed by decapitation and examined macroscopically for pathological changes. The following organs were weighed: heart, kidney, liver, spleen, brain, testicle, ovary, thymus, pituitary, thyroid and adrenal gland. Samples of these organs and of a wide range of other organs were fixed in a 4% neutralised formaldehyde solution.
Detailed microscopic examination was performed on all male and female rats of the high dose and control groups. Haematoxylin-eosin stained paraffin sections of the organs weighed and also of the following organs were examined: lung, salivary glands, GI tract, trachea, skeletal muscle, aorta, exorbital lacrimal gland, axillary and mesenteric lymph nodes, pancreas, skin, urinary bladder, sternum with marrow, prostate, epididymis, coagulating gland, seminal vesicle, preputial gland, uterus, spinal cord and femoral nerve. Microscopic examination of rats fed lower doses was restricted to the liver and spleen.
Other examinations:
No other examinations were reported.
Wilcoxon test

Results and discussion

Results of examinations

Clinical signs:
no effects observed
no mortality observed
Body weight and weight changes:
effects observed, treatment-related
Food consumption and compound intake (if feeding study):
no effects observed
Food efficiency:
no effects observed
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
effects observed, treatment-related
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
no effects observed
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Gross pathological findings:
effects observed, treatment-related
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Histopathological findings: neoplastic:
no effects observed
Details on results:
There were no mortalities during the study. No abnormalities of condition or behaviour were observed. There were no significant differences in body weight between the various groups, although at the three highest dose levels the body weights of the males were consistently lower than controls. Food consumption and food efficiency did not show consistent differences between groups.
In females fed 1.0% TMP, the haemoglobin contents were slightly lower than in the controls. The difference was only significant at week 4. Red blood cell counts and packed cell colume of females were decreased at the two highest dose levels at week 12. The blood smears showed normoblasts and white blood cell fragments in males and females at 1.0% in week 4. In week 12, normoblasts were observed in males at 1.0% and females at 0.3% and 1.0%. The differential counts did not reveal consistent differences between groups.
There were no distinct or significant differences in clinical chemistry parameters between the experimental groups and the controls.
There was no alteration in the urine which could be attributed to TMP.
Spleen weights were significantly increased at 1.0% in both sexes. The average relative weights of kidneys, liver and ovary were significantly increased in females at 1.0%. In males, pituitary weight was increased at 1.0%. There were other occasional significant differences, however there was no dose relationship and therefore the findings were considered incidental.
Moderately enlarged, dark spleens were seen in males and females of the 1.0% group at gross necropsy. No other changes were seen. Occasional lesions found at autopsy such as early signs of murine pneumonia and unilateral hydronephrosis, are regularly seen in rats of this strain, and were therefore not considered to be treatment related,
Histpathological examination revealed changes in the spleen and liver. Increased numbers of small lymphocytes, normoblasts and megakaryocytes were encountered in the red pulp of the spleen in the 1.0% group. The white pulp of the spleen was unremarkable. Normoblasts and an increased number of small lymphocytes were also present in the sinusoids of the livers of the 1.0% group. Slightly enlarged Kupffer cells containing yellowish brown pigment were seen in two females of the highest dose group. At lower dose levels, the spleen and liver did not differ from those of the controls.
There were no other changes that could be attributed to treatment.

Effect levels

Dose descriptor:
Effect level:
0.1 other: %

Target system / organ toxicity

Critical effects observed:
not specified

Any other information on results incl. tables


Applicant's summary and conclusion

The 90 day NOAEL was considered to be 0.1% in the diet, for male and female rats. The dose level is calculated to be equivalent to 100 mg/kg bw/d.
Executive summary:

The oral toxicity of trimethylolpropane (TMP 99) was determined in a 90 day feeding study with male and female rats. The test substance was fed at 0, 0.03, 0.1, 0.3 and 1.0% in stock diet to groups of 10 male and 10 female rats. Rats were sacrificed and subject to necropsy at the end of the feeding period.

General appearance and behaviour, body weight gain, food intake and efficiency, blood serum enzyme activities, serum protein content and urine composition were not affected by treatment. Haemoglobin content was decreased in 1.0% females, whilst packed cell volume and red blood cell counts were decreased in females at 0.3 and 1.0%. Blood smears contained normoblasts and white blood cell fragments in both sexes at 1.0% and normoblasts in females at 0.3%. The relative weight of the spleen was increased in both sexes. Liver, kidney and ovary weights were increased in 1.0% females. Pituitary weight was increased in males at 1.0%.

Gross examination at autopsy revealed enlarged dark spleens in both sexes at 1.0%. Histopathology revealed increased numbers of cells in the red pulp of the spleen, and in the liver Kupffer cells laden with pigment, sinusoids containing normoblasts and too many small lymphocytes were revealed in the 1.0% group. It was therefore concluded that the 90 day NOAEL of TMP 99 is 0.1% in the diet, for male and female rats.