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Description of key information

Subchronic toxicity study performed prior to implementation of official testing guidelines but comparable to OECD TG 408. The feeding of trimethylolpropane to young male and female Wistar rats at 0, 0.03, 0.1, 0.3, 1.0 % in diet (corresponding to 20, 67, 200 or 667 mg/kg bw/d) for three months led to a NOAEL of  0.1 % in diet corresponding to 67 mg/kg bw/day (de Knecht - van Eekelen,  1969 a und b).
No valid studies are available for inhalation or dermal repeated dose 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: scientifically acceptable and well documented
Principles of method if other than guideline:
Male and female Wistar rats were fed with 0, 0.03, 0.1, 0.3 and 1.0% TMP in diet and were observed for general appearance and behaviour.
Growth, food intake, haematology, clinical chemistry data and data from urinalysis were noted.
At week 14 all rats were sacrificed and examined grossly and different organs were weighed.
Histopathological examination was carried out.
GLP compliance:
no
Limit test:
no
Species:
rat
Strain:
Wistar
Sex:
male/female
Details on test animals and environmental conditions:
50 male and 50 female weanling rats from the CIVO-colony were divided according to body weights over 5 groups of 10 males and 10 females each, and fed on stock diet with trimethylolpropane added at levels of 0, 0.03, 0.1, 0.3 and 1.0%..
the animals were housed in screen bottom cages (5 to a cage) in a room of constant temperature at ca. 24°C.
Food and tap water were constantely available.
Route of administration:
oral: feed
Vehicle:
other: test substance was mixed with diet
Details on oral exposure:
the test compound was thoroughly mixed into the diet by means of a mechanical blender.
the diets were freshly prepared once a fortnight and stored at room temperature
Analytical verification of doses or concentrations:
not specified
Duration of treatment / exposure:
90 d
Frequency of treatment:
daily
Remarks:
Doses / Concentrations:
0.03, 0.1, 0.3 or 1.0 % (corresponds to 20, 67, 200 or 667 mg/kg bw/d)
Basis:
nominal in diet
No. of animals per sex per dose:
10
Control animals:
yes, plain diet
Details on study design:
Post-exposure period: no
Positive control:
no data
Observations and examinations performed and frequency:
--mortality and clinical signs
--individual body weights were recorded weekly
--the food intake of each group was determined during the first 4 weeks and in week 11 and 12.
--haematological data were collected at week 5 and were recorded again at week 13.
hemoglobin content, red and white blood cell count
packed cell volume, differential white cell counts
--determinations of serum enzymes were carried out at the end of the experiment.
serum glutamid pyruvic transaminase (SGPT), serum glutamic-oxaloacetic transaminase (SGOT), serum alkaline phosphatase (SAP),
serum ornithinecarbamyl transferase (SOCT), total serum protein (TSF, biuret metnod))
--urinalysis was conducted in week 13
appearancem pHm glucosem albumin, occult blood, ketones and microscopic sediment
Sacrifice and pathology:
--in week 14 all rats were killed and examined macroscopically for pathological changes.
--The following organs were weighed:
heart, kidneys, liver, spleen, brain, testicle or ovary, thymus, pituitary, thyroid and adrenal.
--Detailed microscopic examinations were performed on all male and female rats of the highest dose group and of all control rats.
--Additional to the organs weighed the following organs were examined:
lung, salivary glands, gastrointestinal tract, traches, skeletal muscle, aorta, exorbital lacrimal gland, axillary and mesenteric lymph nodes, pancreas, skin, urinary bladder, sternum with marrow, prostatate, epididymis, coagulationg gland, seminal vesicle, preputial gland, uterus, spinal cord and femoral nerve.
--Microscopic examinations of rats of lower dosages was restricted to
liver, kidneym spleen and thyroid
Other examinations:
no data
Statistics:
yes but method not mentioned
Clinical signs:
no effects observed
Mortality:
no mortality observed
Body weight and weight changes:
no effects observed
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):
no effects observed
Ophthalmological findings:
not specified
Haematological findings:
effects observed, treatment-related
Clinical biochemistry findings:
effects observed, treatment-related
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:
not specified
Details on results:
HAEMATOLOGY (significant changes only)
--hemoglobin content (females)
At 1 % (week 13 ) hemoglobin content was lower than in controls:
15.1 g/100 ml (p<0.01) versus 16.2 g/100 ml in controls
--red blood cell count (females):
at 1 % (week 13) was lower than in controls:
7.5 x10[exp-6]/mm³ (p<0.001) versus 8.3 x10[exp-6]/mm³

CLINICAL CHEMISTRY (significant changes only)
week 13, males
--0.3 % and 1.0%: SGPT
42 R-F units (p<0.05) and 42 R-F units (p<0.05) versus 50 R-F units in controls
--0.3% and 1.0%, SAP
5.2 B-L units (p<0.05) and 5.0 B-L units (p<0.05) versus 7.2 B-L units
week 13, females:
1% SGOT: 162 R-F units (p<0.05) versus 200 R-F units in controls
1% SAP: 3.1 B-L units (p<0.05) versus 4.6 B-L units

ORGAN WEIGHTS
--males and females
at 1 %: the average relative weights of kidneys, liver and spleen were increased in both sexes
--males
at 1 % the average relative weight of adrenal was significantly increased but no pathological or histopathological correlate was reported
--females
at 1 % the average relative weight of thyroid gland, brain and ovar were significantly increased but no pathological or histopathological correlate was reported
--
GROSS PATHOLOGY
males and females
1%: moderately enlarged but not discoloured spleens were seen

HISTOPATHOLOGY: NON-NEOPLASTIC
At 1 % TMP in food:
--spleen, males and females
increased numbers of small Lymphocytes and normoblastsin enlarged sinuses accompanied by an increased number of megakaryocytes and hyperplasia of phagocytically active teticuloendothelial cells
--iver, males and females
increased number of small lymphocytes and normoblasts in the sinusouides m slightly enlarged Kupfer cells containing yellowish brownpigment
At lower levels
spleen and liver were histologically indistinguischable from those of the controls

Dose descriptor:
NOAEL
Effect level:
ca. 0.1 other: % in diet (approx.67 mg/kg bw/day)
Based on:
not specified
Sex:
male/female
Basis for effect level:
other: based on: distinct ill effects characterised by significant changes of clinical chemistry or hematological data from 0.3 % TMP in food onwards and histopathological changes mainly in liver and spleen at 1 % TMP in food
Critical effects observed:
not specified

0.03 and 0.1 % (= ca. 20 and 67 mg/kg bw/d): no signs of toxicity; 0.3 % (= ca. 200 mg/kg bw/d): biochemical blood
observations: decreased activity of SGPT and of serum
alkaline phosphatase only in males; 1.0 % (= ca. 667 mg/kg
bw/d): increased average relative weights of the kidney, the
liver and the spleen, enlargement of the spleens, treatment
related changes in spleen (increase in red pulp) and liver
(Kupffer cells loaden with pigment only in females,
sinusoids containing normoblasts and an increased number of
small lymphocytes), biochemical blood observations:
decreased activity of SGPT and of serum alkaline
phosphatase; hematology: slightly decreased hemoglobin contents and red blood cell counts only in females, blood
smears containing normoblasts and white blood cell fragments.

Executive summary:

The feeding of trimethylolpropane to young male and female Wistar rats at 0, 0.03, 0.1, 0.3, 1.0 % in diet (corresponding to 20, 67, 200 or 667 mg/kg bw/d) for three months resulted in distinct ill effedts only at the highest feeding level. The abnormalities consisted of slightly decreased hemoglobin levels and red blood cell counts and the presence of serum enzymes SGPT and SAP, increased relative weights of the kidneys, the liver and the spleen and microscopical changes in the liver and the spleen. At lower feeding levels no treatment related abnormalities were observed with respect to hematology, organ weights and histopathology. At the 0.3 % level, the only significant differencesto the controls consisted of slightly lower activities of SGPT and SAP; these phenomena did not occur at lower levels. On the basiss of the present results , the NOAEL of trimethylolpropane is conservatively placed at 0.1 % in the diet of rats for three months which is equivalent with 67 mg/kg bw/day (de Knecht-van Eekelen, at the request of Bayer AG, 1969).

Endpoint conclusion
Endpoint conclusion:
adverse effect observed
Dose descriptor:
NOAEL
67 mg/kg bw/day
Study duration:
subchronic
Species:
rat
Quality of whole database:
scientifically acceptable and well documented

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

ORAL APPICATION

There are 2 studies available using the same test procedure, the same concentration levels both over a time period of 90 days:

The feeding of trimethylolpropane to young male and female Wistar rats at 0, 0.03, 0.1, 0.3, 1.0 % in diet (corresponding to 20, 67, 200 or 667 mg/kg bw/d) for three months, resulted in distinct ill effects only at the highest feeding level. The abnormalities consisted of slightly decreased hemoglobin levels and red blood cell counts and the presence of serum enzymes SGPT and SAP, increased relative weights of the kidneys, the liver and the spleen and microscopical changes in the liver and the spleen. At lower feeding levels no treatment-related abnormalities were observed with respect to hematology, organ weights and histopathology. At the 0.3 % level, the only significant differences to the controls consisted of slightly lower activities of SGPT and SAP; these phenomena did not occur at lower levels. (de Knecht-van Eekelen, at the request of Bayer AG, 1969a).

In another dietary subchronic toxicity study, resulted also in distinct ill effects were mainly observable at the highest feeding level of 1% also. At 1 % in diet the abnormalities consisted of slightly decreased hemoglobin levels and red blood cell counts and the presence of normoblasts and white blood cell fragments, increased relative weights of kidneys, liver and spleen and microscopical changes in liver and spleen. At the 0.3 % level the only significant differences to the controls consisted of decreased packed cell volume and red cell counts and increased occurrence of normoblasts in the blood of females. These phenomena did not occur at lower levels (de Knecht-van Eekelen, at the request of Perstorp AB, 1969b).

On the basis of the presented results in both studies the NOAEL of trimethylolpropane is derived at 0.1 % in diet corresponding to 67 mg/kg bw/day (de Knecht - van Eekelen, 1969a und b)

DERMAL APPLICATION

A dermal study does not need to be conducted because there are subchronic studies available using the oral exposure route. Furthermore, in the acute oral and dermal toxicity studies it was demonstrated that TMP is not more toxic when administered via the dermal route. Therefore requirements of ANNEX IX of Regulation (EC) 1907/2008 (REACH) are fulfilled.

INHALATION EXPOSURE

There is no valid study available using the inhalation route. An inhalation study does not need to be conducted because there are subchronic studies available using the oral exposure route. Therefore the requirements of ANNEX IX of Regulation (EC) 1907/2008 (REACH) are fulfilled.


Justification for selection of repeated dose toxicity via oral route - systemic effects endpoint:
key study is used.

Repeated dose toxicity: via oral route - systemic effects (target organ) cardiovascular / hematological: spleen; digestive: liver

Justification for classification or non-classification

Directive 67/548/EEC, Annex 1: Trimethylolpropane is not classified

Directive 67/548/EEC, Annex 1 and Regulation (EC) No. 1272/2008: Based on the available data no classification is required.