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Repeated dose toxicity: oral

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Administrative data

Endpoint:
sub-chronic toxicity: oral
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
1982
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The study has been assessed for the use in a category approach. According to the methodology and to the extent of available details, the study has been judged as reliable with restrictions.

Data source

Reference
Reference Type:
publication
Title:
Short-term toxicity study of metatartaric acid in rats
Author:
Ingram AJ, Buttcrworth KR, Gaunt IF, Gangoli SD.
Year:
1982
Bibliographic source:
Food Chem Toxicol 1982; 20 (3): 253-257.

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
The test substance is orally administered daily in graduated doses to several groups of experimental animals, one dose level per group for a period of 18 weeks. During the period of administration the animals are observed closely for signs of toxicity.
Animals which died or are killed during the test are necropsied and, at the conclusion of the test, surviving animals are also killed and necropsied.
GLP compliance:
not specified
Limit test:
no

Test material

Constituent 1
Reference substance name:
metatartaric acid
EC Number:
609-694-5
IUPAC Name:
metatartaric acid
Test material form:
not specified
Details on test material:
Specification for the test material: an offwhite powder; content, 105.4% tartaric acid equivalent; esterified tartaric acid, 27-35%; specific absorption
E%cm: 0.0076; specific rotation [α]20 c + 132; matter insoluble in water at 20°C, 1-48%; pyruvic acid, 53 ppm, arsenic 0.02 ppm; lead, 0.16 ppm
Specific details on test material used for the study:
Metatartaric acid manufactured by Wormser Oenologie, France, was supplied by Newmark Chemical Laboratories, London. It complied with the requirements of The Miscellaneous Additives
in Food Regulations 1974 (Statutory Instrument 1974, n. 1121) and had the following specification:
an offwhite powder;
content, 105 4% tartaric acid equivalent;
esterified tartaric acid, 27-35%;
specific absorption E1%-1cm:. 0.0076;
specific rotation: +13.2
matter insoluble in water at 20°C, 1-48%;
pyruvic acid, 53 ppm,
arsenic, 0.02 ppm;
lead, 0.16 ppm.

Test animals

Species:
rat
Strain:
Wistar
Details on species / strain selection:
Wistar rats obtained from a specified-pathogen-free breeding colony (SACI Laboratory Animai Division, Braintree, Essex) were fed ground Spratt's laboratory Diet No. 1 ad lib.
Sex:
male/female
Details on test animals or test system and environmental conditions:
The animals were housed five per cage in air-conditioned rooms.
Rats were obtained from a specified-pathogen-free breeding colony.
Groups of 15 male rats (body weight approximately 85 g) and 15 females (body weight approximately 75 g)

Administration / exposure

Route of administration:
oral: drinking water
Details on route of administration:
no data
Vehicle:
water
Details on oral exposure:
Rats were fed ground Spratt's laboratory Diet n. 1 ad lib.
Rats were given drinking-water containing metatartaric acid ad lib.
Analytical verification of doses or concentrations:
not specified
Details on analytical verification of doses or concentrations:
no data
Duration of treatment / exposure:
18 weeks (additional group: 2 or 6 weeks)
Frequency of treatment:
no data
Doses / concentrationsopen allclose all
Dose / conc.:
0 other: %
Remarks:
(Control)
Dose / conc.:
0.1 other: %
Dose / conc.:
0.5 other: %
Dose / conc.:
3 other: %
Dose / conc.:
0 other: %
Remarks:
in addition, five rats of each sex were given metatartaric acid for 2 or 6 wk
Dose / conc.:
0.5 other: %
Remarks:
in addition, five rats of each sex were given metatartaric acid for 2 or 6 wk
Dose / conc.:
3 other: %
Remarks:
in addition, five rats of each sex were given metatartaric acid for 2 or 6 wk
No. of animals per sex per dose:
not clearly stated.
Control animals:
yes
Positive control:
no data

Examinations

Observations and examinations performed and frequency:
Body weight: The animals were weighed before the star t of treatment, on days 1, 3 and 7 of the treatment period and subsequently at weekly intervals up to wk 18.

Food and water intakes: Food and water intakes were measured over a 24-hr period preceding each weighing.

Urine: Urine was collected during the final week of treatment and examined for appearance, microscopic constituents and tbe presence of albumin, glucose, ketone bodies, bile salts and blood. A urinary concentration and dilution test was carried out at the same time by measuring the specific gravity and volume of urine voided during a 6-hr period of water deprivation and in a 2-hr period fOllowing a water load of 25 ml/kg bw . Cells were counted in this urine specimen. In addition at wk 6 and 18 the same measurements were made on the urine collected during a 4-hr period cornmencing after water deprivation for 16 hr.

Blood and serum: Samples of blood were obtained from haematological examination and serum analyses.
Blood samples were examined for haemoglobin content packed cell volume and counts of erythrocytes and total and differential leucocytes. In the absence of treatment-related changes in the erythrocyte counts, reticulocytes were not examined. Differential leucocyte counts were carried out on all the groups at wk 2 but were confined to the control and highest treatment groups at wk 6 and 18. Serum was analysed for the content of urea. glucose, total protein and albumin and for the activities of glutamic-oxalacetic and glutamic-pyruvic transaminases and lactate dehydrogenas

Organs: The animals were examined for macroscopic abnormalities and the brain, pituitary, thyroid, heart, liver, spleen, kidneys, adrenal glands, stomach, small intestine and caecum (with and without its contents) were weighed. Samples of these organs and of oesophagus, trachea lung, salivary grand, aorta, thymus, various lymph nodes, urinary bladder, colon rectum, pancreas, prestate, seminai vesicles, uterus. spinal cord, skeletal muscle, sciatic nerve, eye and Harderian gland and other
tissues that appeared abnormal were preserved in 16% buffered formalin. Paraffin-wax sections 5 µm thick were stained with haematoxylin and eosin.
Microscopic examination of the sections was confined to tissues taken at 18 wk from ali of the rats given 3% metatartaric acid and half of the animals in the 0.5% and control groups.
Sacrifice and pathology:
At the end of treatment the animals were killed by exsanguination from the aorta under barbiturate anaesthesia, following an overnight period without food.
Other examinations:
no data
Statistics:
Student's t test was performed.

Results and discussion

Results of examinations

Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
One female rat in the group given 3% metatartaric acid died and no other deaths occurred during the treatment period and the animals appeared normal.
Mortality:
not specified
Description (incidence):
One female rat in the group given 3% metatartaric acid died and no other deaths occurred during the treatment period and the animals appeared normal.
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
Reductions in the rate of body-weight gain were statistically significant in male rats given 3% metatartaric acid but not in other groups
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Description (incidence and severity):
the intake of food was lower in the treated groups than in the controls.
the consequent reductions in the mean values for the whole period were dose related.
The mean intakes of metatartaric acid from the 0.1, 0.5 and 3% solutions were 0.08, 0.33 and 1.81 gfkg/day, respectively, for the male rats and 0.13, 0.52 and 2. 52 g/kg/day for the females
Food efficiency:
not specified
Description (incidence and severity):
no data
Water consumption and compound intake (if drinking water study):
effects observed, treatment-related
Description (incidence and severity):
the intake of water lower in the treated groups than in the controls.
the consequent reductions in the mean values for the whole period were dose related, those for water intake being statisticaliy significant at all dose levels and those for food intake at the two higher doses.
Ophthalmological findings:
not specified
Haematological findings:
effects observed, non-treatment-related
Description (incidence and severity):
The haematological findings did not show any treatment-related effects (no treated group had both a low red cell count and a reduced packed cell volume).
The observed reduction from control values in the erythrocyte count at wk 18 in male rats on 0.5% metatartaric acid was not accompanied by a corresponding change in the
packed celi volume Similarly, the reduced packed cell volume in the females given 3% was not associated with a comparable change in the red cell count. The results of the serum analyses were similar in the treatment and control groups.
Clinical biochemistry findings:
not specified
Description (incidence and severity):
no data
Urinalysis findings:
no effects observed
Description (incidence and severity):
Cell excretion and urinary constituents were normal in the treated animals.
The results of the urine analyses compared with the controls. rats given 0.5 or 3% metatartaric acid for 2, 6 or 18 wk excreted less urine of higher specifìc gravity when deprived of water for 6hr or during the 2hr period following a water load.
In contrast, at wk 18, male rats given O.5 or 3% metatartaric acid excreted urine of lower specifìc gravity in larger volumes than control animals in the 16--20 hr after the water load. No comparable effects were seen in the females.
Cell excretion and urinary constituents were normal in the treated animals.
Behaviour (functional findings):
not specified
Description (incidence and severity):
no data
Immunological findings:
not specified
Description (incidence and severity):
no data
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
Some statistically significant differences from control values were observed in the recorded and/or relative weights of organs of rats given 3% metatartaric acid (kidney weight).
The recorded weights showed a lower value in males at wk 2 and an increase (P < 0.05) in females at wk 18, while the relative weights showed increases in females at wk 6 and 18 and in males at wk 18.
Similar findings were recorded for the relative weight of the empty caecum, with statistically significant increases in females at wk 6 and in males at wk 18.
Gross pathological findings:
effects observed, treatment-related
Description (incidence and severity):
In the group of male rats given 3% metatartaric acid for 18 wk, polymorphonuclear infiltration of the submucosal layer of the stomach was observed in three animals and in two cases this was accompanied by hyperplasia of the non-glandular epithelium
Neuropathological findings:
not specified
Description (incidence and severity):
no data
Histopathological findings: non-neoplastic:
effects observed, non-treatment-related
Description (incidence and severity):
slight fatty change and small foci of necrosis in the liver of some of the treated animals and in controls
Histopathological findings: neoplastic:
not specified
Description (incidence and severity):
no data
Other effects:
effects observed, treatment-related
Description (incidence and severity):
In the group of male rats given 3% metatartaric acid for 18 wk, polymorphonuclear infiltration of the submucosal layer of the stomach was observed in three animals and in two cases this was accompanied by hyperplasia of the non-glandular epithelium.
Details on results:
no data

Effect levels

open allclose all
Dose descriptor:
LOAEL
Effect level:
0.5 other: %
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: a possible adverse effect on renal function
Remarks on result:
other: The results have equivocai nature, these findings are difficult to interpret, but the possibility of treatmentrelated adverse eftects on the kidney cannot be excluded
Dose descriptor:
NOAEL
Effect level:
0.1 other: %
Based on:
test mat.
Sex:
male/female
Basis for effect level:
body weight and weight gain

Target system / organ toxicity

Critical effects observed:
yes
Lowest effective dose / conc.:
0.5 other: %
System:
urinary
Organ:
kidney
Treatment related:
yes
Dose response relationship:
not specified
Relevant for humans:
not specified

Any other information on results incl. tables

The acidity of the compound in solution was sufficiently corrosive at 3% concentration to produce gastric irritation and probably rendered metatartaric acid solutions unpalatable, a likely explanation for the observed dose-related decrease in water consumption.

The consequent depression in body weight was statistically significant in male rats at the 3% dose level throughout the study.

The increased weights of this organ cannot be confidently interpreted as an adverse effect in the absence of any treatment-related pathological lesions, and most of the changes noted in the urine tests can be explained in terms of the reduced water intake.

However the apparent inability of males given 0.5 or 3% metatartaric acid to concentrate urine under conditions of prolonged dehydration may suggest some impairment of renal function. In view of their equivocai nature, these findings are difficult to interpret, but the possibility of treatmentrelated adverse eftects on the kidney cannot be excluded.

The increase in relative caecum weight at wk 6 in females and wk 18 in males on 3% metatartaric acid is of doubtful toxicological

significance and may bave resulted in part from the osmotic effect of the solution administered.

Applicant's summary and conclusion

Conclusions:
In 3.0% group were observed irritation of the gastric mucosa, reduced body-weight gain and an increase in relative kidney weight, a possible adverse effect on renal function.
In 0.5% group was observed a possible adverse effect on renal function.
The no-untoward-effect level (no observed adeverse effect level) in this study was 0.1% of metatartaric acid in drinking water.
Executive summary:

Groups of rats were given metatartaric acid in the drinking-water in concentrations of 0 (control), 0.1, 0.5 or 3.0% for 18wk.

No effects associated with treatment were seen in the results of the haematological examinations and serum analyses.

The treated ammals consumed less water and food than the controls, probably because of the unpalatability of the test material. Administration of the 3% solution was associated in males with a reduced growth rate, some impairment of urine-concentrating ability during prolonged water deprivation (also seen in males on 0.5%) and histopathological changes in the stomach indicative of an inftammatory response in the submucosal layer. Both sexes of the 3% group showed an increase in relative kidney weight, without accompanymg histopathological change. The no-untoward-effect level in this study was 0.1% metatartaric acid in the drinking-water. equtvalent to a mean daily intake of 80 mg/kg body weight in the males and 130 mg/kg in the females.