Reaction mass of 2,2'-(ethylenedioxy)diethanol and 2,2'-oxydiethanol and ethane-1,2-diol

Repeated dose toxicity: oral

Administrative data

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: basic information given, scientifically acceptable

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1998

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity Study in Rodents)

GLP compliance:

not specified

Test material

Reference

Name:

Unnamed

Type:

Constituent

Type:

Constituent

Details on test material:

purity: 100%

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

At the start of the study the rats were 6-7 weeks old. After one week of acclimatisation the animals were randomised and kept under conventional conditions individually in MakroIon cages on low-dust wood granules. The animal room was maintained at 22 +/- 2°C and about 50 % humidity with 12 h light-dark cycles. The diet consisted of a fixed-formula standard diet and tap water. Feed (except during the urine collection periods) and water were available ad libitum. The animals were identified with the aid of ear tattoos.
The rats were inspected at least twice a day (once a day at weekends and on public holidays) for clinical signs. The body weights were determined daily, food and water consumption weekly. Blood samples for clinico-chemical investigations were collected from the retro-orbital venous plexus under diethyl ether anesthesia or from one of the caudal veins (glucose only).

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

water

Details on oral exposure:

The aim of the study was to obtain data on possible toxic effects of TEG after administration to rats via gavage over four weeks. As several studies have shown treatment-related effects of the structurally similar compound EG on the kidney, special attention was paid to investigating possible toxic effects of TEG on this organ. In order to compare possible treatment-related effects of TEG with those known from EG, a group of males and females was treated with EG.

Duration of treatment / exposure:

33 days

Frequency of treatment:

daily

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 220, 660, 2000 mg/kg
Basis:
actual ingested

No. of animals per sex per dose:

Fifty rats of each sex were assigned randomly to the five treatment groups.

Control animals:

yes, concurrent no treatment

Details on study design:

Toxicity of EG after repeated administration as well as the potential chronic toxicity and carcinogenicity were assessed in several published studies. The studies revealed the kidney as a target in rats. Only slight kidney lesions were observed in males after subchronic treatment of mice, whereas after treatment for two years no kidney changes were observed in this species.

Examinations

Observations and examinations performed and frequency:

Hematological parameters, which were estimated from five rats per dose group in week 4, included erythrocyte count, hematocrit, hemoglobin, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, leukocyte count, differential blood count and platelet count.
Clinical chemistry performed in week 4 on five rats per dose group included determination of alanine aminotransferase, alkaline phosphatase, aspartate aminotransferase, total bilirubin, cholesterol, creatinine, glucose, calcium, potassium, sodium. inorganic phosphate, urea and total protein.
Urine samples were collected in week two (collection time 20 hours) from five animals per group and in week five (collection time 24 hours) from all animals. Samples were cooled during the collection period. Urinalysis included measurement of urine volume, specific gravity, osmolality, N-acetyl P-D-glucosaminidase, lactate dehydrogenase, alanine aminopeptidase, urea, sodium, calcium, potassium. Furthermore, occult blood, protein, glucose, ketones, bilirubin, urobilinogen were estimated semiquantitatively using bili-labstix or multistix or urobilistix reagent strips. Sediment of urine samples was microscopically examined for leukocytes, erythrocytes, epithelial cells, amorphous crystals and bacteria. Additional urine samples were collected on day 2 (five animals per group, collection time: 20 hours) and on day 25 (all animals, collection time: 24 hours) for determination of oxalic acid.

Sacrifice and pathology:

Complete necropsies were performed on all animals at the end of the study. Weights of the brain, heart, testes, liver, lung, kidneys, adrenal, spleen and ovaries were recorded. Tissues were preserved in Bouin's solution and an additional liver specimen in 10 % buffered formalin. For histopathological investigations the brain, urinary bladder, ureter, testes, epididymides, heart, liver, spleen, kidneys and adrenals of control animals and rats treated with either 2000 mgkg TEG or EG, respectively, were embedded in paraffin. The paraplast sections were then staiined with hematoxylin-eosin, testes and epididymides additionally with the periodic acid Schiff reaction.

Statistics:

Arithmetic group means with their standard deviations were calculated from the individual results of the feed intake, body and organ weight determinations and clinical laboratory tests. The values of the test groups were compared with those of the control group with the aid of the significance test at significance levels of a = 5 % and a = 1 % (two sided). Significant differences to control are indicated with * for p < 0.05 and ** for p < 0.01.

Results and discussion

Results of examinations

Details on results:

Clinical signs, mortality, feed and water intake, body weights: Appearance, behavior, mortality, development of body weights and feed intake were not affected in a toxicologically relevant manner by the treatment in any dose group. Whereas water intake of animals treated with TEG was comparable with that of controls, treatment with EG resulted in a slightly increased water intake. Averaged over the study period the daily water intake per animal was 16 % and 21 % higher in EG-treated males and females, respectively.
Hematology: The determination of hematological parameters in peripheral blood (differential blood count, leukocyte count, erythrocyte count, hemoglobin, hematocrit, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, mean corpuscular volume, thrombocyte count) in week 4 gave no indications of treatment-related effects by TEG or EG.
Serum chemistry: The determination of clinico-chemical parameters in blood [enzyme activities (aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase), glucose, cholesterol, total bilirubin, total protein] revealed no unusual features after treatment with TEG or EG. It can be seen that neither determination of creatinine and urea concentrations nor that of electrolytes in peripheral blood did indicate adverse effects related to the treatment with TEG or EG. Some values marked as statistically significant are not considered to be of toxicological relevance, as the differences from the controls were slight and all values were within the range of historical control values obtained in the laboratory.
Urinalysis: Neither quantitative estimation of volume, density, osmolality, pH, urea, electrolytes and enzymes nor semiquantitative urinalysis in week 2 gave indications of any possibly treatment-related effects by TEG or EG. The only findings after TEG treatment were significantly decreased pH values and increased osmolality for males beginning with 660 mg/kg and for females at 2000 mg/kg. However, as the values differed only slightly from control values, this is not regarded to be of toxicological relevance. The estimation of the other quantitative and semiquantitative parameters yielded no remarkable results.
After treatment with 200 mg EG/kg the pH value of the urine was significantly decreased and osmolality increased (females only). Furthermore, excretion of inorganic potassium, calcium and phosphate was significantly decreased in males. Excretion of oxalate on days 2 and 25, respectively, was increased in both sexes after treatment with EG while oxalate excretion did not differ from control values in any TEG dose group. Based on the mean body weights of the animals on the corresponding days it can be calculated that from the administered dose of EG about 1 % and 0.4 % were excreted by males and by females, respectively, as oxalic acid during the urine sampling periods.
Microscopic exainination of urine samples for crystals on week 5 yielded the following results (similar findings were obtained in week 2): Triple phosphates and calcium oxalate crystals appeared in urine samples of animals after TEG-treatment in comparable incidences/gradings as in control groups. This was also the case with amorphous salts after TEG- or EG-treatment, respectively. However, after EG-treatment triple phosphates were nearly absent and calcium oxalate crystals were prominent in urine samples of these animals.
Organ weights: Determination of organ weights (brain, heart, lung, liver, spleen, kidneys, adrenals, testes, ovaries) of TEG-treated animals during necropsy revealed no relevant differences to control values. EG-treated animals showed slightly increased relative kidney weights (males: 14 %, females: 10 %).
Necropsy and histopathology: During necropsy pale kidneys were observed in one male at 220 mg TEG/kg and in one male and one female each at 2000 mg TEG/kg. In the latter dose group the kidneys of two males and one female showed a structured surface. The significance of this finding, which was also seen after treatment with EG, is not clear. However, as the histopathological investigations gave no indication of a treatment-related effect, these findings are regarded to be of no toxicological relevance. In eight of the twenty EG-treated animals kidneys showed subcapsular white or yellow areas.
No evidence of treatment-related effects could be established from the type and frequency of the other gross pathological findings.
Histopathological investigations of selected organs (brain, ureters, urinary bladder, testes, epididymides, heart, liver, spleen, adrenals, kidneys) established no findings, which were related to the treatment with TEG. In EG-treated animals the investigations revealed crystals in kidney tubuli, renal pelvis, and urinary bladder, as well as tubulopathy and epithelial hyperplasia within the renal pelvis.

Effect levels

Dose descriptor:

NOAEL

Effect level:

200 mg/kg bw/day (nominal)

Sex:

male/female

Basis for effect level:

other: not clearly determined, probably 200 mg/kg The study confirmed the kidney as target for toxicity.

Target system / organ toxicity

Critical effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

The study confirmed the kidney as target for ethylene glycol toxicity.